Replicate OEM Suspension - S2/RowSE/NA(part) - Not USA

[cliff]

No response for quite some time now.

Guess this is a dead thread.

[RayD]

I know Tony has been up to the neck in work ... with him being an industrious type I can imagine he'll be back onto it when time allows.

Ray

[m100hoods]

Did this list ever materialise as suspension parts ?
I have just received Tony's (saska) old brg se into workshop and oddly enough the suspension throughout is in poor condition which makes me wonder if the list was completed 1, Why did his car not get the parts or 2, the parts never actually became available.
On another note does any member know anything about Tony's SE / S2 (he passed on Nov 14) and having read the various threads he seems to have owned two elans
I now have one in the workshop awaiting restoration and any info would be appreciated seeing as Tony is no longer with us
Many thanks
Mark

[GeoffSmith]

Mark, Tony did indeed have an S2 as well:

[m100hoods]

Hi Geoff
Thanks I thought as much
The curious thing is that the brg elan se came with a S2 engine (not installed in the se) so I wonder why Tony would have removed (if indeed he did) it from his S2??
Is the S2 still in existence if so where and if not why did he or anon break it ?
The reason I ask is that I would like to trace the S2 and restore both (if S2 requires restoration)

Final point did the suspension kits ever get delivered to the list members?
Thanks
Mark

[madbilly]

Hi all,

Nothing ever came of the list as far as I know. I followed this up with Tony and Gaz two years ago. Tony was never happy with the rear suspension and I think Gaz weren't very interested in improving it, so that's as far as he got. However, I thought that the suspension DID get put on his car, otherwise how would he have been able to compare it? Or maybe I'm getting mixed up about who did what with which cars.

As well as Gaz, I made many enquiries with various firms about replicating the rear suspension, but only really found dead ends. I'll go through my notes and try and summarise what I found out, some of it is useful for the record if nothing else.

Sad news to hear about Tony, but at least it has led to me posting for the first time in almost two years. I'll try and stay in touch better from now on.

Cheers,
Will

[epipete]

....... but at least it has led to me posting for the first time in almost two years. I'll try and stay in touch better from now on.

Does this suggest that you have returned from your french sojourn?

[m100hoods]

Thanks for additional posts
I have now traced the S2 sold by a supposed friend in Lancashire via ebay M805 UKX and it would appear that the suspension was indeed gaz all round - i would of liked to have seen the said suspension parts in the flesh but unless the new owner is a lec member I guess theres no chance !
I am keen to re ignite this thread and more importantly get the products available
Any help is much appreciated as it will result in B13 LAN hitting the road again by way I guess of a tribute to Tony
Thanks again Mark

[madbilly]

Does this suggest that you have returned from your french sojourn?

Hi Pete! No I'm still here, currently having fun with CV joint boots and ball joints. Is my memory playing tricks on me or has your forum location always Cyprus? I can't remember what you said at the last BOLLECKS meet I made it to - I see there have been a few since then too.

I am keen to re ignite this thread and more importantly get the products available
Any help is much appreciated as it will result in B13 LAN hitting the road again by way I guess of a tribute to Tony

Mark, this recent work under the wheel arches has reminded me I still owe the forum a summary of what I learnt on this OEM suspension topic, I'll try and do it by the end of the month. Note there are no promises there but even my current delay of nearly three years isn't even approaching a record for this forum!

Cheers,
Will

[GeoffSmith]

Does this suggest that you have returned from your french sojourn?

Hi Pete! No I'm still here, currently having fun with CV joint boots and ball joints. Is my memory playing tricks on me or has your forum location always Cyprus? I can't remember what you said at the last BOLLECKS meet I made it to - I see there have been a few since then too.

Pete: BOLLECKS to Cyprus. Pinky: BOLLECKS to Indochina (according to Rambo). Me: BOLLECKS to Spain for another month next week. Well, you started it Will!

