Vibration Under Light Braking...

[russj]

My son recently bought a '99 IS200 Sport with about 100k on the clock.

It had a fresh MOT but soon developed a vibration through the steering wheel on light braking.

After a while he got fed up with it so I helped him replace the front calipers, discs and pads which seemed to cure the problem.

Much celebration and back slapping all round!

However, 3/4 thousand miles later, the vibration has reappeared

He's bringing the car down this weekend for me to have another looksee.

Apart from the obvious possibility that something's worked loose, has anyone got any idea of another source for the problem?

Might be suspension related I suppose but can't understand why replacing the brakes fixed it temporarily...

Any help would be much appreciated.

Russ

[kam05]

Are the wheels balanced properly?

Also when you fitted the new discs, did you clean the hubs properly?

Car could have developed a sticky caliper?

[russj]

Are the wheels balanced properly?

Also when you fitted the new discs, did you clean the hubs properly?

Car could have developed a sticky caliper?

Thanks for your reply.

The calipers were brand new Budwegs, so I hope they haven't failed already!

Tyres are new and balanced, with no vibration at speed so I think they're OK.

I think I cleaned the hub surface but can't honestly remember. If this was the problem I'd have expected it to be obvious as soon as he started to drive the car, rather than surfacing some time later?

Russ

[kam05]

What brand of tyres are on the car?

I've been told that cheap/budget brand tyres are impossible to balance.

[dazz32]

Check that the wheel nuts are tightened to the correct Torque settings its about 110 Nm i believe ..i think its in the knowledge section on LOC

Or check that the HUB itself is not warped...

[TigerFish]

Agree with some of the above, check the torque settings on the wheel nuts and that they were done up in the correct pattern. Also check the caliper slide pins are sliding freely. If the slide pins are sticking, that can cause the caliper not to release fully and have a similar effect to a sticking caliper. All the work previously done may have freed the pins enough to work fine for a while.

Some info on the slide pins in this tutorial I did.... clicky

[russj]

We took the car to the local Lexus dealer and a tech took it out for a test drive.

He diagnosed warped discs caused by me not cleaning the hub before installing the new disc.

He said it was a common problem and they now clean down the hub with emery paper first to ensure no rust is present.

What happens is that the disc doesn't run true and quickly develops hotspots as the brakes are used. This in turn causes the disc to warp after a few thousand miles.

Rather then replace virtually new discs, we're going to get them skimmed in situ which ought to eliminate the warp.

I'll let you know how we get on!

Russ

[Solhatt]

Check that the wheel nuts are tightened to the correct Torque settings its about 110 Nm i believe ..i think its in the knowledge section on LOC

Or check that the HUB itself is not warped...

It's 103 Nm

[dazz32]

We took the car to the local Lexus dealer and a tech took it out for a test drive.

He diagnosed warped discs caused by me not cleaning the hub before installing the new disc.

He said it was a common problem and they now clean down the hub with emery paper first to ensure no rust is present.

What happens is that the disc doesn't run true and quickly develops hotspots as the brakes are used. This in turn causes the disc to warp after a few thousand miles.

Rather then replace virtually new discs, we're going to get them skimmed in situ which ought to eliminate the warp.

I'll let you know how we get on!

Russ

Glad you found out what the problem is..how is the car now did you get the brakes skimmed and the hub cleaned...

[dazz32]

Check that the wheel nuts are tightened to the correct Torque settings its about 110 Nm i believe ..i think its in the knowledge section on LOC

Or check that the HUB itself is not warped...

It's 103 Nm

Myself and WIM use 110nm but hey 103 is fine not much in it...

[russj]

We couldn't find anyone in Norwich who could do it on Saturday, so my son is going to find someone in Leeds to sort it this week.

[dazz32]

Keep us updated.. :)

I guess because the disc`s are floating disc`s that the surface has to be completly rust free and smooth when you put the wheel back on as thats the only way the disc`s are held flat ( apart from being held by the calliper itself )

[fil4362]

I wouldnt get the discs skimmed. It takes wear surface of them. Depending on how much they have to skim to get them back straight they could end up 1/4 worn when finished. A high spot will show up on a brake disc as a blue spot on your disc. If you cant see a blue spot chances are you did what i did a few years back on a turbo car i had. I got the brakes nice and warm braking hard. I then drove through a puddle instantly cooling the brakes it buckled them to death. These were drilled and grooved brakes and only been on about 1000 miles i returned them for full free replacement. i have been a mechanic/mot tester 20 years and have never once cleaned a hub before fitting a disc and never once had this problem cause a new disc to buckle. personally if i had bought a set of discs and they buckled within 12 months i would be sending them back. My garage warrenties any part for 12 months and 12,000 miles we simply send them back to supplier and claim our labour from them.

