32 replies to this topic

[simplyminis]

Did the steering go strange just before the breakage?

yes

[tiger99]

Sounds like a broken CV. Jack up one wheel, select 4th gear (engine not running!) Turn the wheel, does it make the engine turn? (Check fan baldes, belt or crankshaft pulley for rotation, and you should also feel the compression).

No engine rotation, check that the drive shaft is rotating and the opposite shaft (wheel on ground) is not rotating. If a shaft rotates when its wheel does not, or vice versa, the CV is bust on that side.

If the shafts seem to behave, check the inner pot joints for rotation. You can just see them down the back of the engine. If the pot on the same side as the jacked up wheel does not rotate, it is broken. If the pot corresponding to the non-rotation wheel and shaft rotates, it is broken.

If everything rotates on the jacked up side and nothing on the other side, nor the engine, there is a failure within the transmission, anywhere from the clutch through the drop gears, gearbox , diff and output splines, so whatever is broken the next step is to have the transmission and engine out, and split them. Or. if you like working in confined spaces, split them in situ and examine the transmission in the car. But it will have to come out for repair and removal of metallic debris anyway.

But the 2 minute check, involving jacking and rotating one wheel, will tell you whether you need to look inside or not. A broken CV or pot joint is comparatively trivial.

[bmcecosse]

As Cooperman says - if the diff or anything else has let go inside - you are looking at a complete strip down, and better hope the debris hasn't gone through the oil pump..... DO inspect it! And wash out the oil cooler if it has......
On the LSD side - I would say a properly set up friction plate LSD (ie Salisbury and NOT set full tight as for racing) is excellent in a rally car - good enough to get the car out of a stage with a broken driveshaft - and pretty well 'bullet proof' too, although like everything else - should be stripped and inspected regularly.
In this case - I'm not convinced the problem is internal........

[Cooperman]

Agreed, it does sound like a broken CV joint.
On the subject of LSD's for rallying in a Mini, the problem as identified by Russell Brookes, is that if you run a bit wide and need to put the power on, instead of the outside wheel spinning, but still giving some grip wilst the inside wheel will give none, the inside wheel grips and the car falls into the ditch (or whatever is off the road. Lifting off does no good either as an LSD will induce understeer, os you'll still go off. My son can confirm that as he co-drove Jim Maker on a Tour of Ypres in an Historic Mini with an LSD and they did exactly that on a 90-left on tarmac with grass on the outside. Instant retirement when the outside wheels went on the grass.
I drove Will Sparrows car back in 1970 with an LSD in the wet on a B-road and just couldn't get the hang of it at all.
But, Sid Ormerod always used one and he won several Historic events in his 1275 'S'.
I guess it's what suits a driver's style.

[bmcecosse]

The trick is not to have the diff set too tight..... and of course - throw the car at the corner and power through with the wheels straight ahead! Easier said than done of course..... I loved the welded diff in my Autocross car......

[Cooperman]

The trick is not to have the diff set too tight..... and of course - throw the car at the corner and power through with the wheels straight ahead! Easier said than done of course..... I loved the welded diff in my Autocross car......

For autocross and hill-climbs an LSD is probably vital.
It's when you're rallying and the corner tightens the problem comes. With a conventional diff in a Mini you just lift off and turn in, then as the oversteer starts you hit the power hard to keep the front in front. With the LSD if it tightens you can't lift off or it'll understeer straight off, so you have to just hit the power and if it's less 'grippy' on the outside, or if you go onto the grass, the LSD will just pull the car off the road. Personally I just can't get on with an LSD and Peter Horsborough who also rallies a 1275 'S' removed his and fitted a X-pin out after driving my car and putting up a better time in my car than in his on a handling test during a magazine test day. Maybe on an all-tarmac special stage rally an LSD might work well as you'll be on full pace notes so unexpected tightening won't happen (unless the co-driver makes a mistake reading them - not unknown!).

[simplyminis]

thanks for the info ill check it out tomorrow

[Carlos W]

thanks for the info ill check it out tomorrow

Please report back!

[simplyminis]

I've jacked the one side up turned the wheel with it in 4th and no compression nothing! Shaft turns cv pot on the diff don't move and the same on the other side

[simplyminis]

Right got that wrong, jack the drivers side up no compression the drive shaft rotates also the passenger side does aswel!
Jack the passenger side up only the passenger side drive shaft rotates

[tiger99]

Something strange there. If the passenger side shaft rotates, with wheel on ground, the passenger side CV is broken. But if the passenmger side shaft rotates when you turn the passenger side wheel, but nothing else moves, then the passenger side pot joint is broken. Two simultaneous failures seems unlikely.

Was it really the shaft rotating in both cases, or perhaps only the pot joint?

It does seem that the diff and gearbox are probably intact. Check that the passenger side shaft is rotating without turning the pot joint, if so the worst case is that the shaft end splines have stripped, damaging the shaft and pot joint, which is still very much cheaper than any internal gearbox/diff problem, and can be fixed in an hour or two.

[simplyminis]

no idea ive got 2 drive shaft ready to change

[simplyminis]

anyone think any different thanks

[Cooperman]

If a CV joint is broken when that side wheel is jacked up the wheel will rotate and the shaft will stay still.
When the other side is jacked up and the wheel rotated both shafts will rotate.
It does sound like a drive shaft/CV problem rather than a diff issue.

[simplyminis]

If a CV joint is broken when that side wheel is jacked up the wheel will rotate and the shaft will stay still.
When the other side is jacked up and the wheel rotated both shafts will rotate.
It does sound like a drive shaft/CV problem rather than a diff issue.

passager side shafts rotates but the cup doesnt