[madbilly]

Pete: BOLLECKS to Cyprus. Pinky: BOLLECKS to Indochina (according to Rambo). Me: BOLLECKS to Spain for another month next week. Well, you started it Will!

So everyone's working abroad now? Or are you all enjoying well-earned retirements?
Anyway, I've obviously failed to write up what I found out about suspension. The short story is the same as I posted this time last year, and by now my research is 3 years old so is probably out of date. If I were going to buy new suspension I would buy OEM, but if I really couldn't find OEM rear dampers I would probably splash out and buy the Nitron kit over anything else...that is unless those who've been running it for 3-4 years have found it unreliable, in whcih case I'd just buy a Gaz or Avon kit.
I'll still try and write up my findings when I have chance, but no promises on timescale this time!

[madbilly]

Hi all,

Finally, after 7 years, here's where I got to on my enquiries about replicating the OEM rear dampers. The TL/DR is that these were all either dead ends or were dependent on a new OEM rear damper to test, and although I did find an OEM rear damper available I didn't get it and pursue anything because I was moving to France and didn't have time nor confidence I would be able to do all this in France as really one needs to be in the UK for this project.

I'll post below correspondence with various potential suppliers:

Roger at LEDA

Me:

I gather that in the past a couple of fellow Elan M100 owners have spoken to you about replicating the OEM suspension setup. One of them (John) said that he'd previously brough your the dampers and springs for measuring and you had all the necessary info (damping rates, dimensions, springfo (damping rates, dimensions, spring rates, etc) for replicating them, is this still the case? Even if it isn't we (fellow owners) have measurements, but our dyno graph for the rear damper is for a used unit so may be a bit tired. If you'd be interested in replicating this suspension for us please let me know, along with an indication of price per unit.

Roger:

Things at Leda have moved on a little since your last contact it would seem. Matt was made redundant about 3 years ago, and EPM stopped trading Leda products and services about 2.5 years ago. We bought Leda and HBE from EPM 2 years ago and moved everything from Draycot to Newark, and have been building the business back up ever since. Currently we seem to be mainly manufacturing dampers for historic race, sports and saloon cars, and BMW Mini's, but are open to looking at everything.

If you still want Leda to look at replicating the OEM set up for the Elan M100, then we would need a damper and spring set to measure and dyno from scratch as there are no records of any previous work. We find it best to use our own dyno rather than results from another dyno as we can control and log the run conditions and therefore know that our correlation is good.

Me:

We're pretty sure we know the spring specs, it's the dampers that are mower pressing. Front dampers are still available at a sensible price for now but rears are obsolete. If I got you a pair of dampers next week how long would it take you to dyno then and produce non adjustable replicas, and any idea how much they would cost? I can give you dimensions and the dyno graphs we have.

Next email:
[snipped irrelevant part]

I see perhaps two options for build of front or rear dampers that replicate
the performance characteristics of the originals, either a twin tube steel
bodied non-adjustable oil filled damper under the Leda banner, or a mono
tube steel bodied non-adjustable gas/oil damper under the Harvey Bailey
Engineering banner as we own both companies.

Which type of damper is decided upon would be dictated by testing of an OEM
damper in our dyno, and any dyno information that can be passed on to us
from other dyno work. Both types of damper have their pros, cons and
foibles, but what it would fall to is which would produce the nearest
replication of the OEM damper.

If a twin tube design were best then we would manufacture using Leda parts,
but if a monotube were applicable then we would manufacture using Bilstein
parts and in conjunction with Bilstein UK. Harvey Bailey Engineering
produces a lot of special and one-off dampers in this way, and has done so
for over 20 years. We give Bilstein UK a lot of business so they will work
with us on certain projects where we undertake and fund the R&D work that
they are not keen to do themselves.

Both types of damper would be repairable and servicable, and the Leda damper
could likely be made with adjustable damping, and upgradeable to include
gas/oil fill and multiple bump adjusters.

