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The mkiv Supra Owners Club

Brakes question


Kevan

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I've read the other threads regarding replacement brakes but I'm still no wiser. I know cheap brakes are a stupid move but there's no indication as to what is considerded cheap.

 

One poster decided agains cheap ones and went for Mintex pads.

 

The rerason I'm asking is that I need to replace the discs on mine as there's a noticable judder under medium braking which I believe indicates warped discs. I've found these on Ebay so I'd like the panel's view. Are they any good?

 

http://cgi.ebay.co.uk/SUPRA-Drilled-Grooved-Brake-Discs-Front-Rear-Pads_W0QQitemZ300320581856QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item45ec8068e0&_trksid=p3286.c0.m14

 

If not, what are the recomendations. The car has std J-spec brakes and upgrading to UK spec is on the to-do list but isn't an option at the moment.

 

aTdHvAaNnKcSe

 

K.

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I've contacted my local Toyota dealer who tell me the discs are probably between £65 and £85 +VAT each and won't give me a price or lead time until I give them a frame number (which I don't have to hand).

 

Anyone got any ideas on a source for Toyota discs or recommendations for alternatives. Anyone like to comment on the ones linked to in my original post.

 

Thanks again

 

K.

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Are the stock discs really better than drilled and/or slotted ones (eg Brembos)?

 

K.

 

Depends on how you interperate 'better'.

 

Stock discs were designed for the Supra and perform the everyday duties of daily driving very well. They are very robust and keep themselves cool enough for most enthusiastic drives.

 

Grooved discs perform a little better for trackdays whereby the pad is kept nice and flat against the disc surface through the shaving affect from the grooves. The cooling is about the same as a stock toyota disc.

 

Pads is where you will notice a big difference in performance. Buy some good pads and you will notice a much better 'bite' on the disc as opposed to stock toyota items.

 

Chris Wilson has some decent pads for various uses and also a company local to myself called 'Carbotech' have some good pads for various applications.

 

 

As for 2-pot, 4-pot, 6-pot, 200-pot brakes etc. etc. .. the number of pots is not a direct relationship to how good the braking performance will be.

Stock UK-spec 4-pots perform well enough for nearly all situations you may ever encounter, on the road or track day.

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Thanks AJI, that was the information I was after. I know how the different types of caliper work and also that bigger discs are generally an improvement over small but I don't have the specific knowledge/experience of Supra brakes.

 

 

 

I'm assuming that the set I linked to are not particularly good as no-one has commented on them. My main concern is that the discs that are fitted (I believe they're Toyota) have warped. I had a similar issue with the OEM discs on my MX6 and I'd like to ensure that I at least get a full life out of the next set. Improved braking performance would be a bonus.

 

Other forums (for different cars) have advised that Mintex pads are pretty good (for normal road use) so I am interested in this forum's opinion. Although I'm going to get some from Chris Wilson as they seem to be the pads of choice.

 

K.

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But would cooling not be better on larger discs due to the larger surface area compared to the stock j-spec even with good pads?

 

I have seen people put on huge discs and then only use a the same size pad...so in effect only using the pad's area of contact on a huge disc....totally pointless.

 

The heat comes from the pad contact on the disc and the amount of heat is converted from the kinetic energy from the car slowing down through the braking force.

 

The overall amount of heat generated will be the same no matter which disc/pads you have as you are converting the same amount of k.e. to heat.

But the different discs and pads 'handle' the heat in different ways.

 

The rate at which the heat is then 'lost' from the pads and discs is governed by the cooling designs and materials etc.

 

It is rare that you will over-heat a disc or a pad....most commonly it will be the brake fluid that absorbs too much heat and the moisture within the fluid will start to expand and cause a 'spongy' pedal.

 

Some pads do get hot and gasses form between the pad and disc but I think I'm correct in saying that nearly all modern pads use materials that do not produce enough gasses for this to have an adverse effect.

(I stand to be corrected of course).

(And I think a lot of people on track days mis-interpret the 'brake fade' between too much heat in the brake fluid and too much heat in the brake pads).

 

Back to your original question..yes larger surface area of brake discs are able to transmit heat to the air over a larger contact area. But it is the vents that do most of the 'work' in cooling.

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This is exactly what I mean, but I'm thinking that having double surface area on dics would result in better cooling.

But if it actually is the vents that does most of the cooling (this might be why the brakes cool so much faster by driving compared to stopping the car waiting for brakes to cool), why are there so much fucus on larger brakes from car manufacturers lately?

Cars have gotten heavier and faster in a straight line and therefore needs better stopping power, but if the difference is marginal sizewise then why not opt for better stock materials and stay the same size (saving weight and material)?

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As with most things in the automotive industry, fashion is king. There are a _lot_ of people out there that know nothing and will blindly follow whatever Top Gear, Max Power or other media say.

 

On the other hand, a larger disc does have other advantages as well as the slightly better cooling. Basic physics dictates that the greater the length of a lever, the smaller the force needed to operate it. The disc effectively provides a lever for the braking force to act through so a larger one requires less force. This is, of course, theory so may not be so apparent in real life.

 

And no, before anyone asks, I'm not going to find and post the formulae/proofs ;o)

 

k.

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remember that a stock Supra weight is much more that a lot of other cars out there, so using some of the 'recommended' pads that other car owners have will not necessarily be any good on the Supra.... probably 'stating the obvious' but worth noting.

 

On here most popular pads used are either stock or CW for your current setup (Unless someone else knows otherwise!).

 

AJI summed up everything else.

 

Warped discs can occur for a number of reasons, one being the age/wear of the discs.

 

Personally I'd use stock discs at least.

Edited by SteveL (see edit history)
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