Suspension overhaul

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Suspension overhaul

Postby dapinky » Sun 17.11.2013, 20:19

Warning - this is a long post, with only 1 picture (at the moment).

As some of you may already know, I have decided to do a minor(?) overhaul of my suspension - but project creep means that it is extending towards a more major project!

It all started 4 years ago, when the elusive Bob Brown offered to fabricate front lower wishbones for the forum, and i joined the list.... at that time, mine were okay, but would no doubt benefit from a change as the bushes were 18 years old.....

I had already obtained a set of the upper wishbones from the aftersales list, and the rear wishbones had been replaced with galvanised ones, along with the S2 upper links.

Anyway, that never happened (see another thread if you don't already know the full story), but i was still collecting bits and pieces as I went along - and recently had the great oportunity of watching another forum member change out his front suspension (thanks Nick!).

That now meant that I had experience of doing the back end (done it all on the red one), and now knew the pitfalls of doing the front end (more than we imagined, despite Ian telling us it was a simple task - fogetting to mention that when he did his, the prongeron, driveshafts and gearbox were already out of the car :twisted: ).

I just needed a few more supplies.

I had already collected a set of AVO shocks (bought from a forum member at Donington this year, together with newish springs) - so they went back to the factory for a re-build (it only took them 5 days from my door to being returned, and the price was good too - 25 quid each, plus VAT + postage, so for £140 I had a set of 'as new' shocks to go on the car....the price depends on what needs doing, but mine only needed re-sealing and new bushes/bump stops etc fitting). Altogether, a lot cheaper than buying new ones (£110 each plus VAT and P&P).
Okay, so I decided that they needed a coat of paint and a good clean, but the saving made it worthwhile. I cleaned them up in the parts washer (just using paraffin and a toothbrush), cleaned the threaded body with a wire brush, and cleaned the couple of rusty bits on the bottom loops, then painted the metal with chassis paint.

I chose that particular paint for a few reasons, all of which make it better than Hammerite or similar -
1) I'd got some on the shelf :D
2) It contains a mild acid so it 'etches' into the steel to stick better
3) It's got a built-in rust protector
4) It's quite 'thin' so it flows into the small gaps between the threads on the body without gumming them up so the spring platforms will still move quite easily
5) It's hard-wearing.
6) touch-dry in 20 minutes, but fully cured in 24 hours, leaving a lovely smooth satin black finish.

The springs, although only a couple of years and a few thousand miles old were in 'mixed' condition - mainly the black coating was good (when they were cleaned up), and most importantly the right colour coding spodges were still visible, but the rear springs were showing a few rust patches, and the front ones were very tight in the spring mount platforms (had to be forced out with a BIG hammer and chisel) - all four had peeling paint on the bottom 2 coils.

I adjusted the size of the bottom 1 1/2 coils with an angle grinder to take 1/2 mm off the outer radius so they would fit into the spring mounts better. I know that it will make an ever so slight difference in the spring rate, but it doesn't matter a lot for the amount you need to remove!

A wire brush in the angle grinder got them down to bare metal, and then they were dipped in phosphoric acid (my new 'Best Friend') to convert any remaining rust to Iron Phosphate, protect the steel from future rusting and etch the surface for painting.

For anyone not familiar with this stuff, it is the basic ingredient of most 'rust converters' you can buy at Halfords (Jenolite etc), but is freely availlable as 'food grade' in larger quantities for a cheep price. It comes in various 'strengths' between 20% and 85%, and is simply diluted with water. It is the 'nasty' bit in Coca-cola which rots your teeth but cleans stains.
As such, in lower concentrations it is harmless to people, but I wouldn't wash my face with it! - it is non-toxic in all strengths, but common sence should prevail in its use.
As with any acid, always add acid to water, not water to acid (exothermic reaction, and risk of splashing) - it is considered to be a 'saturated solution' at 22%, so anything above that is pointless - hence you need to dilute it. It will still work at extremely low concentrations, but will take longer - at 10% i left the springs submerged for half an hour and it was job done!

As a 'dapinky top-tip' - dilute it with fizzy water, not tap water - the Carbon Dioxide in the 'fizzy' will help the chemical process - it both agitates the mixture and assists by releasing CO2, which in turn forms Carbonic Acid which speeds it all along a bit.

The rust turns black, the steel turns a grey/brown, and it needs rinsing off in clean water (just a dunk in a bucket!) and you're ready to go - if you don't dry it off straight away there is a risk of it rusting up again if you use a too weak solution.

