Rear calipers

[gmg31]

My rear calipers are so frustrating. Despite having them reconditioned 2 years ago, The difference between ineffective and too tight is tiny. Every year I have an almighty battle to adjust it to be just good enough to pass the MOT. I've just had to take them off again and deliver 1/4 turn to the piston and as usual I have a struggle to get it back on. Is there an alternative after market caliper that I purchase please.

[epipete]

Yes. Go to PNM and buy theirs this will solve all your problems - forever!

[alan e]

]Yes. Go to PNM and buy theirs this will solve all your problems - forever

[Simon_P]

Make sure the pins slide freely.

Don't use anything other than silicone brake pin grease - Other greases swell the rubber and jam the pin

Ensure that the seat for the rubber is absolutely free from rust or it forces the rubber onto the pin and jams it.

[rdodger]

]Yes. Go to PNM and buy theirs this will solve all your problems - forever

[lotusflasherman]

Yes. Go to PNM and buy theirs this will solve all your problems - forever!

Really? Read this first...http://forum.lotuselancentral.com/viewtopic.php?f=41&t=22242

[John_W]

The PNM calipers are great.
The problems referred to in the other thread were from people trying to fit them to non-standard rear brakes ("Bob-Brown" style separate hub and disc), but even that has now been sorted. The only remaining issue is that the space-saver spare wheel won't fit over them. Anybody found one that will?
John

[Artaban]

The only remaining issue is that the space-saver spare wheel won't fit over them. Anybody found one that will?

And if possible to fit in the same space as the current spare.

Agree that PNM's rear callipers are great and have solved all my MOT handbrake issues and I've not had to do anything to them since they were fitted a few years ago. If you ever had a problem I think Pete would resolve it quickly anyway.
Andy

[maz_r]

I think we need to ask Jamie (from fife etc) kindly to take one of his (now famous) trips to the breakers and see what he can find in the way of space savers that might fit (and have the correct PCD etc etc)...

Oh and back on topic, PNM are the way to go imho

[Rambo]

The only remaining issue is that the space-saver spare wheel won't fit over them. Anybody found one that will?

And if possible to fit in the same space as the current spare.

Agree that PNM's rear callipers are great and have solved all my MOT handbrake issues and I've not had to do anything to them since they were fitted a few years ago. If you ever had a problem I think Pete would resolve it quickly anyway.
Andy

I also agree. Had a long chat with Pete Musgrove recently about Cybox exhausts, clear front indicator/sidelight fittings. Got onto the subject of OEM rear brakes and PNM's rear brakes which he said improved rear braking performance in leaps and bounds. Had a chat about proportioning valves too which was quite interesting

[vinnie]

Please enlighten us on the proportion valves

[Simon_P]

What brake balance do you get with PNM rear brakes?

I'm not defending the original calipers but the last thing I want is "improved rear brake performance" a handbrake that works? yes. More braking on the rear? no thanks.

[Fredjohn]

What brake balance do you get with PNM rear brakes?

I'm not defending the original calipers but the last thing I want is "improved rear brake performance" a handbrake that works? yes. More braking on the rear? no thanks.

I have the PNM kit fitted along with the original proportioning valves, but I have Wilwood brakes up front. All the 15" set up.

I haven't taken any measurements to work out the balance front to rear (although the MOT figures would probably provide that), but have observed the following:

It passed the MOT
The handbrake is wonderful
The car pulls up in a straight line when braking hard from 60mph, hands off (sorry officer, I did it on a private road)
It exhibits no signs of the rear overtaking the front under braking at any time.
The brakes are very good, but probably need more bleeding (!)

My conclusion is that the extra braking performance of the front Wilwoods is nicely balanced by the increased performance of the PNM rears and the proportioning valves at factory settings remain effective.

So in my case I do need "more braking on the rear", as I suspect would most who have up-graded their front brakes. But I can only speak from my own experience and without any measurements, just how the car feels.

The only problem I have is that the spare wheel has been dumped in the garage and I carry a full size spare in the boot. Still enough room for 10 days 2 up touring though

[lotusflasherman]

What brake balance do you get with PNM rear brakes?

I'm not defending the original calipers but the last thing I want is "improved rear brake performance" a handbrake that works? yes. More braking on the rear? no thanks.

, with some reservations...

Elan OE rear discs don't work very hard so discs have a tendency to rust and pads get contaminated if car isn't used regularly and driven hard. I have 'a procedure' that I use my Elan regularly and drive the 400 yards out of the village 30mph zone pulling the handbrake up and down - until it's time to have fun.. Never had an MOT problem and handbrake works fine so I will defend the OE calipers but not the OE discs integral with the hubs - what a silly idea!

If your Elan's rear brakes are struggling to pass the MOT a PNM upgrade might be good, particularly if fronts have been upgraded already, but I recently had my Elan up on a small lift to replace the alternator and was surprised to find the Centre of Mass appears to be across the front jacking points so it's quite 'front heavy'.

When I raced a Mini, another 'front heavy' car, I was sent photos of me braking for the 1st gear hairpin at Mallory Park showing both rear wheels between 4 and 6 inches off the track - the Mini's 'standing' on the front wheels so was very easy to spin in that situation. No point in upgrading the rear brakes there... (In fact I used standard front shoes (twin leading) with some of the friction material cut away!)

The Elan has tried to counteract this 'front heavy' characteristic with 14% anti-dive built into the front suspension, 5° anti-lift in the rear suspension of original design, reduced to 2.5°for US cars and the applied to all later cars, plus the Brake Proportioning Valves. Nevertheless it remains that most of the work will be done by the front brakes. Because of energy dissipation etc, improved rear brakes on an Elan might be useful when loosing 30 mph by braking hard from 70mph to 40mph, when not a lot of weight transfer takes place, compared to braking from 40mph to 10mph when a lot of weight transfer takes place and the rear end can get lively indeed. Braking hard for a corner, make sure you brake in a straight line, come off, then turn in.

