pulling to the left......... and then pulling to the right!

[minimans]

Could still be a warn pin though I had one doing the same thing until it broke then it just pulled left hard and fast!!

[Spider]

Regarding the diff pre-load and pulling on the steering as I mentioned earlier, that is not possible. The The diff hemisphere is effective solid from one bearing mount to the other, so, in the extreme, even if one bearing was seized, it still wouldn't cause the steering to pull one way or the other. In regards to which side to fit the shims or which way the diff should be biased before shimming, from a pre-load and steering view point, it doesn't matter as the loading will transfer evenly from one bearing to the other.

The manuals state +0.001" - Really?

The reason for this isn't all that obvious. It's sweet bugger all to do with the steering or the 'action' of the diff itself. It's to maintain - as precise as is possible - the centre to centre distance between the centre line of the Diff assy and the Main Shaft, to ensure that the FD Gears have correct mesh. On Gears on the size that we have in our FDs, Mesh distance should be set and maintained to +0.003" / -0.000", so if there's not enough pre-load, the Mesh distance will increase.

Mind you, many of the Gearbox Cases I've measured are outside of the spec.

[evonaut]

what happens if you decelerate and brake does it still dive about

under braking there is a little pulling but not as pronounced as the moment the throttle is lifted, and / or depressed. the braking can be put down to the slight and within tolerance difference in brake balance recorded on the MOT documents.

the car only does its strange lunging at the moment the throttle pedal is depressed or lifted. as soon as the car moving under constant throttle it runs straight? its as though it is related to how the mass of the car moves at the moment of deceleration or acceleration. you know, how lift oversteer affects occurs......

[surf-blue-850]

Worn engine mounts or tie bar bushes?

[Dr S]

I think i'd be tempted to run it up on a set of axle stands (Your approach to such matters may differ!) and spin it up in say 3rd and lift off.

I think you'll see the wheel pull back in the arch as the tiebar is letting it move. On mine it felt ok, but as you added more load it just pulled through.

[ianh1968]

I think i'd be tempted to run it up on a set of axle stands
(Your approach to such matters may differ!)<SNIP>

BIG WARNING: I did this once and ripped my CV boots to shreds in seconds as the angle of the
drive shafts ended up very different to how it normally would be. Given that I'd just changed the
boots for some new ones, I was a bit pissed off...

OK, so I was winding it from lock to lock as well, but I'd be very careful...

To be "more successful" next time, I would put chocks under the bottom swivels to make the
height of the wheels somewhere close to what it should be under normal running.

Ian

[ianh1968]

its as though it is related to how the mass of the car moves at the moment
of deceleration or acceleration. you know, how lift oversteer affects occurs......

OK, the balance of the car may be all wrong - All the weight is taken across two diagonal
wheels, eg the front left and the rear right... (The remaining wheels are just like the stabilisers
on a kid's bike, they just stop the car from falling over).

Say you've got a lot more weight on the front left than the front right, this may well mess
things up. I think that mine are suffering from the same problem... I have adjustable
coil-over springs at the back and uprated standard rubbers with HiLos at the front.

I "haven't got round to" getting the corner weights checked yet... I just set them up
by eye and made sure that the lengths if thread showing were somewhere about the
same. However, when I go over speed-humps, the car kind of wobbles from side to side.

You can make the car dead level from side to side, but this is not the whole situation...

A set of cheap corner weight scales is on my "wish-list".

Ian

[rich@minispares.com]

A set of cheap corner weight scales is on my "wish-list".

Ian

ive got a set of expensive scales and they make corner weighting a car easy - once you have used them you struggle to understand how people set cars up without them (badly, I suspect..... )

[nick rogers]

I have not replied to this because my answer will seem bonkers but I have seen this problem. Someone brought a car to our workshop many years ago which did exactly what is described above. I test drove it and under acceleration it pulled strongly to one side. On lifting off to change gear, it lurched the other way. Re-applying the throttle and it went back the other way. Very dangerous. We brought the car in and lifted the bonnet and noticed the rocker cover sloped to one side. We took a few measurements and then went under the car. It soon became apparent that some previous owner had fitted a manual unit to an auto subframe. One mounting had been bolted up but the other sat very low in the frame. The solution ? Drill the subframe lower down to line up with the mounting. Result ? Horrendous handling.

