Crabbing ... advice please

[WNX700H]

Been driving my car (which is to be used for historic road rallies) yesterday after having reassembled the rear suspension / subframe.

Noticed the car feels strange when driving in the straight ahead position , lots of small correction to the steering when travelling straight ahead, bumps in the road seem to amplify the feeling of instability. The car is not hugely unstable but does not instill confidence that one would want to do high speed with this characteristic in the handling at present.

Have determined the car appears to crab slightly ( tendency for the near side rear to steer towards nearside of road ) from visual assessment whilst following the car.

Heres what I have changed or modded

I have removed the adjustable camber brackets and replaced with std rover ones but have filed the radius arm hole in order to get the wheels vertical ( actual measurement now is n/s -0 degrees 8 minutes negative / o/s 0 degrees 5 minutes negative )

Have replaced the radius arms with new Rover units

Had the car on four wheel alignment with two shims behind the outer radius arm bracket mounting left and right side of the car
measurement on the rear showed I have 1degree 37 minutes of toe out on nearside and 35minutes of toe out on drivers side. I shimmed the brackets on the basis I thought I would have toe in with its standard setting ( no shim ) as I was aiming to get the rears to run parallel

I then removed both shims from the nearside and one shim from the offside but have not had the vehicle measured since.

In this condition the car exhibits slight crabbing and feeling of instability.

Having read the Minispares site the shims I have used should only alter the toe by around 10minutes so if this is accurate then I should have approx 1degree 17 minutes of toe out nearside rear and around 25 minutes of toe out on offside rear.

This does beg the question that although the Mini should be toe in usually in standard form my car does not show it has that.

I could file the radius arm hole in the nearside bracket to bring the outboard end of the radius arm on the nearside closer to the heel board to remove the toe out and bring the toe on the rears to parallel.

Sensible comments and advice please before I do anything further.

[JC T ONE]

Hey W,

I have seen this many times, when a rear subframe, has been replaced.

the 2 major problems are that the wheels, sometime run positive camber

or that the innerhole for the long radius arm bolt, is sitting too far forewards, but most of the times, only in one side
so one side actually spread/turn a little, all the time.
On one Mini, we had to move the inner hole 18mm to get toe in.

the camber is easy, just hold a mesure stick with a float, up against the tyre/wheel, and see that it is atleast straight up, and not running positive camber, this will make the rear VERY much alive

next you find a long & 100% accurate piece of metal/wood, and place it up against the rear tyre, it should point IN, so it dissapears under the sill, just around he middle of your door = running atleast 0 (straight) or at 1mm toe in.

If these 2 things are checked & OK, the car should behave

[Dino]

... the Mini should be toe in usually in standard form my car does not show it has that....

I think you've answered your own question here!
Running toe out is definitely going to give you problems. Personally I'd aim for about 1/8" toe in.

[mk1]

I'm no suspension expert, but the toe out on the rear is definitely the problem.

It is very very difficult to determine if a car is really crabbing driving behind it is notorious for giving a false impression expecially when you are expecting a car to crab. Measure the distance between front & rear wheel centres, if these are equal the car can't be crabbing.

My advice would be to concentrate on the toe on the rear. If the suspension is correctly set up it shouldn't really matter where the body is sitting.

[guru_1071]

Noticed the car feels strange when driving in the straight ahead position , lots of small correction to the steering when travelling straight ahead, bumps in the road seem to amplify the feeling of instability. The car is not hugely unstable but does not instill confidence that one would want to do high speed with this characteristic in the handling at present.

this sounds more like the tracking is out at the front.

lots of rear toe would tend to make the car make sudden (and probably very hard to catch) oversteer type moves.

[WNX700H]

Have had the car on 4 wheel alignment and have 1degree 27 mins toe out nearside rear and 37 minutes toe out out offside rear ..... front axle is within spec for toe and castor with 0.5 degree neg camber .

Only real change to the car is the radius arm brackets , the car did not feel as nervous previously ...... will have a play around this weekend and swop bits around to see if I can make things more acceptable.