16 replies to this topic

[Cerberus]

1992 Rover Mini

Standard 8.4" discs with EBC Ultimax pads

 

I've had this issue since buying the car, solved for a bit after fitting new discs but it keeps coming back.

 

I originally bought a new set of discs and pads from Minispares to try and get rid of this vibration.  Put them on, and I think it was ok for a bit, but then came back.  Took it to a local mini place, and they ran the discs up on a lathe to check the run out, which turned out to be well over the maximum, also found out my drive flanges weren't quite flat either, so they skimmed a touch off them to flatten them out too. Bought a new set of discs from them and refitted everything.

 

Problem seemed to clear up then, but it came back after a few hundred miles, and steadily got worse.

 

It only seems to happen under light braking, if I press the pedal harder, it's fine, plenty of braking and nice and straight, but under light braking, like gently slowing down for a junction or whatever under normal driving, the wheel really vibrates.

I know my column bushes are pretty worn, as when the cars stationary, I can move the steering wheel about (up/down and left/right), and I can see the inner shaft moving but not the outer one.  I'm going to look into changing these and getting them sorted soon.

 

I've had the wheels off and worked the calipers, which are refurb'd ones bought from here about a year ago, the pistons still look brand new and they move easily and pretty evenly in the caliper.  The pads don't seem to be binding either.

 

Going to be checking the run out on the discs in the next day or two to see if the discs have warped.

 

The engine steady bushes were replaced about a year ago, and both still look fine and there's hardly any play when trying to rock the engine.

It's got Minispares adjustable tie rods, with the rubber/poly bush setup, and adjustable lower arms with the offset bushes.  Nothing looked broken when I had the wheels off the other week, and the tracking is about right, it may be a little too much toed out on the fronts but not by much.

The u bolts holding the rack all seem okay, and the pinch bolt at the bottom of the column is not loose.

 

 

I'm after any other suggestions of things to check while I'm at it, other ideas on what could be causing this as it's getting annoying and I'd like to get it sorted.

[sonikk4]

With the bushes worn in the steering column this will transmit any vibrations that much more. I think checking the discs for run out may well be the right direction. There have been a few members who have suffered with disc's warping with very few miles on them. I'm getting vibration on my 7.5" set up and they are less than five hundred miles from new.

[Cerberus]

I did think it could be the column bushes exasperating any smaller vibrations, but my Dad thinks something else must be amiss to cause a vibration in the first place, it really does wobble the wheel, whatever it is, the column bushes won't be helping though.

 

Going to have to sort the column out, is it an easy job, not looked into it much yet apart from seeing a few threads on here.

Edited by Cerberus, 13 June 2013 - 06:40 PM.

[sonikk4]

It is relatively easy. Drilling off the old mounting bolts can be a pain but once these are off then its a case of stripping off the indicator stalk etc. disconnect the ignition barrel as well. loosen the steering wheel to make sure it comes off easily but leave it on. Then release the pinch bolt at the bottom of the column. You may have to open the pinch slightly then tug the column out. (hence leaving the steering wheel on)

 

Once the column is off grip the outer barrel of the column and pull the core out. On your model you will have a nylon sleeve at the top and the bottom. The old style ones like mine has a felt bush at the bottom.

 

Then its a simple case of putting it all back together again. It is that easy, done both types now and the last one took me about an hour to strip, rebuild and refit.

 

You will need two good quality bolts to replace the items you have had to drill off.

 

I'm not sure if your year of car has a Air bag fitted. If so then follow the instructions in the Haynes manual carefully.

[Cerberus]

Thanks, sounds easy enough.

 

No airbag on mine, so that makes it even easier

 

 

My Dads confident on doing it as he's just refurb'd the column in the TVR, so we should be ok, hopefully,

[sonikk4]

The worst job is drilling off the two shear bolts. i used a high speed grinder and oval burr to sort mine out on Paddy. The pinch bolt can be a pain but i used a small wedge to gently open the pinch and this worked a treat.

