Front Discs - choices....AGAIN ! !

[ChrisSZ]

Never warped stock Toyota discs Chris?!!!

 

Gaz.

 

Me? No! But I have used discs other than stock with much better effect (not on a Supra though) - fast road stuff - no track, with no problems at all.

[Matt Harwood]

I read an article a while back that seemed to make sense. Apparently, whoever wrote the article believed that most 'warped' disks are not, in fact, warped at all. He believed that it was residue from the pad bonding material burned onto the disk surface that causes uneven patches on the disk surface resulting in the feel that the disk is warped.

The cause of this is usually after a heavy stop, when the disks have built up a lot of heat and the driver keeping the brake pedal pressed, causing the pad bonding to break down and partially bond itself onto the disk surface.

 

I've got through more disks than pads since I've had Supra's. I don't honestly know if I do sit with my foot on the brakes after a long haul stop, but I've certainly tried to be more aware of not doing so since reading that article.

 

Terry S has a set of DBA disks on his car. I know he doesn't drive lightly, and they're still going strong. Maybe them, plus keeping the above in mind is the answer....

[carl0s]

I read an article a while back that seemed to make sense. Apparently, whoever wrote the article believed that most 'warped' disks are not, in fact, warped at all. He believed that it was residue from the pad bonding material burned onto the disk surface that causes uneven patches on the disk surface resulting in the feel that the disk is warped.

The cause of this is usually after a heavy stop, when the disks have built up a lot of heat and the driver keeping the brake pedal pressed, causing the pad bonding to break down and partially bond itself onto the disk surface.

 

I've got through more disks than pads since I've had Supra's. I don't honestly know if I do sit with my foot on the brakes after a long haul stop, but I've certainly tried to be more aware of not doing so since reading that article.

 

Terry S has a set of DBA disks on his car. I know he doesn't drive lightly, and they're still going strong. Maybe them, plus keeping the above in mind is the answer....

 

I read this too Matt. We discussed it a bit here and not many people were prepared to go along with the ideas..

[Matt Harwood]

I read this too Matt. We discussed it a bit here and not many people were prepared to go along with the ideas..

 

After getting through 4 sets of front disks over the past few years, (and just about to change again), I'm prepared to try anything!

[Steve W]

I can't see BETTER pads being the answer (?) cos if the Toyota

ones weren't as good then why would they be overheating the

discs ??

 

I still haven't checked the bearings yet, but went up to Colchester yesterday

at a fairly decent speed, with bumps, and corners, and there's absolutely

no 'noises' or vibrations from the steering EXCEPT when braking.

 

IF it's bearings why no noises like any 'normal' car... wheel bearings on all

the cars we get at work start whining/groaning way before they're a problem,

and even then never cause wobble/vibration on braking ?!?!?

 

YEAH, i can see the thinking behind the pad-material-on-disc-surface thing,

the pads on my ZZR1100 seized on because of crappy/salted calipers and

me being a lazy fart, left 'em like that for months.....when i finally stripped

and re-sealed the calipers (sorry...HAD IT DONE BY SOMEONE !) the brakes

work fine but now give the same sort of on/off feel as you slow down to stop

like ABS ???

 

SORRY, did i even MENTION that the Soop brakes were doing THAT too ??

They do the vibration, and, then as you slow right down they start that

on/off feel ?!?!?!?!?

 

FatS.

[Chris Wilson]

Atr the calipers and discs UK spec on the front AND on the rear?

[Steve W]

Sorry, MINE Chris ??

 

YES, discs/calipers/pads all Toyota UK.

 

(obviously, just took the easy way out with the 'dust'shields/cooling plates(?)

and just ground them off, does that cause great difference...on an N/A ??)

 

FatS.

[Lazarus]

Been following this thread of yours Steve, I've got exactly the same symptoms as you describe (Na with full UK spec front and rears, all genuine Toyota parts), first started doing it when I had the J-specs on, thought it was warped discs so changed them for a new set of j-specs discs all round, it was fine for a couple of months then it started up again.

At this point I put it down to them being crappy old J-spec set-up (11 year old sliding calipers probably not being very efficient anymore, although none were binding) so decided to upgrade to the full UK set up (ground off back plates, same as you), again great for a couple of months, now its back again.

I've just about convinced myself that it can't be the brakes themselves as I've been through the different set-ups (original j-specs, new j-spec discs, new UK specs) and keep getting the same symptoms returning, I,m thinking its something to do with the hubs or bearings, I've even purchased a pair of front hubs to swap out to see if it cures it.

Tho I'd never heard of the scenario laid out by Matt before:search: sounds plausible when you think that you usually end up keeping on the brakes while waiting at junctions in an auto.

