D2S

Hello Everybody, I was wondering if anybody could help me with a question I have:
Two weeks ago I changed my front brake discs, from standard to Tarrox G88 I also changed the pads from standard to Ferrodo Racing DS 2500, believing that this would be one of the best options before upgrading the size of the discs.

After having these parts changed as soon as I got on the highway I noticed that the car was shaking quite a lot at high speeds, and if I braked hard at 200kph the steering wheel would shake a lot, ‘I mean a lot!!!’ but this also would happen at 120kph, obviously my first conclusion was that the wheels hadn’t been aligned, and that this needed to be done after changing the discs, so the following week I went and aligned the wheels, the wheels were wrongly aligned so said the mechanic who put them correct, but after taking the car away from the alignment centre I felt the car was fine, obviously it felt like that after before experiencing that big shaking car, but after a few days I feel the car still shakes a little in hard braking, and you don’t even have to brake that hard to feel the shake, one of the test I do is drive at 120kph and take my hands of the wheel, I brake and I can see my steering wheel shaking. I have out ruled the possibility of alignment so it must be something else, and it can’t be the wheel balancing because if it was that the car would be shaking all the time.

Before you ask me any questions let me inform u, I changed the discs and pads not at Subaru, but in another garage due to the fact that Subaru will not fit aftermarket products in Spain, and the car is a WRX01.
I would appreciate if anybody who knows or that has had the same problem or similar one and that has fixed it, that if you could tell me the reason and what should be done in order to make the car drive smooth again. Thank you!!

Dom

Ian D

1) Maybe the discs are warping... does it get worse after braking (ie as the brakes/discs heat up?). If so the discs could be warping.

2) Are the brakes binding due to sticking calipers/sticking pads in the guides? To check brake hard from 5 mph, then go for a drive on a suitable road for a few miles without braking at all and coast to a halt. Fell the temperature of the discs, they should be cool or barely luke warm. If either/both are hot the brakes could be binding on.

3) Have the discs been fitted correctly? If they are not sitting flush on the hubs due to rust or cr*p on the disc inner face then they will be running out of true and may produce the symptons you describe. A runout test with a DTI (dial test indicator) would show up a runout problem.

good luck
Ian

D2S

Hello Ian, I’m not sure what you mean for ‘warping’? do you mean like a bit twisted? I’ll tell you one thing the car does, when the brakes have warmed up, if I brake fairly hard I get this sound coming from the discs, its not a squeaking noise, the noise its like a big ‘Wooooouuuummmm’ and its sounds all along while I step on the peddle,

Tomorrow morning with out doubt I will do that test of touching the discs on my drive to work, and see if they are warm with out having used them.

Now you have made me think that they also may have not fitted them correctly, I’ll do that test tomorrow and start from there, it’s a real pity the car is like that, when before it was very nice and smooth.

I appreciate your help Ian, Thanks!!!

Dom

Ian D

Dom

Warping is when the discs are not not perfectly flat but have a slight twist in them meaning as you brake the pads grip the discs but because they are warped that unevenness is transmitted through the steering. Usually as the discs heat up after moderate/heavy braking the warping gets worse and the steering vibration gets worse. I had this on a Fiat Coupe, the pads were sticking in the calipers and rubbing on the disc even when not touching the brakes and this caused the discs to overheat and warp, but the test in my previous post should check if this is the case..

Ian

D2S

I understand now, well this as you say will be visible tomorrow after the test, so hopefully it’s just that and they have to be refitted and this will solve that problem, I hope so!!!
Thanks a lot Ian, I’ll tell you the out come of the test tomorrow!!!

Cheers!!!

Dom

Ian D

Let us know the outcome...
Usually the brake pedal judders as well if the discs are warped, does yours?

A dumb question, are the wheelnuts are tight!

Ian

stockcar

you make no mention of "bedding" the brakes in.......this is VERY important, and could well be the cause of your problems......the strange noise you have sounds like the pads are "glazed" and are therefore not working correctly!!
just a few thoughts,
alyn - asperformance.com

D2S

Good evening, Today I did that test you told me about Ian, and the discs were a bit warm, not a lot, but they were quite warm, I also took the car down to the garage and spoke with the man who did me the wheel alignment and explained him the situation, what he first did is that he put the car into the DTI and he did find problems with my front left disc, he said this could be caused by over hearting,

Now I will tell you something that when I originally changed my discs at this other garage in Alicante, once they were fitted the manager took the car for a test drive, in which he said has to be done to all cars, to guarantee that the ABS works correctly, to be honest I didn’t like the idea and told him so, but he insisted that this they had to do for legal reasons, anyway he took the car for a run, in which I wasn’t present, and waiting for the ‘*******’ 15min when he came back I said to myself, have a little touch of those discs see how much he has used the brakes, well, I burnt myself, hahaha yes you can all laugh but this is the truth, I went straight for this man and I said what the f’u’ck have you been doing with the brakes, I just burnt myself, he gave all the bull**** that the ABS had to operate and he had to test it hard, well after him doing this and speaking with chap today which told me, that when u have new brake discs and pads, you have to run them in, and you never take the car out for a test drive using the brakes to 110%, so here I have mixed opinions, any of you know what the proper way is, should you test the brakes 110% when u put them new, or should you give it a nice smooth running in?

What this person today said to me is that if this person did this, he could of well, f’u’cked up the discs and pads straight away, so you can imagine how my blood is rushing now in anger, the bad thing is that this garage I had it changed is 500Km from Malaga, where I live, because two weeks ago I was in a friends wedding in Alicante and I live in Malaga so it’s not that easy to go and discuss this matter on the phone, its more a face to face thing, and if the right hand has to be used, then it will. And why did I change it in Alicante you may ask, well the discs and pads had just arrived before my trip and the old brakes were squeaking so I stuck this stuff in the boot and decide to change it up there, definitely not expecting this.

So what I will do tomorrow is have everything checked and refitted, to be sure of the reason or if this person f’u’cked it up in the test drive, and if so I will wip their ***, one way or another, but what most pisses me off, is that I spend €500 in-between discs and pads, thinking this is the best option and then some idiot, garage manager goes and f’u’cks it up, anyway I’ll tell you boys what is the outcome of tomorrow revision of the discs and pads, and will see if they are glazed also?

Cheers everybody for helping!! I’ll keep you informed!!

Dom

Ian D

Dom

Brakes should be broken in gently, I fitted some pads and discs to a Fiat Coupe last year and the sensible advice on the fitting instructions was for the first 100 miles or so regularly brake from 50 mph but not to a standstill (ie brake from 50 mph to 20 mph when possible)and this helps bedding in.

Also note that it does not take much braking for the discs to get very hot to the touch, even regular moderate braking would make them pretty hot if you touched them straight away.

Good luck
Ian

stockcar

normal recomend with new discs (even for competition vehicles!!) is to do a min. of 100-150miles of light to medium braking, then gradually build the power over the last 30-50miles so that you are using full pressure by the time you have finished.......std pads would need the same, however some "competition" style pads require a very aggressive "bedding" process so we always recomend using old pads to sort the discs THEN fit the new pads........
with the set-up you are using then the ds2500 will "bed" with light use so this should of been the course of action!!
never heard of the one about testing ABS.........??!!

alyn - asperformance.com