8 replies to this topic

[Rusty Nut]

Afternoon all

Mini MPI 2001 about no. 570 from the last one.

 

My problem - 

The cornering is wildly different from left to right. If I go round a roundabout clockwise its as stiff as a dead pheasant. Holds perfectly. No body roll. No rear swing out. No dip. No oversteer, or understeer if pushed a bit.

Go round the same roundabout the other way** and I get all of the above. First the front right corner dips, it feels really squidgy, then the rear starts to creep out, to the point of oversteer if pushed. It’s like driving a boat - or driving on a very deflated tyre or two.

 

What I’ve done - 

Front doughnuts were severely flattened so changed those about 4 years ago. Car now sitting at the correct height.

Fitted adjustable hi-lo’s and adjusted both sides so that chassis height is the same and as original spec.

New front hubs, all new ball joints (there was some play in the lower ball joint).

Steering rod lengths checked with new ball joints and wheel alignment done as original spec (string method - sorry).

New Spax shocks on the front. Original Koni at the rear. All shocks are tight, balanced and passed several MOTs.

New heavier duty tie rods, new harder poly bushes (outside) and new rubber bushes (inside) fitted. Adjustable tie rods set to original 14 5/16ths as the old (bent) ones.

Tyres are all new (2000 miles) and properly inflated.

 

Camber and caster not checked. But everything else is adjusted to standard.

 

Even with the very elegant Mrs Rusty Nut in the passenger seat to even things up a bit on the weight front, its exactly the same.

 

What I’m wondering about - 

Could this be front subframe mounts?

The engine moves around when turning the wheel - but then that’s with the car at a standstill.

I was considering solid rears, solid top tower, poly lower tower, and standard teardrops.

I have not checked the state of these mounts beyond visual, except that they are all the original ones and pass an MOT.

 

Should I consider rear subframe mounts too?

 

Or is it a duff doughnut? But ride height is good as is bounce.

 

Perhaps someone can shed some light on this.

 

** The roundabout is unused in a private car park at the weekend.

 

 

[nicklouse]

Ride height may be equal and correct but it sounds like your corner weights are way off.

[Spider]

Adding to Nick's suggestion, I think you should have all the suspension angles - front and rear - checked as well and also on the front, if they can check the suspension angles when the steering is turned each way by the same amount.

Also, if you are swapping the front subframe mounts from rubber, either go all flexible or all solid. Mixing them will only put more stress in to the body, leading to cracks (it seems usually around the toe board).

[absx2]

Nicklouse knows his stuff and the corner weights will be way off but i`m going to bet your castor angles are way off as I have set a few minis up lately and two cars ended up with a difference of 8mm in length from one side to the next in the tie rods. Both cars now corner on rails and one was a one owner late Cooper all original and never crashed so that puts accident damage out of the window.

If you are going to drive the hard you really should solid mount the front subframe and get four wheel alignment.

 

Damn, I type slowly :)

Edited by absx2, 13 June 2021 - 08:34 PM.

[Cooperman]

I also suspect castor angles plus possibly rear camber slightly positive on one side. Also check camber angles on front wheels.

When fitting sub-frame mounts for optimum road-holding, handling and steering response you MUST go all-solid and never 'mix & match' with solid & poly.

Once you have done this, plus fitted adjustable front tie-bars and got the suspension settings correct, you will be amazed at how it steers and drives.

[Rusty Nut]

Thank you gentlemen

As always on this forum the voices of experience put me to shame!

 

I’ll get stuck in and I hope to report back one day, but finding someone who understands the finer points of mini geometry in South West France is a challenge. There’s a guy who races minis in Pau. And I came across a race prepared 60’s model over the border in Irun, Spain, that I could have eaten my lunch off the front suspension of. Full race front subframe. Mad.

[Rusty Nut]

Quick update - just as a very rough start - wheel centres have about 15-18 mm difference from left to right.  Right is shorter at 2m03.5. Left at 4m05.2 . Wheels set straight.

So I'm going to look at caster angles to see if they are close or not.

Try to find the root of the problem - and get some measurements of some fixed points on the rear and front subframes and diagonals  in case something has shifted.

 

Then on to a geometry shop when I find one.

 

Bought the car in 2009 and dont know if any previous accident history.

[Steve220]

Another vote for caster angle. If you get it set up, and they use the standard rover figures, you'll find your wheels will move forward, so much so they'll begin to hit the arches and the wing. It's a terrible compromise on the sportspack

[sonikk4]

Or how about worn radius arms?? I know when the radius arm on one side of my wife's mini back in the day had really weird handling, the car felt completely wrong going into a roundabout etc.

 

Replaced the arm (it was beyond repair as the pin had worn through the bush and actually wore into the arm itself.)