Brake Bias

At Knockhill the other week, I had some problems with my REAR wheels locking up under hard braking - did a nice piruette for the Macintyres marshall [image][/image] TWICE!!! - anyway, I know this shouldn’t happen as the bias is supposed to be to the front and I have just read thru the post on this subject from a while back. No one really gave a description which I feel got to the bottom of it, there was discussion of how this shouldn’t really happen and some useful stuff about how Lotus designed/set-up the exige bias, but nothing that really clued me up on why this might happen.So,… today I took the rear wheels off my car and found that the INNER pads were worn down paper thin while the OUTER pads were about a third worn. The FRONTS were about a third worn all round. ALL pads had worn nice and evenly parallel and the discs are in pretty good nikk. The pads were EBC greenstuffs and have done about 3000 miles including about half-a-dozen track days. One of the rear caliper piston seals showed the effects of heat damage and was torn (and it looks recent as the piston was clean with no erosion)Firstly … any ideas ?? [image][/image]Secondly … Anybody out there fitted a brake bias device ?? What are your opinions? What do the collective think of fitting such a device??All comments welcome - including casting any nustirshums about my driving… [image][/image]

Honest answer?Don’t use ****e brake pads (and that includes EBC)with the std brakes, you should never get into that kind of situation.What it sounds like is that some pads were offering more friction than the others.If your planning on trackdays etc, stick with Padgid, I know that are not cheap, but they are in the long run.Simon (S)

Thanks SimonIt is a standard brake set-up and I did get into that situation… They might be ****e pads but PAGIDS wouldn’t be all that safe for me on everyday use - don’t they need heat in them to make them work properly?? I ai’nt that rough on the brakes on HRH’s highway.Now the bit about some pads offering more friction than others sounds reasonable but how do you think the INNER rears had suffered much more wear than all the others? And if your gonna put this down to ****e quality pads - i don’t buy it because the way the pads were worn would be too much of a coincidence.

Nah, the RS14 pads are plenty good for road driving, they squeal a bit thou (you soon get used to it, adds to the racecar feel [image][/image]

RoxRS14 are fine for general road use - trust meAlso look at the rear caliper and see how it works, the pressure direct from the piston is on the inner pad !

Also if your “sliding” pins are not sliding like they should you will not transfer teh pressure even so the inner pad will wear quicker - I would check the sliders are not seized up or something Cia

RS14s - night & day!Even the squealing has stopped now they’ve bedded in.Ian [image][/image]

RoxIf Pagid cost is an issue - go for Mintex 1144s - about 1/2 price of Pagids.

True enough, but they are also crap in comparison.If you really must use Mintex, 1155’s is the lowerst spec ones you should use, 1144’s will only overheat the disks and last 5 mins.which to you want to keep replaceing, disks or pads?Simon (S)

SimonSWot would you recommend as the best pad/disc set up 4 track/road use??SimonE

AndyDThanks for your helpful advice – the calipers and pistons are working fine (evrything moving smooth & straight etc) and while i agree your opinion about the piston being inside the FRONTS are the same but are currently wearing evenly all round so this still leaves me [image][/image]. What d’ya think??AndyD, IDG, LR DriverThanks for your advice telling that RS14’s are 'a’okay for normal road-use. I also spoke to Geary about this and he says the same. I had, for some reason, been under the impression that RS14’s were scary on road use when cold. SO I will definately get some when other bills are a bit easier.PeskyI will probably have a go at Mintex at some point as I know you are a bit of a fan of them and others have said they are okay.Simon S???We all know that PAGIDS are the best but it doesn’t mean we all need to think of everything else as crap!!.. I know you pretty much know yer stuff and I’d like to hear your helpful advice regarding the problem I outlined above, not listen to you rant about how crap everything is. The comment about replacing discs or pads is cool except that RS14’s are nearly as expensive as the bleedin discs!!!Miniman, Phil, RussTI would value your opinion as to what the problem may be.thanks for listening

What about BRAKE BIAS devices – who has experience or opinion about getting one fitted to my exige?

