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MG Midget and Sprite Technical - Steering wheel shake

I have started driving at 60 to 70mph (where legal of course) and up to 60 my steering wheel is well behaved and OK. Over 60 it starts to shake a fair bit but not so bad that my arms are falling off. (If I keep my fairly heavy fore arms attached to the wheel it cures it without any added force). The car keeps going fine and in a straight line and of course (I predict) its no worse over 70 ;-). I haven't been going this fast before the last few days as I wanted to sort of bed things in and have not gone over 60 for 3750 miles and that all seems to have worked fine and the car sounds good and runs better all the time from an engine noise point of view. So far no knocking or crank noises so quite happy. Ran at 70mph in one go for about ten miles today and apart from the shake it is going good. The engine revs in 3rd to just 4500 rpm with no shake so must be suspension or wheel related.

I havn't had the front suspension generally apart yet since the long lay up.
It is well greased.
I have removed the arb as it needs a refurb. (Since last Christmas).
The nearside damper is new.
Nearside hub was removed to replace back plate but replace was good and no play in the dreaded b******s.
Tracking was re done when damper changed with no wear so far.

Any pointers? Things I could check fairly easily without total disassembly? Stuff that can be done to improve the suspension as it is in original config without spending much money? (The budget is for the engine refurb).

Dave
Dave Squire

Well a couple of thoughts

Jack up the front end and grab the wheel at 12 & 6 for a good shake, then agian at 9 & 3 for a good shake

If play at 12 & 6 = wheel bearings if play at 3 & 9 = itr wear

But you said... you removed the anti sway bar...deduct 20 points

Also you only replaced 1 lever arm... im gonna say deduct 5 points

If you got the roy wheels... well thats another 10 point deduction as they will always have some shake no matter how many wheel weights you load up

Another area is UJ, and of coarse worn out or deteriated motor mounts

Another look would be loose exhaust system...ither the muffler or not fully secured pipe from the exhaust manifold to the muffler

Loose leaf springs

And really just a good wrench on all the bolts... esp around the body

And lastly...to much beer before driving

So.... hows that saterday looking for you now

:-)

Prop
Prop and the Blackhole Midget

Itr = inner tie rods

I forgot to mention worn out brake pads and warped rotors

And out of true propeller shaft

Prop
Prop and the Blackhole Midget

Wheel shake from simple out of balance wheels usually only comes on at 60. You don't normally feel it below that speed. So if you have only recently started going over 60 then its probably as simple as that. Get the wheels balanced, esp the fronts.
Guy W

But not balanced at a modern day shop if you have roy wheels

They have to be balanced on the old stuff with the fingers ... the center hole in the wheel is not exactly the center of the wheel, because its a 3 part welded wheel so it has to be centered Im guessing by the wheel lug nut holes in order to balance them properly

Modern day shops wont know this or how to set the wheel up and most of the time the shop equipment is to new for a roy wheel

If you have the roy wheel centered on the center hole..the balance could become an oblong cartoon wheel

Prop
Prop and the Blackhole Midget

But not balanced at a modern day shop if you have roy wheels

They have to be balanced on the old stuff with the fingers ... the center hole in the wheel is not exactly the center of the wheel, because its a 3 part welded wheel so it has to be centered Im guessing by the wheel lug nut holes in order to balance them properly

If you have the roy wheel centered on the center hole..the balance could become an oblong cartoon wheel

Prop
Prop and the Blackhole Midget

All indicators are out of balance wheels. You can try swapping fronts and backs in the hope that it's just one rogue wheel. When you trust a specialist to balance your wheels you make an assumption that the machine is still "in calibration". Not always the case, as I have found to my cost.
Allan Reeling

Mine doesn't like 55-60mph but below and much higher than that, it's smooth again. I've had hands off the wheel at over 100mph on track and on foreign motorways and it's straight and smooth (though quite noisy!).
frogeye Gary

Apart from balance the other thing to check carefully is the tyre sidewalls for delamination (small bulges). I had this a while back on the modern and as it was on the inside it wasn't visible on the car and indeed was hard to see off the car but if you ran your hand round it you could just feel it. As Gary says if it is balance you can usually drive through it if you can go fast enough whereas if its a bulge it won't go away.

Trev
T Mason

Probably lost a wheel weight Dave - very common. Look for the tell tale marks on the wheel where the old one was.
Mark O

Thanks one and all.

Its definitely the front.

I have a reliable wheel and tyre man (who also is the fitter) who runs a classic pergola top in the summer as his day car and has a steady stream of classics through his branch. Our vans and the modern go to him as well and he has given us good advice and service over the years. We are talking about tyres and sizes for the Midge anyway at the moment as the tyres on it are cheap. (the rolling project cheapest part worn you can get approach earlier this year). So its off to him for a chat to see if he can fix it or tell what to fix if not. (After replacing the offside damper to match the near side Prop; its there awaiting the mechanic).

If not I will then crawl around the suspension.

Thanks again.
Dave
Dave Squire

Dave,
my first thought is as Guy has put wheel balance

one I don't think has been mentioned is a tyre (or tyres) with uneven spots in the tread area you can’t see, moving the tyres to the other side or front to rear to wear through these spots might solve it

certainly get the sidewalls checked don't take chances with them

and yes replacing one damper and not the other isn’t usually the best idea even though reconned LA aren’t exact matched pairs
Nigel Atkins

This thread was discussed on 06/11/2013

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