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MG Midget and Sprite Technical - Front Wheel Rubbing

I have just put my steering column back into the car alighned it with the rack by leaving it all loose and letting it find its own position before tightening up. But the front offside tyre rubbs the inner wing on full lock I have clearance on the nearside... Tyres fitted are 165x13 on rostyle wheels. I have not dissmantled the rack it was just removed from the car and replaced at present the car is up on stands so the suspension has no load on it, will it make a difference when the weight of the car is on it?
IAN Pickering (68 Midget) Getting There!!!!

yes it will, but I think it should still fail the MOT.

The rack does not set the end-stops, they are set by ears on the kingpins
Will Munns

I sounds like the rack is not centered, that is one outter tie rod end is turned on further than the other so that the rack is not centered with the wheels pointed straight ahead. Try loosening the outer tie rod jam nuts and adjusting the inner tie rods to make the amount of threads showing is the same on both sides, then adjust the toe moving each side the same amount until you get the toe setting you want. They try your stops again, I think you'll find them closer to equal and it should take the same number of turns of the steering wheel to reach each stop from the center position.
Bill Young

the stop is not in the rack, it is on the kingpins.

There is a limit of travel in the rack, but it would stop the whels before they got to the kingpin stops not after and so would not cause this problem.

if all you have done is fiddle with the rack then this problem was there before
Will Munns

Will
are you saying that the ears maybe worn or even damaged on my kingpins?
IAN Pickering (68 Midget) Getting There!!!!

Will, I'm not disagreeing with you at all. With the suspension at full droop the axle is closer to the centerline of the car because of the angle of the
A arm, so a tire that rubs there might not when the suspension has weight applied. Even so if the rack is centered in the housing and the outer tie rod ends are equally adjusted I can think of no other reason other than physical damage to the tub why one tire would rub and not the other. If the tire is rubbing on one side then it's probably not reaching the stop on that side and probably limited by the internal stop in the rack on the opposite side from reaching the kingpin stop while the tire still has clearance. Only when you're sure the rack is properly centered can you determine if the wheels can turn enough to reach the kingpin stops evenly.
Bill Young

How do I centre the rack?
IAN Pickering (68 Midget) Getting There!!!!

Bill,
I think Will is saying that there is no way that the rack can move the wheel far enough over to rub on the tire UNLESS there is something wrong with the actual ears on the kingpin that are supposed to prevent it from moving that far. It is possible that the rack not being centered could affect how far the rack is trying to move the tire, but the kingpin ears should still prevent it from moving far enough to rub even so. The ears DO affect both clockwise and anti-clockwise rotation on the kingpin.
David "I am waiting patiently for someone to tell me how to compensate with this for my 185/60 autocross tires that rub at full lock in both directions" Lieb
David Lieb

Ian, disconnect the outer tie rod ends from the steering arms, rotate the steering wheel until you reach the stop in one direction then reverse and count the number of turns to the other stop. divide that number in half and then turn the steering wheel back that amount and lock or tie in place. The rack is now centered in the housing in relation to the pinion gear. Now make sure the outter tie rods are turned on each side an equal amount and reattach them to the steering arms. Now you can adjust the toe with weight on the wheels making sure you turn each side an equal amount until the wheels are straight and you have the toe setting you need. Once you have things set, tighten the jam nuts and try rotating the steering wheel and check that the number of turns from center to lock is the same for both sides. You may be off a slight bit, but it should be pretty close. If it isn't then you may have a bent steering arm or such.
Bill Young

Thanks Bill will give this a try tomorrow
IAN Pickering (68 Midget) Getting There!!!!

most probable your larger tyres are causing the rub, and you've just never noticed before as the suspension was loaded, by all rights the MOT ought to fail on this, but my MGF does it and never caused a problem
Will Munns

Will
you say larger tyres what size should I have fitted?? these come with the wheels but I will replace them when the car is ready to run
IAN Pickering (68 Midget) Getting There!!!!

The question of the ages!
The car came with 145/80 x 13 bias-ply tires. There is NOTHING in that size currently available that is worth putting onto your car. The 165 size usually works fine. I run 175/70R13 radials as street tires on my RWA midget and 185/60R13 Yoko A008R tires for autocrossing. Your 68 is probably better off with the 165s that you have. It is so hard to find even a mildly fun tire any smaller than 175...
David "too many tires" Lieb
David Lieb

Build up a little weld onto the inner face of the offending lug at the bottom of the king pin, then grind a new flat on it. As Will says these are what controls the maximum turn of the wheel. If the rack isn't centred, that is a different problem, but fixing it won't affect the limit of the angle that the wheel s turn in by. If you are not convinced, then disconnect the steering arm and rotate turn the wheel and see if the tyre hits the inner wing, or comes against the "ear" stops first as it should.
Guy Weller

A word or warning....

The bushes isolate the kingpins, so if you connect the mig to the body then it will use stainless steel brake hoses to conduct.

They get hot and melt the insides, leading to no brakes.

Go on, ask me how I know.
Will Munns

This thread was discussed between 15/04/2008 and 16/04/2008

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