In reply to a message from Syd. 91 XJ40 sent Mon 22 Sep 2008:
Syd,
It is true that I don’t know the actual Toe-in on my car.
Having had the car returned to Jag dealers multiple times to
have the alignment ‘done properly’ which never resulted in
satisfactory steering / handling but always resulted in
uneven tyre wear, I had the alignment set (theoretically!)
to the maximum Toe-in (0.8 mm each side, +1.6 mm Total Toe)
at a local tyre shop when they fitted new P6000(J) tyres and
from that datum, I ‘tweaked’ the Toe progressively until I
was happy with the steering / handling.
Now, here is the problem.
I don’t know whether the tyre shop accurately set the Toe to
+1.6 mm in the first place - and they certainly did not pull
the car down so that the underside of the front cross-member
was the prescribed 150.8 mm above the ground.
Having said that - I’m now not convinced that the 150.8 mm
pull-down has any great effect on the front Toe measurement.
It certainly does on the Camber angle but since that is not
adjustable in service, it is probably irrelevant!
I know that from that (uncertain) datum which I carefully
marked, I increased the Toe-in each side by a half or one
flat of the hexagon at a time and road tested the car on a
known piece of road until the steering became too ‘twitchy’
- and then I backed it off a little until I judged it to be
‘just right’.
[A tiny adjustment makes a noticeable difference to the
steering / handling characteristics of the car and certainly
to the wear characteristics of the front tyres]
So I have no idea what the actual Toe is - or even if I
started from the ‘maximum’ total Toe of +1.6 mm and I don’t
trust the local tyre jockeys to measure it accurately now.
They could tell me any figure and I would be loathe to pass
that on to any other XJ40 owner because it may not be
accurate and in any event, it may not be suitable for their
car bearing in mind that my car has the lowered ‘SportsPack’
suspension.–
The original message included these comments:
My car wonders a bit when driving straight. Reading earlier posts
say that this is probably due to lack of sufficient toe in. I’m
When you had the same or may be worse steering problems, do you
know if you started out with zero toe in and increased it or did
you already have supposedly the correct toe in and then increased
it? From reading your posts it seems you have no idea just what toe
in you actually have, is that correct?
I have also heard that the front of the car has to be at a certain
height in order to get the correct toe in. This was not mentioned
in the posts I read. Do you have any information on this?
–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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