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MG MGA - Stiff Steering? - non centering

Just beginning to get a feel of my car now after 4 yaers off the road with full rebuild. I have noticed that the steering doesn't self centre unless in a tight curve going round a roundabout. Also its pretty stiff, direct, but at 80mph + it seems to go light which is a bit disconcerting.

I have checked the king pins, loaded up by axle stands under the pans and with the track rod disconected. The nearside needs thumb pressure on the link arm on the king pin to rotate it and the offside one is easier to rotate with my little finger. So they are not really stiff. The column is aligned with the steering shaft and the column has my delrin bearings in it and rotates very freely. The wheel spins the rack freely too.

So I'm not quite sure if the steering is actually stiff and at higher speed the car lifts slightly and unloads the king pins making them slightly freer. I haven't yet checked the toe in yet. The lack of self centering is a bit perplexing too even at high speed when it all goes light because the camber/castor is fixed. But then I am not turning the wheel much at 80 so not sure how much self centering I will feel.

Any comments on what level of self centering you would expect to see. In the 35 years I've had the car I have always felt the steering was really direct and don't recall a lot of self centering but it was pointed out to me recently that it lacked it and now I notice it!!

Thanks

John


John Francis

Toe-in has an effect, or in your case it sounds like toe out. If the wheels toe out it will make the steering feel vague and reduce the feeling of self centering.

My car doesn't exactly ram the steering wheel back in my hands, but there is a self centering feeling, albeit somewhat light.
Neil McGurk

I agree with Neil the toe angle will have a big effect on your problem and must be set up before more comments.
However unlike Neil I set mine to parallel/toe out, just gives me a better turn in. That said a tad of toe in is a safer option.
Bob Turbo Midget England

If you totally refurbished the car then you probably installed new felt bushings in the steering column. These often have to be shaved down as they are too thick. They will definitely cause the tight steering problem you're describing because it happened to me. It won't feel very stiff when the car's on jack stands but parallel parking and self-centering after a low speed corner can be a problem. If it really bothers you then you'll have to re-do the bushings- they won't wear down in any significant fashion any time soon.
Mark J Michalak

Mark, he says he has the Delrin bearings.
Art Pearse

Had the alignment checked today and it was toe'd out by about 1.5 degrees! Set it parallel with the result that it feels much lighter through the seed range but still doesn't have much self centering effect. So I'm still a bit puzzled but will do more investiagtion at the weekend.

John
John Francis

What tyre pressure are you running ? If it is too low, that will significantly reduce any self centering tendency, Too high and the car will bounce around like a ping-pong ball.

dominic clancy

Tyre pressure is 27 psi on Firestone tyres.
John Francis

John run 32psi in the fronts and 28 in the rear and see how it feels Sean
S Sherry

Sean

That seems high to me. I have always been told to keep mine at 27 psi as per John's tyres.

Steve
Steve Gyles

Did you check the steeling rack plungers? They may be too tight, therefore creating too much friction inside the steering rack.
Look at Barney's page on this subject and check you have the right amount of shims.

The MGA has normally quite a strong 'self-centering' effect.
Gonzalo Ramos

Steve I always run tyre pressures on the high side, the cars turn in better, especially the pre sixties British designs runing generious positive camber. I run 35 PSI in the fronts of my 2.5 lt. '50s Riley other wise it's like a truck to manhandle.
My understanding is that today's tyres are a lot softer in the side walls and need the support of higher pressures. Sean
S Sherry

Higher pressures make the car turn in better Sean??

I have found the very opposite. Higher pressures make the steering much lighter which naturally is indicative of poor front end grip but that is only my opinion. :)

Not sure how that would affect pre 60s cars with as you have noted "positive" cambers. :)
Bob Turbo Midget England

I had the same problem when I did my mGA over.

I found out that the steering rack was'nt aligned properly.

If you loosen the link in the engine compartment you can feel if it can slide without resistence. And if you take it of you can see if the ends align.

I found out that when I put on the newly painted body back on the frame I pressed the upper steeringcolumn to far down, and with the link of it was clear to see.



