Skyline Braking Issue

[stranger12]

Hi All,

My firs post here so hi all:)

I am in the UK and have recently purchased a skyline r34 gtt .

I am well pleased with it but have few questions .

when brakingfrom 50mph upward the wheel vibrates badly , does anyone know why?

I think it is warped disc as it shakes and have an off and on feeling when coming to stand still at traffic lights.

I have checked the front tyres and one side have a very small ball joint play but that will not cause such a huge vibration .

Many thanks

[Trex]

what thickness are the rotors? You may be able to have them machined.

[stranger12]

so do you think it is the rotor ? I am not sure it should be standard rotor.

[Trex]

if they're that bad you can spin the rotor and feel it sticking at certain points.

[GTSBoy]

And rotors warp so seldomly that it is not going to be a warped rotor. It will be irregular deposition of pad compound on the rotors. Usually caused by braking hard then sitting at the lights with your foot on the brake pedal. Or by letting the wife drive the car (I don't know how they do it!)

[MrStabby]

Check the rotor first, but it can be other things like radius rod bushes. ^ good point about it sticking at certain points. If you get that, take the rotor off and clean the rotor and hub mating surfaces until they're perfectly clean. Might as well get the rotors machined while they're off as long as they have enough meat. I'd guess it would only be 5 pounds (euros?) each for that.

Do you have a dial gauge and calipers that can measure thickness over the lip that's typically on the outside edge of rotors? If so you may be able to avoid the rotor machine with the right measurements.

[Trex]

And rotors warp so seldomly that it is not going to be a warped rotor. It will be irregular deposition of pad compound on the rotors. Usually caused by braking hard then sitting at the lights with your foot on the brake pedal. Or by letting the wife drive the car (I don't know how they do it!)

Disposition?

Have to agree and disagree, the newer civics had a problem with warped rotors within 30k. The pads were causing the warped rotors. But that could have been bad rotors to begin with and a cheap fix would have been different pads.

[Trex]

Check the rotor first, but it can be other things like radius rod bushes. ^ good point about it sticking at certain points. If you get that, take the rotor off and clean the rotor and hub mating surfaces until they're perfectly clean. Might as well get the rotors machined while they're off as long as they have enough meat. I'd guess it would only be 5 pounds (euros?) each for that.

Do you have a dial gauge and calipers that can measure thickness over the lip that's typically on the outside edge of rotors? If so you may be able to avoid the rotor machine with the right measurements.

Being a timber machinist now, verniers are invaluable. Wish i used them more in mechanics than the old tape measure.

[GTSBoy]

Disposition?

Definitely deposition. As in from the root word, deposit.

Crappy 18mm thick shitto FWD rotors might warp, but thumping huge 30mm thick rotors have a much harder time doing it.

[Dobz]

Check for play in the wheel bearings too.

[Trex]

Definitely deposition. As in from the root word, deposit.

Crappy 18mm thick shitto FWD rotors might warp, but thumping huge 30mm thick rotors have a much harder time doing it.

you're right. All these big words make me confused.

[stranger12]

so check wheel bearing and rotor.

I could clean the rotor to see what difference that makes .

what size are the uprated gtr ones so can buy those as I am buying them anyway rather than machining etc .

would you get the drilled ones ?

[warps]

And rotors warp so seldomly that it is not going to be a warped rotor. It will be irregular deposition of pad compound on the rotors. Usually caused by braking hard then sitting at the lights with your foot on the brake pedal. Or by letting the wife drive the car (I don't know how they do it!)

Very likely this. Although warped or incorrectly seated rotors can cause uneven wear, which also contributes to uneven thickness of the rotor (google brake rotor DTV). When seating a rotor, it must have a face runout of less than 0.1mm (0.004" for us old farts and you poms) which you cannot see by eye. You need a dial gauge to set up the rotor properly, which I guarantee most mechanics will never bother with. I've experimented with rotor assembly, and a tiny speck of dirt under the rotor can be enough to cause excessive runout.