As for cost, an oil filled twin tube damper excluding spring would cost in
the region of £270 each, and a monotube gas/oil damper about £220 each for a
single pair of say rear dampers. If this is all absolutely possible
(dependent upon test results), then the more pairs that are ordered, the
cheaper they would become within reason, perhaps up to 25% cheaper for 4 or
more pairs.

What we need now to proceed is OE units to test and dimension, and any
information on dyno work by others, spring information, perhaps a look at a
car, indeed anything and everything that will help. We can also dyno other
manufacturers dampers if you require, and see how close to OE they are, they
may be very close, or not at all! We tend to charge Dyno work at our
£25/hour labour rate, but as mentioned at the top of this email, we could
manage a certain amount of dyno work under our R&D budget.

As an asside to this, we also happen to know one of the designers/engineers
that worked on the M100 back in the day, and may be able to gleen some
helpful information from that source.

Me:

Thanks for your detailed and thorough answer and taking the time to do so. You are right that we've spoken to other manufacturers one of whom developed a set but there were issues with how well they matched the OEM setup which is one reason I decided to look into other options again, however the prices you've indicated are about twice what this project was aiming for so unfortunately I don't think your suggestions are what we're after. There was another project that was developing a higher quality road and track setup which successfully completed using a twin-tube arrangement and that is in the price range you have indicated; in case anyone wants to investigate another option I shall pass on your proposal to the other members.

My current thoughts

I did the calcs and I think that the price worked out as similar to the Nitron kit and therefore I didn't think it worth having two options which are similar. Several years have past so this may be worth looking at again.

[madbilly]

David at Gaz:

Me:

I'm contacting you to follow up some development work that Tony Wright was working with you on to produce replacement dampers for the Elan M100 that could be set as close to OEM settings as possible. He tells me that you got the front dampers spot on as were your springs for the front and rear but the rear dampers still needed some work, work that unfortunately he has been unable to progress due to his business commitments.

I want to replace my suspension by the end of July and was watching this development with keen interest so if possible I would like to see it through to conclusion. I can understand that you may have become frustrated with it given nothing has really happened for the last 18 months or so, but I can assure you there is a very real need for this kit, particularly the rear dampers as the OEM units are no longer available.

Is further development of the rear dampers something you would be prepared to undertake to produce the whole kit? I don't know what you would need to do to the design to match the OEM setup but I assume it is the valving. If you are reluctant to match the OEM setup I'd be interested to know why, whatever the reason.

I know you also have an existing design of front and rear dampers for the M100, if possible I'd like to see the dyno graphs and dimensions for those units please so I can understand the effect of mixing the sets or just using your existing kit.

Whatever your response I still want to change my suspension so please can you tell me your prices for your dampers (both your normal version and the OEM matching version you were developing for Tony), what material/coating options etc there are for these, and the cost of springs to match each setup (so whatever you recommend for use with your normal setup and the ones to match the OEM matching dampers).

David:

Following the development with Tony we are now supplying revised valving on the units and to date we have had no adverse comments.
Probably a good idea to give me a ring.

Me:

Is your new setup the same as what Tony has or is it a development of your normal setup? I presume the prices are the same as what's online for your normal setup? What about springs?

[Phone call took place]
Me:

Thank you for the explanation of where the work with Tony Wright got to. Would you be able to send me your dyno graph for your latest version of the OEM-matching dampers please so that I can replace the out of date ones? You mentioned on the phone the spring rates you were using rates from Eibach. I looked up this info on our owners' wiki and I these rates (Front 290 lb/inch Rear 150 lb/inch) were calculated by another owner from data supplied by Eibach, but weren't actually spring measurements from Eibach. Another firm measured the springs for Tony's project and provided this information:

