caster shim design and fabrication

[Hoghead]

Tiger and Alpine caster angle is set by the aluminium wedge between the front crossmember and frame rails. If I understand correctly, this is +3.84 degrees with the car at a level stance

I am about to make some of these shims caster shims and it is a simple matter to make the rear wedge pad thicker to increase caster to 5-6 degrees, without causing alignment problems at the rear bolt.

What is the collective experience on an optimal caster angle for a street Tiger?

 

[spmdr]

My vote is stock, ...or less

Just wondering why anyone would want more caster?

3.5+ is already more than a lot of cars.

DW

 

[michael-king]

My vote is stock, ...or less

Just wondering why anyone would want more caster?

DW

Dan i thoght some people add more caster to the front end to help give stronger self centering for the steering which is somewhat slow due to the ackerman issue... I recall someone talking to me about this when i first bought my tiger

 

[ABSunbeams]

Got wedges for my SV Alpine from Doug J, will see how that goes on a stock Alpine suspension.

 

[65beam]

Got wedges for my SV Alpine from Doug J, will see how that goes on a stock Alpine suspension.

Doug had the reproductions made at a shop in Dayton using originals as the pattern.

 

[ABSunbeams]

This is what Doug sent me, would it have the same issue? If it is an issue.

 

[65beam]

Those are the ones he has made. If you compare them to the originals you'll see why these are much better. The entire wedge touches the frame rail.

 

[ABSunbeams]

Found that the Super Minx Estate, which has the same cradle, has no wedge at all. Of course it is not handling like an Alpine.

 

[65beam]

Found that the Super Minx Estate, which has the same cradle, has no wedge at all. Of course it is not handling like an Alpin

Al, it could have to do with the platforms that the cars were built on. Maybe they changed the angle of the frame rail. When the fast backs came into production the only adjustment was toe in. There was no crossmember of the type used on Alpines and Tigers. or upper control arms.

 

[Hoghead]

Dan i thoght some people add more caster to the front end to help give stronger self centering for the steering which is somewhat slow due to the ackerman issue... I recall someone talking to me about this when i first bought my tiger

My thought as well.
The stock caster was designed for bias ply tires. Modern tires and suspension design seem to have a lot more caster than 3.84 degrees.
Never mind that the self centreing on a short wheelbase, powerful tail happy car might be helpful..........

As I originally hinted, +7.2 degrees will cause rear bolt alignment problems. Others report using 5 degrees and aside from a slightly higher steering effort, are happy with the change in overall steering. I am thinking of 5 degrees for my own cars.

 

[Hoghead]

Those are the ones he has made. If you compare them to the originals you'll see why these are much better. The entire wedge touches the frame rail.

Not sure yet if a constant taper is actually better though.........................
The factory part is cast, and could just as easily been a constant taper, which makes me wonder if there is a production reason for the stepped design.

It is far easier and cheaper to make it constant taper if done on a manual milling machine - not so much on a CNC

As we all know, the cast alloy turns to mush, and why I am thinking marine grade aluminium

What is the resultant caster angle using the constant taper shim in the pic?

 

[Hoghead]

A

Got wedges for my SV Alpine from Doug J, will see how that goes on a stock Alpine suspension.

Alpine Series 1-5 caster wedges are the same as the Tiger

 

[theo_s]

My vote is stock, ...or less

Just wondering why anyone would want more caster?

3.5+ is already more than a lot of cars.

DW

Doesn't it (also) depend on the steering axis inclination with respect to the spindle? Since the steering axis is inclined (I don't know offhand what the angle is - and I forget if that is specifically given in the workshop manual), if you have less caster than the inclination angle, you'll lose camber as you turn the wheel into a corner.

 

[spmdr]

I have found that steering geometry is a give and take of compromises.

And when you go to the extremes of settings (big static negative camber, to start...),

other things have different results.

The bottom line is personal choice.

My choice, to start, is LESS steering effort.

More caster is going the wrong direction for me.

And how many cars, these days, DON'T have power steering?

YMMV.