Brakes perform like the car weighs 10 tons. Advice please.

Most of the time my Supra feels really heavy when braking like when going down a steep hill and trying to stop. Occasionally I get wheel lock up, ABS panic attacks, even at slow speeds on warm, dry days and after an hour of driving.

The brakes are j-specs, the tyres are Nangkings with loads of tread, Bilstein suspension, auto transmission from a Soarer.

Is it possible that when braking, the rear brakes are doing such a poor effort that the car could still be pushing against the fronts so much they lose grip? It's always the fronts that lose traction. This is the only RWD auto I've driven and the braking ability is way off what I would expect. My auto Celica was better, my wife's tiptronic Leon is vastly better. All FWD though so can't fairly compare. I'm going to get this checked over but I always like to have an understanding beforehand.

Seeing as you have a V8 in the front I thought it would be lighter too?!

Personally would recommend you go to a meet & drive another, though something is VERY wrong if you are locking up at low speeds. One common failure on the JSpecs is you get sticky pistons which could be one issue you are having?

Nangkings - A cheaper version of Nankangs? If so then this will be your problem. If it's Nankangs and just a typo, then that's DEFINITELY your problem. Liquorice would make for better tread.

Brakes - The fact that you can easily lock up the brakes definitely rules out the front brakes as being the main issue. I would rule out the brakes entirely but there is no guaranteeing that the rears are OK so they really need checked out too. Once everything else is checked out and OK it's time to come back to the brakes.

Tyres - Your tyres are really crap, they aren't up to scratch for stopping a supra... let alone going round a bend. First things first, invest in some decent rubber.... it's the only thing in contact with the road and really is the difference between life and death in these cars.

Geometry - Poor geometry leads to bad grip. Bad grip = poor handling and poor braking ability. Get the geo setup by someone who knows what they are doing.

Nankangs, sorry was a typo I almost put NagKings.. I know they are a cheaper brand, it's just what what on the car when buying and this is a weekend car so does less than 4k a year. Even so, car always feels like it's still pushing whilst braking. The geometry was done 2 years ago at JPS on their hunter laser tracker. Will look into those sticky pistons when I have this checked over.

The engine is lighter but not sure to which 2JZ. Turbos and intercoolers probably weigh a fair bit so maybe it was to the 2JZGE.

Next meet I go to I'll ask to try another Supra with J-specs. There is another V8 guy not far from Kettering so that would be the closest comparrison.

Thanks for the suggestions.

Tyres - Your tyres are really crap, they aren't up to scratch for stopping a supra... let alone going round a bend. First things first, invest in some decent rubber.... it's the only thing in contact with the road and really is the difference between life and death in these cars.

 

Geometry - Poor geometry leads to bad grip. Bad grip = poor handling and poor braking ability. Get the geo setup by someone who knows what they are doing.

This. DitchFinders on a Supra = pain...

The geometry was done 2 years ago at JPS on their hunter laser tracker.

2 years may as well be a lifetime - even driving too fast over a particularly dodgy pot hole can knock out your geo'... Some decent (think "I'd better budget £1000...") rubber is job one then a full geo' check.

it mite be werth bleeding the brakes. and new brake fluid.

If the brakes are the original set that came with the car i'd be having a close

look at them first.

Check to see if all the pistons move freely and the calipers move freely on the slider

pins on both front and rear.

If the above is all good then i'd be looking at the brake lines if their the stock hoses

and as suggested be doing a full fluid change.

what about a split in the vacuum line or the vacuum line not being connected!? surely that would also make the brakes feel stiff. Probably a silly suggestion but worth a shot

If the brakes are the original set that came with the car i'd be having a close

look at them first.

 

Check to see if all the pistons move freely and the calipers move freely on the slider

pins on both front and rear.

 

If the above is all good then i'd be looking at the brake lines if their the stock hoses

and as suggested be doing a full fluid change.

He's locking up the front..... surely it can't be an issue with the brakes? Jspecs locking up is a pretty good feat in itself so that would suggest to me there are issues further down the chain than the brakes.

Could be worn/plastic tyres, worn/leaking shocks or seized caliper pistons(This will cause lots of locking up on jspecs.) I had all of these issuses at one point!

I believe Quicks**t do a free brake test if your looking for the lazy option, but take what they say with a pinch of salt!

Brakes could well be original. I'm going to get this all checked at the weekend as a matter of priority. Thanks everyone.

These are my tyre sizes:

Rear, 265 35 R18

Front, 235 40 R18

Any particular tyre brand suggestions? The ride could be smoother too.. Going over rumble strips brings on the need to wear a support bra.

Absolute bare minimum Falken 452s imo. Toyo's, goodyear, michelin etc are all good

As above, I'd be surprised if sticky brake pistons are causing this. Anyhow, you can tell if a piston (or brake in general) is sticking by going for a drive for 20 mins with plenty of braking, then park up and with the back of your hand as near as possible to the brake disc (without touching it!) carefully feel for excessive heat. Use all 4 corners as a reference as to what's excessive: hopefully they won't all be sticking.

Worth checking your brake pads are in good nick.

Going over rumble strips brings on the need to wear a support bra.

Video or it didn't happen.

As above, if the brakes are locking up, your problem has to be tyres and possibly geo, I don't have ABS ony supra bad dearly wish I did, it's a bloody life saver.

A geo isn't too expensive, though the rubber could set you back. I run Bridgestone Potenzas, they are brilliant. Run flat though so ruin your spine. I don't have a spare wheel though.

My Supra has had an examination of the brakes etc today at a motorsport company and they are all in good order. What they did find though is that with the brakes on and in drive, the car is pushing too hard. They suspect that somewhere in the gearbox system there is too much pressure and this may be causing the rear wheels to keep powering on when they should be backing off. The rear brakes don't really bite hard enough to counter this. I do have a speed sensor error code and a flashing overdrive light, possibly related?

If you've got excessive pressure build up in the box then my first port of call would be to drop the fluid, take the sump off and replace the filter/strainer.

Will need to find a man with a bigger spanner than mine. Cheers, will look into that.

i had the same problem on mine turned out it was the rear pads not gripping cause the pistons were sticking ,when i removed the pads the inner was almost shot and the outer was barely worn ,serviced the calipers and now all is fine

Very good point that. Non-working rears and good fronts would lead to the fronts doing all the work..... hence the locking up at the front while still having a sense of not stopping correctly.