[miniman24]

Im having the same problem, have had it pretty much since I drove the car 200 miles home after buying it, pretty heavy wobbling of the steering wheel left and right under any braking except very heavy - 7.5" discs on mine too, around 3000 miles old. I have heard of it happening with some discs from new, do you reckon the discs are going the same way as the ball joints, worse quality and sloppy manufacturing procedure? I was lucky to come across a set of NOS 7.5" discs for a very good price on here which are waiting to be fitted which I hope solves the problem as my tracking is knocked out any time I brake slightly harshly.

[sonikk4]

Im having the same problem, have had it pretty much since I drove the car 200 miles home after buying it, pretty heavy wobbling of the steering wheel left and right under any braking except very heavy - 7.5" discs on mine too, around 3000 miles old. I have heard of it happening with some discs from new, do you reckon the discs are going the same way as the ball joints, worse quality and sloppy manufacturing procedure? I was lucky to come across a set of NOS 7.5" discs for a very good price on here which are waiting to be fitted which I hope solves the problem as my tracking is knocked out any time I brake slightly harshly.

 

I would like to hope not. I have been really careful with my discs, no harsh braking etc so time will tell.

[jaydee]

Fitting new discs wont cure your problem, is clear that your problem doesnt lie in the discs, and that they now can be run out of true as a consequence of un-even braking and violent juddering.

At first check that the pisonts are all moving freely and are not sticking.

Then you need to investigate wheel bearings and caliper bolts torque (40lbs) these are more likely the cause of your vibration under braking.

[Cerberus]

Pistons are all moving freely.

 

I'll check wheel bearings, but there's no other symptoms of wheel bearing failure and the caliper bolts should be tight, I'll check them anyway.  Thanks for the suggestions.

[jaydee]

They dont have to be tight, they have to be all at the same torque, 40 lbs, and change those pretty useless old washer springs.

Wheel bearings couldnt make any noise if causing judder only under braking conditions, in that case its just a strip down and inspect for any suspicious wear.

 

 

Really use a torque wrench for caliper bolts and drive flange bolts, dont trust the people saying 'ive done that ******* tight for 30 years and had no problem!'

Edited by jaydee, 13 June 2013 - 09:28 PM.

[Cerberus]

All was done with a torque wrench when I renewed the calipers and discs, so unless they've come loose, they should be the correct, as I say, I'll check them anyway.

 

Just out of interest, what would have to be wrong with a wheel bearing to cause juddering under braking?  Would it be wear allowing the disc to move side to side, like if it was warped?

[jaydee]

Yes, seen it happened a few times, all with genuine timken bearings, maybe they werent seated properly.

[Captain Mainwaring]

The worst job is drilling off the two shear bolts. i used a high speed grinder and oval burr to sort mine out on Paddy. The pinch bolt can be a pain but i used a small wedge to gently open the pinch and this worked a treat.

 

You can sometimes undo them with small mole grips or water pump pliers. The bush at the top can be easily made with a 3/4" PVC solvent weld socket and a 22mm flat bit if you live in the sticks like me and don't want to fire the lathe up.

 

To add to the above - try giving the top and bottom swivels a very heavy packing of grease and see if that temporarily helps.

[Cerberus]

Changed the upper column bush today, didn't do the bottom one as it didn't feel as if there was any play down there and I didn't fancy drilling out those shear bolts, .

 

The upper bush was definitely ruined though,

 CIMG8590.JPG   54.78K   4 downloads

 

No bushing left at all, and it had disintegrated and came out in multiple pieces.

 

New one in and the steering feels so much better, but there is still vibration under braking (most of the time, sometimes it's ok).

The vibration isn't as violent now, as the steering wheel doesn't bounce around inside the outer column,

 

Checked the run out of the disc on the passenger side and it was only 0.1mm, which I didn't think was too bad, but according to haynes max is 0.15mm so, maybe it's not great.  Couldn't feel any play in the wheel bearing in any direction.

 

Didn't check the drivers side as it was getting towards dinner, and with the drivers one, when the suspension is at full droop the driveshaft rubs on the lower arm pin.

 

 

The subframe bushes are probably quite worn, with the car stationary, while wiggling the steering, you can see the entire subframe moving left to right.  Would like to put solid mounts on, but the welding of reinforcement plates for the rear mounts is something I can't do, so might just renew with rubber mounts.