Propshaft.

Fitting the propshaft all seemed quite straightforward. The challenge was to make sure I get all the measurements right in the first place to send off the Bailey Morris to get propshaft made and balanced.

Bailey Morris supplied a form that I could put some key details in but I also did a drawing for them that I understood as well!!

Additional Drawing

Bailey Morris Form

I read various opinions about just how much of the slip yoke shaft should be protruding from the back of the gear box and therefore, how long the propshaft should be.The yoke is at the end of a splined shaft that slips over the splined output shaft of the gearbox. The length of the splines is something like 100mm to 120mm. The slip yoke cannot be inserted all the way  into the gearbox as there needs to be some float to allow for any potential movement between the gearbox and final drive. But it is not going to move any more than 5mm so that should be sufficient. But some comments were saying that there needed to be 25mm of yoke protruding from the end of the gearbox. That would mean that there is 20% or so less engagement of the output splines and given that there is 400hp+ transmitted through those splines I kinda thought that the greater engagement the better.

One of the reasons I can see for the 25mm allowance is to overcome a fitting issue. I had a long centring spigot in the middle of the final drive flange that stops the propshaft being manoeuvred into position once the slip yoke is inserted in the gearbox.

  












If you fit a shorter propshaft, you can slide the slip yoke right into the gearbox, then raise the propshaft flange at the final drive end over the centring spigot and slide the propshaft rearward over the spigot so that the propshaft flange and final drive flange meet. This would result in approx 25mm of slip yoke protruding out of the back of the gearbox (and a reduced engagement between the output splines).

I decided to keep the amount of shaft protruding to a minimum so in order to do that I took a disc cutter to the final drive spigot and shortened it so that there was just enough left to go through the propshaft flange to ensure it was centred. That was a lot easier than I thought and has left me with about 8mm of float in the propshaft that should be more than enough.

Propshaft float. The shiny bit between
the UJ and the gearbox

I had to use socket head screws to bolt the final drive and propshaft flanges together as there was insufficient clearance to get a normal bolt head passed the UJ. Even then I had to grind a flat on the screw head to get the clearance I needed.

So the propshaft is now fitted. 

It doesn't look right to have the level of mis-alignment between the gearbox and final drive but it appears it is standard for this build and not a problem. After all that's what Universal Joints are for but I must remember to keep them well lubricated.