[Steve W]

But, every time you've changed the discs...it's gone ??

 

So it can't be anything you haven't changed....can it ??

 

If it was the bearings, surely ("don't call me Surely") it wouldn't 'cure'

when you change the discs !

 

[really must get it up on a ramp and shake/spin the wheels ]

 

Could see if they'll let me do some investigating on the Brake Rollers..

..see if i can SEE any 'wobble' on either front wheel

[Chris Wilson]

Sorry, MINE Chris ??

 

YES, discs/calipers/pads all Toyota UK.

 

(obviously, just took the easy way out with the 'dust'shields/cooling plates(?)

and just ground them off, does that cause great difference...on an N/A ??)

 

FatS.

 

Yes, yours. Is it on stock wheels? Beleieve it or not, a wheel with the incorrect hub face to disc contact area can allow or even cause a disc to warp.

 

I did countless track days with my MKIV TT on stock discs and J-Spec calipers, with the discs red hot (literally) and they never wrped. Decent pads, decent fluid, bit otherwise factory stock.

[Steve W]

He even bled the brake fluid right though ALL FOUR lines when he

changed the brakes over.

 

As i said, the only 'difference'/wrong bit is the thin shields now missing

behind the discs - but i don't think they were cooling aids (??) more

dust/debris covers ??

 

I'm tending to opt for the auto-keeping-hot-pads-clamped-on theory

so far.

 

ANYWAY, if i get the machinist at work to START to skim 'em, he should be

able to TELL if they're warped.......shouldn't he ???

[Lazarus]

But, every time you've changed the discs...it's gone ??

 

 

Yeah fella, I know what your saying, but I find it difficult to believe that I'm warping discs (through my driving) after only a couple of months use no matter which type of spec I'm using.(I don't do track days and don't drive like a tit)

 

I'm not saying that the brakes aren't warped, maybe they are, what I'm trying to say is that its got to be something else on the car thats putting the discs in a situation where they are surceptable(sp?) to warping.

 

The other "spanner in the works" is I can brake through it, ie. if I "stand" on the brakes I don't get the warped disc wobble, with the UK solid calipers if the disc was warped you should feel the warp all the way through the braking range, I find it too difficult to believe that the caliper can put enough force on a warped disc to "true" it up, but if it was a wobbly bearing perhaps the caliper could apply enough to straigten that up?

 

don't know...maybe I'm clutching at straws...I just want it fixed same as you.

[jason m]

I hope I am not being paranoid - and am fairly sur the car isn't paranoid, but it has just started doing the same thing. It does feel very much like warped discs (I have had em on a bike before)

 

So question (prob for CW) do you think it could be my wheels ? (the volk ones) I have got some hub rings as you suggested but have not got them fitted yet. I am assuming the discs looked ok when you fitted the rears.

 

Thanks

 

BTW did you get my e mail a few days back ?

[Chris Wilson]

I can't find a mail from you, but due to work load I have been less than dilligent answering e-mails recently, it's impossible to keep up with them all so I have had to be pretty ruthless with deletion and filtering. It could well be the wheels, you MUST use wheels that are both properly located on the hub snout, and which properly spread the clamping and heat path loads on the disc to wheel interface.

[jason m]

Ok will try the rings and see how it is - will re send e mail

 

Ta

[Chiefgroover]

FWIW IMO based on my personal experience, Toyota discs are good. This is a similar problem to s13 200sx. Toyota pads are no good for high speed stops from the 130 to 150mph and beyond area nor are TRD, nor are many other well recommended brands by the "experts".

It seems par for the course to blame the discs, when its often a pad problem.

I have found that the "right pad" for hard driven road or track day supras was a matter of trial and error. My result is Endless CCX. Expensive yes, but they lap again and again with consistant performance. I have used these on Std and DBA discs, even on a very hot day on the ring, raping the car as I lapped it, the CCX did the job, providing i didnt do the numpy thing and drive into the pits and stop the car, instead i would slowly cruise around the local roads for a few miles to aviod chances of warping the discs, while they got back to a reasonable temp. These pads have superb feel, and dont give off black dust, instead they give off red dust! which looks very cool on chrome edged rims!.

After 4 sets of discs and "recommended" pads I got the Endless, and never looked back. For those reading this who rarely go over 120mph, believe me when i tell you the extra heat created by each 10mph above is a bigger demand on your pads than you can imagine when braking is repetitive.

Toyota and DBA, both very good dics IMO, but both are usless with crap pads. I could start a name and shame here but I wont, but believe me, good feel and steady performance is a rare thing in brake pads.