Hi guys,

 

yesterday had a pretty heavy session of using my Z32 TT on a private runway for testing purposes for a company, basically I was taking the car at very high speeds and braking hard before the end of the runway and turning around, doing this a few times.

 

well the question is, after a while the brakes felt shit, felt spongey like if there was air in the system, at one point almost went of the runway but luckily the runway was very wide so managed to do a high speed U-Turn(didn't think it was possible lol)

 

anyways, I checked the brakes after they seemed fine, and after I let the car cool off and made my way back home the brakes were fine, so I'm guessing pads/discs and possibly brake fluid being overheated is the culprit here?

 

Thanks

The brakes on a zed will never be that great especially for real constant hard use - you have a few options

 

First ensure all the pistons are free - seized pistons are common - you can rebuild the calipers with some decent pads & discs, I done this a few years back & it does make a big improvement

 

next is a big brake upgrade - brembo discs & calipers from an R33/R34 GTR or Z33 are a big improvement - upgraded mine to this a year ago & very impressed

 

other option for a big brake upgrade is aftermarket kits - K Sport or D2 kits are the cheapest or get some AP racing brakes if you are rich LOL!

what he said ^^^

 

been on standard brakes and there ok

got on vented/slotted discs with ebc red stuff ... very very good

now ready to put on 8 pot 356mm D2 brakes :)

Thanks Paul and Mark, I don't tend to use the Z for constant track use, a nice brake upgrade would be nice though! :D

Personally, before you go the whole hog on a Big Brake Kit, and once you have ensured the calipers are in tip top order (no stuck pistons etc) put on braided brake lines and flush and replace the whole systems brake fluid (full system flush) and replace with decent quality fluid

 

DOT brake fluid is "hydrophilic". This means the fluid will absorb water from the air. Rumor has it that you can fill a shot glass with DOT fluid and after an hour or so the glass will overflow. The DOT brake fluid absorbing moisture from the surrounding air causes the volume increase. This is why every container of DOT fluid requests that you keep it closed when not in use. As the fluid absorbs water its vaporization temperature (or boiling point) is reduced. DOT 4 becomes no better than DOT 3 and eventually degrades in performance to the level of DOT 2.

 

Amazingly enough, a small amount of moisture will be absorbed right through rubber seals and nylon hydraulic lines (virtually any material except metal or glass). This is why car manufacturers recommend brake fluid replacement every two to three years

Are all brake fluids dot rated? Is there anything we can use that isn't hydrophilic and has a higher boiling point?

Is there anything we can use that isn't hydrophilic and has a higher boiling point?

 

a parachute or an anchor :lol:

Not all, some special fluids to exist, which i cant remember what their rating name is. But we cannot use them on road cars as they require all the seals to be made of a special material, similar reasons why you should never for DOT 5 in a road car, itll just eat all the seals in the system and pretty much destroy your whole braking setup

 

As you probably know DOT 5.1 is technically the best brake fluid you can put in a road car, it has the highest boiling point lowest viscosity (its about half as viscous as DOT 4) and has the lowest volume change in relation to temperature (basically it doesnt expand or contract as much when hot/cold so it give a more consistant pedal feel and braking effort)

 

My stock zed brakes are as close to mint as they can be, all new pistons seals sliders and pins, DS2500 pads and DBA 4000 discs, but the single biggest improvement in the braking department in terms of how the brakes feel and how much effort and pedal movement was required was the combination of braided lines and a complete system drain and replace with Motul DOT 5.1

 

- - - Updated - - -

 

sorry, that should read "you should never use DOT 5 in a road car"

I have R32 GTR calipers... tempted to stick them on... not a huge upgrade but they are rebuilt with good pads... hmmm!

Theyre exactly the same as 94+ zed calipers

You have had some brake fade mate, just prolonged use of brakes with out the chance to cool properly, I believe putting braided hoses will help with the matter a little bit, as the fluid in the rubber hose from your calipers is so hot it will expand the rubber hose instead of exert preasure to the pad and effectively give you less braking force under your foot, most of the car is solid brake lines anyway so braided hoses to the calipers will help as they keep the rubber from expanding,

is there such a thing as pipe replacement for the brake lines? used Goodridge braided on my previous zed. which were much better than stock ones. now thinking of doing the same with my current. though wondering if there are hard pipes to eliminate any give on lines.

Hard pipes won't work as you need to be able to turn the wheel, braided is your best option.

 

Contact Silver_Surfer on here, he has some brand new Goodridge braided hoses for sale