Toe in degrees.

[rmd24]

I want to get the toe in checked on my S4 and I see that the workshop manual gives a toe in setting of 4.76 mm.
My local tyre shop has some fairly sophisticated equipment but I guess that they will want an angle rather than a distance. I've done some sums and used up several hundred sheets of paper and I THINK the answer is .375 degrees toe in. Can anyone confirm this or if I'm wrong, tell me what the figure should be.
Thanks,
Roger.

[Baggy2]

I've only ever seen toe in (or out) quoted as a distance rather than an angle but I see you are in France so maybe its different over there?
All the best
Baggy

[types26/36]

Here is a pic of my W/A gauge set for a 13" rim.
4.76mm (+ -) equates to approx 47' (minutes) or just under 3/16"

[john.p.clegg]

Sorry Roger,had a couple of glasses of red,but,if you have another sheet of paper and some log tables at hand it should be TAN . 1/2 track difference (front to rear) divided by wheelbase.


John
SOH.CAH.TOA.

[andyelan]

Hi Roger

3/16" or 4.76mm toe in equates to an angle of 48.7 minute (or 0.81 degrees) which is assuming toe in is specified at the wheel rim

I have seen some cars where toe in is specified at tyre diameter. If this were the case the the angle would be 27.5 minutes (or 0.46 degrees) however I dont think this applies to the Elan

Andy

[john.p.clegg]

Andy

Surely angles at any radius would be the same..

John

[GrUmPyBoDgEr]

Andy

Surely angles at any radius would be the same..

John

P'raps you shouldn't be posting quite so late at night John

Cheers
This John

[andyelan]

Hi John

The toe-in for the Elan is actually quoted as a distance and it's from this we're calculating the angle. So what we calculate does depend on the radius.

Sorry if I didn't make this clear

Andy

[john.p.clegg]

Sorry All

Totally sober now and I've done the math

Series 1 and 2 elans....27 mins 23 secs

Series 3 elans............-2 mins 24 secs (toe-out?)

Plus 2.......................18 mins 20 secs

all less than one degree....

P.S. Type23/26,you have the tool,can you convert to approx distance " at radius " ?

Thanks

John

[john.p.clegg]

EDIT

[john.p.clegg]

edit

[GrUmPyBoDgEr]

Sorry All

Totally sober now and I've done the math

Series 1 and 2 elans....27 mins 9 secs

Series 3 elans............10 mins 19 secs

Plus 2.......................17 mins 52 secs

all less than one degree....

P.S. Type23/26,you have the tool,can you convert to approx distance " at radius " ?

Thanks

John

"all less than one degree".... But worthy of an "O-Level" I'd say

[andyelan]

Hi John

I think your formular you have for calculating toe-in is incorrect.

My understanding is that toe (in or out) is the difference in measurements taken between front and rear of the wheels (or tyres) on the same axial. Usually the front ones as this is the only toe in which can be adjusted on the Elan.

Regards
Andy

[john.p.clegg]

Andy (at Al)

The figures above are per wheel,if you take a look at the optical gauge set for 13" wheels it reads approx 48 minutes,so it would appear this reads for the pair of wheels.


All the sites I have looked at vary on where to take the linear measurements,across the rim,across the tyre wall,across the tread centre,also some quote the measurements per side or in total....or leave one to assume...very confusing.


Maybe someone in the know (and there are many of us out there ) could tell us how Lotus,back in the 60's, meant their measurements to be interpreted? I have yet to see this in print.

John

P.S. Andy,have you measured the toe-in on your rears?

P.P.S.
Does anyone know how the rear track varies between the Series 1,2 and 3?
Is it the frame?,Is it the hubs?

[bcmc33]

Hi John

I think your formulae you have for calculating toe-in is incorrect.

My understanding is that toe (in or out) is the difference in measurements taken between front and rear of the wheels (or tyres) on the same axial. Usually the front ones as this is the only toe in which can be adjusted on the Elan.

Regards
Andy

Here we go again.
From my teachings (which I know goes back to the horse-and-cart era), is that toe-in/out is measured from the wheel pivot point to the wheel rim. That's why it is common to measure the total wheel rim difference and halve the result to get the true dimension.
In the US it was common practice to measure from the center of the tire.

Somewhere in the annuls of history - there were even differences of opinion on how to measure toe-in/out among the members of Team Lotus.

Due to so many differences in understanding and practice around the world, the auto industry made one of it's better decisions to specify toe in/out in degrees.
This way even us no-hopers should not get it wrong - but only when we can agree on the measurement points so that the elementary math can be done correctly.

Having said all this - measuring the front toe-in at home with our simple bits of string - I will continue at 5mm on my 14" wheels.