FRONT B100C0086F Yellow/Yellow/Green
Diameter of Wire d (inches) 0.531”
Inside Coil Diameter(inches) 3.298”
Outside Coil Diameter(Inches) 4.360”
Number of Coils: Total 8.5
Free Length (inches): 10.690”
Actual Load Rate Measured on Test (Pounds per inch): 300 Lbs / IN
Loads at Testing:
10.000” = 186 Lbs
9.000” = 485 Lbs
8.000” = 785 Lbs
7.000” = 1087 Lbs
6.000” = 1390 Lbs
Remarks
BOTH ENDS CLOSED & GROUND FLAT & SQUARE
TIPS JUST TOUCHING APPROX THICHNESS 50%
EPC BLACK WITH CC = 2 X YELLOW 1 X GREEN STRIPES

REAR B100D0071F Green/Yellow/White
Diameter of Wire d (inches) 0.406”
Inside Coil Diameter (inches) 3.338”
Outside Coil Diameter(Inches) 4.150”
Number of Coils Total 6.6
Free Length (inches) 9.490”
Load Rate (Pounds per inch) Actual Load Rate Measured on Test (Pounds per inch) 144 Lbs / IN
Loads at Testing
9.000” = 65 Lbs
8.000” = 210 Lbs
7.000” = 354 Lbs
6.000” = 495 Lbs
5.000” = 642 Lbs
Remarks

BOTH ENDS CLOSED & GROUND FLAT & SQUARE
TIPS JUST TOUCHING APPROX THICHNESS 40%
EPC BLACK WITH CC = 1x GREEN 1x YELLOW 1x WHITE
STRIPES

Me:

I've had another look at the latest rear damper dyno graph you sent me and I'm a bit confused, it looks like you've designed it so that it can never be setup stiffer than oem, only the same or softer, is this right? Also the amplitude of the dyno is different on this graph from the others, 8.64"/s on softest and 6.65"/s on hardest, why was this done and how would this affect how the damper appears on the graph?

David:

They are only ever tested at one speed 12" a second as this is what we have both dynos set at & we never alter them. The damping can be altered to stiffer than the oe one & our current lead times are 3-4 weeks once the order is placed.

A few other things I found in my notebook:
Dampers are normally zinc coated, £8/damper extra for Nickel which apparently has better corrosion resistance
Spring seats are anodized aluminium.

My current thoughts:
I was never fully satisfied with where this research came to, mainly because there seemed to be a reluctance from Gaz to do any further work. Anyway, these are all still available as an option and I think that Gaz will supply the Elan set to two specs - their specs and Tony's specs, but I never got a clear answer on this. I don't think there's any point in trying to work with Gaz to improve the set-up any further, not because they're not a good supplier, just because their set is already developed and available for purchase as an option and more options is good.

[madbilly]

Nigel at AVO

Me:

I'm looking to replace the suspension on my 90s Lotus Elan and would like to have it original but the rear dampers are no longer available. Please can you tell me what setting on your dampers is closest to the OEM setup, and what the dimensions, spring rates etc are, as well as some dyno outputs charts for the proposed setting if possible? For info, here's the OEM setup, if you can give me measurements to compare against I'd appreciate it.

[Note I posted hyperlinks to Saska's website here but they don't work anymore, but thankfully someone (probably Tony) had the good sense to archive them: https://web.archive.org/web/20161202074 ... /lec/susp/]
Nigel:

Our units are adjustable in damping rate, so the spec can not be 100% compared to o/e dampers as in lengths and rates, our length are shorter than o/e due to the extra space needed for the adjustment control and the fact they are designed for cars which can be lowered from original spec, we do not supply springs for this application, the dampers we supply are made to take o/e size springs or can be changed to accept 2.25" i/d race type springs

Damping rates [snip as irrelevant] unfortunately we do not hand out this type of data, on these applications our min setting is lower than o/e and our max setting is higher that o/e, howeverthis is not that important, it is the fact that the ration between bump and rebound is correct for the application, as the units are not independently adjustable for bump and rebound, we feel that we have the ratio correct and have never recieved any complaints from already supplied customers are specialist dealers, however again we do not give out this information due to the cost of development etc asother who will copy.

our units are £110 each + vat fronts in stock, rears 2-3 weeks

Me:

I'm sure your kit is good quality and will be totally satisfactory to me if I set it up right and get suitable springs. Please can you give me a few more details about your dampers for the M100, for instance what they're made from, the range of adjustment (damping and ride height), location of adjustment knob, etc.