RoxI’m Miniman under a new login [image][/image] … old one and others didnt work anymore [image][/image] so I went all sensible [image][/image]Anyhow, the rear caliper only has one piston on the inside - the pad on the outside is making contact by the slider - the front calipers have a piston both sides …So I can see that the inside pad would wear quicker - not that that explains your lock ups - unless the rear pads are somewhat softer than the front ones for a strange reason … I can see from your problem why you would want to fit brake bias but I have found only the fronts locking - the rear calipers appear to be acknowledged as “marginal” so bias favours the front - On the other hand it could be that the fronts are not working well enough or start to fade before the rears with the pads you have ( or is the air in the front ) making the rears work harder and thus making your problem … Brake bias valves just restrict the pressure to the rear and I think you need to sort the standard setup out first otherwise you mask out the problem.What happens on a flat road with cold brakes - front or back lock up - then with hot brakes ?

Cheers AndyGood reliable advice as usual - I’ll replace the fluid and pads over the next few days - I also don’t have braided hoses yet but have ordered some.I’ll leave the bias valve on hold for the time being as I agree it would be better to get the std setup sorted first. However I would still like comment on this from anyone who uses one on an Exige.It is absolutely possible that the fronts were fading first.Thanks, speak soon [image][/image]

Hey Rox,just logged in after a few days of absence.You know you just started getting braking problems when trying to break later.What most likely happened is that your front brakes (EBC greens are not that good) faded after getting overheated. Then the rears take more of the work.That’s normal. And a real brake bias device uses a double master cylinder (at the pedal. The Exige has only one, so you could use ony a pressure restrictor for the rear circuit. Not the best idea.You just need to upgrade to better pads.I bit the bullet and went for Pagids and Geary’s alloy belled disks up front. Rear I’m going to stick with the normal disks and Green’s, the originals in the rear have stood well.Now, your problem in the rear is the uneven wear, but I see that you’re already looking for a service kit. That’s good. Just make sure that the sliding mechanism works perfectly when assemblying. just clean, polish and grease everyting as if it was new. [image][/image]Cheers,Uldis

I agree with Uldis - sort the fronts with 14’s & belled disks (not sure about leaving greens on the rear tho’ - I would think you need better on the rear, not worse), and make sure your calipers are sliding freely.Cheers

Russ, UldisThanx

-------------------------Simon S???We all know that PAGIDS are the best but it doesn’t mean we all need to think of everything else as crap!!.. I know you pretty much know yer stuff and I’d like to hear your helpful advice regarding the problem I outlined above, not listen to you rant about how crap everything is. The comment about replacing discs or pads is cool except that RS14’s are nearly as expensive as the bleedin discs!!!-------------------------That’s the point I was trying to make!If you run cheap soft pads, they WILL overheat the disks, thus you end up having to change both.Yes, Padgids are not cheap, but they will out-last any of the other crap out there by some mark, thus in the long run they work out cheaper.Simon (S)

SimonWe’re not all as tough on our cars as you are [image][/image] Quite understandably, you see things from a “racer’s” viewpoint, whereas most of us here use our cars mainly on the road, & try & do as many trackdays as we are able. In 2 years of Exige ownership I’ve covered 25K miles, & done 22 trackdays. I put Mintex 1144s on at 10K miles & replaced them again, along with Geary’s belled disks on the front, about 1K miles ago. I’ve not at any stage experienced overheated/warped disks, nor did RussT when he was using the 1144s before he changed to the RS14s. So, in my opinion, if cost is a factor when upgrading the pads, it’s worth trying the 1144s before splashing out on the RS14s, which I am very happy to accept are the best available [image][/image]

I take your point.I am basing this on other peoples cars that I have worked on at track days etc, Greenstuff I have seen destroyed in 1x30 min session at Rockingham, and they killed the disks too.1144’s are not as bad but still are a road only pad really, when pushed (even in a std car) they WILL cook the disks, (Causing the disk will crack),1155’s are OK, they will last, but have very little pedal feel and are approaching Padgid money.I would also suggest though that RS4-2’s are not double the cost and will last over twice the time that Mintex 1144’s will, (RS4-2=�175 vs. 1144’s=�100).I know people that are running RS4-2/RS14 and have got over 25K miles life out of them (and these guys do more trackdays than most).At the end of the day it’s personal choice, but from an economic perspective, EBC/Mintex are a false economy.Simon (S)