I'm sure that Shaun could give you all the information in a more scientific explanation on the chemical reactions, but basically it turns nasty rust (Iron Oxide) into harmless coating (Iron Phosphate).

One other consideration, but probably irrellevant - if you leave your metal in for too long then the metal can absorb Hydrogen and become more brittle.

For painting, I didn't want to use 'normal' paint as it tends to flake off with age due to the nature of springs being springy (flexing), and couldn't be bothered to take them anywhere for powder coating (although that is probably the best method). I decided on using Plastidip as it remains fully flexible, (being basically a liquid rubber) and comes in a variety of forms (aerosol and tins, 'hard' and 'standard' finish, lots of colours etc) - I went for a tin of 'hard' satin black, and then made a bit of a mistake with applying it.....

.... I had already fabricated a 'dunk tank' of the right size to acid-dip the springs - just a length of plastic gutter pipe which needed to be opened out a bit - using a hot-air gun to soften the plastic - a bit of plastic from the wall of an old 5L paraffin container, and a hot glue gun to stick it all together - simples!

I decided to dip the springs in the paint to get an even coating - but it didn't work as well as I had hoped - the paint is far too thick, and I didn't have any thinners (celulose doesn't work with this stuff!) - the result was that the springs sat on the workbench had huge globby drips :( . I cleaned them up with a paintbrush, but it all took a lot longer than if i'd just used the brush to paint them to start with. And then it took 2 days to dry :( :(
2 or 3 thinner coats with a brush would have been far quicker and less messy - the beauty of the 'paint' is that as you apply a second (or more) coat, the solvent melts it into the underlying coat and you end up with a single (increasingly thicker) layer of flexible material, which ends up nice and smooth, with no brush marks anyway.
Looking back, the best method would have been to aerosol spray them, but I leant the hard way, so you can benefit from my experience.

The rubber gaiters from the shocks just got dunked in hot soapy water to get the worst of the crud off them, then into the dishwasher with the plates from tea time - good as new.

Painted the spring mounts with a couple of coats of the chassis paint, and all assembled on the bench (please note, that AVO shocks use an imperial thread on the top pin, so don't try to force a new metric (M8) nylock on it - it's a 'standard' 7/16 UNF thread, easily available).

Other amassed parts included a pair of top ball joints (on the aftersales list for £18 each, but availlable from SWL at the same price, except you have to pay VAT and delivery on top!).

I spent a fun afternoon going through the parts list to make up a 'shopping list' of every nut, bolt and washer in the entire front and rear suspension, then researched the best place to get new ones in suitable materials. I wanted to replace everything which mattered, just for the sake of 'whilst I'm here, I may as well do it'. I would have used new nylocks anyway as a matter of course, but having found out on Nicks' car that some nuts/bolts need to be chopped to remove them, wanted to have an easier time of the job by using all new ones.

I decided on Stainless Steel where possible (just in case I still have the car in another 20 years time when it all needs to come apart again), but am aware of the material limitations of some grades.

Mostly, I obtained bolts in A4-80 grade stainless (eqivalent strength to 8.8 High Tensile BZP), nuts in the same grade, washers in A4-70 ('cos they're a few pence cheaper!), and the 'fine thread' nylocks for the ball joints in A2-70 ('cos they don't make fine thread nylocks in A4-80).

A2 is good enough for the corrosion resistance anywhere on the car (A4 is for a 'caustic marine' environment), but they only do them in a -70 strength and I wanted -80 to be equivalent to the OE bolts.

Some of the bolts on the car (notably those through the top ball joint, and those which hold the shock absorber to the cast iron brackets) are listed as being a higher tensile strength of 12.9, so i have had to get non-stainless versions for those applications.

Then I had to get new bushes for everywhere - simples (or so I thought!).....

....I had already decided that I am quite happy to use Poly bushes for the wishbones, but wanted to retain rubber (metalastic) bushes for the rafts.

Getting the poly was easy enough - Steve at SJs lists them all as an 'alternative' on their website (albeit that some are £3 cheaper at SWL).

Getting the rubber ones 'should' have been easy, as they are listed on the same website......

....However, some are also availlable from aftersales for half the price of SJs (not always worth the hassle of a seperate order, but if you need anything else, it is!).....

