Fitting Prop Shaft

[jlan1978]

Hi all

I had the rubber boot on the prop shaft eat itself, so I took off shaft and had a new boot put on.
Less than 100 miles later the new one has also eaten itself.
Is there a specific process to refitting the shaft I'm missing?
Just trying to establish if I'm making an error fitting or the new boot repair was poor
Thanks

[Carledo]

I'm assuming it's a Sprint with the central CV joint and the little rubber boot to seal it.

If so (and it's manual transmission) then there is a rather counterintuitive fitting of the centre bearing mount bolt "ears" where one is above the bracket on the floor (as you would THINK correct) and the other sits below the bracket. This is to stop the perfect alignment of the prop front section with the gearbox tailshaft which can result in resonances, vibrations and early failure of the front UJ.

However, it's my opinion that, if you HAVE done this wrong, it's not responsible for the destruction of the boot. More likely is that the boot you have fitted (or had fitted) is one made for a FWD driveshaft, which is not up to the centrifugal forces generated by a propshaft which spins around 3 times faster than a driveshaft. It's quite a common mistake due to the OE boot being unavailable for some time now and people hunting for something similar to use instead.

I believe Alun Nicholas (xvivalve on here) has been investigating remanufacture of an OE spec boot but I don't know how far he got.

Steve

[jlan1978]

Thanks Steve
Ok I'll go back to the place that fitted it. So would a RWD boot be heavier made?
It drove smooth with no vibration or noise.
The refitting of the shaft was tricky, I have an workshop manual so I'll follow the process in that.

[Carledo]

Thanks Steve
Ok I'll go back to the place that fitted it. So would a RWD boot be heavier made?
It drove smooth with no vibration or noise.
The refitting of the shaft was tricky, I have an workshop manual so I'll follow the process in that.

I used the FWD as an exemplar. A driveshaft is the other side of the differential which reduces the rotational speed of the propshaft by a figure of (usually) three point something to one. A driveshaft in a RWD application (IE something like a Sierra independent setup) will still have that speed reduction, so any boot made for that driveshaft application would have the same limits as one for a FWD. What we NEED and what seems to be not currently available is a boot designed specifically for the much faster propshaft application. Barring the odd NOS original that crops up from time to time, there just isn't anything usable about. Hence Alun's interest in remanufacture as ALL Sprints have this CV jointed prop.

My own solution is a lot whackier, I have custom props made by Proptech in Hartlebury for my Vauxhall powered Dolomite restomods. But I don't start from scratch, I modify (usually) a 1500 automatic prop which has 3 UJs instead of a CV and 2 UJs and, importantly, a rear mounted sliding joint. Then I get an inch taken out of the rear end to compensate for the Sprint's longer diff and the front end of the front section adapted to suit whatever gearbox i'm using. This typically costs around £100, including dynamic balancing, plus another £50 if I have a new centre bearing fitted. Plus of course, whatever I have to pay for the 1500 auto shaft in the first place (they're not usually expensive, but can be hard to source) But that's the last expense, as any further servicing in the way of replacement UJs or bearings, I can do myself. I can't imagine a scenario when it would be impossible to buy a QH 15002 UJ or reasonable facsimile! So it's futureproof!

Steve