[xj] '79 Series II XJ12 toe-in/out specifications

I just renewed the tie rod outer balljoints and off course want to
set the front wheel toe allignment for my '79 XJ12 fuel inj. But
what and where? Haynes mentions 0 to 1/16 in (0-1,6mm) toe out.

and the ROM also mentions 0 to 1/16 in (0-1,6mm), however toe in.

-What is correct, the ROM? Is Haynes mistaken?

-Are these figures total toe-in/out or per side?

-Measured at the rim outer diameter or the tread outer diameter?

Thanks

Michiel–
Michiel, Double Six VdP 1979.
North West Holland, Netherlands
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In reply to a message from Michiel Mooij sent Wed 6 Feb 2013:

Jaguar changed their advice over time but eventually settled on
1/8’’ (3.18mm) toe in across the range.

That’s a total figure.–
The original message included these comments:

and the ROM also mentions 0 to 1/16 in (0-1,6mm), however toe in.
-Are these figures total toe-in/out or per side?


al mclean '05 X 2.0 D Estate- '93 XJS 4.0 - 05 X350 2.7TDVi
Telford, United Kingdom
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In reply to a message from almcl sent Wed 6 Feb 2013:

Thanks almcl. Is that measured at the rim or tread?–
Michiel, Double Six VdP 1979.
North West Holland, Netherlands
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from almcl sent Wed 6 Feb 2013:

Thanks almcl. Is that measured at the rim or tread?

In principle, Michiel - the rims, periphery, are always used for such
measurements, and specs refer to the rims fitted at the time of the specs…

As Al says, Jaguar changed specs from toe ‘out’ to the almost universal toe
‘in’ at some stage, for reasons unknown - may be related to other changes in
geometry? But excessive toe out will make any car very unstable in straight
lines. The specs given is the ‘total’, ie from ‘straight’, ‘0’ toe, the
front should be within 1,6 mm narrower and the rear some 1,6 mm wider. It’s
an awkward measurement to take as the weight of the car must be fully on the
road wheels - and some ‘roll-out’ is required for the suspension to
settle…

…in principle; any adjustment should ensure that the track rods finish at
equal length, ie using both sides ‘equally’…

Frank
xj6 85 Sov Europe (UK/NZ)-----Original Message-----
From: Michiel Mooij
Sent: Thursday, February 07, 2013 10:52 AM
To: xj@jag-lovers.org
Subject: Re: [xj] '79 Series II XJ12 toe-in/out specifications

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In reply to a message from Frank Andersen sent Wed 6 Feb 2013:

The specs given is the ‘total’, ie from ‘straight’, ‘0’
toe, the front should be within 1,6 mm narrower and the
rear some 1,6 mm.

Many thanks Frank.
It appears that Haynes gives ‘early’ specs (toe out) the
ROM the revised specs (toe in) and both mean ‘per side’,
whereas it is common (?) to speak of a total difference
measured between front and rear of the rims, like Al does.
Or Jaguar doubled these specs somewhere in the past.
Confusing.
Anyway, I’ll set it up like you said.–
Michiel, Double Six VdP 1979.
Schagen, Netherlands
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from Frank Andersen sent Wed 6 Feb 2013:

The specs given is the ‘total’, ie from ‘straight’, ‘0’
toe, the front should be within 1,6 mm narrower and the
rear some 1,6 mm.

Many thanks Frank.
It appears that Haynes gives ‘early’ specs (toe out) the
ROM the revised specs (toe in) and both mean ‘per side’,
whereas it is common (?) to speak of a total difference
measured between front and rear of the rims, like Al does.
Or Jaguar doubled these specs somewhere in the past.
Confusing.
Anyway, I’ll set it up like you said.

It’s very impractical to measure the toe-in individually for each wheel,
Michiel…

…or was, prior to the advent of electronic alignment - which usually uses
degrees in relation to the car’s centre line. The toe complements the castor
angle in keeping the car running straight. With toe-in; as one wheel is
running ‘straight’ the other wheel runs at an angle, which causes greater
rolling resistance - pulling the steering wheel to ‘straight ahead’ as
well…providing the track rods are equal, but encourages the car to go
straight anyway. There are some other drawbacks of unequal track rods, but
within reason they are minor, related to some bump steer and some effect on
wheel tracking during turns…

With neutral toe, the responsibility of ‘straight’ falls on the castor
angle - which is perfectly adequate to do so, though the car may feel a bit
more twitchy. With toe-out the geometry fights the castor effects - but the
castor effect still wins…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)-----Original Message-----
From: Michiel Mooij
Sent: Thursday, February 07, 2013 6:34 PM
To: xj@jag-lovers.org
Subject: Re: [xj] '79 Series II XJ12 toe-in/out specifications

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