...anyway, he would have needed to order-in all of them from Lotus as he didn't keep stock, and anyway, one of them has now gone obsolete :(

I just ordered the stuff he had in (poly bushes), and phoned up the ever-helpful Bob Chapman at Stratton Motor Company (01508 530491) - THIS IS AN UNASHAMED PLUG FOR A VERY HELPFUL CONTACT - who told me that the front lower raft bushes (4-off), part number C100C6006F, had gone obsolete on 13th October this year, with no knowledge of them being re-produced at any time in the future, but he could get the others (lower raft, rear (2-off) D100C6001F, and top raft (4-off) D100C6018F) from Lotus in a couple of days. He would honour the aftersales price (£3.33) on the top bushes, but had to charge list price (£13.02) on the other 2 - Top Man!

Still without the missing bushes, i was making progress!

Steve Roberts (SJs) had offered to get some made in Poly - but I didn't really want to go that route at this stage, whilst looking for an alternative.

I phoned round the 'usual suspects' (Paul Matty, SWL, Christopher Neil) to see if they may have a set on the shelf - all negative.

I decided that as it is a part which may have a future need, we may be in a 'source or fabricate a replacement' situation. As such, I contacted Lotus and asked if they were likely to be getting any more made in the foreseeable future – they aren’t. I established that the OE bush is made in France by a company which is part of the Michelin group, but that the part-number on the rubber bit of the bush means nothing to them (or at least, that is how I interpreted the reply I got in a short email). I couldn’t find any reference to it on t’internet…..

So I thought I needed to find an alternative – I was still waiting for the information I needed for the material specifications and sizes (I had already found a company that would make them, but the price was dependant on numbers ordered – for 4 of them it would be hugely expensive per unit, but for 100 they were quite cheap).

I found a Peugeot/Citroen part (front suspension arm bush) which looked promising as it seemed to be the right size and certainly had the correct bore diameter, but the rubber composition was the unknown factor….

Then the stuff arrived from Strattons (I was sort of hoping that the rear bush could be used somehow on the front – but it is a much larger diameter, and there isn’t enough material in the raft to open out the hole to fit it.

In the meanwhile, I stripped down the spare front units I had (which had come off Nicks car) – the rusty arms went off to Geoff (to try and see if they are possible to fabricate elsewhere at a reasonable price), and the top wishbones went into the bin.

It was a job and a half to get the rusty nuts off the top wishbone pivot stud – but a combination of big bars, and holding the raft down by standing on it meant it only took about an hour to do.
The pivots were in good condition though, so cleaning up the threads and dipping them in the acid got them good as new (they’re cheap enough for new ones anyway, but as these are good, there’s no need)
The bolts holding the lower arms were rusted solid, and even an impact driver would only rotate them a bit before the compressor lost interest and had to re-charge the tank….

…out with the angle grinder, chop off the rusty nuts, job done!

Then the ‘small’ (8mm) bolts which hold the metal plates over the end of the wishbone bushes to make the pivot point…..

…there are 4 on each raft, and as usual, 7 came out with the impact driver and a spanner to hold the nut, one didn’t want to play at all.

It was so seized that the head of the bolt sheared off flush with the alloy raft. Trying to then tighten the nut the other side to ‘draw’ the bot shaft through just snapped that end off 1mm inside the raft.

I was now left with little option than to either throw the whole thing away and hope that the one on my car would come off easier, or get it out somehow…..

…the best method would have been to take it to a proper engineering place and get it machined out, but who wants to do it the easy way – where’s the sense of achievement in that?

So I did it the hard (time consuming) way – with a cordless drill and a few sharp bits. Starting with a 2mm bit I made a pilot hole, opening that out to 3mm, then 4, then 5 (still central!) – then when the hole was about 1 1/2” deep (the bolt shaft is about 4” long, high tensile and stuck to aluminium) the bit snapped and wouldn’t come out – I now had an even harder material to try and remove, with no access to it…..

….time to change tack and do something different whilst I gave it a coat of thinking about….

I got the old rubber bushes out of the other raft.

I have no access to a hydraulic press at home, so had to revert to the old-fashioned (but effective) way – you can’t twat it with a big hammer as the aluminium could well break, like you can with a bush into steel arms.

As such, a gas blowlamp to burn the rubber works a treat. Simply play the flame on the bush/central sleeve until it gets hot enough to burst into flames – loads of thick (toxic) smoke and bits of black yucky (equally toxic) dust falls onto the floor….

