Rear wheel aligment (and front) with strings method

[vilas66]

Hello folks, I know that the subject has been discussed many times and with conclusions spreading into different points of view....
I have six cars in my fleet (2 of them are 75's) plus a bunch of cars into my family.
I purchased my first 75 (tourer) with very few miles on it in 2006 and she was, for what I read on this forum, with the rear toe out of spec from factory as rear tires worn unevenly, until I went for a 4 wheel alignment. After two attempts with two different tyre fitters (I don't even want to tell how the car was driving) I made a third attempt to a third tyre fitter and he said that the rear was a bit misaligned so he aligned the rear, then the front and the car was driving well again but with the steering wheel out of centre. So, fed up of cowboys I came home and, with a string (by supposing that the rear was fine), I aligned the front wheels and steering. I've done 150.000 kms since, the car was nice to drive, all tyres worn correctly as they should.
Since then, with the strings method:
- I aligned the front wheels of my Rover SD1 very very good results
- I aligned the front wheels of my wife BRAND NEW Fiat Idea which was pathently out of spec and she has done 80.000 kms without evidence of side effects;
- I have been with my sister to the Alfa Romeo Dealer as her 155 bhp Mito was during warranty worning tires unevenly and the mechanics aligned the front wheels with string: She is also now a 180.000 KMS car that drives and worn tires correctly.
Don't misunderstand me: I still do beleive that a 4 wheel alignment system is and should be much more accurate than a piece of string PROVIDING that calibration of equipment is correct and the operator knows what to do so convinced that I found the right one I placed my trust to another garage where I went:

- with my Tourer to check if, after 15 years, was still "aligned" or not and came out from the garage with the steering wheel out of centre;
- some months after, with my newly acquired belgian 75, and I came out with car pulling toleft and steering of of centre !

In both cases I used at home the string method once again which seems (in my experience and only in my experience) to give better results by supposing the rear aligned...

I want to go further now with my string and my gauge and try to find out how to align (if necessary) the rear toe.... Any ideas ?
Thank You and happy Christmas

[T-Cut]

Originally Posted by vilas66

- - with the strings method:
- I aligned the front wheels of my Rover SD1 very very good results
- I aligned the front wheels of my wife BRAND NEW Fiat Idea which was pathently out of spec and she has done 80.000 kms without evidence of side effects;
- I have been with my sister to the Alfa Romeo Dealer as her 155 bhp Mito was during warranty worning tires unevenly and the mechanics aligned the front wheels with string: She is also now a 180.000 KMS car that drives and worn tires correctly. - - -

That sounds amazing. You really should write up a HowTo with photos of your setup. Members here have talked about DIY tracking for years, but nobody's explained in practical detail how it's done. How to measure the toe angles, etc. Have you measured the rear toes? This is the crux of course.


TC

[rrobson]

I aligned the front of my 25 with string. I wanted a couple of degrees of toe in for high speed stability and understeering characteristics. Since then I've changed the set up for a more neutral set up but you can also do it with laser pointers. If you've got the car on a level floor and have the car directly opposite a wall you can measure the distance between the dots to calculate the angle. You just need a reference for the centre.

[Richcl]

Did mine with string as the car was wondering over undulations at speed.
Drives lovely now.

I've done it on a few cars now.

[vilas66]

Originally Posted by T-Cut

That sounds amazing. You really should write up a HowTo with photos of your setup. Members here have talked about DIY tracking for years, but nobody's explained in practical detail how it's done. How to measure the toe angles, etc. Have you measured the rear toes? This is the crux of course.


TC

Hello T-CUT
Like I said, I always suppose that the rear end is aligned and this is true for a rear axle car like the SD1 and for cars with the rear that can't be set such as the small Fiat and Alfa.
I've just used a method like the one described in this video (https://www.youtube.com/watch?v=kfMdvQn55hI). it is an Italian video but easy to follow and understand ( The mechanic, in the video, insists that the rear suspension should have no damage).
I always use a digital gauge instead of a ruler and a very thin string to have more accuracy, the rest is trigonometry. ... I graduated a few years ago, but if my maths doesn't deceive me, there's no reason to worry about the toe angle if You are within a 1 mm of difference between the rear side of the rim and the front (I mean the measure showed used in the video).
I feel sorry but in Rave I quote:
- Toe in unladen condition (unladen ???)
R 75 - 0,17°+- 0,25°
ZT 0.00°+-0,25°
I have two cars one saloon with 16 inch rims, the other is a contemporary with 17 inch rims what are the best values for my cars?
And, also, perhaps there's someone or some equipment on earth, in a workshop, really able to measure these angles ?

I have an idea on how to measure the rear toes by starting, this time, from the front wheel hub centers with two strings, but is only an idea, never tried before so waiting yours :-) https://the75andztclub.co.uk/forum/i...s/icon_lol.gif

[vilas66]

Originally Posted by T-Cut

That sounds amazing. You really should write up a HowTo with photos of your setup. Members here have talked about DIY tracking for years, but nobody's explained in practical detail how it's done. How to measure the toe angles, etc. Have you measured the rear toes? This is the crux of course.


TC

A simple calculator-how to, really a DIY 4 wheel alignment system with strings. Courtesy of web. I think the writer is a racing driver.

https://robrobinette.com/DIYAlignmentCalculator.htm
Enjoy and happy Christmas

[KWIL]

There is only one acceptable alignment system (to me) and that is the Hunter.

On another laser system I had to take the fitter out on the road to demonstrate that his first (and second) attempts were inadequate inspite of him believing it was OK. First requirement was a flat (no camber) stretch of road.

[ratchet]

Originally Posted by KWIL

First requirement was a flat (no camber) stretch of road.

Easier said than done. I've recently treated myself to a trakrite and have been scouting local supermarket car parks etc in order to find a flat piece of land to check and adjust my tracking. No luck so far..............anyone know how sensitive these trakrites are ? - does it have to be bowling green flat ?

[Ross R75]

Originally Posted by KWIL

There is only one acceptable alignment system (to me) and that is the Hunter.

On another laser system I had to take the fitter out on the road to demonstrate that his first (and second) attempts were inadequate inspite of him believing it was OK. First requirement was a flat (no camber) stretch of road.

Hunter actually works in exactly the same way as the strings method, it's just a bit more comprehensive in its analysis. Laser tracking assumes the rears are correctly set, strings don't. The strings will get you pretty much dead on, probably within the amount of adjustment that tightening a track rod lock nut would throw any other system out by anyway.

[RoverP480]

With the Hunter system, the rears need to be checked/ reset first before any attempt at the fronts. That's where a lot of cheap places fail as they don't check the rears are OK first.