Broken Pinion Shaft (Not my Rover)

SydneyRoverP6B

SydneyRoverP6B

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A friend in Sydney had the unfortunate experience just recently of having the pinion shaft shatter. The car was out for a brake test as part of the annual registration requirements here in NSW, Australia. Reportedly, after having stopped following a brake test, his Rover then failed to move forward, instead making crunching sounds. Returned to Graham Cooper Automotive on the back of a truck, his Rover then awaited a spare pinion extension case complete with all internals to be fitted. A new pinion oil seal was fitted at the same time. The following photos illustrate the damage and the broken shaft. From memory, his Rover has around 140,000 Miles (225,000km) covered. He said that there had been a vibration within the car for the last few years, but could not be located. None of the usual suspects were the problem. After having the replacement complete pinion extension case fitted, the vibration has disappeared. It may well have been the broken shaft delivering a warning some while in advance prior to complete failure.

Ron.DSC09737.JPGDSC09742.JPGDSC09737.JPGDSC09742.JPGDSC09743.JPGDSC09746.JPG
 
good to see whats in there if nowt else
- lost complete drive with my father car years ago,
he'd just driven home from work in it...!
i hopped in to borrow -last one in first one out scenario- and wouldn't reverse....
luckilly i'd recently bought a rtc1390r from unipart when they were selling off ......
we never bothered stripping it to find out,so could of been a similar prob
thanks for sharing
neil
 
Hi, No it's solid, it's twisted or peeled apart rather than the usual snap straight across like a carrot. To the OP - is there any sign of an inclusion or scar as a starting point? I bet that was a bit dramatic.

Colin
 
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I've only ever had one of those break, and that didn't break the casing. The coupling between the rear of the pinion shaft and the front of the diff is supposed to be the weak link but I've never seen one of those broken.
 
Hi. Grey Rover was facing uphill at the traffic lights in the city, when the clutch was let out instead of moving forward we rolled backwards and there was a rattling sound, luckily no one behind, so Rover went home on the back of a truck.
On examination the shaft appP1010083.JPGeared to have a forgingforging flaw.
 
colnerov said:
Hi, No it's solid, it's twisted or peeled apart rather than the usual snap straight across like a carrot. To the OP - is there any sign of an inclusion or scar as a starting point? I bet that was a bit dramatic.

Colin
Click to expand...

Hi Colin,

I am advised that the failure appeared to have originated from 'a seam' running along the length of the shaft, from when it was forged possibly. Rob, the owner of the Rover felt that it may have been a manufacturing fault.

Ron.
 
Hmm, so that could have been the stress riser. Probably did well to last the amount of time that it did, I expect it will have had an easier life of late compared to it's early days.

Colin
 
That is quite likely Colin. His Rover definitely has an easier life these days than 25 years ago.

Fortunately it might be the case that such failures are a fairly rare occurrence.

Ron.
 
Along a similar vein... Worked at an aluminium smelter in the 70s, which had a certified metallurgical lab for testing. One of the guys had a Fiat DOHC car that he flogged very hard in rallies etc. One of his pistons failed. He brought it in to the lab, who sectioned the failure area, polished it, took lots of high magnification pics, wrote a very official looking report of the opinion that the failure was caused by improper heat treatment, sent it off to local Fiat dealer. Engine was replaced no charge.
Porsche 928s use a shaft to connect from the crank to the rear mounted transaxle. In the autos from 86 on the shaft is clamped rigidly at both ends, with no freedom . It seems that over many years the shaft pulls out of the clamps, effectively stretching, and applying end loads to the crank until the centre thrust bearing fails and the block is scrap. Nobody seems to know what the ultimate cause is, the only control being to check end float regularly and loosen the clamps, release the end loads and reclamp.
There was also a change to the size of the shaft from 24 to 25mm diameter. The catalyst equipped cars had a feature that detected a problem with a cat overheating and cut fuelling to one bank of cylinders, called limp home mode. If the car was used for long in this mode the shocks caused by the uneven firing pulses eventually caused the shaft to fail at one of the steps at the end of the splines. Any chance some misfiring occurred in the case, even some time ago?
jp
 
jp928 said:
If the car was used for long in this mode the shocks caused by the uneven firing pulses eventually caused the shaft to fail at one of the steps at the end of the splines. Any chance some misfiring occurred in the case, even some time ago?
jp
Click to expand...

I don't recall his Rover suffering from misfire for anything like hours let alone days. I know as we would always go to each other's house and work on our Rovers with his Dad. It is more likely a manufacturing defect that was the cause.

Ron
 
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