Rear toe?
 

Not sure if it's been asked before but what should the rear toe be on a Sierra based car, I'm thinking 0 but I doubt that's correct

That is what I did mine at 0 toe and 0 camber, straight up and down and side to side;)

zero toe, never ever toe out on the back. I'll probably put 1/4 deg rear toe in on mine and a little negative camber but haven't got round to playing with it yet.

General setup.
 

Westfield setup from Westfield world.

Front Ride Height Approx 160mm Determined by wheel/tyre combination
Front Camber 1.5 - 2.0 Degrees Negative (Radials) 0.5 - 1.0 Degrees Negative (Crossply Slicks)
Front Toe in/out 0.5 - 1.0 mm Toe in
Front Damping 2 - 3 click from fully soft
Rear Ride Height Approx 170mm - 175mm approx 10mm - 15mm higher than front
Rear Camber (seiw only) 1.0 Degrees Negative 0.5 - 1.0 Degrees Negative (Crossply Slicks)
Rear Toe in/out 0.5 - 1.0 mm Toe in
Rear Damping 2 - 3 clicks from fully soft

I think I'll set it at 0 degrees then!
How does degrees relate to mm?

It's fairly easy to set both the front and rear to zero toe you just need a 40ft ball of string. Tie it so that it makes a big loop and place it about 200mm up from the ground around all four tyres, the string should be tight against the edges of the tyres. Get on your hands and knees and you should see the difference in the gaps between the string and the edges of the tyres.

http://www.circletrack.com/chassiste...ng_your_ car/

this is the string method phil is talking about works really well used to use it for setting up my race cars back in the day

thought I had stumbled on to a bondage site,hands and knees and 40 ft of rope .:)

Its a good starting point but after a shake down it would be worth checking and perhaps experimenting with. Out of the box it will probably be good but with some fine tuning it will be brilliant. There is a utube vid somewhere of a guy and a westie messing with set up at a track, the difference in handling when he finished was quite amazing and it was all in the small detail.

Bob

its only easy if it's adjustable, which on the rear it's not.

TT

Any ideas where I can get some shims from?

I just clamped a long spirit level to the spindle and measured how much it diverges from parallel with the side of the chassis. I cut shims out of a beer can. The can was 0.1 mm thick and each shim was worth 0.1° or so.



Simple trig: If I get 8 mm divergence over 550 mm, the toe for that wheel is arcsin(8/550), that's approximately

8 / 550 * 180 / 3.14 = 0.83°

8 / 500 is really the sine of the angle, but in the vicinity of 0 sin(x) is close to x, then 180/pi just converts radians to degrees.

P.S. Toe in millimetres means the slant between the front and rear of the tyre of some unspecified size. Sierra tyres are about 57 cm in diameter. You can use the same trig to convert that into degrees.

I will get flack for this but here goes,the suspension mounting points are fixed so shim's will put tension on wherever it is fixed or mounted,you can bet that it will break at the wrong time and the only sure way to make it adjustable is with rose joints or eccentric washers and bolts.

I've got custom lower wishbones fitted on my car, which are adjustable for toe. Think they were manufactured by 3GE when they existed.

Caterham racers have been using shims for years with no problems/

must be value beer if the can is only .1mm .

TT

[quote=alga;98287

Simple trig: If I get 8 mm divergence over 550 mm, the toe for that wheel is arcsin(8/550), that's approximately

8 / 550 * 180 / 3.14 = 0.83°

8 / 500 is really the sine of the angle, but in the vicinity of 0 sin(x) is close to x, then 180/pi just converts radians to degrees.

P.S. Toe in millimetres means the slant between the front and rear of the tyre of some unspecified size. Sierra tyres are about 57 cm in diameter. You can use the same trig to convert that into degrees.[/QUOTE]

Let me get this right, the diameter of the outside edge of my rims is 410mm so if I have a variance of 2mm over this diameter I get,

2/410*180/3.14 = 0.28 degrees of toe

If I want 1 degree of toe I need 7.25 mm variance,

7.25/410*180/3.14 = 1.01

I'm I correct?

J

+1

The face plates that the bearing hub bolts too is never properly flat anyway because of the distortion when welding, I am going to flash them off on the mill when I sleeve the hub down to fit the bearing carrier. I am thinking of a redesign of the lower wishbone to have two outer adjustable joints that could deal with toe and camber and leave the top one solid. I wont be shimming behind these bearings because they are ali.

Bob

I tried several brands of domestic and imports, looks like 0.1mm cans are the norm now.

Albertas

I agree with you, it's not the cleanest solution. If you're worried about stress and deformation of the bearing carrier, you can stagger the shims to make the slant more gradual. However, both the upright and the brake back plate are painted, so there is no precise metal-on-metal contact anyway.

Yep, that seems to be right. Keep in mind that if both wheels have 1° relative to the chassis, you have 2° total, which is a lot.

Agreed again Albert,but why introduce more stress on a stressed component.
Purely my own view on something I personally would not do and if needed would sort a solution like adjustable arms/mounting points,as I said my personal preference.

How would you go about making adjustable arms?