[James Marks]

I've had exactly the same problem, as I'm sure many IS200 owners have, which was cured by cleaning up the hub faces before fitting the discs.

In reference to the post above, as a mechanic, you should always, always be cleaning hub faces before fitting discs!, and it certainly can cause problems if you don't with corrosion, and indeed various bits of dirt and gunge which will have been caught there and disturbed during the removal of the old discs, not allowing the discs to sit flat against them.

It is also common (but not always done) to put a light smear of copper grease on there as well (very light coating and smeared around to stop the grease itself holding the disc away too much!) to stop the discs from becoming corroded to the hub!

Not trying to start an argument or anything here, honestly :)

[fil4362]

Never have cleaned or greased behind a brake disc. Never had a problem not doing it. I must fit at least one set of discs a week over 20 years thats a whole load of discs i have never had a problem with. Besides the first post said the brakes were ok for few thousand miles.If the disc were not sitting straight there would have been a wobble from day one not from few thousand miles after. Once the wheel is on its clamps the disc to the hub so no dirt is going to get behind there and any water ingress is burnt of when brakes are hot.

Like i said i have never greased or cleaned behind a disc and never had a problem, maybe its luck, but if its luck i better play the lotto this weekend.

[russj]

Sorry its taken me so long to update this but my son has been living with the vibration and juddering and has only got the car sorted this morning.

A place in Halifax skimmed the discs on the car for £40 per wheel and all is now OK. Whether this lasts, only time will tell... I'll let you all know in due course.

Obviously everyone has their own views on the cause and cure for such issues and I certainly wouldn't hold myself up as an expert.

We were told by the mechanic at Lexus in Norwich that failing to clean the mating surface was a frequent cause of juddering a few thousand miles after replacement. The disc running out of true develops hot spots which can cause it to buckle slightly, so causing the judder. A skim on the car compensates for any hub/disc mismatch and only takes off a very small amount of metal.

In addition, Brake Parts UK who supplied the discs, calipers and pads, specifically exclude this problem from their warranty as its deemed to be operator error rather than manufacturing faults.

If I was doing the job again I'd make damn sure that the hub was clean and flat - well worth spending a few minutes over in my opinion rather than extra expense and faff sorting things out later.

Russ

[fil4362]

Well i have been an mechanic for 20 years my foreman has done 18 years and my just qualified apprentice has done 5 years. thats 43 years between us, non of us clean brake disc mounting flanges, on any car when fitting new brake discs and certainly dont grease them. Never had it cause a buckled disc yet. If it has caused a buckled discs why didnt it buckle the repalcement set??,or am i just lucky??

As for the company brake parts uk what make of brakes did they supply i stopped using that company 5 years ago as all the products i got from them had a picture of a mouse with big ears on the box. i have used there parts many times and always end up with 30% coming back with squeeky brakes so now i dont use them.

[russj]

Well i have been an mechanic for 20 years my foreman has done 18 years and my just qualified apprentice has done 5 years. thats 43 years between us, non of us clean brake disc mounting flanges, on any car when fitting new brake discs and certainly dont grease them. Never had it cause a buckled disc yet. If it has caused a buckled discs why didnt it buckle the repalcement set??,or am i just lucky??

As for the company brake parts uk what make of brakes did they supply i stopped using that company 5 years ago as all the products i got from them had a picture of a mouse with big ears on the box. i have used there parts many times and always end up with 30% coming back with squeeky brakes so now i dont use them.

Actually, I was wrong. The parts came from Brakeparts.co.uk, the other company was out of stock. The discs and calipers were "Budweg" and the pads Mintex.

I've been messing around with cars for the last 40 years and this is only the second time I've come across this problem. I can only assume its because the discs are not bolted to the hub in any way. My Z3M Roadster had a similar problem which I resolved by having the discs skimmed but off the car.

Both use vented discs so perhaps they are more prone to warping? The guy who did the work on my sons car said that he often did this work on Lexus 200, Rover 25 and a couple of other models which I forget.

I guess people can read the thread and make their own mind up about what to do. As I said I'll let everyone know how long the fix lasts in due course.

[russj]

As promised I'm letting you know how the cars getting on.

Well, several thousand miles later (both motorway and around town journeys) there is still no trace of brake judder.

I'd be pretty confident in recommending an on-car disc skimming session if you're plagued by braking vibration.

Hope this helps someone...

Russ