Nigel:

The units are made from steel
The body is threaded so allow for a max drop from std of 30mm
The damping rate,, its all about the ratio, you can not give a % increase from min to max, damping rates dont work like that

Me:

Okay, I understand that the bump/rebound ratio is fixed and that you won't tell me your max and min settings, but can you tell me the ratio? Can you also tell me the piston travel on the front and rear dampers and how far the bump stop is set from the top, or if it's adjustable? A picture would help. A dyno graph for each damper at its hardest and softest setting would be ideal.

Will you make springs to given specs or do you just supply the ones in your catalogue? What is the warranty on your parts?

Nigel:

Forgive me for asking, but... you are asking alot of technical questions with regards to a basic replacment damper for a road car, what are you using your car for and what problems have you experienced with other makes, i think you may be looking a bit too deeply into what is just a basic replacment unit for a road car application, however if you are racing the car and trying to get more out of the units, then i am sure we can help, but the damping rate for a road application to a race car would not be the same at all, as ride quality etc is not taken into account as we do on our road applications.

Me:

Yes, I'm asking a lot of technical questions because I'm an engineer, it's in my nature to check the detail and I want to make sure I get the right thing.

I know AVO make good kit and I'm sure the kit you've put together for the Elan is a great for the purposes of improving handling characteristics to extract maximum speed from the car - plenty of other owners have said they like the AVO kit. My (and the project's) objective is not to find the best suspension set up to do this, the objective is to be able to source replacement dampers that match or get as near as possible to the OEM setup so that we can maintain the combination of ride and handling that it came with from the factory. The OEM dampers are no longer available and the front ones will eventually be sold out so we need to find an alternative. Ideally the alternative would be an off the shelf setup (like AVO's) that required little or no special adjustment, and as a bonus it could provide the option of lowering/hardening the ride for when owners' want to do that. If we knew what "click" setting to set the AVO dampers to then it would be easy. That's all I'm trying to find out.

To answer your questions - I use my car for driving on the road only, I've never driven it on track but that doesn't mean I won't want to in the future. I haven't tried other makes, I've just got worn OEM dampers for which there is no direct replacement.

Nigel:

We are at present out of stock of these units, however i have a batch coming through in the next few days
i will get a graph done and report back to you the damping rates we have.

[Snipped as irrelevant]

Later, after I resent the graphs:

the graphs dont really show anything as we dont know what the stroke of the test rig is set too or the speed of the damper

however, to compare units like for like you must make sure the scales are the same eg our units are tested over 2" stroke and in lbs force and at 1 - 10 inches per second

so at 10" per second i can tell you are dampers are

front bump min 80lbs max 200lbs rebound min 150lbs max 500lbs

rears bump min 80lbs max 200lbs rebound min 50lbs max 400lbs


however this will not be true at say 3" per second etc you build into you damper what you think is needed for ie ride quality or out right performace, the lotus valving is based more on ride quality as the damping rate does not really increase that much until you get around the 6/7/8 inch per second area

so your gaz graphs are showing a damper at one particular point only, which we do not know what the point is to compare to ours

i hope this is a little more of help, but dont look too deeply into a fast road damper valving, in short ours are valved with ride quality in mind, other may not be.

My current thoughts
If we can get a new OEM rear damper and spring, and a front damper and spring, and send to AVO they will probably still compare against their current offering and help us understand how to set their kit up to match as closely as possible the OEM setup - this will be similar to what Gaz did, in the end.

