Wobbly steering under braking when cold

[Ta2272]

ok i have noticed this problem with my race car, when braking when the brakes are cold it shakes the steering wheel around like hell.

I have only had the car on the track twice but i am looking at doing sprints and hill climbs in it, and seeing for most of these i will be starting with cold braking i have a problem on my hands.

The car is a datsun 1600 with Vr commodore brakes all around, with vented disks sizes to suit.
Brake pads on the front are Greenstuff.

I think that the only thing thats needs to be changed are the pads, as possibly the greenstuff doesnt respond well when cold.

Any Ideas

Jason

[oldcorollas]

brake shuuder is usually uneven transfer of resin from pad to disc... perhaps try the ned in procedure again and see if it clears it up...

or ask on performance forums brake section..

[gianttomato]

Get rid of the Greenstuff.

[86TT]

Get rid of the Greenstuff.

Agreed...Greenstuff has a lousy rep .

[faulksy]

look at the pads and see if they have uneven wear. while they are out try another set of pads. if continues many your discs need a machine.

[takai]

Money is on the Greenstuffs, especially if you have slotted rotors.

[Ta2272]

it only happens when cold,

[Squid]

look at the pads and see if they have uneven wear. while they are out try another set of pads. if continues many your discs need a machine.

Wouldn't warped discs continue to effect it once it has warmed up? Certainly does in my house mates subaru...

[myne]

What's the wheel alignment like?
Worn tyres from positive camber can lead to wobbles, though it should also suffer speed wobbles.
Is it possible that cold tyres could be resisting, but as they warm up, they flex more and the problem goes away?

[Ta2272]

It has very sticky rubber racing semi slicks,

here is a link to a website for the car

http://www.crombie.com.au/thecar.htm

[myne]

They're not sticky when cold though. When cold they'd be quite solid, as they warm up they become almost a fluid. Have you tried doing a few laps without braking and then trying the brakes? That'd rule out tyres/alignment

[Ta2272]

yeh i can try that, i guess it also could be tyre pressure as for a hill climb we would start with much higher pressures and for track u start with a lower pressure.

[oldcorollas]

Get rid of the Greenstuff.

i was going to say that but i thought i'd be polite nah, jk..

greenstuff seems to have a reputation for poor resin transfer, and results in brake shudder that many people often mistakenly identify as warped discs.
read about greenstuff on Performance Forums, and take note of DBAsteve and Dattoman?'s posts..

but they generally recommend to redo the break in procedure to try and even out the resin, and if that fails, clean discs with emery paper or whatever.. and if it comes back, change pad.
ferodoDS2500 seems to be recommended often...

i don't know myself tho


oh, did i mention you car is sexy!

[faulksy]

Wouldn't warped discs continue to effect it once it has warmed up? Certainly does in my house mates subaru...

Depends on the level of warping. Effects are always going to be more noticeable when the brake pads are hard and cold causing jarring on the disc. However, reading what people what said it seems that the brake pads are the most probable cause at this point of time

[Mr DOHC]

if u wanna try a cheap alternative for some testing, get the brand "race brakes" GSA wholesale sell them in slacks creek, they are worth like, $35 bucks a set, but alot of ppl swear by them