bodilx6 Posted June 13, 2014 Share Posted June 13, 2014 I've upgraded to 4/2 pot brakes, have TRD rotors as well as braided lines and fast road car pads from Chris Wilson. Also 300+ degree c brake fluid and the brake cylinder brace. I still fell squishy brakes after a few corners on track. Never on the road though. When I get the (used) set of brakes, I fully renovated them but the squishiness have been constant. Actually I have cone back to OEM pads, as they have a better feel on regular roads, but doesn't not work optimally on track either. I've run with or without shims, same result. Any ideas where to go next? As far as I can figure, I should not need to go with a big brake upgrade, as my driving on track is not aggressive nor often enough for this to be needed. Two times a year to the Ring and two - three trackdays is all. As my issues shows themselves within a very short distance on track, I'm guessing I can eliminate it being be over braking. I never go aggressively in brakes (as instructors usually tells me to do) to avoid the fade. Except checking for seized calipers (which should be weird, as problem has been constant for years since renovation and they were sliding nicely then) can anyone come up it any other ideas? By the way, I'm going to Orlando and Titan Motorsports later this year, so should I feel rich, does anyone know how large brakes the 18" TTE/Lexus wheels will take? (I will probably avoid this, as non-stock brakes are illegal in dk) Thanks! Quote Link to comment Share on other sites More sharing options...
2soops Posted June 13, 2014 Share Posted June 13, 2014 Not sure about advice with brakes but I'm 100% sure I saw your car at the ring about 2 years back, probably May time Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted June 13, 2014 Share Posted June 13, 2014 Are the callipers on the correct sides? Ive don't that before... Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted June 14, 2014 Author Share Posted June 14, 2014 @2soops: this is very likely. Usually the time of year I'm down there the first time. @Swampy442: that would be bad, if that is a possibility. As far as I remember there is a 'L' and 'R' on them, right? Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted June 14, 2014 Author Share Posted June 14, 2014 What is the difference, if you did that? I mean; why would they heat up faster? Quote Link to comment Share on other sites More sharing options...
2soops Posted June 14, 2014 Share Posted June 14, 2014 What is the difference, if you did that? I mean; why would they heat up faster? It would make the bleed nipples sit at the bottom and make it hard to bleed Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted June 14, 2014 Share Posted June 14, 2014 I've notice a bit of travel in my brake pedal, I wouldn't call it squishy exactly but the brakes are not immediate with the first bit of movement of the pedal. I personally don't mind this feeling but I'd imagine it's down to the car's original brake master cylinder being mismatched to the 4/2 pot calipers I fitted. The master cylinder designed for the 4/2 calipers is a slightly bigger diameter than the unit fitted to a car with 2/1 calipers, so the smaller piston in the smaller cylinder must travel further to push enough fluid into the larger calipers to produce adequate braking force. The further the piston moves the further the pedal must move. Could this be the case here? Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted June 14, 2014 Author Share Posted June 14, 2014 Ah...no, my nippels are up high... Ehm... @pedreosixfour: no,mi would not think so. Are you talking on track? What you describe is like my experiences with different brake pads and road driving.. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 16, 2014 Share Posted June 16, 2014 (edited) Pad knock back, the front uprights on 95% of road cars are as stiff as a rubber band when given a proper work out on a race track. They bend and the disc pushes the pads back a tiny amount, so the next brake application needs to take up this excessive pad to disc clearance. Race uprights have a stub axle (where the wheel bearings sit) of over 2 inch OD, the Supra just over one inch, with similar disparity in hub bearing sizes). Road car suspension design is usually shown inadequate on track. This is one reason race cars use floating discs where regulations allow. You can add light springs behind the pistons, inside the calipers. AP racing sell them in sizes that may fit. These pre-load the pads slightly. Running *NO* anti squeal shims, and *NO* anti rattle junk may also help, albeit they'll probably rattle on rough road surfaces. It may also help to ensure the master cylinder cap is breathing properly, and the master cylinder is utterly clean with no sediment in the bleed back hole (rebuild it after blowing out with brake cleaner and an air line, using new seals). Edited June 16, 2014 by Chris Wilson (see edit history) Quote Link to comment Share on other sites More sharing options...
Ian C Posted June 16, 2014 Share Posted June 16, 2014 Pad knock back, the front uprights on 95% of road cars are as stiff as a rubber band when given a proper work out on a race track. They bend and the disc pushes the pads back a tiny amount, so the next brake application needs to take up this excessive pad to disc clearance. Can you do a left foot brake tap near the end of a straight like the Aussie V8 supercar guys do? Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted June 16, 2014 Author Share Posted June 16, 2014 Thanks Chris, I was hoping you would chime in... So, you are saying (ignoring the possible sediment and master cylinder breathing issues), that all supras have soft brakes even before any real heat get in there? And without non-realistic (for a road car) upgrades and costs, it is the way it is? So if you would install huge look-at-me-bling-bing-12-caliper-insane-brakes, you would still have this issue, except it would never translate into actual fade as the 4/2 brakes can do if you really go at it? This is bad news as it gets really hard to heel and toe when braking hard into corners.. Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted June 16, 2014 Author Share Posted June 16, 2014 Ian, that is actually worth a try. It would confirm what CW is saying (and sadly, he is usually right..) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 17, 2014 Share Posted June 17, 2014 They are no better or worse than most road cars used on track. If you spend a huge amount on an aftermarket kit I would make sure it had floating discs. Pad knock back is usually mild and just gives slightly longer pedal travel on the first brake application after a hard cornering manoeuvre. Your problem sounds more excessive than that, if I read it right? Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted June 17, 2014 Author Share Posted June 17, 2014 I think it is, as the pedaltravel i probably double than it is on road/before any usage. But I will definatly think about what you are saying. I will not spend £££ on a crazy brake setup, as my entire plan has been to keep the car stock looking. However, if it was the only way to really enjoy it on track, i might do it. But I will check seized pistons, master cylinder breathing and gunk before going forwards. /Stefan Quote Link to comment Share on other sites More sharing options...
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