Steering judder when braking - help

[jason]

Ok this is begining to really annoy me and I need to get to the bottom of it.

I'm getting really bad juddering through the steering wheel when on track and the brakes get hot. Its so bad it is really spoiling the day and ruining my confidence going into corners - any suggestions?

For the record...

Car is on new brake fluid and new discs....it did it before I replaced the front discs...and its doing it again after replacing.

I've tried braking very late and very hard and less hard much earlier and neither makes any difference.

I always warm them up over first lap or two and always have a full cool off lap where I don't touch them (and it doesn't sit in paddock on the handbrake).

I've done various track days in various other porkers and never had this problem?

 

[peanut]

sounds like either your disks or the pads might be glazed . or the disks may be warped ?
might be worth trying some differant pads .
I take it that you have checked all the wishbone arm,steering rack bushes ,tie rod joints and suspension mounts etc for free play .

 

[Stewart H]

Jason. Did you put in new pads when you changed the discs? It sounds like warped disks but if they are new, you can't have abused them that much yet. It could also be a caliper which needs rebuilding - one piston could be sticking.

 

[Keith Calder]

jason easy answer with mine was swapping the pads, i found standard porsche textar pads melt on the track and leave deposits on the disc causing judder. when it first started i thought discs were warped and had ninemeister fit a new pair and after the next trackday the judder returned so swopped to crossdrilled discs, same problem, finally fitted performance friction pads and problem solved. i only have standard C2 calipers but sounds like you have the same problem, sanding the discs should cure it for the road tho. i did find a website that gave good advice ill try and find a link for you

 

[Keith Calder]

here it is
solved my judder
http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

 

[jason]

Thanks all - they are pagid blue pads and they were the same ones before and after the discs were changed? Do you think it could be these? I don't get it on the road....guess they don't get hot enough?

 

[rs phil]

i had pagid blues on m3 sport evo before and had similar problems,pagid yellows are way better rs 29,although i am running trickstuff blue all round now and find these better than the pagid for half the price,if your discs aint warped it has to be the pad,i think you might feel worn bushings without braking,like when you hit kebs and bumps etc,i hope

 

[George Elliott]

Jason, keep us posted pls - I wish I could help but I have the same problem. Just as you say - when they get hot (even on the road - rumble, rumble etc)
Not sure what pads I have fitted, - I did not fit them.
George
944t
964rs

 

[jason]

Rob houslow has the same problem too and he is running same pads and set up as me. Be interesting to know what pads you are on George

 

[Keith Calder]

quote from stop tech website

In fact every case of "warped brake disc" that I have investigated, whether on a racing car or a street car, has turned out to be friction pad material transferred unevenly to the surface of the disc. This uneven deposition results in thickness variation (TV) or run-out due to hot spotting that occurred at elevated temperatures.

 

[964rsdatabase]

Jason, I had the same sort of problem late last year and mine turned out to be a knackered steering rack end. Hope yours isn't the same problem as a new RS rack wasn't cheap! But it did solve the problem.

 

[964rh]

I'm running Pagid Blks rs14's now Jason but as you know it's still there.

Didn't swap the front discs when I put them in so doing that tomorrow, going to make sure the hub surface is sparkling as well.


I'll let you know how I get on.

 

[Melv]

New discs? New pads!!

 

[smallspeed]

had a similar problem with padgid pads in one of my previous cars, and swapping back to standard pads cured the issue after a bit of driving.. went with mintex pads in that car and the problem didn't come back; I thought at the time maybe the padgid pads deposit bits of material onto the surface of the disk which makes the brake pads "grab" at the disks when hot..

ben

 

[pncarrerars]

Also check that your hubs and/or stub axles are not out of true. Mine were & replacement cured the judder.

Pete

 

[Tony]

Lots of good advice already posted but one or two other things to consider.
1) are the discs on the correct side? silly I know but it does make a difference
2) are the discs running true? even if the discs aren't warped if the hubs are damaged, discs aren't seated properly or there is undue bearing where the won't run true when fitted.
3) Front end geometry correct, bushes and bearings sound

The fact you've still got the problem after new discs would suggest these might be areas to look at.


Tony

 

[PhilRS]

Jason, check that the calipers themselves are working properly. If one of them sticks, and if they stick asymmetrically, then you might get judder. Had this on an Audi S8 (which BTW uses the same Brembo calipers as 911s)

 

[Matt]

Chaps

Interesting to hear I'm not alone in having this problem too.
The first set of front discs i had were replaced due to the cracks finally meeting from the drilled holes. OEM Porsche items. Ran with Pagid Orange.

New OEM discs fitted, lasted a few days only then juddering started. It got so bad on track that it drove me to dispair - although it became less pronounced when the brakes got really hot.

I got the discs skimmed at GT1 (fairly cheap) as whilst I don't believe they were warped it got rid of the uneven deposits which seem to be the issue reading all the articles.

Once skimmed problem solved. Been runing a set of standard oem pads due to running out on track, and whilst the pads have lasted 2-3 track days there has been no juddering..

Spent ages on the phone with the chap who supplies my pagids. he has never heard of this before and phoned pagid to check if they had. Apparantly not. Like Jason I cool the pads down every time, and also make sure I bed them in properly.

I am planning therefore to change to Pagid Yellows and to see if theres any issues with them.
The only thing I can point to is either the discs have changed somehow (they don't seem to be cracking around the holes like the last ones), or there has been a dodgy batch of pagids.

i'll let you know how i get on with the yellows.
Jason - try getting the discs skimmed as a first step - will be the cheapest option i think

Matt

 

[tim court]

Jeez this is real back to basics stuff imho.

Discs don't warp - fact.
As with a lot of track driving the harder you go the hotter they get and when they're outside their operating range you end up with judder.

As Mel spotted putting your old pads back didn't exactly help matters....

Clean the uneven pad deposits which cause the judder off your discs (bit of wet and dry) and move up a grade on your pads. Assuming you have decent fluid RS4-4 Orange is probably not enough of a step so you could try RS14 Black (not RS4-2-1 Black) or RS15 Grey (sure I have read these are a bit hard on discs) or go the whole hog and try the wooden RS19/29's (but with your light car you may end up back where you started!)

Or change to a decent pad [] - (again imho) Performance Friction are fantastic! (for a GT3).

 

[jason]

Ok I'm starting to believe its the pads! It would explain the juddering feeling and also only when really hot as theres probably not enough to give impact under road braking yet being new discs.

I'll clean the deposits off and change them.

Running top fluid so thats not a problem.

Performance friction pads seem to be recommended......someone tell me where or give me a link[]