[madbilly]

Monroe
I called Monroe because there was a suggestion in earlier LEC threads that they may have made the OEM dampers. I called them and a helpful lady said she would ask and a colleague overheard her and she just said "he's shaking his head, bye!" and put the phone down! So, I think we can rule them out

[madbilly]

Finally, here's some feedback from Tony on what he developed with Gaz:

The front Gaz dampers are very good. Dimensional and damping control are
perfect. They also supplied springs which are perfect both front & rear.

The problem is the rear dampers where the valving is wrong. I sent them
back once but they are still no nearer. The dynos show this -- I posted
the OEM and Gaz dynos on LEC so you can look at them -- note that the
left and right sides of the Gaz rears are nearly vertical instead of
curving in smoothly like the OEM.

If you set them firm enough that the rear balances well with the fronts
in a corner then the rear 'jiggles' over bumps. If you set them soft
enough to stop them jiggling over bumps then the rear feels loose in a
corner.

So what should you do ? The Protechs are not dimensionally correct and
nobody knows what settings are closest to OEM. AVO do replacements but
again no one knows what settings are closest to OEM. The Nitrons are
expensive and again no one really knows what settings to use. They are
also using much harder spring rates.

Observations / Suggestions:
1. The biggest difference came from putting in new springs -- my ride
height was well down both ends. None of the original dampers were
leaking and hand compressing/extending them felt very similar to the
brand new dampers -- not scientific I know.
2. Order front & rear springs from Gaz (or anywhere -- the specs are on
the LEC thread) along with a set of my Gaz OEM front dampers (David
Lyons knows these).
3. That then leaves what to do with the rear dampers. You might be able
stay with the OEMs you have if they are in reasonable condition. The
other option is to get a set of rear AVO dampers and ask them to supply
a dyno of the dampers with them. You (or I) can then calculate from the
dyno what setting is closest to OEM.
4. If you haven't got dyno data then you can do a rough & ready test
with a vice a couple of heavy weights & a stop watch. Put the damper in
the vice upside down and fully compressed. Attach say a 50lb weight and
then time how long it takes to go from fully compressed to fully
extended.
Then repeat with a 100lb weight and time. Then put the damper upright
fully extended and time how long to achieve full compression with both
weights. If you do this with a used (but not leaking) set of OEMs and
then set the AVO rears to where you obtain the same times as the OEM
then you'll be very close. I would then set the AVOs a click or 2 harder
assuming the OEMs were worn and the oil had thinned. Then drive it and
see what it feels like.

I'm assuming in all this that you want something that retains OEM ride
height and characteristics.

Me:

I've asked [Gaz] for the latest dyno graph which hopefully he'll send to me but he said that when MaxF is set to 240 then the MinF will be 90ish (I can't remember exactly), so not too far away - from my calcs this is much closer than would have been possible with the damper for which the dyno graph above is for. He seems to think he supplied you with a pair of dampers to this new spec, so if you're not happy with this then perhaps the fact the OEM damper that was dynoed was used rather than brand new has given us misleading info.

Spring rates, he said he was supplying the rates that Eibach supplied (which I think are here http://wikilec.9600.org/index.php/Springs) - is this what you were expecting or should he be using the Turton's rates?

Tony:

I don't think so -- the OEM rears we sent to Gaz were virtually brand
new and if you compare the OEM rear dyno with the Gaz rear dyno you can
see that the sides of the Gaz graph are vertical lines rather than
tapering gradually in like the OEM -- particularly noticeable at lower
left and lower right quadrants. Compare:

http://kact.co.uk/lec/susp/oem_rear_C10 ... dyno_t.jpg
http://kact.co.uk/lec/susp/gaz_rear_dyno.jpg

The shapes are wrong -- too squared off.

I wrote the Wikilec page on springs and the parameters there are as
measured by Turtons -- I sent brand new front & rear Lotus S2 springs to
them. The springs David Lyons did for me to that spec. for the project
are perfect.