Don't get cross drilled rotors - you don't even see too many race cars using them anymore. Guaranteed to crack. Slotted are OK as long as they are a proper performance rotor, not just a "top shelf bling" version of the standard road rotor (some manufacturers found their slotted rotors performed worse than their blanks).

[sonicz]

Make sure all bushes are in good order especially radius rod bushes, i.e the ones ones that keep the caster in check. They are the huge massive ones sitting low at the front of the car and they have a big role in keeping the suspension components tight under braking. Either go poly bushes or this is a good time to fit adjustable caster rods if thats your thing.

Make sure all ball joints especially the steering rack ones like the tie rod and tie rod end are in good order and have no play.

Now, change both the front wheel bearings, preferable use genuine. THEN At the same time this is being done, get the brake discs machined and fit new pads. Hand in the air "I swear I will not kill anyone" pledge, problem solved.

I have gone a lot of my life with theese types of problems, and its almost been bad bearings no one will tell you about. Mechanics will just always go to "machine discs", but then they vibrate again after a few months, machine discs, vibrate again, machine discs, vibrate again, brake squeal, new pads, bed in, few months, sequel again, machine discs, new pads, vibrate again, sequel again.

In my case at least its always been bearings causing play, and the problem has always been fixed by new bearings as long as everything else is on order, even though I was always told bearings are fine. I never realized how easy is it for bearings to have play in them and cause problems, most people will tell its obvious if your bearings are bad, in other words if its not making a humming noise and you cant feel play in the wheel then its fine. Its not the case. Bearings can be bad without you knowing.

Or by letting the wife drive the car (I don't know how they do it!)

Haha, so true. I noticed this exact same thing a long time ago. It seems to apply to women of all ages, elderly people or people not into cars. My guess is its because they go over kerbs and bumps at massive speeds without slowing down especially when they are alone. You would not believe how fast they take obstacles if you saw them alone.

They also press the wheel against the kerb when turning and keep turning without realising how much pressure they are excreting due to power steering and that they are up against a kerb,

They accelerate like crazy just to close a 100m gap when approaching a red light with cars stopped at it, even though they can clearly see the cars and red light, just to brake like crazy just seconds later, barely stop right against the car in front of them, then just sit there with the brake pedal still as firmly mashed down as when they were stopping, until its go time again.

Repeat x100 per day. Has its toll.

Edited April 18, 2015 by sonicz

[stranger12]

Today i was driving in motorway and brakes were bad almost no braking power and the pedal felt softish

I dont think it needs bleeding rather disc is gone bad time

If i am to change it , i want to get the bigger routers and set of pads

Looking around it seems my rotor is 310mm , and gtr is 324

Is it a direct fit?

[GTSBoy]

Today i was driving in motorway and brakes were bad almost no braking power and the pedal felt softish

I dont think it needs bleeding rather disc is gone bad time

If i am to change it , i want to get the bigger routers and set of pads

Looking around it seems my rotor is 310mm , and gtr is 324

Is it a direct fit?

Oh. I totally disagree with the concept of linking the first 2 lines of your post. Even a disc that is worn to below minimum thickness will not cause you to have "weak breaking power" (to paraphrase your post as a statement in other words). Poor braking effort is almost always a hydraulic problem or a pad problem. If the discs are massively grooved, then maybe they might cause you grief. But not otherwise.

And no. You cannot fit 324mm rotors under you caliper. Think about it.

[Trex]

Unless you get spacers for the caliper. But I find that kind of redundant as the pad will only contact the same amount of rotor as the smaller rotor.

Also I agree 100% with gts as many people have said that standard skyline brakes are more than capable with good pads, fluid etc

[Ben C34]

You can't space a calioer out by that little amount. The bracket would be mental.

[Trex]

Forgot it was a 34 he had. But you can get them for the 33 http://www.gktech.com/index.php/r33-gts-t-caliper-bracket-to-suit-324mm-r33-gtr-rotor-1.html

Am I correct I. My thinking that they would be almost useless? Minus heat transfer

[stranger12]

So change disc then only ?

Would 15 mm give any noticeable improvement?