steering at 150 bhp problem
Turbo Mini Forums

the car has a problem !!
on power overtaking and 70 ish , it starts to dart from side to side this is not with power on and off ,this is with steady torque application , the torque curve of the engine is pretty flat . so no sudden inputs .

the car has solid rear mounts and uppers half solid , tracking 16th out camber 1.5 neg 12*6 wheels revolution .um , if feels as if the drive is being swapped from side to side ,and im then steering to compensate ,and i wonder if the single pin diff is the prob ,maybe a 4 pin would help to blend the power to the 2 shafts more evenly ? (yes i know i should have one lol b4 tom say's it !!)

any input greatfully recieved ,oh incidentaly at low speed when wheel spinning its very straight and non torque steery!
thanks
robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Hi,
Any play in the rack? I guess you've probably checked it anyway.
Also is the rear higher than the front?
Castor angle?
Cheers,
Gavin :)

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blimey that was quick gavin ,thanks , um yes back is about 3/4 inch higher , rack seems fine ill have a really good go at the rack tomorowcastor angle i dont know ill find that out on wed , it is even both sides and id guess i set it at standard so 3.5 .weird thing is its not a power on /off situation , its a steady power on !

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Tracking @ 1/16" is this a four wheel alignment figure or have you just set the track on the rear wheels?

On 5th Sep, 2011 Vegard said:
I stand corrected. You should know

My guess would either be that perhaps you have some wear somewhere? Radius arm maybe?

Or it could be an impending problem with the diff planet wheels perhaps? The single pin diffs do the job for a time, it is just the potential damage to the rest of the engine from swarf when they self destruct that I don't like!

Tracking again robert check this out

also stiffen the shocks up at the rear this will help somewhat as the car rear will not then squat down and lose the front steering so much

increase caster to 5.5 deg this will help a great deal

after you check out all the other obvious things

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

On 8th of Apr, 2007 at 08:04pm BENROSS said:
Tracking again robert check this out

also stiffen the shocks up at the rear this will help somewhat as the car rear will not then squat down and lose the front steering so much

increase caster to 5.5 deg this will help a great deal

after you check out all the other obvious things

Edited by robert on 8th Apr, 2007.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I've had similar problems in the past when I had a front shock start to degrade. Might be worth pulling them off and checking to see if they feel similar and that there is no sign of leaks etc.

The only other thing I can think of not mentioned here is the tyres. In the past I have noted that certain tyres feel far more stable than other, namely the old Bridgestone Potenza and current Continetal on 13s (never found a tyre I was happy with on 10s). Not saying it is a problem but sometimes I have been sure the tyres were making / breaking grip under acceleration. Certainly my car accelerates much cleaner and straighter with the two mentioned tyres than Yoko A539s.
Based on this it may be that the tyres have passed their peak performance capability.

Maybe one tyre is no longer round (happened to me once with the Porsche after she was stood for many months without moving).

Just suggestions.

Every day is a school day ...........

How fast and how expensive ...... the same question...

im going with the castor too, im running 5.5 or 6 deg too

thanks roger and nic , ill check my caster on tues ,and if its low ill adjust it up , also ill chech the dampers thers deff no oil from them but whats going on inside who knows ,the symptoms only really come about when doing high speed and then trying to steer a little bit ,eg putting on power and then turning the wheel to overtake , a v small steering input becomes a dash to the oposite verge ,and then when one corrects it realizes an affinity for the car one is overtaking!! if i accelerate hard with no other car in the way ,and just hold it straight ,its fine , it only happens when i try to change direction , it reminds me of when i had 2 gearboxes in the tvr and could change to 4th whilst being in reverse , every input was massively exagerated ,but thats another story ,i degress .lol

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Robert, I think it would be well worth giving the back end a thorough check.
Subframe mounts, Radius arms, and wheel bearings.
From you description there is something seriously wrong and it should be very obvious what it is when you find it.
Does the car still corner as it used to or is it different left to right, if it is different that should tell you which side to look at.
I suspect it's the rear wheels steering the car.
Regards
Dave

thanks dave ,

it steers and handles really well with 122 bhp , all seems fine , and variuos mini experienced passengers remark on its excellent handling ,

only at the 150 bhp mark does this raise its ugly head ,it feels even side to side but as if it has a 1 to 1 rack ratio!!
it really feels as if its got a lsd in it and its shifting power from side to side .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

You last sentence would suggest the diff is locking up under the increased torque.