To my knowledge Eibach did their springs based on an SE (290 frt, 150
rear) whereas I did them based on an S2 (300 frt, 144 rr -- probably
actually 145 as springs usually go in 5lb steps) since Lotus recommended
using the S2 springs & dampers for all non-USA SE.

Me:

I can see the dyno graph for the gaz rear damper is squared off compared with the OEM one, yet so is the dyno graph for the front gaz damper so is there not more to it?

Tony:

The Gaz fronts are not as squared off as the rears -- I agree they
aren't quite as rounded as the OEM but the lower right quadrant is
nearly perfect.

Additionally when you calculate the closest click on the Gaz front
damper to OEM for MaxF and then do it for MinF then they are the 1
click apart on the fronts but 7 clicks apart on the rears. So the Gaz
fronts can be set very close to the MaxF and MinF of the OEMs whereas
you can't on the rears.

Later:

Apologies but it occurred to me after posting that you might not be very
used to reading dynos. On the Gaz dynos there are 2 graphs -- inner and
outer.

The inner corresponds to the damper set to 0 clicks (softest), the outer
is the damper set to max clicks (21). If you run the MaxF & MinF
calculation to find the closest click setting on a Gaz front to OEM then
you'll find it is about 6 clicks down from Max. This puts the damper at
71% towards maximum firmness.

Now go back to the Gaz dyno and imagine what the graph looks like with a
line that is 71% towards the outer graph from inner graph.

So about 30% of the straight vertical line at the sides is removed both
above and below the X axis. You should then be able to see that it is
very close to the OEM graph in 3 quadrants and not bad in the lower
left.

Me:

I've attached the latest dyno graph from Gaz, please tell me what you see.

IMG_0001.jpg

Tony:

Gaz dyno:
Softest Setting MaxF = 77 MinF = -161
Hardest Setting MaxF = 98 MinF = -236

OEM MaxF = 73 MinF = -238

http://kact.co.uk/lec/susp/oem_rear_C10 ... dyno_t.jpg

So the MaxF of the Gaz softest setting is close to OEM and the MinF of
the Gaz hardest setting is close to OEM but there is no setting on the
Gaz damper that gets both MaxF & MinF close to OEM

Is that what you see?

Me:

Yep, it looks worse than the previous one, which makes me think that there mut be more to the performance than what's shown on the graph - is one graph sufficient, do they need to be done at different rates? One oddity I've noticed is that the stroke/amplitude (?) of the dyno is shorter on this latest graph than the others. Also this latest one can't be made stiffer than OEM, only softer, which is odd.

Tony:

I've looked at the latest Gaz dyno again and I think I got it wrong. It
looks as if the 2 dyno curves were done at 8 clicks and 11 clicks (not
at min & max) as I first thought. See upper left: Piston Comp & Reb

This puts a different light on the damper entirely. If you set the
damper at say 9 clicks then my calculation goes:

MaxF = 98 - 77 = 21 / 3 clicks equals 7 per click
Therefore at 9 clicks 77 + 7 = 84
OEM is 73 so: 84 - 73 = 11 / 73 X 100 = +15%

MinF = 236 - 161 = 75 / 3 clicks = 25 per click
At 9 clicks 161 + 25 = 186
OEM is 238 so: 186 - 238 = -52 / 238 X 100 = -22%

At 10 clicks it goes:
MaxF 77 + 2(7) = 91
OEM is 73 so: 91 - 73 = 18 / 73 X 100 = +24.65%

MinF 161 + 2(25) = 211
OEM is 238 so: 211 - 238 = -27 / 238 = -11.3%

Not great as ideally you'd want both values well under 10% variation
from OEM at some click setting but not as bad as I first thought. For
reference the Gaz front David did for my effort was within 4% of both

My current thoughts:
Well re-reading this conversation shines a different light on what I posted from the conversation with Gaz above as it seems like Gaz may well have made more changes to the setup based on feedback from Tony. The only way to know is to buy them and see what we think. Still, I think it's clear that these are not a "replica" of the OEM damper.