[evonaut]

fixed!

apparently a 2 thou shim? somewhere in the dif? and its fixed!!!!!! i was thinking that surely 2 thou is too thin to make a difference but having reread this thread and there was talk of 1 thou making a difference? its beyond me…….

anyway, its like a new car! FUN TO DRIVE! now, where did that summer go?

[R&R]

I'd be surprised if its the bearing preload shims, but it could be the thickness of the thrust washers behind the output shafts maybe. One side being tight, and the other free running. We have built "tight" diffs using standard components with some preload for gaining a bit of advantage in certain motorsports so the potential is there to do it.

[Spider]

Sorry, I just cannot see anyway that this would be the diff;-

Since collecting my fully restored hydro car, it seems to have developed a steering / suspension annoyance. Or at least its got considerably worse.

The effect is pronounced travelling at speed, about 70 ish, although it is detectable at slower speeds.

The car is stable and straight whilst driving at constant speed and throttle, but as soon as you lift of the gas it lunges quite violently to the left, and this is then countered when you reapply the gas, lunging to the right.

The tracking also gradually went out but i had this reset and it has not cured the problem. The steering / suspension garage that looked at the tracking suggested that the bushes could need shimming and trimming? does this sound likely? we looked at the car whilst it was on a ramp and all the steering and suspension arms etc are tight - no lose or wobbling bits?

The vast majority of original steering and suspension components were used in the re build. Obviously bushes and other consumables were replaced.

Does anyone have a view on the above? wouldn't mind knowing if it sounds feasible prior to having a garage spend a day buggering around.

Many thanks

Evonaut

Keep in mind, the internal gears of a diff are stationary (or nearly so) in relation to each other when travelling in a straight line. It might feel OK at present, but if it was there before, I'd say it will be back.

You did mention in your original post that the tracking 'Gradually Went Out' How did it 'gradually go out'? Was something loose or some part(s) 'settle'. It also appears from your description that this tugging one way, then the other was slight to start with and then got more and more pronounced, is that right or am I reading too much in to this?

Also, given your description, it is consistent with a worn steering rack bush (assuming RHD Car), worn / loose rod end on the LH End of the Steering Rack (which is not easy to pick up as they are spring loaded) and / or loose steering arm on the LH Hub and / or Ball Joints on the LH Hub. It doesn't need much movement at all to do what you have experienced.

[R&R]

I'm with you spider, I'd be looking to see if a bent inner steering column is causing the rack to work loose.

Sometimes a particularly badly tracked up car can be pretty skittish down the road, although my favourite all time handling malady came about because my customers dad had told him that minis don't have dampers! He was half right of course.....but in this case he was very wrong.

[surf-blue-850]

Has anyone mentioned the steering arms on the hubs? Early and late ones are different resulting in bump steer as the Ackerman angle is out.

[Spider]

Has anyone mentioned the steering arms on the hubs? Early and late ones are different resulting in bump steer as the Ackerman angle is out.

Not as being the wrong arms, but somewhere to look;-

I'd say one or both the Steering Arms are loose. The bolts for these often stretch and while they feel tight with a spanner, they are not tight on the Arm, only in the Thread. New bolts are sometimes the answer.

It could be the steering rack itself, but usually by the time they get to the point like you have described, they also get very noisy.

When the tracking has been done, it was set for Toe OUT and not Toe in wasn't it? Though this usually make them weave ever so slightly all the time.

[Lord Croker]

This might sound absolutely way out, but I have known this before, on a 1400 S, we spent hours looking for a mechanical problem & the gaffer, with a stroke of genius removed the front wheels, stood them together & one tyre was noticeably larger in diameter than the other, even though they were both of the same make & tread pattern. A change of front tyres & the problem was overcome, apart from the normal torque steer, which all powerful Minis suffer from.

Regards, Rich.