…obviously, wear rubber gloves and a breathing mask (or better still, do it in the garden) – burnt rubber of this vintage (anything over 10 years old) emits nasty stuff which if it gets on your skin can creep into it and melt your bones from the inside – it can’t be washed off and is irreversible!

After a couple of minutes the central sleeve will pull out of the burning bush with a pair of pliers, allowing the rest of the rubber to burn away (takes about 15 minutes a bush).

Once it has cooled down, hoover up the bits, wipe away as much crap as you can, and you’re left with (hopefully) just the metal outer sleeve with a sooty residue, inside the aluminium casting.

Use a hacksaw to carefully cut outwards through the steel outer sleeve without going into the aluminium (if you can). A single cut is enough, and then using a suitable punch (I used a standard panel-pin punch) and a small hammer, you can tap round the edge of the bush and it will come out (obviously it will only go one way because of the flange on it!).

Having done that, I realised that the other raft may have got a seized bolt because there is very little material between where it runs, and the bush – maybe pressure of the bush was stopping it from coming out?
As such I burnt the bushes out of that one as well.

I saw that the nice centralised hole I had drilled wasn’t actually that central, and it had veered off to one side causing the drill bit to break through the alloy and into the bush, and hence it was ‘bending’ and snapped. At least I could drift the broken bit out now that the end was sticking out into the hole where the bush had been!!!

I also had a nice view of where I was needing to drill for the remainder of the job – and only a small bit of repair work to have to do afterwards….

So, a few more hours with the drill, and I had gone through all bar the last 20mm or so to a diameter of 6mm.
A bit of time with a punch and hammer got bits of steel out, leaving most of the aluminium in place – then a final smack with the hammer got the 10mm ‘plug’ out of the other side – job (nearly) done.

A small amount of repair work to the aluminium raft (luckily I had some aluminium repair rods, so I could braze up the gaps, having fitted an 8mm bolt where it should be to give it some shape). When cooled, run an 8mm drill down the channel, then tidy up the excess ‘splatter’ with a dremmel – good as new.

Back to the quandy about the unobtainable bushes…

The ones which I needed looked very much like the (cheap!) top raft bushes – except for the length….

A check with the callipers showed that the diameter is the same, the bore is the same (M12 bolt), the amount protruding at the flange end is the same – but the whole thing is too long (by about 11mm).

The number pressed into the rubber is similar to the one I wanted, and simple mathematics (subtraction!) showed that the number appears to be made up from the diameter, length and bore of the bush. The rubber has the same compliance as the other one (same shore rating), so it just needs the available ones to be cut down to the right size for the unavailable ones!

This is a simple, but time-consuming process – only because if you get too much heat into the bush you run the risk of the glue which bonds the rubber to the metal melting and becoming unstuck – not good.

A picture is worth a thousand words, so I took one which explains the process I used….

raft bushes.jpg


From left to right:-

1) M12 bolt cut to exact length to fit inner sleeve of old bush
2) Inner sleeve of old bush
3) Outer sleeve of old bush
4) ‘new’ top raft bush – scribed to correct length, and cut with a dremmel without getting it too hot (takes a few goes, with a good rest in between)
5) ‘scrap’ bit of outer sleeve removed with a Stanley knife through the rubber
6) Excess rubber removed with same Stanley knife
7) Finished item

The final cut with an angle grinder through the inner sleeve was achieved by putting the bolt (1) through the sleeve and cutting it down to the same height. Again it takes a fair while to keep it from overheating – I found that once the short bolt got too hot to easily touch, put the bush to one side and do a bit on the next one. I also put another M12 bolt into the sleeve to act as a bit of a heat sink to cool the work down as much as possible.

Once all 4 were cut down and cooled, it is a simple case of holding 2 together (as they will be when fitted) and measure the total distance from the outer ends of the inner sleeves – I measured the total length of the 2 ‘old’ inner sleeves as 47.10mm, and gently ground the protruding ends of the new bushes until they were exactly the same length (measured when cool) – not all are exactly the same, but within a mm or so, and the important bit is to ensure that each pair total 47.1mm.

You can’t really see it from the photo, but the inner sleeve protrudes about 3 1/2mm from the rubber on the inner edge of the bush.

I brushed a bit of Phosphoric Acid on the shiny cut ends to stop them rusting (unlikely due to their fitted position, but easy to do now).

