Ian Mackenzie Posted August 21, 2014 Share Posted August 21, 2014 I'm just about IVA a supergrad racer and the break bias is touch and go..... Sometimes the front offside locks first, and sometimes I think it is the rear! When I think the rear locks first the car feels like it gives a small kick to the left at the rear( clockwise rotation), to me this indicates that it's the rear offside locking first. So I'm testing my theory here, then if this is correct to balance the car better under breaking, I can either decrease the spring platform on the rear offside, or increase the rear near side spring platform. I know both will change the rake, but at present I just need to get through the IVA first. I'd also be grateful if anyone can let me know the Standard pads that Caterham use, or a good combination to reduce the rear braking eficiency as well. Many thanks Ian Link to comment Share on other sites More sharing options...
mav Posted August 21, 2014 Share Posted August 21, 2014 if its on std from callipers, not the AP hobbies, Richard Price has written a lot about this type of experience and can be accessed with a quick search... Link to comment Share on other sites More sharing options...
BigCol Posted August 21, 2014 Share Posted August 21, 2014 My car failed its IVA on this very thing... Caterham simply supplied me some more aggressive front pads (having failed to notice the issue at the PBC!) I then took a very circuitous route to the retest surprising pedestrians with what they saw as my poor driving and anticipation as I locked up frequently as I came to a halt, in order to bed the brakes in and check whether the fronts or rears locked first. You should've seen the smile my face when ten minutes before my appointment, the fronts only locked! Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted August 21, 2014 Area Representative Share Posted August 21, 2014 Ian, Do you know what pads are currently in your car? If it has previously been a race car, then they may well be pads that need temperature in the brakes before they work properly ( which is not a suitable arrangement for a road car.......) If you don't know what any of the pads are, then I'd replace them all. Mintex mgb533m1144 in the front, and standard in the rear, should give you safe brakes for IVA. Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted August 22, 2014 Author Share Posted August 22, 2014 Quoting Richard Price: Ian, Do you know what pads are currently in your car? If it has previously been a race car, then they may well be pads that need temperature in the brakes before they work properly ( which is not a suitable arrangement for a road car.......) If you don't know what any of the pads are, then I'd replace them all. Mintex mgb533m1144 in the front, and standard in the rear, should give you safe brakes for IVA. Hi Richard Thanks for this ,I suspect that you are right with my existing pads. I did take a quick note of the pad numbers, but a quick Google did not reveal anything... So it looks like new pads all round. Once again many thanks for the advice. Cheers Ian Link to comment Share on other sites More sharing options...
Myles Posted August 22, 2014 Share Posted August 22, 2014 Whoooah on the pads! Are you sure the system is properly bled? I remember having a nightmare of a time in my early days of ownership bleeding brakes - and I clearly remember one occasion when I took the car out for a shakedown run (maybe after fitting new calipers) and found that the wheel that locked first was entirely random depending on which bit had the most air in. Link to comment Share on other sites More sharing options...
elie boone Posted August 22, 2014 Share Posted August 22, 2014 Start from a basic set up, set the front shock absorbers equal, set the rears at the desired rake then ad 2 turns upwards on the drivers side. This will give you a decent balans Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted August 22, 2014 Author Share Posted August 22, 2014 Thanks for the updates.... Yes, brakes have been bled several times and it has a decent pedal (no signs of air on the last bleed), all the tyre pressures were also checked as well. Regarding the set up, I've set the rake and ride height. The spring platforms are equal on the front. I wound up the rear drivers side, but I do think it is a bit too far and could come down a little. The driver (me) is about 90kg Cheers Ian Edited by - Mackei23b on 22 Aug 2014 10:51:52 Link to comment Share on other sites More sharing options...
CharlesElliott Posted August 22, 2014 Share Posted August 22, 2014 If it came straight from being a racecar it should be setup ok - who's car was it? Does it have a brake bias adjuster? Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted August 22, 2014 Author Share Posted August 22, 2014 Hi Charles. It was Sean Mighalls old car, no brake bias adjuster is fitted. It did have some new rear pads fitted just before I got it, but I don't know what pads were fitted, and I'm not sure if it was driven with the new rear pads. Cheers Ian Link to comment Share on other sites More sharing options...
CharlesElliott Posted August 22, 2014 Share Posted August 22, 2014 Ok, well setup could be variable then 😬 (sorry Sean!) If you have standard front pads, you need standard (read rubbish) rear pads. Aggressive front pads allow better rears. 1144 in the front will need the rubbish rears. To make uprated pads work in the rear you will need 1177 or similar (Pagid etc) What sort of pads do you want to go for? Link to comment Share on other sites More sharing options...
CharlesElliott Posted August 22, 2014 Share Posted August 22, 2014 However, it also sounds like the car isn't corner weighted which makes it hard to judge whether it is pads or balance that is the problem. Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted August 22, 2014 Author Share Posted August 22, 2014 Hi Charles Yes, I agree with perfect corner weights it may be OK as I don't think the bias is too far off, for the IVA I just need to make sure that the bias is to the front when the tester drives the car. As I don't know what pads are in the car, it looks like the consensus with Richrad and your good self is 1144s in the front and rubbish rears to get the bias towards the front. I think I can probably unwind the rear offside platform a little as well to get both fronts locking closer together and reduce the tendency for the rear near side to lock first. Many thanks for your suggestions. Cheers Ian Edited by - Mackei23b on 22 Aug 2014 21:35:57 Link to comment Share on other sites More sharing options...
CharlesElliott Posted August 23, 2014 Share Posted August 23, 2014 Or WD40 on the rear discs :-) Link to comment Share on other sites More sharing options...
Mankee Posted August 23, 2014 Share Posted August 23, 2014 Sean Mighall. That name is a blast from the past for me. I met him back in 2006 when we were both part of a charity run in cheap, sh*tty cars to the 'Ring when no one really cared what sort of heap you took on track. I followed his progress for a bit when he built and raced the Super Grad car in the early days and even flogged him an ARB, but then lost touch. Good luck with the IVA and I'd be interested in seeing the car as it is now. His progress blog thingy with photos might still exist on 306gti6.com Link to comment Share on other sites More sharing options...
Graham Perry Posted August 24, 2014 Share Posted August 24, 2014 When I built my car back in 1990 I had this same problem except that mine was dangerous. It regularly swapped ends under braking including on the road I did all of the advice above including, multiple bleedings, cornerweights, a move to softer pads at the front, fitting front four pot calipers (two different types), larger Triumph Vitesse front discs etc all improved it a bit. However it still occasionally had a habit of spinning when braking rather embarrassingly at sprints. The only solution was to fit a balance valve (which once adjusted was then locked) which did finally entirely cure the problem. Link to comment Share on other sites More sharing options...
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