Ole
Ole Aaen

The fact that it can be moved with finger pressure when the tyres are off the ground would indicate that the problem is not with the steering rack or column. That's why I suggested that the tyres may be under inflated as an addition to the other comments pointing at the tracking.

dominic clancy

John, if you are running radial tyres, 24 psi front and 27psi rear is the best starting point, recommended to me once by the MGOC. Originally with the supplied crossplys pressures were 17F / 21R. Don't want you losing it with the wrong pressures...
Pete
Pete Tipping

If you have no front sway bar, then a bit more pressure in the rear is appropriate. This is because the rear springs are too stiff, overloading the outside rear tire in fast cornering. Go by the book for (4-ply) bias ply tires, at least 5-psi more for radial tires (but varies with tire manufacturer).

If you run a front sway bar (and I do), you will likely benefit from more pressure in the front tires than in the rear. With radial tires and the sway bar I run 27F/25R for casual touring (2 to 5 psi more in the rear for trailer towing).

For autocross competition it's more like 32F/27R, +/-2 depending on pavement condition. I run 4 to 7 psi less in the back, but never less than 25 psi. Too much pressure spoils the footprint and grip. Too little pressure allows the tire to scrub on the sidewall with vigorous cornering. For tight corners at moderate speed the front tires see a LOT more harsh sideways loading.

Once you get the pressures close to what's needed for maximum grip, increasing pressure will spoil the grip slightly. If you have understeer (pushing at the front), add a little pressure in the rear. If you have oversteer (tail swinging out), add a little pressure in the front. Once you get off the track, put it back down in the mid 20's for the comfort factor.

MGA steering ratio is fairly quick, so steering will be moderately heavy at very slow speed (stopped or parking). For casual touring at road speed a few fingers should do it. For strong turns at speed, keep a good grip on the steering wheel and point it where you want it to go.

Much the same applies to manual brakes (no power assist). They work well as long as your foot is heavy enough to do the job.
Barney Gaylord

Hi Barney

Thanks that's useful. I'm having the steering checked this week and a sway bar fitted.
John Francis

I had the steering looked at this week by Oselli who took the king pins out and lapped them in to the trunions. The steering definitely feels lighter at all speeds now and there is more self centering. I haven't run it at high speeds yet but it feels a lot better.
John Francis

John what did Oselli use to lap the trunions in to king pins. I think I have the same problem and would like to know what they used and how they did it.

thanks Andy
60 Coupe
Andy Preston

Just reactivating this thread. The seals on the swivels split and I have some new ones from Brown and Gammons which look OK. The rubber feels good quality. However, taking the trunions off the king pin I found that one trunion is quite tight on the king pin and is hard to turn by hand. The top trunion is easy to turn but still not completely free.

These are both just four years after a complete professional rebuild with new trunions and everything is still really clean. I am just wondering how free the trunion should be on the thread on the king pin. Also has anyone experienced a similar problem with new trunions and found a solution?

John Francis

John, Both tops and bottom trunnions on mine were quite easy to turn by hand.............Mike
m.j. moore

Just reading the workshop manual and it says they are a free turning fit without slack but "an appreciable amount of slack is permissible in these threaded bearings and they do not need renewal unless they are very slack".

So any advice on freeing up the new swivels? I have new bronze ones and am thinking that some fine valve grinding paste might be an approach. However, that is not ideal as they should have been machined correctly in the first place but re-machining may not be easy.
John Francis

I'm not familiar with adjustments on the MGA, but I do know that increasing the caster will cause the car to track better...It will have an effect on the steering effort, but if your steering is very light, now, a slight increase in caster won't hurt, and it will not affect tire wear.
Edward
Edward Wesson 52TD

Ed, caster is fixed on the MGA.
Art Pearse

Art
Thanks for the info....One less thing to worry about with my latest project ('60 MGA)...
Strange that the engineers left this important adjustment out, especially on a car that might be used for racing.
Edward
Edward Wesson 52TD

This thread was discussed between 26/09/2010 and 20/05/2013

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