So my advice to anyone who wants it is to get some of the cheap ones from aftersales whilst they are still available – at some point you will probably need to replace the raft bushes you have (they are all likely to be a bit knackered by now, and it is the correct fitting of this component which makes the FWD elan handle the way it does). Even if they do become available again in the future, they are cheap as chips to do it this way (and the last list price for the ‘proper’ ones was far higher than these ones).

Obviously, I have had to get another 4 of these bushes for when I fit the raft to the chassis – but from how Nicks looked, and the hassle to swap them (can’t really burn them out in situ!) – I might not bother to replace them – they obviously don’t wear out very much, and certainly aren’t a big seller or Lotus wouldn’t have enough left to put them on the aftersales list!

I’m bored with writing now, and if you’ve got this far you’re probably bored with reading – so I’ll do a further ‘hints & tips’ post soon, there are a few other points worth mentioning for those who intend to do anything to the front suspension – you can avoid the ‘mistakes’ I made, or benefit from the short cuts I found.

I will also provide a total ‘shopping list’ of every nut, bolt, washer needed for any aspect of the job.

Hopefully, I will also be able to show you how to avoid the worry of breaking the lower anti-roll bar balljoint/shock absorber mounting (new ones are £80 odd, with an SJ ‘alternative’ at £35, but a ‘dapinky alternative’ for a hell of a lot less) – just need to finish it all off and verify the parts used.
Dave

Just the one now, but this one's mine! - and it will be finished eventually..... - but also temporary custodian of a project until it is finished enough for Angie to drive it

go on - click this link - you know you want to!
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Re: Suspension overhaul

Postby HJ2 » Sun 17.11.2013, 22:00

Holy cow!

Are your fingers bleeding? (from typing i mean :-D )
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Re: Suspension overhaul

Postby Peter_W » Mon 18.11.2013, 21:47

Thanks for the write-up and obsolete bushing solution. I've been experiencing some handling symptoms that make me think replacement bushings are in my near future - your write-up will be a big help :smt023
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Re: Suspension overhaul

Postby nicowalker1 » Wed 20.11.2013, 17:53

My car had been suffering from a swimmy feel when cornering, as soon as we (Dave) had swapped the whole lot over ther car stiffened right up(still need to get the geometry done). I would think quite a few cars would benifit fro. Changing the raft bushes. Be warned it is a shitty job. Im glad I had Daves patience, if id have tried it the spanner would have been thrown!
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Re: Suspension overhaul

Postby epipete » Sat 06.06.2015, 15:07

dapinky wrote:I spent a fun afternoon going through the parts list to make up a 'shopping list' of every nut, bolt and washer in the entire front and rear suspension, then researched the best place to get new ones in suitable materials. I wanted to replace everything which mattered, just for the sake of 'whilst I'm here, I may as well do it'. I would have used new nylocks anyway as a matter of course, but having found out on Nicks' car that some nuts/bolts need to be chopped to remove them, wanted to have an easier time of the job by using all new ones.

I decided on Stainless Steel where possible (just in case I still have the car in another 20 years time when it all needs to come apart again), but am aware of the material limitations of some grades.

Mostly, I obtained bolts in A4-80 grade stainless (eqivalent strength to 8.8 High Tensile BZP), nuts in the same grade, washers in A4-70 ('cos they're a few pence cheaper!), and the 'fine thread' nylocks for the ball joints in A2-70 ('cos they don't make fine thread nylocks in A4-80).

A2 is good enough for the corrosion resistance anywhere on the car (A4 is for a 'caustic marine' environment), but they only do them in a -70 strength and I wanted -80 to be equivalent to the OE bolts.

Some of the bolts on the car (notably those through the top ball joint, and those which hold the shock absorber to the cast iron brackets) are listed as being a higher tensile strength of 12.9, so i have had to get non-stainless versions for those applications.


Dave,

I am due to replace a rusted NS Top Link, (as a precursor to more extensive 'refresh' of front and back suspension). I have obtained a couple of used, but sound Top Links which have been dipped in our beloved Phosporic acid :D There are a couple of pointers I'd appreciate your thoughts on

I'd like to replace as many fixing as possible with Stainless Steel but obviously some bits will not be available (eg the Cambolt thingy) or necessary (eg bushing sleeves), is there any issue in mixing SS and conventional fixings, either chemical or stress related?

How do you determine the torque necessary for SS fixings?

What is a Snubber Washer?

And more cheekily, perhaps, but you don't happen to have that list on excel do you, I'm currently mired between De roure, SJS, the after sales list, and various photos and hair is being pulled out!!!

