Front End Vibration

[David53]

I've just returned from a week away in the Minor during which I covered around 300 miles. The car performed beautifully. The only thing I noticed was a small amount of vibration in the front end. It was not felt through the wheel (like wheel balance prob) but more a slight shaky vibration occassionaly especially when going over a rough surface. If I had to describe it I would say it felt as though there was some play in the steering rack, but as I say this did not transfer to the steering wheel. The car drives and steers very well as a general rule and it doesn't feel like anything is loose when driving.

Also, if I have to slam brakes on hard from speed I get a slight vibration which is not felt through pedal or the steering wheel.

Do you feel this is normal? What checks can I do to determine if there is any play anywhere in the front end, suspension and steering? Trunnions and Ball joints were all new when I rebuilt the car, and have only travelled around 3,000 miles since.

[MarkyB]

I'd suggest looking very carefully at the front tyres.
Try jacking up the front then spinning the wheels while just skimming the tread with your hand.
A slight bulge could give the symptoms you describe.

[David53]

Thanks MarkyB will check. But it feels a little more "mechanical" if you know what I mean. Tyres are all new and there is no vibration at all at speed on a smooth road. Its not really a major problem, and may just be normal for a 50 year old design compared to modern cars but I'd like to be sure

Is there a list is standard checks for the front end which I can carry out one by one to eliminate possible causes?

[MarkyB]

What shape are the shock absorbers in?
There is a condition known as wheel patter that can happen if the aren't working over the full range of travel.

My thinking is that a road wheel is going up and down in an unusual way, which you would hear, but not feel through the steering wheel.

[beero]

When you had new trunions did you renew the bushes in the eyebolt and on the tie bar? These could be worth checking.

[chickenjohn]

I agree with checking the tyres first- even if new they could be faulty, I also agree with checking the suspension bushes.

Another common source of front end vibration which I once had in the Traveller was a slight engine missfire- due to a very slightly burnt exhaust valve. The car still performed well, but was down on compression on one cylinder- the only symptoms were a slightly uneven idle and vibration at certain speeds (50-55mph).

Also worth checking the engine and gearbox mounts are not perished- these can cause vibrations, and check the prop shaft UJs- if this is worn at the front you will get vibration at speed.

[rayofleamington]

vibration under braking is nearly always related to worn/old/tired tie-bar bushes. If the brake drums are distorted this will cause a similar effect but as you get vibrations also when not braking I'd be looking at the suspension bushes first.

[David53]

Thanks for the tips. All bushes were renewed when I started the restoration but that was some years ago - they may have gone a little soft. I will check the Tie-Rod bushes first. Any opinions on the poly bushes as compared to traditional rubber?

When I say "vibration" it is more like a "shake" when going over a bad road surface, and also when hitting the brake pedal hard. Gentler braking is fine, and as I say there is no shaking through the streering wheel or pedal.

[David53]

Have just checked tie rod bushes and they seem fine. They are Poly Bushes which I now recall replacing a year ago or so.

Now just wondering if perhaps I need to replace all front suspension bushes. I think when I rebuilt the suspension about 9 years ago I used a set of rubber bushes. The car has only travelled 3,000 miles since they were done but was wondering if perhaps the rubber has perished somewhat over time. Is there an easy eay to check the condition of the bushes, especially the eyebolt ones which can't be easily seen?

Also, does anyone have experience with the Poly Bushes sold by ESM? They seem a lot cheaper than those from Polybush. Are they OK?

[bmcecosse]

I got good bushes from Tom Roy - because he attended the National event and was offering a discount! They were fine. No easy way - but it's only 20 minutes work (each side) to pull them out anyway. Obviously best to have spares (poly or rubber) in stock first.

[David53]

Yes have decided to do a complete overhaul. It has been nine years since it was done. Not many miles since then but the car was sitting for a long period of time, so maybe the rubber has perished. I have ordered some Poly Bushes from Superflex. I think a total strip down and rebuild is in order.

Once I have the swivel pins off what am I looking for as regards wear in the trunnions? Looking back at my notes and receipts I did NOT in fact renew these at the time. If they screw on and off nice and firmly with no wobble is that an indication they are OK to refit? And if I do need to replace them, was there any change in the trunnions over the years? Mine is an early car with MM style suspension (combined hubs and brake drums) and I have found many parts for the 1000/1098 simply do not fit my car.