Toe-in

[Ian Vincent]

Following on from a recent thread here about checking toe-in, I checked my TR3a earlier today.

 

I did it using a laser line and piece of wood as suggested on the other thread, and did it twice, once when the vehicle was sitting up on axle stands with the suspension at full droop and again when it was back on four wheels, but after driving it in and out of the garage to make sure that everything had a chance to line itself up.

 

I was pretty careful how I did it both times and checked for repeatability in my readings by performing each measurement twice from scratch. The results were:

• Car up on axle stands - 0mm
• Car sitting on its four wheels - 2.3mm (19') toe-in.

Is that what one would expect to see?

Rgds Ian

[ianc]

Have a look at topic "Revington Steering Kit" in the TR2/3/3A/3B area, and also follow the link given in the second posting therein - should help explain what's happening.

Basically, the steering geometry prior to rack & pinion is not right, so bump steer occurs. Either you live with it or you take corrective action!

See also Keith Read's article about TS2 in the latest (#287) TR Action and Phil Tucker's notes on the righthand side of that same page.

Ian Cornish

[TriumphV8]

Later versions with rack and pinion are also not perfect.

Both of my TR6s could be improved dramatically by

tweaking both the suspension and the geometry.

 

What all TRs I drove had in common is the steering

that seems to become "light" at higher speed.

 

One reason is the castor. The old TRs had ex works 0 degrees

and the later ones should have 2 3/4 but seldom have. For my V8

I went to something about 4 degrees to get a safe high speed feeling.

The 6-cylinder got a refurbish of the 2 3/4 degrees as good as possible.

The fastest I went was a bit more than 150Mph what definitely is not

recommended or safely possible with the stock setup.

 

TR6 is often lowered and the TR3 sometimes. This creates negative camber

what also is bad for proper straight and secure driving. I would recommend

for the TRs about 0 degree or slightly negative camber and a little bit toe-in.

 

The other reason is from geometry, when suspension bounces

the wheel turns inside the corner additionally what gives a unsafe

feeling. That can be reduced by reducing suspension travel

and adding anti roll bars.

 

Repositioning of the rack and pinion is the trick to cure the

problem at the roots but is totally against the law and gives a

lot of possibilities to make something wrong. Same is with the

modification of tie rod lever.

 

Last thing that is not correct but does not play a role is the

"Spurdifferenzwinkel" whatever that means in English. It is

defined as the difference of the wheels when full turned.

The inner wheel makes a smaller circle and needs more

turn not to rub on the street but our TRs perform really

bad when we drive sharp turns on tarmac.

[Nick Jones]

"Spurdifferenzwinkel" = Ackermann angle from your description. Not something that seems to have been understood by Triumph engineers as it's way out on all the small chassis cars as well.

 

Nick

[John Morrison]

Ackerman principle, was ever a compromise on any vehicle, known in the trade as TOOT toe out on turns.

 

Pointless trying to measure alignment if the car is not on the ground, I.e. The wheels are not doing what they are supposed to do - end of!

 

All our cars should be parallel to 1/16th of an inch toe-in, I.e. Parallel but err on the side of toe- in

 

John.

[Motorsport Mickey]

Ian,

 

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Mick Richards