Steering Vibration Conundrum

[ukkid35]

My car has never suffered from steering vibration, but suddenly I have a problem.

The only change I made was to replace the front brake discs, but sadly I dropped off the old discs at the tip before realising I had an issue (so I can't refit them to rule out the new discs).

I have changed everything at the front of the car within the last 12 months, all bushes and thrust washers, and I've just checked all suspension bolts. I found one of the steering rack bolts was loose (tightening it has helped somewhat). I've had all four wheels balanced, but the vibration issue is still present.

It is easily prompted by using the brakes lightly, that sets up a horrible harmonic. But I can still feel a vibration through the steering wheel without braking at about 90mph while coasting out of gear.

I can't believe the new discs can be the culprit, that just seems absurd. But I'm out of ideas so any suggestions are welcome.

[portzi]

So vibration at 90 mph and braking makes it worse, yes?

1, Assuming all you steering is nice and tight the UJ's connected to the steering splines are also nice and secure. Have you grabbed each front wheel first whilst off the ground and given it a good shake to check any movement or play?

2, l had a new set of discs which warped within a month, pagid branded so will never buy again, running Bosch now and all fine.

[QBee]

It does sound like the disks to me.

Ask Chilliwhizz about new brakes causing horrible vibrations if you have a spare hanky and a couple of hours.
He fitted a complete new set of front brakes (well known and reliable make) and had horrendous brake judder and steering vibration issues thereafter.

For others suffering this, the other possibility, though you have had this checked, is to check you haven't thrown one of the stick-on wheel weights off.
I used to lose them regularly, so now I gaffer tape them in place before I leave the tyre depot.

[Englishman]

Does sound like out of true disc(s), but did you also check that the calipers operate freely and the inner part of the caliper is not stuck? Can result in only the outer pad actually pressing on the discs?

[ukkid35]

Replaced the new discs with a well used pair donated by another owner - vibration gone. Now awaiting refund from the vendor.

[TvrJohn]

Earlier this morning i was talking to a local garage which has the on car disc brake skimming capability, they said they often have BMWs in that have had new discs, but often need skimming on car to eliminate braking vibration.

Something to consider, as i am currently

[QBee]

Brake disc manufacturers should be lined up and flogged with braided hoses.

I bought a pair of new front disks, well known make, for my Saab. One fitted perfectly. The other had the holes drilled in the wrong places, out by about a centimetre.

[robsco]

Paul, could you perhaps PM where you purchased the discs? I am having the same problem with a set of very recently fitted discs and pads, I have had all other avenues checked and all is well. It didn't vibrate on the old discs.

[ukkid35]

robsco said:

Paul, could you perhaps PM where you purchased the discs? I am having the same problem with a set of very recently fitted discs and pads, I have had all other avenues checked and all is well. It didn't vibrate on the old discs.

Actually I can't, the PM link is broken on your profile. Can you PM me instead and I'll email you.

[robsco]

ukkid35 said:

Actually I can't, the PM link is broken on your profile. Can you PM me instead and I'll email you.

You have mail.

[portzi]

QBee said:

Brake disc manufacturers should be lined up and flogged with braided hoses.

I bought a pair of new front disks, well known make, for my Saab. One fitted perfectly. The other had the holes drilled in the wrong places, out by about a centimetre.

Wow 10mm is really poor quality you say you bought a well known make but were they expensive?. I bought pagid which is a well known make, as a good mid range priced set of discs after 2 track days and spirited road use they were warped?

[QBee]

Mine were Mintex. We would have taken them back, but they were bought as the factors were closing for the night, and by the time we realised, it was 6.30 pm and I was 80 miles from home, so the garage proprietor re-drilled them. They have otherwise been fine, done 17,000 miles on them so far.

[taylormj4]

I had this after a few 1000 miles with EBC brake discs. I understood that they could harden differently due to uneven heating of the disc. This creates hardenned spots that don't wear at the same rate as the rest of the disc, which then cause high spots that overheat during braking, which worsens things. There was lots on the forums about it at the time.

[ukkid35]

taylormj4 said:

I had this after a few 1000 miles with EBC brake discs. I understood that they could harden differently due to uneven heating of the disc. This creates hardenned spots that don't wear at the same rate as the rest of the disc, which then cause high spots that overheat during braking, which worsens things. There was lots on the forums about it at the time.

There is a similar issue highlighted by StopTech, pad deposits causing vibration when braking.

http://www.stoptech.com/technical-support/technica...

However this was different - Vibration from new, when coasting not braking, but exacerbating by light braking, and going over bumps.

[Sardonicus]

Dont dismiss the fact that sometimes the hub flange are not always true and no quality of disc will cure that one (Ford, VAG & BMW) both spring to mind on this one and you wouldn't believe the times I have had disc run-out and vibration to sort mainly on euroboxes to be told by the owner that they DIY fitted them and that the faces were spotless inc any corrosion/scale only to remove said brake disc and finding out different never had to back a Pagid disc yet but returned a few sets of Mintex and ATE would you believe and usually just one is the culprit many of us dont check run-out on the initial fit and if any will only get worse with use and heat

[hardtailer]

Agree to the above.
Overtorqued wheelbolts (with an airgun and then 'torqued to spec' using a torque wrench...) causes the flange to distort. Probably during service of the old disks.