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MG MGB Technical - Vague steering

Hi all,
I quick question which i hope will give an easy fix

I have fully rebuilt the suspension on my 1969 MGB V8 Roadster as part of a restoration.
I now have the car on the road and the steering is vague at any speed must over 50mph
The car has the original crossmember on it and all new bushes, arms etc.
The tracking has been set to parallel
Tyres are 175 65 R15 with 30 psi in them

if you get much over 70mph the car is dangerous as it drifts around the road and it is hard work keeping it in a straight line

Steering is heavy at low speed if that is any help

ideas please
thanks
Steve
Steve D

Steve,
You don't say what type of bushes you have used, or what else you have modified, it anything, or whether you have a re-built rack, or new U/J. Harder poly-bushes are fine with parallel tracking, but standard bushes need toe-in. Also your pressures are a bit on the high side, my V8 Roadster runs at 22 front, 24 rear on 185 65R15! B steering is heavy at parking speeds, especially if you have fitted a smaller steering wheel, but if it seems abnormally heavy, especially with high PSI in the fronts, if could well still be toeing out. If you have done a fair few miles the tell tale will be "scrubbing" on the inner edges of the treads. Make sure that the tracking is only adjusted after a low speed stop using ONLY the hand brake.
Also check the torque of the cross member to chassis bolts There are a few other things to look at, but that's enough to be going on with.
Allan Reeling

You said that the tracking is set to parallel and I think that's where
your problem lays.

If memory serves, the toe-in should be set about 1/16" - 3/32"
and that should help your car from wandering/floating.
Daniel Wong

Might want to check the ubolts on the back axle as well. If they get loose, they cause interesting steering conditions.
David "you didn't say if you did the rear suspension as well" Lieb
David Lieb

Most tyre fitters have only ever worked on FWD cars and so tend to set everything parallel the difference when you put toe in on the car is dramatic.Also, double check your tyre pressures
Stan Best

Steve. Yes, check all of the areas previously discussed. Tire pressures are not a player here unless they are too low--yours are not. I run 35 PSI, front and rear, on my MGs. You should find out where the problem is in your investigation. I suspect alignment as the others have mentioned. If not that, however:

We had new tires put on my wife's 92? Mustang. Good quality tires (Michelin) of a type suggested by the tire store. A few months later, I drove the car on the limited access highway and noted the characteristics you have described. Contacted Michelin and mentioned the problem, the fact the mechanic noticed the problem and could find no mechanical problems, and the tires installed. Michelin e-mailed me back that the tires were designed for a much heavier vehicle and would not be suitable for use on a Mustang. Tire dealer (Discount Tire) replaced them with the recommended tire at no charge to us. So, it can also be the tire itself causing this problem.

Les
Les Bengtson

thanks for all the ideas. i will start by taking the car back and having the tracking adjusted.
The bushes are all poly apart from the lower arms which are standard V8 spec.
The rear suspension has anti tramp bars but apart from that is standard
The crossmember is standard chrome bumper and I have moved the rack mountings to take a rubber bumper steering rack (needed the longer shaft for the steering to clear the exhaust manifold).
The steering has no play and feels positive at low speed

thanks
Steve
Steve D

Hi Steve,
Looking at the rack mounting, presumably you have had to lower them on the chrome X member? If so you may have altered the steering geometry enough to get into bump steer. When the car is on it's wheels, what angle, from horizontal, are the track rods at?
Allan Reeling

This thread was discussed between 22/09/2009 and 26/09/2009

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