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since changing over to my brembo's i have been having some problems.
i am having this issue of vibration at the moment, i will wait till later tonight and go out when the roads a clear and do the rebeding process.
60 to 5 , 10 times with a little cooling time in between.
i have bought some new disk anyway so if it does not work for me than i will have to fit the new disks and get the old ones skimmed for next time i need them.
i have checked the current disks surface with a dial gauge and only seem to be able to find a 0.2 mm difference in surface. which i would not have thought would make a massive impact on braking, but i get a really violent judder depending how hot the disks are, and what speed i have been doing.
for instance if i travel at speed X with out braking i get no vibration, then i brake and all feels good.
but if a travel at speed X +20mph i get vibration without breaking as if the pads are dragging on the surface of the disk causing friction heat build up. then when i brake the vibration if really bad.
i have checked the piston movement in the calipers and all 4 pistons operate as expected they slide in an out freely, the larger ones moving before the smaller ones due to the surface pressure difference behind the pistons.
oh well something else sent to test me.
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0.2mm is actually quite a difference. I would guess that would be the problem. The only other thing I could think of would be if the surface of the hub was slightly rusty or uneven and in turn caused the disc to sit unevenly.
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having spent £1500+ on my KAD setup I too have horrible vibrations under braking. If I brake at anything up to 40mph there is no evidence of problems, 40-50mph and vibration is present through pedal and wheel, above 50mph and it's less noticable. At no time is the vibration present without braking and it certainly doesn't reduce the capability as far as I see. I'm not going to pay out another £500+ for discs i that is the issue, I'll live with it thanks.
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ok. Having read this and understood some things and some things not. This is my problem. When i'm breaking there's a noise in the rear brakes which i'm assuming is vibration but i can't feel in the peddle. I was thinking pads are done or something because if i brake hard the abs fails.
Ps my first car. Glad its a vr4. Love it.
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Could be a few things really but the best thing to start with is physically checking the abs ring and all of the braking components.
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ok. But i'm new at this. Abs ring? Would an uneven disc cause this problem? So thereby skimming solve the problem
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I'm never sure it's worth skimming. I'd personally put new discs on. I'd also be checking the bearings.
Noise and vibration are not necessarily the same thing. If you have grooved discs you will have a noise even when everything is perfect. Check the car over, or get someone else to if you aren't confident. It might be you have no problem at all, or it might be you need to get something done quick!
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thanks. Will have it checked.
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Having read this I can see I'm going to have to try to make changes to my driving habits!! I'm in the process of refurbing a set of calipers then fitting good used discs with yellowstuff pads to get rid of the fade i get with the cheap 'suck it and see' pads i currently have fitted. However, as below, this article shows it may not be the brakes fault that they judder and are frankly crap..
Driving an auto has made me lazy and when i come to a stop i keep the brakes pressed on unless it's at red lights, even then i may keep them on. Reading this article has really stressed how important it is to use the handbrake and let off the brakes! Better adjust the handbrake then...
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Ive read that first post several times, its a lot of text to take in! Now my eyes hurt :P Lets see if I understand correctly:
Disc vibration is caused by uneven build up of brake pad material, which is caused by exceeding the pads temperature range?
Once the pads temperature range have been exceeded, skimming the discs will even out the vibration but the pads will still continue to deposit unevenly resulting in the vibration coming back?
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That's a part of my understanding. My thoughts are that the VR4, especially the auto VR4 suffers more because of the pad and disc size, combined with the fact that the brake pedal is often held down after the car has stopped. An Auto VR4 will obviously start moving again if left in drive and no braking is applied.
So I believe that the overheated pad in constant contact with the hot stationary disc is the biggest creator of "warped discs" in the VR4.