Pete
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Re: Suspension overhaul

Postby dapinky » Sat 06.06.2015, 15:48

epipete wrote:
Dave,

(1) I am due to replace a rusted NS Top Link, (as a precursor to more extensive 'refresh' of front and back suspension). I have obtained a couple of used, but sound Top Links which have been dipped in our beloved Phosporic acid :D There are a couple of pointers I'd appreciate your thoughts on

(2) I'd like to replace as many fixing as possible with Stainless Steel but obviously some bits will not be available (eg the Cambolt thingy) or necessary (eg bushing sleeves), is there any issue in mixing SS and conventional fixings, either chemical or stress related?

(3) How do you determine the torque necessary for SS fixings?

(4) What is a Snubber Washer?

(5) And more cheekily, perhaps, but you don't happen to have that list on excel do you, I'm currently mired between De roure, SJS, the after sales list, and various photos and hair is being pulled out!!!

Pete


Pete,

as numbered above.....

1) Nowt to say on this one....

2) No problem with mixing the items, but if you use a SS bolt, you should use a SS nut as the 2 items have different material properties - whilst there is no great problem with mixing them (materially speaking), the 'stretch' of each will be different, so I don't know how that may or may not affect the torque figures (probably not a lot, if you use the figures for the bolt!) - but as the nuts are cheap enough, it made sence to me to use SS ones.

3) Basically, SS needs about 3/4 of the torque figure of Mild Steel - but if you can't be bothered to do the maths, I've added a .pdf document with all the numbers added in red.

4) Havent got a clue (where is it referenced, and I'll have a look).

5) No.....




























.... I don't like spreadsheets.......



































..... but i do have a list on Word :D .............


































...... and I've converted it to .pdf so I can add it here :D :D :D

suspension bolts.pdf
(286.58 KiB) Downloaded 462 times


Where there are multiple options of material listed, it was just that I was looking at options - for the bolts listed with an 'HT' option, I used non-stainless items in the end as I wasn't sure that SS would be good enough (the bolts through the wishbones/balljoints, shock yoke etc) - and got them in 12.9 grade.

I used Westfield Fasteners for most of mine (and ebay for extra bits and bobs of non-important strength) - for the nuts and washers, you don't need to get A4, A2 are fine - I haven't included them on the above document as I just got a big bag of M12 nylocks and washers (form 'A') - and added to it with the odd form 'G' washer, penny washer and plain nuts as appropriate. It is fairly straightforward to use the parts list to
add up how many you will need before you order them.

My prefered ebay sellers for SS (and other) fittings are these guysand these guys - great service from both, sometimes one is cheaper than the other, but generally they are both good - can't remember which one off-hand, but sometimes they list bolts with 'free' nuts and washers, one is cheapest for self-tapping screws, one for hex bolts, one for button-head bolts etc, so worth checking both if you want to save a couple of quid.

suspension settings.pdf
(351.94 KiB) Downloaded 394 times
Dave

Just the one now, but this one's mine! - and it will be finished eventually..... - but also temporary custodian of a project until it is finished enough for Angie to drive it

go on - click this link - you know you want to!
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Re: Suspension overhaul

Postby epipete » Sat 06.06.2015, 18:12

Thanks for that Dave,

Yeah, I'd appreciated the need to marry up SS Bolts with appropriate SS Nuts :D as I'm using the original Top Links it was the two bolts that allow adjustment to the length, obviously one of them can be replaced in its entirety but the other is a 'Cambolt' (ie a bolt with an off centred washer welded to it) which I will need to reuse and therefore match up with a standard Nut (stainless washers should be ok though - as I have loads).

Thanks for the diagrams and details, that saves me (and perhaps many others) a load of work.

The Snubber Washers are washers that appear to be placed next to the bushings (items 36 & 52 of your rear suspension diagram), are they sized to contain or protect the bushing under stress? What is special about them?

Seems the Bushings that you doctored from the after sales list are now all gone least ways I couldn't see them on the latest version.

Pete
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Re: Suspension overhaul

Postby dapinky » Sat 06.06.2015, 18:55

Ah, I see what you mean about the washers, now - I've got the later tubular top links, so ignored most of the references to the 'U' channel ones.