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Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

thats what i suspect axel ,thinking maybe a 4 pin would stop this ,ill check all the other stuff first though ..
thanks
robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Yes, I agree, having had a standard diff fail on me in the past (planet wheels lost teeth and locked up) it does make the car drag itself about all over the road. Fingers crossed its something else though, when I first got my 205 the rear beam was sh@gged with lots of play in the radius arms, this had a similar effect to the one you describe in that when driving it hard, applications of power would cause the car to steer on its own from the rear, countering with steering made it worse LOL. Obviously its far easier to check out the radius arms and rear wheel bearings etc before stripping the engine to get at the diff, also if you have adjustable rear brackets have these moved perhaps?
Another one is to dump the oil and go fishing in the bottom of the gearbox with one of those extendable magnets on a stick to see if theres any debris in there.

my mini does this and ive never been able to find out how to stop it. the only thing ive noticed is that if the tyre pressures on the front axle are slightly different then it make it alot worse or if the tyres are too hard. ive been runing 15-18 psi in mine. this has made it quite a bit better!

Pointing more towards low castor with every post!

Every day is a school day ...........

How fast and how expensive ...... the same question...

Mine had a similar problems, except mine did it at all speeds..it kept wandering all over the place.

I'd replaced one the front tyres that had worn due to incorrect tracking. As it wasn't worn at an angle anymore to compensate for the tracking being out it made it a whole lot worse than before.

Sorted my tracking out today and have no probs anymore. :)

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1/4mile in 13.2sec @ 111 terminal on 15psi

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

5.5 to 6 deg castor is the way forward.... literaly

Every day is a school day ...........

How fast and how expensive ...... the same question...

WELL I HANG MY HEAD in shame :(...
why you ask ,!
well
i checked the geometry on the spud mobile last week , and woe woe woe unto me ,it was wonky !! oh yes .

front end was fine on the left 1.75 neg camber ,4.75 degr castor ,all ok .
then the other side ..well i must have had a fade of the grey matter changing the rose joints in a hurry in 05 , cos it was .5 neg and 3.5 castor !!!
so got some other arms and ties which are adjustable on the car so cleaned those up and painted them then when fitting them realized the bottom swivels had about 3mm up and down movement !!! oh the disgrace :$
then taking off the hub the back inner race stuck on the shaft and wouldnt come off ,so then had fun with that ,,oh and getting the hubs off was a chernobul type operation too ..still all fun eh ,at least will be when my back gets better ...oh yes also decided to get the metty 4 pots on so had to get long bolts and spacers cos im not using the metty flanges due to thier increasing offset ( this is bad) !

then fun with the locknut stripping on the bottom arm ,and then oh fun bleeding the brakes a pipe flipped out of the pot and sprinkled brake semen all over the front arch ,frantic rush to kitchen ensues after of course spasmodic spitting at arch !!(you can never get a mouthfull when you want one )

then bestest hoot of all ,geometry of the front end ..so i set both sides at 1.5 neg very carefully ,then ok now we are cooking with gas,just the castor ,then tracking ,got the castor at 5.5 then thought hmm wonder how thats affectd the camber STUFF ME RIGID AND CALL ME AVRIL!!!!!!!!!!!!
poxy camber now at THREE POINT BLOODY 5 NEG...oooof
gosh darn !!!!!!!!
so back and forward i go every now and again forgetting to bounce on the wings and settle it just to shoot the blue bird of logic in the head now and again ,and that was me done for the day ,at the mo its at 2.5neg and 4.75 castor .so back on it again tomorrow .!!!!
for some reason i keep getting the image of a bottle of petrol with a wick in it ,can anybody analyse that image for me !!!

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

be paitend rob and persistant that way you will get results

incedentley rob fitting the metty 4 pots with longer bolts and the spacers ?? where did you get these form

rob