markwild

I'm getting some brake judder on my 335 Godspeed kit - only when braking from above 60... (Standard 4 pots)

If I get some heat into the brakes it seems to help, but soon comes back (same journey) - Also, its not every time, when it doesn't do it the brakes are fine.

There doesn't seem to be any issue with the stopping power, but the judder makes the braking experience pretty awful.

The steering wheel oscillates about a half inch I'd say - and there is no veer off in any direction, simply like a bad wheel balance.

Pads and disks have been on for 2 months - about 5000 miles.
I'm at TSL on Friday for 60000 mile service (which includes renewal of brake fluid (I think)), so I'll ask them to take a look - but if anyone has any ideas what to have a look for, either in the meantime or at the weekend, I'm open to suggestion....

Thanks,

Mark

richiewong

Could be uneven pad build up on your discs.
Some 100+ heavy breaking may help to clean the disc, it may not get rid of the judder but its fun

bigsinky

@markwild.

same for me mate. **** i thought i was the only one. emailed ian godney a week or so ago but no reply. i thought it might be a warped disc but then it would judder at any speed. this only seems to happen when i am trying to scrub off speed from 100+ mph. will keep you informed of what ian has got to say.

@admin
any chance of reinstating ian's scoobynet account?

cheers

sinky

markwild

OK _ I'll post if TSL find anything on Friday... Had a look, but can't see it being pad material, as I can't see any on the disk -

Plus, it doesn't always do it - which is odd...

Mark

ylee coyote

check that the calipers are exactly true and central
My first godspeed set (princess calipers ) were not and I had judder like you describe
cracked the discs eventually !
put on the brembo 335 conversion and took a lot of time shimming them straight and central..
pure braking pleasure

markwild

In what way 'exactly true and central' ? Surely if the caliper is to one side of the disk (within reason), the pistons will simply move to adjust it ?

I guess that if the caliper were offset more at the bottom than the top, this could cause some problems, but even then, I'd expect the pad to wear into the form of the alignment -

Or am I barking up the wrong tree ?

Ta,

Mark

PS _ I suspect that they are NOT central OR true... (e.g. more inboard at the top than the bottom on the O/S)...

ylee coyote

within reason yes
but a little beyond that ,if one or two of the pots are a bit sticky then you are going to get an imbalanced push on the discs..the results of this eventually crack the discs at the interface between the hat and the friction surface
I guess my pistons were a bit sticky too and the combination of the two problems caused the juddering
trueing them will help imho (as well as servicing them...)

awd wrx

Yes it could be sticky pistons if you are using the standard subaru four pots as they are not new , they dont have to be siezed solid to cause problems , if they do not release properly they will overheat the pads or discs , overheating the pads could leave deposits on the discs, you may not see these deposits but its basically a lump on the disc that when they go around the pads go over the lump and moves the steering , by lumps they could only be thousands of a inch which you may not see but would feel through the car at speeds , overheating the discs for long periods of time can warp them , if this is the case its not the fault of the discs as this could happen to any discs

markwild

Thanks for the input - I'll take a look at the weekend - the pots pushed back OK by hand when I fitted the disks, so I figured that they were OK. Interestingly, it didn't do it this morning, even at 100+ (err - on the test track on the way to work...)

Thanks again,

Mark

awd wrx

Check for any play in any bushes , track rod ends or the track control arms as this could cause these problems , if its intermitent then it cant be the discs , if the discs are warped they are warped all the time , you get more shaking the faster you go

TARManiAC

Took my Bugeye with Godspeed 335mm Subaru kit /Ferodo DS 2500 for 4 trackdays now.

First time was to The Ring. Result was a shaking steering wheel when braking.

Next time was to two tracks in Sweden. No problems.

Last one also in Sweden, Knutstorp, also known as The Nurburgring of Scandinavia. This resulted in 4 small cracks in one of the discs. Cracks are approx. 2mm long going from the inner towards the outer of the disc.

Funny thing is that the brakes are working perfect (the last trackday was arranged as a race and I won it) apart from some light jerking when braking on the roads. This eventually disappears with some mileage.

markwild

Just to update this - I've changed my pads, with some help from John Felstead (Well, John did it and I watched ) to EBC Redstuff Ceramics - All is now great...

The old pads seemed to be leaving different coloured bands on the disk - for the different temperatures across the pad (obviously not so compatible with my driving style). Anyhow, the colder areas were leaving pad deposits, causing judder....

The disks were cleaned up with wet wet'n'dry and the new pads fitted (which were standard size, not over-size). After about 200 miles, the disks were a single banded colour where the pads touch the disk...

Mark