18 replies to this topic

[mini93]

After visiting castle combe today iv noticed...and not for the 1st time i might add that i have some traction problems when exiting corners, well obviously weight shifts and grip lessens and when applying the power it over somes the contact, thus spinning.

my question is...whats the easiest way to over come this, by easiest i mean easiest on my wallet haha

i do have rose jointed and fully on car adjustable suspension geometry which was set up last week at southam mini metry centre, obviously knowing there stuff, i dont have a LSD or ATB and the cost does put me off, wondering if there's anything else i can do besides seek one. Would anti roll bars work? and where do they mount if yes because it is a rally car and would need them safe from impacts

Regards

Dave

[Sherlock]

You could try experimenting with your shock absorber settings, as far as anti roll bars are concerned, Miglias use them on the back but you may find such a fitment prone to damage in rallying situations because they have to have enough clearance to go under the exhaust system. They bolt via brackets to the brake backplate mounting bolts on the radius arms & run in bushed brackets bolted to the underside of the subframe side members. May help if you're competing in an all tarmac rally.

[1275 SPRITE]

I dont think ARB's would make much difference to off the corner traction. Have you thought about an X pin diff? they are supposedly meant to reduce torque steer, which I would guess would maybe improve traction?

Did you adjust your tyre pressures when you went on the track?

[jaydee]

Antiroll bars are pointless in a mini, because of the subframe desing.
You have to change springs rating, which in rubber cone suspension, will mean getting red dot cones.
I would try with different caster settings, but that can give you torque steering issues too.
Now i dont know if you already have a x pin diff, but on a mini with around 100 bhp its worth fitting one.

[mini93]

its not torque steer, that was reduced with correct car geometry, it was handling outstandingly apart from the squirm it has under uber heavy braking.

yeah, front tyre pressures were lowered before going on track, backs were normal road pressures due to having better tyres on the rear than fronts, tho i still add front tyres were more than adiquate, i had the same problem when i was at rockingham with matching tyres all round and lower pressures all round.

yep already for a x-pin otherwise it would have snapped long long ago.

i dont think mini's are best suited to gravle rally's so yeah, if i can afford to rally again it will be sealed surface, but some rallys that are considered sealed arent smooth by any means and would knock stuff off if allowed to

[mini93]

Antiroll bars are pointless in a mini, because of the subframe desing.
You have to change springs rating, which in rubber cone suspension, will mean getting red dot cones.
I would try with different caster settings, but that can give you torque steering issues too.
Now i dont know if you already have a x pin diff, but on a mini with around 100 bhp its worth fitting one.

got red dots already, no problemo there.
castor is optimum, just enough feel with self centering bla bla (castor the same as KPI?)
and i was 3/4 through a hardened pin so yep x pin in

[1275 SPRITE]

No castor and KPI is different.

KPI is the angle between the top strut mount ant the bottom ball joint, off the verticle. Not sure how that would work on a mini, maybe the andle between the top and bottom ball joints off the verticle?

Castor is the angle of the strut from front to back. Hard to explain but basically the struts are angled foreward slightly at the bottom.

[jaydee]

But you feel the car undresteering? Or it is just slipping when giving throttle?
It is likely to be suspension settings related imho, if that happened to you on the track, you would have tryied to change caster/toe settings, give a couple more psi at the wheels pressure and lowering height, then see how it goes.

[mini93]

Im not sure KPI has its place on the mini, obviously i think of strut suspension there. im with you on the castor anyways, its why i have adj' tie bars.

yeah, i felt a fair bit of understeer but it wasnt unmanagable as such but its when i tried to throttle out the corner it would spin the inside. obviously the car isnt going to be the lowest out there by any means but as i said, its for bumpy rough tarmac too...soooo nothing i can do there.

i need a slipper diff

[jaydee]

King Pin Angle on a mini is fixed. You can alter caster, once you change caster angle you can restor camber and you have to restore toe out.
Obviously, set the height depending on use, on bumpy crappy roads i wouldnt go lower than the standard mini height..

[Bungle]

i know i run a lot less power than you but i have found if i run the car too stiff at the front i have the same problem

after 19 years of playing on my mini i have found the best set up to be to run the shocks softer at the front than the back

i find this softer set up will allow the car to roll a bit at the front keeping the wheels on the ground

i'm by far a expert on racing mini's but i do have 19 years of tweeking 1 car

[Wil_h]

Antiroll bars are pointless in a mini, because of the subframe desing.
You have to change springs rating, which in rubber cone suspension, will mean getting red dot cones.

Why does the subframe affect the use of an ARB. I wouldn't fit one to a road mini on road tyres, they're just not needed, but I run front and rear ARBs on my hillclimber, with great sucess.

The main reason for this is that the yellow dot cones are just not stiff enough, the ARB means I get the advantage of stiffer cornering with reasonable compliance, important on a hillclimb.

I think the answer to the originla question was obvious and has been answered, to stop the inside wheel spinning you need an LSD or ATB. But the simplest thing you can do is use a bit less throttle and get stickier tyres, when power exceedes grip then you're screwed.

Edited by Wil_h, 27 September 2009 - 08:12 AM.

[icklemini]

How exactly is the car setup?

[MRA]

I dont think ARB's would make much difference to off the corner traction. Have you thought about an X pin diff? they are supposedly meant to reduce torque steer, which I would guess would maybe improve traction?

I think that there is a little confusion here..... a cross pin diff does very very little for traction, with the exception of have a slightly hifger internal friction than a standard diff and that is all.

On the other hand ATB will give you better traction as the power is automatically fed to the wheel with grip and works far quicker than any human intervention, some not all ATB's have an internal "clutch" type of friction device to preload the gears that tie inside the ATB (normally 6 left and 6 right hand worm gears) these are fitted to Focus RS and are available for loads of different vehicles including the 2 types available for the Classic Mini.

Better still for traction is an LSD (Limited Slip Diff) which can be preloaded to the point that almost no slip occurs (not good for corners)

Another traction control system is the better types of aftermarket ECU's available.... DTM being one of these but by no means the only one.

Rose jointed suspension and solid mountings on the subframe will nearly always put an END to torque steer............ A cross pin diff will do absolutely nothing for torque steer........... but are a minimum modifiaction for road safety.... as anyone who has had a diff pin let go at speed will tell you

Edited by mra-minis.co.uk, 27 September 2009 - 09:54 AM.

[mini93]

sounds quite bad but i just told southam to set it up because i was going to combe and i didnt ask for an info sheet, was there while they were doing it though and no doubt colin knows what to set at.

what settings do you advise?

but yeah, think i best start looking for a slipper. Anyone know if a decent 2nd hand jobby?