MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Front caliper adjustment

I have a vibration in the front end at 60 mph. Tires have been balanced and rotated(roystyle wheels 1977B).
Tie rod ends and front suspension tight and drive shaft ok. I read somewhere that the front bakes might cause a vibration if they were to bind. If I spin the front tires I can hear a rubbing noise at the caliper. Is this normal and can the front calipers be adjusted? Wheels spin freely but can hear the rub.
JCH Hibbard

Rostyle wheels must be located on the balancing machine via the stud holes and not by the centre hole as the centre hole may not be exactly in resister with the stud holes.

It made a big difference on my car.

Not all tyre fitters have the equipment to do that and not all tyre fitters who have the equipment use it!

Also check the sliding joint in the prop for slop.
David Witham

The calipers are not adjustable. The pads will be noticeably in contact with the disc immediately after being applied and released, then will ease off to a light rubbing, and on the road the end-float will probably knock the pads back a little more so there is no rubbing at all. If they are binding it will cause the disc and pads to overheat, which in my experience doesn't cause a vibration.

I doubt that is anything to do with a wobble at the steering wheel between about 60 and 75 or so, that always seems to be wheel balance. I had problems for years with the V8 alloys, repeated rebalancing did nothing, neither did new tyres in the fullness of time, and that was using both the centre-hole and an adapter that held it by the stud holes at various times. The problem with the latter is that it was a universal gizmo with studs in swivelling arms to fit any stud circle, and I wasn't very confident in its accuracy. Eventually I found a place with a Road Force balancing machine which uses a set of adapter plates with holes spiralling out, they put pegs in the appropriate holes, and that is far better in my opinion. The difference was immediately noticeable, and a welcome relief! However I was still left with a very slight occasional tremor, which seemed to vary with the road surface. There were a number of odd features with these wheels, including a massive weight on the inside of one wheel put there after the Road Force balancing, which I found loose but despite tightening it I eventually lost it, but there was no change in the balance as detected at the steering wheel!

I've since had the front tyres replaced again, balanced on a different machine using the centre hole, but again there was no worsening in balance just the slight tremor over some surfaces. That led me to suspect the balance machine at the place I have been using for years.

Quite independently I was investigating a knock when braking and found the track-rod ends worn (not found on the MOT), and having changed those even that slight tremor has gone. Incidentally I only found this when I had cracked the tapered joint to the steering arm and found I could wobble the ball and socket joint freely.
PaulH Solihull


David Witham is 100% correct.
The rostyle wheel center hole is not the center. You must either find a balance shop with the finger adapter or a shop that will spin balance on the car. Those are few and far between.Some people have made an adapter by using a front hub and modifying it to fit the balance machine. Your wheel is mounted on it and then on the balance machine.
Sandy Sanders
SANDY SANDERS

They were spun balanced on the car. I was doing some further investigation today and noticed a slight play in the right front wheel if I grasp it at 12 oclock and 6 oclock. Not real bad but play none the less that doesn't exist on the left side. Tie rod ends are fine, could this be bearings?
JCH Hibbard

There should be perceptible play in the wheel bearings *both* sides, this is the .002" to .004" end-float that should be there (cue claims it should be 'pre-load', the hub nut should only be finger-tight etc.). A properly balanced wheel (they are all 'spin balanced' as tyre places in the UK, I wish we could still get 'on-car' balancing if that is what you meant) should eliminate any consistent and continuous steering wheel wobble, but play/wear anywhere between the hubs and the steering wheel (i.e. wheel bearings, king pins, trunnions, dampers, A-arms, track-rod ends, rack, column UJ, column) could cause some intermittent effects depending on the road surface.
PaulH Solihull

JCH.. Have you actually lifted the front wheels off the ground and slowly rotated the wheels. Spin balancing is only as good as the operator.. I would check to see if you have out of round tires or even a slight bump in one. Also check and see if the wheels themselves are true. Spin balancing can hide that also. I would also check you shock absorbers to see that they are full as poor ones can display those same symptoms.
Look closely at the tire tread as you rotate the wheel. If the tread is not straight then tread seperation is looming.
Just last weekend an aquaintance of mine had a vibration in the rear of his MGB. He said he would lookat it at home. He never made it as the tire came aoart and tore the complete lower section off the rear wing. These were low mileage tires but over ten years old.
Sandy
SANDY SANDERS

Thanks Paul and Sandy. Tires are in good shape no out of rounds or bump. I'm going to go back under this weekend and recheck A arms, pins, etc. this weekend. The first check everything was fine but maybe I missed something. I was reviewing John Twist's info on wheel bearings and interestingly he states that the hub nut should have 60# of torque on it.
JCH Hibbard

JCH,

There is a range of torque to account for ending up at a place where the castle nut lines up with a hole in the axel stub. I don't remember the number for sure, but I think it is something like 40 to 70 ft lb. I'm sure the value is on Paul's website.

However, you need to know that someone has not removed the spacer and shims that fit between the bearings before you torque it up. If they are missing, your bearings will be shot in short order with that torque.

Also, you could swap the wheels front to rear to see if it makes a difference.

Charley
C R Huff

As well as having 4 of my wheels balanced properly I also measured the sideways and vertical run out at the edge of the rim. I did this because I have about 12 rostyle wheels and wanted to know which ones to put some effort into restoring. Of the wheels that had been balanced recently the one with more run out than the others also had more weights on it. I moved that wheel to the back and once I have restored a good one from my stock I hope to move it to the boot.

So you might want to try measuring the run out. All I used was a dial guage and something solid to mount its magnetic stand on.
David Witham

40 to 70 ft lb is what the Leyland Workshop Manual says, i.e. a minimum of 40 then to the next split-pin hole which should be before 70 is reached.
PaulH Solihull

This thread was discussed between 03/11/2010 and 05/11/2010

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.