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I am building a 1300GT motor for my Mk1 Mini to use for road rally work and general fun.

It will be mildy tuned - perhaps 85bhp, with good torque.

I have a CR SC gearbox with ST ratios and 3.44 final drive.

Can anyone say at what stage it would be wise to fit a X pin diff? Would such a diff provide noticeable drivability advantages as well as the obvious one of strength.

Thank you

Jon

A stock diff will certainly be strong enough, however, the X-pin type will last considerably longer, apart from that, it offers no advantage what so ever over a stock diff.

If you want a diff that will make a difference, fit something like a Quaife. I have them in nearly all my cars now and will NEVER go back.

edit> you could also consider an LSD, however, I have never found these comfortable to drive with only to race on.

Thanks Spider,

I looked at a Quaife ATB diff for my Elan but concluded that it provided no advantage on the road given the very compliant long travel suspension.

A front drive Mini is however a different matter - for what I intend to do will the std diff, in your experience, be reasonably driveable without undue wheel spin/torque steer in tight bends / hard acceleration? I'd not considered a ATB diff in a Mini .... but now you've got me thinking. I do recall driving a Mini with an old fashioned LSD however and it was horrible

Thanks for your comments.

Jon

An ATB is absolutely AWESOME on a road going Mini. It's rare to get the best of both worlds in anything but this is one case you certainly do.

the atb 'lady diff' is great in a mini, no torque steer or anything like that, the big advantage of the newer ones is that they come with the outputs fitted and use a standard crownwheel - so offer a huge cost saving over plate type diffs

their only weakness is that they don't work if you have a wheel in the air, or snap a shaft - but stuff like that only happens in the forests or grassing.

id fit one into every mini I owned if I drove them hard enough

My experience has been similar to Rich's and Mark's. They have very little more torque steer than a stock diff, a real plus (having lived with a Sailsbury for a while). You'll still get wheel spin, however instead of just sitting there, smoking it up s it were, you'll have some considerable drive with the ATB.

When I fitted my first one, first thing I did was take the Mini out to the road, with one wheel in the gravel and the other on the tarmac, a few revs and dropped the clutch. I'm still smiling

The only down side (if you can call it that), is it will make the steering a bit heavier, but not unduly so.

I don't believe anything is perfect, however, IMO, the Quaife comes very close.

Spider (who will never go back)