track lengths

[littlejim]

Here’s one for you.

 

When I first bought the 4A, the handling in corners was very exciting.

It would start with understeer then snap into oversteer in sharp corners.

The rear wheels had slightly differing amounts of toe in, but from memory a few cms each side.

During the restoration I shimmed it out until I had zero toe in on both sides, or as close to zero as I could get.

I just went for the toe in, didn’t try to keep the wheelbase length the same on both sides.

The handling became a lot more pleasant, maybe slight understeer, but almost neutral.

The blap up the Clyde Mountain hairpins was the most fun I’d had for years.

 

Out of interest I measured the wheelbase length on both sides today and got the following results:

 

Driver side 224.3 cms Passenger side 223.7 cms

A discrepancy of 0.6 cms

 

 

 

Would you bother having another go to try to get both sides the same?

(Sorry about the heading. I blame old age.)

Edited April 12, 2015 by littlejim

[peejay4A]

If t'were me I'd leave it.

[Peter Cobbold]

I woudn't worry. Unless the car handles differently in left or right bends, or pulls to one side in a straight line.

 

"cms " of toe would be extreme - mm I guess?

 

The stock rear toe settings would have been designed to allow for the compliance of rubber bushes.

PU bushes will compress less so less toe is needed. I use Silentblocs so set the rear at zero toe.

 

Any "semi-trailing arm" changes its toe as it moves up and down in bends. So the working toe can go either side of the static setting. Toe changes with roll: roll steer.

The camber is easier to see changing : it goes more negative as the spring compresses and that helps rear grip and deters oversteer. However the roll of the chassis offsets some of the increase in camber as the t/a rises.

 

For semi-trailing arms the only cure to toe and camber changing in bends is to make the suspension stiffer with uprated springs and an antiroll bar ( and that then means stiffening the front too). The minimised rear toe and camber changes can then be matched with some front negative camber and the handling becomes more pleasant - to me, others will differ ( but the ride is not improved ).

.

Peter

Edited April 12, 2015 by Peter Cobbold

[LGFromage]

I would not worry as the old Renault 16 was designed that way to take account of the rear transverse torsion bar suspension.

 

Tim