I had a pair of new cambolts in stock from a GB many years ago so didn't have to use the old rusty ones - you can still get them on ebay from southwest lotus.
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Re: Suspension overhaul

Postby epipete » Sat 06.06.2015, 20:29

Thanks, but I'd seen those bolts and they are numbered A100D0059F and fit the rear Wishbone whereas the Top Link bolt is C100D0033F. They may be the same but there is no detail of the Nut size on the 59F. Or it's length. The ones that have come out will be ok to go back in but I'd have preferred SS if for no better reason than that it feels the job is only half done otherwise.

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Re: Suspension overhaul

Postby dapinky » Sat 06.06.2015, 21:15

Oops, yes - you're right........ Once again I totally discounted the fact that I've got the tubular ones so don't have that particular adjusting bolt to worry about.

If you know the size of the top cam bolt it may fit (but if it did, Lotus would have used the same part to save a couple of sheckels).

Getting a cam bolt made isn't too hard - it's only an offset washer welded to a bolt - can't be hard to knock up a SS version......
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Re: Suspension overhaul

Postby epipete » Sun 07.06.2015, 10:44

Finally (well hopefully :oops: ) what was your rationale for dispensing with the poly bushes in favour of the rubber? Was is performance, durability or some other factor that persuaded you?

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Re: Suspension overhaul

Postby dapinky » Sun 07.06.2015, 12:01

My rationale? (that actually sounds like I thought about it - are you creditting me too highly?)

Okay, I did - but it isn't to say that I'm right!

Firstly, for the purists out there who only want to use OE stuff - fine.

Secondly, for the experimenters who only want to try something new (welcome to my world) - fine

Thirdly, i do NOT pretend to know more than the Lotus designers/engineers, but some modern materials were just not available 30 years ago - and they are changing all the time.

My own preference is based on the purpose of the bush, and whether it is the type which loads/unloads during twisting, or is there to reduce vibration.

Most suspension bushes (in rubber) are the former as they have a bonded inner and outer sleeve, whereas the Polybushes rotate around a 'loose' sleeve (although it is actually tight, but not bonded). They are designed in such a way as to replicate the OE movement, but have the advantage of being easy to make in small numbers (so perfectly suit the aftermarket of a small production-run car). They also have the advantage of being not-so-critical when you do up the bolt through them. With pre-loaded rubber bushes the bolts should ONLY be tightened up with the car on its wheels so the suspension bush gets no 'twist' in its resting state - as the Poly ones can rotate, there is no NECESSITY (but it is still best practice) to do that, and they can be tightened up with the car in the air and the wheel off - hence they are used in a lot of competition cars where service times are essentially limited.

I decided that Poly is suitable for all pivoting bushes (wishbones) but rubber *may* be better for the raft. That said, Poly would work, but not necessarily be better (and as the OE ones become extinct, will be the only reasonable alternative).

The 'trick' with Poly bushes is to fit them correctly - they should be a tight fit in the outer sleeve, but not 'bind' as you press them in. If you use a smear of silicone grease when fitting them (or fairy liquid if you don't have any at hand) they go in easier - otherwise if they catch against the metal of the sleeve they will compress slightly, and that leads to squeaky suspension movement over time, and premature wear of the material.

Many original bushes are (were?) made from rubber with a metal sleeve (Metalastic bushes) as they are cheap and easy to make in large volume, and simple to fit - in some cases (engine mounts etc) they are made to offer different levels of damping in different directions - and so need fitting the right way up (usually with holes or differing thickness of rubber in the doughnut) and so are harder to replicate in Polyurethane.

That said, Poly can be made in different shore values, and is a simple 2-pack liquid poured into a mould, so there is nowt to stop someone who knows what they're doing creating a specific bush with differing hardness in different places.

There is a lot more to it than I've explained here (before someone tells me that the information is wrong!), but in simple terms, that was my thought process.

Whatever you choose, it is probably going to offer a big improvement over worn-out old bushes anyway - but it is better to not mix the 2 sides of the car with different types in the same application.
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Re: Suspension overhaul

Postby epipete » Sun 07.06.2015, 13:19

Dave, you've clarified that very nicely, thanks.
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Re: Suspension overhaul

Postby epipete » Sun 07.06.2015, 22:34

dapinky wrote:Then I had to get new bushes for everywhere - simples (or so I thought!).....

....I had already decided that I am quite happy to use Poly bushes for the wishbones, but wanted to retain rubber (metalastic) bushes for the rafts.

I decided that as it is a part which may have a future need, we may be in a 'source or fabricate a replacement' situation. As such, I contacted Lotus and asked if they were likely to be getting any more made in the foreseeable future – they aren’t. I established that the OE bush is made in France by a company which is part of the Michelin group, but that the part-number on the rubber bit of the bush means nothing to them (or at least, that is how I interpreted the reply I got in a short email). I couldn’t find any reference to it on t’internet…..

