Toe-in as degrees

[Sander]

I have bought a used professional laser wheel alignment tool. The brand is KOCH and it is made in Germany. After what I can read about the system it is very accurate. But the system only works in degrees and not actual measurements in mm or inches for the toe-in setting.

Does anyone know the front and rear toe-in setting measured in degrees per wheel (not total degrees).

[MarekH]

I was told to slightly toe-in at the front, say half a degree, and that'd be good. I'm not sure how you'd easily alter the rear.

kind regards
Marek

[Sander]

Marek,

Sorry, my mistake. You are right toe-in/out can´t easily be alter at the rear (fixed by the length of the radius arms).

The half a degree at the front is that total for both wheels or for each wheel?

Jesper

[Allrand]

1/2° = 1.7mm at the wheel rim.

[mgcjag]

Hi Jesper..old school measureing tools measured across the wheels..the Jag manual isnt clear so i take the spec 1/16- 1/8 as across the wheels..setting each wheel turning in at 1/16 toe in will give a total of 1/8 so within spec..There are various online tool calculators to convert inch mm deg.. .have a look at this one https://www.wisefab.com/toe-converter

[rfs1957]

I can't see anyone agreeing, anywhere, on either Jag-Lovers or our Forum, or anywhere else on the Net for that matter, what the actual value in degrees/minutes is the equivalent of the oft-quoted Jaguar figure of 1/16" - 1/8" of toe in at the rim, note the manual refers to a rim and not rims.

The only thing everyone agrees on is that it's Toe-In

Like Jesper's original post said, nowadays all wheel geometry is expressed in degrees/minutes, so I thought I'd have a stab at expressing the E-Type toe-in in those terms.

The principal obstacle, as Steve rightly points out, is that you first have to decide what Jaguar's values actually refer to.

To keep it simple, I'm going to work it out on just the higher 1/8" figure.

1. Is it a TOTAL toe - which might mean the difference in the distances between the leading and the trailing edges of both front wheel rims plural.

If so, then each rim moving 1/32" inward at the front, and 1/32" outward at the rear gives a toe of 1/16" per wheel, or 1/8" for the pair, which equates to 13' per wheel (that's 13/60 of a degree).

(Note - Rim edge actually has 8.25" radius, as our famous 15" refers to the tyre seating diameter ; and tan-1 of 1/32 divided by 8.25 equals 0.217 degrees, or 13 minutes of arc https://www.calculator.net/scientific-calculator.html)

2. Or is it the toe of just ONE rim, singular.

And if it were the toe of just ONE rim, what does that mean ?

You can take it to be just literally how much the leading edge of the wheel rim is turned inwards, in which case 1/8" per wheel gives a TOTAL toe figure of 1/2", and the angular measurement is then 52'.

Or you can interpret it as the total toe of one wheel, in which case it's 1/16" turned in at the front, 1/16" turned out at the back, and the angular expression is 26'.

So you can read it as 13', 26', or 52' according to how you interpret the upper limit of the original expression, and 7', 13', or 26' if you take the lower value.

That's a variation of from 1 to 8.

Now, my reflective guru in Connecticut, who sets up Italian racing cars - same period as ours - for a living, Goodwood, LeMans, Monaco etc, said this is how he would read it :

Toe per wheel. So if the rearward side of the rim is zero reference, the forward side is 1/16-1/8 inwards. Total toe of the set (front or rear) would be 1/8-1/4. As a side note I never run toe in on the front unless the Ackerman is really big like a go kart. For a road car it wont make too much difference. Road cars usually are set up "safe" to understeer, and toe in helps that.

So because of that, I'm nailing my colours to the mast for TEN minutes of pinch on each wheel

It will put some conviction in my step when I next go to my measuring guy.

Incidentally, I'm now SOLD on the use of the suspension-setting tools that Jaguar insisted be used when making these measurements ; without them you are never measuring the same thing twice.

Feel free to pick holes in my maths.

[bitsobrits]

Toe in on the front is always total toe-in, as setting toe in per side (at the front of the car) is essentially meaningless as when the car is rolling straight toe-in is the mean of the individual wheel toe-ins.

Toe-in at the rear is always measured per side relative to the centerline to ensure they are equal, because if rear toes are not equal the car will have a thrust angle when in motion (i.e. dog tracking).

[Gfhug]

From this website (previously linked by Steve (mgcjag):
https://suspensionsecrets.co.uk/toe/

"Toe is the angle between each wheel with relation to the longitudinal axis of the vehicle. It is usually measured when the car is static and is measured either in degrees or in millimetres. If it is measured by distance then it is usually the difference in distance between the two rear edges of the tyres and the two front edges of the tyres."

On the E Type it is between rims not the tyres

Geoff

[rfs1957]

Further exchanges with Connecticut yielded this :

Radial tires in general are less sensitive to static toe and the numbers are larger to get the same effects. So I would go with 1/8 per side minimum - translates as 26'. Also, the camber curve for a bias tire will be too gentle for a radial. You will probably find the cornering grip better with pressures on the high side. If you can add static camber, do it.

and so I've changed the nails in the mast and am now going to aim for 30' - which, happily, is also Marek's pitch.

Here are a few calling cards ........... 1962 and 1965, must be relevant to us !

[Gfhug]

I’d be interested to hear from those who’ve set up their own camber, castor, toe in at home in their garage.
Have you got a nice driving car from your set up or a bit of a dog?
Simple kit, set ups and adjustments have given repeatable measurements on my S2 FHC AND produced a car that is a pleasure to drive. As confirmed by one of our alumni.
Light and steady at speed without being twitchy and not unusably heavy at parking/manoeuvring speed.

Perhaps we all need to be careful of following rules for a 60+ year old car on crossplies against on modern radials? I can’t see any changes in settings for the change to radials from the original crossplies, yet, surely, there should have been?

Just my thoughts for what they are worth

If your car feels nice for you, why piss about?

Geoff

[MarekH]

If you can add static camber, do it.

and so I've changed the nails in the mast and am now going to aim for 30' - which, happily, is also Marek's pitch.

My view on camber is that can be some good logic to "adding" camber.... It goes like this:- you have a classic car - if you do relatively few miles per annum, your tyres will be life expired long before you'll have a chance to actually wear them out, so you may as well set them up to extract a little more cornering grip and go out and enjoy yourself. You'll be throwing away the tyres and replacing them before the tread is worn down anyway. Ignore this if your annual mileage is high.

kind regards
Marek