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MG TD TF 1500 - Oversteer on a TD

My TD has all new suspension components. It does however, have a small bit of oversteer and wants to wander a bit. I believe that the toe in is not correct. I have set in the past to what I generally believed to be correct. Apparently it is not right. Rather than do my own testing I'd like to know if more toe in or less toe in will correct the problem. I think that I should have a bit more but I'd like the collective wisdom of this group instead of my own instincts which often are wrong.
Mark Strang

Here's what the WSM says. No toe-in at all works well for me. As I recall, there are a number of archived threads on the subject.
Joe

Joe Olson

The WSM recommendation applied when crossply tyres were fitted, with radials a little toe in is desirable.
Dave H
Dave Hill

I think 1/2 degree negative. Driving tends to slightly force the wheels outward at the front edge, with slight negative they will be parallel under load. Double check all fasteners, esp. the rear spring shackle bolts and make sure the nuts are not bottomed out at the end of the thread. Looseness here very common. What tire pressure are you running? Anything over 28 with modern radials will be really darty. Toe adjustment would only effect straight line on center feeling on a really flat road, unless way out, but would effect tire wear. George
George Butz

I have seen 1/8" toe-in said a lot on forums.

Peter
P G Gilvarry

I set my cars at 1/16-1/8" toe in, and there is no wandering. Also check the tire pressure and existing wear - everyone has their favorite setting. I use 28/30# with radials.

Tom Lange
MGT Repair
t lange

I run 1/8th toe in and 26 lbs pressure on the TF. Had it out yesterday, run it at 65 mph, speed limit here and no issues. We have a lot of high pitch roads which will affect the wandering issue if the settings are wrong, mine seems to work very well. PJ
PJ Jennings

OK, I've learned something here. George's explanation is good, but why are radials different from bias ply tires? Should I change my setting if the car is handling well with no toe-in? I can't yet detect any unusual wear in the tires. I run 26-28 psi and rarely go over 60 mph. Thanks for any advice.
Joe
Joe Olson

Also try checking the rear tire pressure. Underinflation at the rear will definitely contribute to over steer.
Lew Palmer

I run bias ply tires because I restored it to be period correct for AACA shows. I run at about 28 psi. Sounds like I might want to increase the toe in a just a bit to see what happens. I run radials on my other TD. It seems to be much better with the same toe in. Also the tread depth is greater on the bias ply tires which I suppose would cause a bit more of a mushy feeling and perhaps cause it to drift easier than the radials. Tire wear is good. Thanks,

Mark
Mark Strang

George's explanation is correct - the flex in the system (suspension and tyres) tends to force the front of the wheels outwardly. With a radial tyre the walls are more flexible, so you need toe- in to compensate.
Dave H
Dave Hill

I've just changed my TF's rear spring rear bushes, because the rubber flanges looked a bit frayed, and found they were appallingly worn - right thru the rubber on the RH side. With the new bushes (I used B bushes with the flange thinned down) the whole rear end feels a lot tighter. I haven't really noticed much difference in steering, but I run a heavy anti-roll bar, which would affect it.

Might be worth a check, too.

David
D A Provan

David,

I was wondering what you call a 'heavy' anti roll bar, and how you find it. Is it a 3/4" ?

Kind regards,
Michael
M R Calvert

Michael, it is a 3/4". Several of us in Christchurch have fitted them. I put mine on initially for the track, because the inside back wheel just spins up on power in corners without a bar. Now it will, at the limit, lift the inside front, but I can still put power on the road.

The interesting thing is that all our wives/partners love the bar. It makes the car much more stable for passengers, with less roll at road speeds and cornering loads.

The photo isn't my car, but it's similar. I put another 1/4" bolt thru the A arm and spring pad to make it easier to fit and remove the bar. The bar shape is quite critical to maintain clearance.

Regards, David

D A Provan

David what front springs are you using?
Len Fanelli

Standard springs, Len. I do get a lot of understeer on the track, but it's pretty balanced for road use.
David
D A Provan

David,

That is both interesting and very encouraging. I have a 3/4" bar ready to install and was having some misgivings based on occasional remarks on this forum suggesting 3/4" may be too stiff.

I told my wife about your saying “The interesting thing is that all our wives/partners love the bar” but for some reason she did not seem all that excited. I suspect the diameter of an anti roll bar is a bit too abstract a concept.

When you say the shape is quite critical does this mean that there are bars with differing shapes? I thought that any bar sold as standard fitment for an MGA or MGB would be essentially the same shape and OK on a TF. Mine is described on the B&G invoice as 'MGB tuning' all associated bushes, brackets and end stops they list as 'MGA/B' and the short links they list as 'TD/F MGA'.

What do you think?

Regards,
Michael
M R Calvert

I have read that the aftermarket bars may be slightly different shape to the MGB OEM bars, causing some fouling.

There are many discussions about shortening the link to position the bar below the steering.

I have seen people say the link bar can be shortened to 3" centre to centre?

Thoughts????

Thanks.

Peter
P G Gilvarry

Mine are 3 1/4" and just about touch the paint on the steering arms on full extension (without interference), so I reckon 3 1/8" is the optimum. But it will depend slightly on the geometry of the set-up. I have std MGB bar which is less than 3/4".
Dave H
Dave Hill

3.125" centre to centre?

Thanks.

Peter
P G Gilvarry

Yes.
Dave H
Dave Hill

3/4" Bar is likely a bit heavy for regular road use. I have the original MGB bar (forgot the diameter... 9/16 perhaps?) In mine. It does get rid of the over steer, but I actually kind of miss the over steer. It was so very predictable and fun to do with a passenger who didn't know it was coming. I was usually able to pull this off on dry pavement when turning left at a light. Super fun!
Alex Waugh

This thread was discussed between 15/05/2017 and 17/05/2017

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