Lotus went for a compromise based on fluid pressure for the BPV but later cars I've owned have a mechanical link that closes the BPV when the rear rises and the suspension droops and current Subaru calculates it all electronically! Dave Pink posted an interesting thread about BPV's here - forum.lotuselancentral.com/viewtopic.php?f=41&t=23606

I've changed from 15" rims on my SE to 17" and while I was happy with OE size discs in 15" rims they now look a bit silly so have a 'brake upgrade project' going on. Already fitted rear hubs to take separate discs so I'll let you know what I eventually decide on sizes etc.

[lotusflasherman]

The only problem I have is that the spare wheel has been dumped in the garage and I carry a full size spare in the boot. Still enough room for 10 days 2 up touring though

By choice I used to carry a full size 15" SE spare to the south of France because I didn't want to be speed restricted on that silly 'bicycle tyre' or 'taken to the cleaners' when trying to buy a new tyre in France. (Puncture at speed normally destroys the sidewall by the time you stop so a new tyre is needed, though you can buy 'runflat' or 'slime' to make them 'runflat'.)

I'm now on 17" rims and about to increase disc size considerably so was considering this....www.ebay.co.uk/itm/Emergency-Tyre-Sealant-500ml-Puncture-Rapid-Repair-Fix-Tire-Foam-Holts-HT4YA-/331751999543

[tb10]

I have 'a procedure' that I use my Elan regularly and drive the 400 yards out of the village 30mph zone pulling the handbrake up and down - until it's time to have fun.. Never had an MOT problem and handbrake works fine...............

Snap!! (and I thought it was just me.....!)

[Simon_P]

All,

The PNM kit looks great nothing against it or them. The original rear brakes are high maintenance not great but they do work correctly if maintained.

Braking is serious stuff. All the usual caveats apply - It is your responsibility

There is a reason that Lotus put a proportioning valve to restrict rear pressure to 30 % and later 20 %. with different brakes that is out of the window - You would be as well to at least maintain the original bias, unless you know more about vehicle dynamics than they did.

I suspect that the real difference happens when braking hard at speed. The rear is already light at speed due to lift, break hard and it gets twitchy (and that was on an Autobhan with standard brakes.)

We can all brake hard in a straight line, it proves very little.


Fred,
By definition your original brake "Upgrade " to the front had a detrimental effect on the stopping distance of your car vs a standard car - not much of an "upgrade".

You are now correcting that with another "Upgrade" but you don't know by how much or if it will be stable under all conditions. Maybe you should correct more ... maybe less. You need to be sure of what you are doing first and then make subjective judgements after.

[Simon_P]

I have 'a procedure' that I use my Elan regularly and drive the 400 yards out of the village 30mph zone pulling the handbrake up and down - until it's time to have fun.. Never had an MOT problem and handbrake works fine...............

Snap!! (and I thought it was just me.....!)

I have one that includes the front brakes as well - I like to know that they are working!

[lotusflasherman]

I have one that includes the front brakes as well - I like to know that they are working!

me too, but this is a thread about rear brakes so didn't mention that. Never had a problem with fade on OE front pads but went EBC slotted and dimpled discs and Green Stuff pads as an 'upgrade' as everybody said it was an improvement and found I needed left foot on the brake to pre-warm them before I needed them in anger for the first corner ... OK after that but not anything to get excited about.

Must admit I've become a bit OCD about keeping my rear discs rust free - even to the extent of jacking car up and removing wheels to clean rust of the discs with a flapwheel on a rechargeable anglegrinder if I haven't used it for several weeks. I found if you can wipe rust off on your fingertips it will act as a lubricant between disc and pad initially and get embedded in the pad. I have a set of OE disc/hubs that I machined oblique slots in similar to the front discs. That works well but there's an annoying 'zt, zt, zt' noise as each slot passes across the pads which is really bad when the hood is down. Fitting a Quicksilver exhaust on that car 'drowned it out' quite a lot..

Whenever I see another M100 I can't help looking at the condition of the rear discs - no wonder some owners complain they don't work. Those sold on ebay have to be seen to be believed as well. www.ebay.co.uk/itm/LOTUS-ELAN-M100-SE-TURBO-S2-REAR-BRAKE-DISCS-WITH-BEARINGS-/201566085113?hash=item2eee465ff9:g:lYMAAOSwdrRXGLMj

[Fredjohn]

Fred,
By definition your original brake "Upgrade " to the front had a detrimental effect on the stopping distance of your car vs a standard car - not much of an "upgrade".

You are now correcting that with another "Upgrade" but you don't know by how much or if it will be stable under all conditions. Maybe you should correct more ... maybe less. You need to be sure of what you are doing first and then make subjective judgements after.

Thanks for your thoughts Simon, I will try to get some meaningful measurements next time I am on a rolling road/brake test.

However I don't quite follow your point on my front upgrade alone not being an upgrade without rear brake mods. If I am reading correctly you are inferring that everyone who has fitted Wilwood Hi-spec/PNM AP etc front brakes but retained OEM rears hasn't upgraded at all. This would apply to most on here who did it before the PNM rears became available. And I am sure all who did would say their brakes were better by far.

I don't think this is what you meant though, so perhaps you could explain a bit further, even in a new thread as this one is for the rears!
Thanks
PS I still have the proportioning valves in place, it would be foolhardy to remove them!