Cheers

[madbilly]

Hi all,

I spoke to Miles at Fibreglass Services following a tip from Chris at DeRoure. Miles says it was Armstrong that made the original units, which was bought by Monroe and now there's definitively no source for new OEM rear dampers for the M100, sadly.

I still don't understand why Monroe would have been so deliberately evasive when I called them, perhaps it was because as the OEM they could only make the Lotus-spec for Lotus themselves and not for just anyone ringing them up.

I might try and contact Lotus directly and ask if they'll cooperate to help us - if they don't want to remanufacture anything themselves then they can at least let us do it to their specs.

Cheers

[Brit-Car-Nut]

Lotus will not provide any specs. Not because they are being difficult, but because the company has changed owners multiple times since 1989 and every time they got a new owner, the first thing they were told to do is "streamline" the business and getting rid of parts for cars long out of production was a great way to reduce their overhead. Thus the AFTER-Sales program that we were watching.

Unfortunately, I have been told by both Lotus USA and Lotus UK that almost ALL of the design details for any of the parts for the M100 have been lost or destroyed. I made a really hard push for details about who made the petrol tanks and asked for the engineering details and I was told all of that info is long gone and very few of the people who designed the car are available to pick their memories.

I have an extremely good relationship with Lotus UK and my "supplying dealer" (I can't order directly from Lotus) has always gone to great lengths to help me source and buy obsolete parts including clear-outs from other dealers that didn't want the carry that inventory anymore.

Monroe is a small piece of a huge manufacturing conglomerate and absorbing Armstrong was done so they could get a "foot in the door" of the European sedan and truck suspension supply business. They would have little interest in making up a new run of probably 1,000 shocks for the few remaining M100s world wide and a small production run would price the shocks at 4 or 4 times the price if they were making 100,000 in one run.

I really think you are flogging a dead horse. Better to contact DOUGLAS VALLEY BREAKERS or Apollo996 or margaret_65 on eBay since they are breaking M100s on a regular basis. I don't like it that anyone is breaking M100s, but there are many that are no longer roadworthy due to accidents, abuse or abandonment so they are filling the void with "almost" affordable used spares.

On a SERIOUS SIDE NOTE, I have just realized that Lotus has placed the turbo head gasket on the discontinued / NLS list. That may be a very important issue since that is a part that is not available from any other source. I tried Isuzu and they show it as being discontinued as well, so be kind to your engine. Parts are getting very difficult to source.

[madbilly]

Hello BCN,

Thanks again for your insights. I already emailed Lotus so we'll see what they say but I have no doubt that you are right.

I'm not sure about flogging a dead horse though, after all this thread is about finding a match for the OEM suspension, not only replicating it. I'm far from an expert (not even a novice really!) on suspension but it's something physical which can be measured and quantified and therefore we should be able to find which aftermarket models match the OEM setup closest and even be able to get a near-enough replica made, if we want to.

Cheers

[Brit-Car-Nut]

I applaud your tenacity but wonder if you realize that getting parts made is never a 5 or 10 piece process.

When I was looking into getting a few unobtanium parts for my car and 10 extras for inventory, I was told that the cost for an order for 10 pieces would be the same price as an order for 500 pieces (their minimum) since the cost of setting up the tooling and interrupting the current manufacturing line would have a financial impact. And I was only looking for replacement cushion springs for the window regulators.

The only way you will be sure that other shocks will fit the specs is to buy each of them and have them measured and tested. Engineering companies will gladly do that but they are not cheap.

The day is fast approaching when we will not be able to buy any NEW parts for the M100, so have you looked into the fact that there are 3 different specifications (and part numbers) for the different versions of the M100 and NONE of them are now available? SJs has their substitute available for £93.58 each.

I am not harassing you, rather trying to let you see the hill you are really facing.