TR7 steering wheel shaking/wheel wobble

[Stag76]

Hi Russ,
It makes the steering a bit heavier...not a lot but enough to be noticed.

[FI Spyder]

Re: my steering wheel wobble. I've just taken my front wheels in to get balanced. The tires are old but not worn (after ten years they still look new). When I got them back the weights were completely different than they were. The owner said they had to turn the tire on the alloys to get them balanced. He said the manufacturers recommend replacing tires after ten years if parked on concrete (I think not being exposed to UV helps too). They felt balanced but the "looseness" was still there and there was a slight shimmy sometimes as if a harmonic built up. I had removed the steering rack nut to remove a shim but there were none to remove so I just put it back in place. I had also backed off the bearing nut 1/2 flat rather than recommended 1 flat to cut the wheel bearing slop in half. The Steering wheel was slightly out so I checked toe in with string and it was the same as I adjusted it ten years ago. I shortened the left tie rod a 1/4 turn to increase toe in a bit more. That tightened up the steering to get rid of "looseness" a noticeable amount but the shimmy can still appear. I think new tires would possibly get rid of what's left but for now if I keep to the speed limit or slightly over (65 mph) I'll be good to go (not as much fun). Going into this there was/is just a perceptible (almost imperceptible) amount of play in steering, can't notice anything outstanding, slight amount in steering coupling (normal amount of wear for over 100,000 miles) none at tie rods/ball joints, nothing that would indicate warn parts but felt loose going over uneven ground or backing up for an extended amount (not turning out of a parking space) that the extra 1/4 turn of tie rod pretty much took care of. I think new tires would do it (like they did 10 years ago). Maybe next year.

[John_C]

It was the rear axle causing the steering wheel wobble in my car. I think this rather illustrates just how sensitive these cars are to this phenomena and how critical the whole setup is. Multiple causes for the same effect mean it's very difficult to pin down the cause.

[Hasbeen]

Don't expect new tyres to fix the 60 Km/H wheel wobble on a 7/8. It will not.

I had fitted a set of high end Yokohama tyres to one of my 7s, at the distributors for Yokohama. They did not have on car balancing equipment, but did a very careful off car balance.

I was almost straight on to the expressway when I left, & had the worst wheel wobble I have had on a 7 the moment I got to 58 Km/H.

Later that day I took the car to a Bob Jane Tyremart, who did an on car balance, & the wobble totally disappeared. Well it disappeared for a few weeks, only to reappear when I removed the front wheels to do a job. Even though I marked the wheel & a stud so I could replace the wheel in the same spot on the car, the wobble was back, until I had another on car balance.

As many know I bought my own on car balancer after that.

Incidentally, the problem is worse with most after market wheels, which do not centre on the hub. It takes just a few mm off centre to cause the wobble. Fit a spacer to fix this & you've fixed the wobble.

My 8 has Symonds alloy wheels, with conical nuts. These always centre, & the car never has a wobble. Another 7 I know, with MG wheels, also fitted with conical nuts likewise never has a wobble problem.

There is another wobble our cars can suffer with. This is a low frequency, high magnitude wobble at a speed lower than our normal wobble. It occurs around 50 to 56 Km/H, as against the near 60 Km/H high frequency wobble. This one is caused by excessive toe in, [or out], & will disappear when the toe is adjusted.

Hasbeen

[FI Spyder]

Never had a wheel wobble at those low speeds (60 kph) only at 60 mph. Although we use kph here in Canada I often use mph because a)I was born and grew up using it (they changed it in my mid twenties) and b) my car is US so marked in mph (although kph in small numbers). The wheel wobble that the new tires fixed was 55 to 65 mph. After 65 it would disappear so you could drive through it. With new tires I changed wheels (5 wheel tire rotation) several times over the years will no ill effect. I had the car on jackstands over the winter to work on it the first number of years so no standing tire sets. This went on for 7 years I would say. The wheel wobble I have now from 7 to 10 years on is different. While at the same speeds (relatively, after 65mph) I can't drive through it, if I sneek up on the speed, it may not happen, sometimes it comes and goes. I lowered tire pressures on the front (from 32 to 28) but it made it worse not better. The good news is if I obey the speed limit (at least around here), it won't happen. The take away, (I guess) is there are many things that can cause it with many different manifestations so the only thing you can do is keep trying different things until you hit on the one that works.

[Hasbeen]

Sorry my mistype, it was 58 MPH, not Km/H.

Hasbeen

[John_C]

FI Spyder, I've had lots of different causes for the TR7 steering wheel wobble over the years but the most recent one caused by the rear axle was different and it sounds like the same symptoms you're currently having. The shaking didn't occur all the time and sometimes I'd think it was gone but then we'd get to a change in road gradiant and it would creep back in. All this within the 55mph to 65mph range. At other times the wheel would be shaking, we'd come to an uphill gradiant and it would disappear. This told me something was moving and therefore an on-car wheel balance would not fix it. After years of frustration the near-side rear halfshaft was cited in the recent MOT. Robsport supplied a replacement and the installation gave the immediate and surprising effect of curing the steering wheel wobble. From that we can deduce that the vibration in that halfshaft was going up the propshaft, through the gearbox, into the engine and shaking the subframe which in turn shook the steering. The problem appeared in 2011 for no obvious reason and that failing halfshaft has gone through every MOT since and shown no sign of a problem but all the time we could have lost a wheel and a possible catastrophic accident.

[FI Spyder]

FI Spyder, I've had lots of different causes for the TR7 steering wheel wobble over the years but the most recent one caused by the rear axle was different and it sounds like the same symptoms you're currently having. The shaking didn't occur all the time and sometimes I'd think it was gone but then we'd get to a change in road gradiant and it would creep back in. All this within the 55mph to 65mph range.

Similar but I think slightly different unless I misunderstand you.

It starts at 65 mph.
It doesn't decrease at higher speeds so you "can't drive through it".
I can drive all day at up to 65 mph but when I go to the 70 mph (or higher range) it will creep in in varying amounts.

As an aside I have a friend whose has a vibration felt by seat of pants but not through gear shift or steering wheel and thinks it might be rear wheel balance and is going to get rear wheels balanced.

[FI Spyder]

It can be caused by fatigue in the sub-frame resulting on zero or minus caster angle.
There are adjustable strut tops available that allow it to be corrected.
I made some saddles that moved the sway-bar forward by 10mm and increased the caster angle.
This cured the wobble and made the steering track straight instead of following
the variations in the road surface.

I get how moving the ARB forward changes the angle of the struts (at the bottom rather than the top) but don't quite see how these attach. It would seem the forward hole would be too far forward unless you drilled new hole in sub frame and made custom clamps. If you did this was any additional reinforcement needed? Do you have picture of them installed?

[Stag76]

The saddle locates in the same place...the relationship between the ARB and mounting holes in the saddle is different.

[FI Spyder]

Got it! They are the clamps, not the spacers.