Does road camber affect steering?
 

A couple of weeks ago I had a new NSF tyre on the S90. No big issue, and I'm very happy with the price and service. The tracking was done at the same time.

Now this could be my imagination, but it seems now as though the steering wheel is turned slightly the right more of the time - but is a RWD car just more sensitive to road camber?

I ask because drive on the "wrong" side of the road and the steering wheel is turned slightly to the left.

Drive on the crown or on a very flat road and the steering wheel is just about centred. All our other cars are FWD, and so have much more precise steering anyway. And although I've had the S90 for 3 years I have never really thought about it until now.

The rear tyres are in good shape with no obvious uneven wear to suggest a rear-end alignment issue, the brakes pull up straight and true, the steering feels no different to how it felt before, I'm just conscious of the steering wheel position.

I know that the S90 / 960 is blessed with what some describe as barge-like steering, and that's a part of its charm. But is it worth worrying about, or is steering that is "road camber sensitive" just a feature of big old RWD Volvos?

Cheers

Jack

Is the problem that you only had one tyre fitted?

The wear on the other tyre will affect the wheel alignment that's why they should be changed in pairs. Had this trouble loads of times when doing wheel alignments and then it would pull to one side, I would swap the front and rear wheels around and the pulling would disappear.

I have found my 940 is very sensitive to road camber as it is but even more so after fitting polybushes about 2 years ago.

My 940 is sensitive to road camber exactly as you have described.

Must say I've never noticed this on my 960 or Omega-both rwd of course.

Whoever did your wheel alignment n't centming the alignment. Start the engine and let it idle, set the steering wheel in the straight ahead position, now turn it to full left lock counting the turns. ON the 7/9xx cars it should be 1 3/4 turns. Now return to straight ahead position and turn to full right lock. Again it should be 1 3/4 turns.
If either are different, the rack isn't centred when the steering wheel is in the straight ahead position.
This means that although you're driving straight, the rack thinks you are turning ever so slightly and applies power assistance causing wandering.

Had this problem with my 760 following a supposed wheel alignment - the wheels were toeing out like Charlie Chaplins feet afterwards though so they got something seriously wrong! :err: :eek:

Bought a Trackace Laser alignment kit and did it myself after centeing the rack correctly. Also stopped mine boiling PAS fluid and it frothing out of the reservoir and leaking all over the place!

To answer your question, road camber can effect the steering, there is a rumour (not sure how true it is) that the chassis rails on Jeep Cherokees are shorter one side than the other to account for the excessive camber on many American roads - makes getting them to drive in a straight line pretty tricky! :err:

I have found in over twenty years of 940 ownership that “experts” with expensive four-wheel laser alignment rigs rarely get the alignment right on these cars. The most satisfactory alignment I’ve had done has been by my local general garage using basic tracking gauges.

I’ve also rendered it acceptable myself. Like the Laird, I bought my own DIY laser alignment kit. However, unlike him mine has never come out of the box and I have tweaked my alignment when it has irritated me sufficiently based on feel / trial and error.

Whilst I shouldn’t recommend this approach, for anyone interested from a purely academic point of view the adjustments involved are quite basic.

If the steering wheel is offset right when travelling straight ahead you need to shorten the nearside track rod and lengthen the offside one by equal amounts, e.g. half a turn at a time. So long as you are careful to keep the left and right adjustments opposite and equal they should not affect the total toe set at the last professional alignment.

I have also increased toe-in to improve straight line stability by shortening the nearside track rod a bit more when the car seemed to be pulling to the left. This is getting into more controversial territory because when you start actually changing things it can affect tyre wear and bump steer. However, since large pot holes that can easily throw the tracking out far worse seem to fall within the acceptable safety standards for British roads I’ve never let it worry me too much.

The one slight downfall with tweaking both track rods as you describe is that if a pothole has moved for example the control arm in relation to its bush, your alignment will still be out, despite the fact you're now traveling in a straight line. I've done it myself as a temporary setting to make a car drivable (my other beast has seriously strong self-centring at low speeds) and then corrected the alignment later with the Trackace. It's a simple tool to use, you should really get it out and have a play with it, you might find your alignment is fine but also that it's a way out. If it's driving ok despite being out it points to wear in things like the spaceship bushes as they tend to be a weak point. The faff comes when you have to make an adjustment and then recalibrate the Trackace, however i see that as a small price to pay for gitting it right myself at home and saving £40 per pair of wheels to have aligned.
My other beast has adjustable alignment on the rear as well as the front so starts getting expensive for both ends! :err:

Similar to Forrest, I have occasionally “tweeked” the track rods slightly.
I read some time ago that as a rule of thumb to correct a 1 degree error at the steering wheel it is necessary to adjust the track rods by 30 degrees. That’s 1/12 of a turn, equivalent to 1/2 a flat on the lock nut. To avoid stupid errors I first wrap masking tape around the track rod end and the track rod and mark them in alignment. I mark both so that I can return to the original position if I need to. I then loosen the lock nut then finger tighten it until it is barely touching the track rod end so that it will turn with the track rod. I then adjust the track rod in the appropriate direction noting the relationship of the lock nut with the mark on the track rod end. Movement of 1 flat of the lock nut relevant to the mark on the track rod end is equal to 60 degrees of turn. So, in theory, Forrest’s 1/2 a turn ( 180 degrees ) would adjust the steering wheel by 6 degrees
Someone may wish to check my maths.

Thanks All

In the end I telephoned National Tyres, who'd supplied and fitted my new tyre and had originally done the alignment. They promptly offered to re-check the alignment this afternoon, and 20 minutes later returned the car to me saying that it was all sorted.

And indeed it is totally sorted. The steering wheel now sits exactly true, and the steering feels as light (and as barge-like!) as it ever did.

The Depot Manager said that possibly the fact that they'd had to heat one of the locking nuts last time might have influenced things, possibly the car has settled on its suspension in the intervening weeks, or possibly the fact that it's an old car with old nuts and bolts just all added up to the steering wheel not quite lining up true last time out. He also said that sometimes they don't get it right first time, but they're always only too happy to check and re-adjust if needs be. You can't say fairer than that.

Whatever, I absolutely believe that it's not what happens it what you do about it that counts, so full marks to National Tyres Selby for their excellent customer service.

They did say that although the two front tyres are different (Cooper and Avon) the two brands are actually made by the same factory on the same production lines, and are very similar - and certainly, it's hard to tell the tread patterns apart. They reckon it unlikely that this of itself would be enough to cause the issue, and the difference in tread depth is too marginal to matter.

Thanks for all the comments - as ever, this site is a mine of really useful information and insight.

Cheers

Jack