Unusual failure
Discussion
On a rally the weekend before last I had a most unusual failure. The spilt pin holding the hub nut failed on the left hand side. The remains of the split pin could still be seen in the drive shaft, so there was definately one fitted. After failing to fit a pin many years ago, I'm extra particular about this, as one may imagine. This led to very spongy brakes on one test followed by fracture of the brake disc radially around the disc root where it meets the horizontal portion. As I was not carrying a spere disc assembly, we had to retire.
Now, has anyone else ever had a split pin failure at this location? I've certainly never heard of one there in 45+ years of 'Mini-ing'.
Now, has anyone else ever had a split pin failure at this location? I've certainly never heard of one there in 45+ years of 'Mini-ing'.
ive no personally had what your just suffered, but what you are describing is called epicycloidal progression[i think thats how its pronounced]the action of the drive flange trying to move it under acceleration and braking., basically your nut has managed to work lose[ by not being tightend to the critical torque] only by fractions of a degs at first, then it gathers momentom, too- ing and fro- ing intill it chavels its way through the split pin, basically nothing will stop the nut eventually champing through even a termpered pin if left long enough.
i have had a nut come loose with no pin fitted but never toughed it for about three years m then at a track day near side came loose causing same damage as yours.
i have had a nut come loose with no pin fitted but never toughed it for about three years m then at a track day near side came loose causing same damage as yours.
Edited by fastcarl on Monday 7th April 21:54
fastcarl said:
ive no personally had what your just suffered, but what you are describing is called epicycloidal progression[i think thats how its pronounced]the action of the drive flange trying to move it under acceleration and braking., basically your nut has managed to work lose[ by not being tightend to the critical torque] only by fractions of a degs at first, then it gathers momentom, too- ing and fro- ing intill it chavels its way through the split pin, basically nothing will stop the nut eventually champing through even a termpered pin if left long enough.
i have had a nut come loose with no pin fitted but never toughed it for about three years m then at a track day near side came loose causing same damage as yours.
Was on a bus for the first time in years a couple of weeks ago and 5 mile up the road the rear wheel came off! Similar to this epicycloidal progression, the nuts musn't hae been tightened and we were left with a wheel stuck up in the arch and a collection of nuts with the severed remains of studs stuck in them.i have had a nut come loose with no pin fitted but never toughed it for about three years m then at a track day near side came loose causing same damage as yours.
Edited by fastcarl on Monday 7th April 21:54
Did have a wheel come off a trailer many many years ago when the hub nut came adrift, never did discover why
pete
this is a common problem with the mighty minis.
they also suffer with the cv thread snapping behind the nut, though this is probably due to nipping the nut up repeatedly when the nut starts comming loose.
its nearly always the passenger side one that does this as of course the nut is trying to undo all the time.
i think that this is a problem that starts with a worn hub or a drive flange with a chewed up rear face, this wear gives the bearing room to shuffle about, which makes the problem worse. once the nut snaps the pin all that holds the wheel on is the disc in the caliper, so the brakes come and go as the pads are forced back into the caliper, then (as you nearly found) the disc cracks and the wheel, flange and centre of the disc escapes.
if i where you i would replace the hub, bearing and flange. this was the only wway we found to cure it.
that and drill the c.vs for fatter pins and 'wiggle check' the pin before every event!
this is a common problem with the mighty minis.
they also suffer with the cv thread snapping behind the nut, though this is probably due to nipping the nut up repeatedly when the nut starts comming loose.
its nearly always the passenger side one that does this as of course the nut is trying to undo all the time.
i think that this is a problem that starts with a worn hub or a drive flange with a chewed up rear face, this wear gives the bearing room to shuffle about, which makes the problem worse. once the nut snaps the pin all that holds the wheel on is the disc in the caliper, so the brakes come and go as the pads are forced back into the caliper, then (as you nearly found) the disc cracks and the wheel, flange and centre of the disc escapes.
if i where you i would replace the hub, bearing and flange. this was the only wway we found to cure it.
that and drill the c.vs for fatter pins and 'wiggle check' the pin before every event!
Had it happen to me a while back,lost both the nut and taper washer off the hub,only the caliper holding the hub and wheel on! This was on my daily user,only a standard-ish MG Metro unit, on 7.5 S discs. Scary! GeoffSounds like a huge bodge but I had the same problem and fitted new bearings and had new drive flanges anyway. I was aware that there was NO PLAY in the system and still it sheared pins. So, drilling the hole out a bit larger and using a piece of iron dowel, I put it in properly. You might also find that the nut is starting to wear. Take it off and have a look at it. Is it wearing from being jiggled around.
Funnily enough, I was only talking about this yesterday.
Funnily enough, I was only talking about this yesterday.
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