Steering wheel vibrations at 70 mph

[JD-JAG66]

Hello,
I need some help before ordering some parts to solve some strong vibrations in the steering wheel when approaching 70 mph.
Some websearch turned up possibile causes, so I started with the most obvious ones, and took the front wheels to a tyre shop to have them balanced.
1 out f the 2 was fine, the other one was requiring only minor weights, with both rims being perfectly round.
When fitting them back onto the car I could find that, while spinning the wheel by hand, 1 brake disc had a minor warp, with it touching the pads, but not to stop the wheel from turning, but still being "audible".
I also checked and adjusted the stub axle shaft nut, greased it up, and went for a drive.
Vibrations have lessened, but are still there.
So I went onto the SNG website and put 1 brake disc (they have done only 400 miles) in the shopping cart.
Before I hit the order button, any suggestions on what else to look for (aka = order and replace?)
Any feedback welcome.
Jan

[mgcjag]

Hi Jan...do you have wire spoke wheels....a standard tyre shop cannot balance these properly unless they have special cones for wire wheels .....typically they will say they can and set the wheel on their machine and balance it....and it will run on the machine ok.....however loosen it and reposition the wheel again about 90deg... then spin it up and it will be out of balance......so check that your shop has special cones.....have you checked the tracking and the suspension ball joints and bushes and most important the steering rack mounts....Steve

[Gfhug]

Jan follow Steve’s advice, Geoff

[rfs1957]

It will be nothing to do with the brake disc.

You can take it out of the cart.

IF it had warped after 400 miles, which I don’t believe for a second, all it would do would be to push the pads apart, by forcing the pistons further into their caliper bores, and you would only get the wobble when you braked.

No standard tyre shop ever has the right kit to balance Rudge Whitworth hubs.

They require a specific male cone to replicate the Jaguar splined hub inner seating, and a FEMALE cone on the outside to replicate the centring effect of the eared outer spinner.

These wheels are NOT centred by the splines.

I actually now have the dimensioned drawings, at home and not with me as I travel unfortunately, that show where the critical surfaces are, which I have been intending to put up on the Forum for weeks so people could make their own tools.

I had some made up in aluminium as a replacement for the ubiquitous Smoothride cones that many people use, but which I find (being nylon) unconvincingly soft, and the outer - female - one is very easy to crack.

If you can wait I will put the drawings here next week.

I have even seen tyre fitters to whom I had GIVEN the cones continue to use their own MALE on on the outside, because they just don’t get the nuances of the system.

They therefore add weights to your eccentricly-mounted wheel until their machine reads «  zero », and when you fit the wheel on the car, where it runs « true », the thing vibrates like hell.

[JD-JAG66]

Thanks for the feedback everybody.
I do indeed have wire wheels, so this weekend I will take all the advice and go through every point and see what I find. And yes, looking forward to those drawings!
Again, thanks!
Jan

[mgcjag]

This clearly explains how to balance wire wheels and how the cones differ from those of standard wheels...this is for smaller MG wheels but same principal

[RICHOT]

When I had a steering wheel wobble around 70mph, I swopped each front wheel with the rear one, one set at a time and took the car for a test drive.
I then found when I swopped the o/s front with the o/s rear, the wobble went!
So I then knew which wire wheel it was and sent it to a specialist to check/realign or whatever.
Problem solved

Worth you trying swopping them similarly??

Good luck, Richard

[rfs1957]

Here are the drawings, steel or any alloy will do.





It's important - if you're getting someone to make these for you - to grasp which surfaces and which geometry is critical, as parting-off (neatly) on such a big diameter (like the cone) will not be easy for all lathe-users.

Knowing what matters and what doesn't is helpful, and some of the sizes are really not critical - 125mm seems to be the standard to seat the male cone properly on the back-plate, but if you were using 150mm stock there's no point in reducing it.

The female cone can have whatever OD is easiest, 100mm is probably a safe minimum to protect the lip in case the cone were dropped.

Bear in mind these are for a 40mm shaft wheel-balancing machine - this seems to be the common standard around here, but you had better check that that's the case in your area, as 38mm exists too.