So I thought I needed to find an alternative – . I was still waiting for the information I needed for the material specifications and sizes (I had already found a company that would make them, but the price was dependant on numbers ordered – for 4 of them it would be hugely expensive per unit, but for 100 they were quite cheap).

I found a Peugeot/Citroen part (front suspension arm bush) which looked promising as it seemed to be the right size and certainly had the correct bore diameter, but the rubber composition was the unknown factor….
.


Dave, the missive from which the above quote was extracted was written quite a while back, more of the metalastic bushes must becoming obsolete, perhaps it is time that some enquiries were made to achieve an ongoing provision. I note the comment above (highlighted), did you ever get this information and was it for each unit or is it a generic standard throughout the car? Did it come in a format that is universally understood by fabricators?

I'm currently trying to compile a list of every Bush for each corner, and whether anyone (SJs, SWL etc claim a metalastic stock holding) similarly, I intend to do the same with Poly to see what 'gaps' there are in that substance.

If it gets to arduous and there seems no shortages I may bale but I'd like to get my head around the supply (and the demand) for these items.

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Re: Suspension overhaul

Postby dapinky » Sun 07.06.2015, 22:58

Nope - never really bothered to progress anything as I got sorted, and didn't see any great demand at the time.

The real issue is to establish the exact sizes - the rubber composition is likely to be either ~70 or ~80 shore (but others sometimes get used in bespoke applications).

TBH, as Poly is cheap and easy to work with, they can be made in small quantities by anyone with a lathe and a digital calliper.

Certainly, both Steve at SJ's and Phil at SWL have had most of the bushes re-made in Poly, and I suspect that they both get them from the same supplier, but I don't know who it is.

In the past (when the stainless steel rear wishbone GB was started) I did some work with Chris Wittor at Superflex to sort out something suitable, but as with all things, it comes down to volume production to become cost effective.

Really, unless it is possible to come up with a complete 'kit' and get enough interest from members, it is far easier to let SJ's and SWL do the leg work and just buy them as and when needed... especially as both will approach their supplier to come up with anything new that becomes obsolete.

All I can say is that it isn't Chris Wittor that they get theirs from (I've known him for years and done lots with him in the past), and whoever it is will only supply via them (unless it's someone I haven't looked at - but all the major makers don't list the Elan in their catalogues) which is fair enough as there was undoubtably a development cost involved.
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Re: Suspension overhaul

Postby epipete » Sun 07.06.2015, 23:59

dapinky wrote:Really, unless it is possible to come up with a complete 'kit' and get enough interest from members, it is far easier to let SJ's and SWL do the leg work and just buy them as and when needed... especially as both will approach their supplier to come up with anything new that becomes obsolet.


Well, I think you're probably right, I suspect 'tis a dead horse I'm flogging here. But thanks for the advice/clarification.
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Re: Suspension overhaul

Postby Grant » Tue 30.06.2015, 16:33

Hey all, I am about to embark on refurbishing the front upper wishbones on my car, but before I tackle this project I have a question for you. Is it possible to remove the long stud on the upper pivot point without detaching the raft from the chassis? It looks as if there is not enough room to slide the long stud out in either direction. Has anyone done this successfully?
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Re: Suspension overhaul

Postby epipete » Tue 30.06.2015, 17:16

image.jpg
If you mean item 35 then I'd say no. I've never removed this part but would suggest that removing the two nuts (#39) either end and the bolt (#16) should either allow sufficient leverage to allow you to remove it, if this doesn't work then the two top bolts (20 & 24) on the upper ball joint should let it all come apart. In fact I'd release all of these and take it off this way nothing gets strained.
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Re: Suspension overhaul

Postby Grant » Tue 30.06.2015, 21:09

Thanks epipete.
Yes, I am talking about the stud (#35). Sounds like you are suggesting splitting the top wishbone to remove it. Maybe I could then slide the stud to the right to remove the left side wishbone, and then slide the stud to the left to remove the right side wishbone, vs trying to remove the stud completely. Is this what you are saying?

Has anyone successfully done this?
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Re: Suspension overhaul

Postby Simon_P » Tue 30.06.2015, 21:52

I have a vague recollection that the stud will come out, but you are unlikely to need to take it out.
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