Prop shaft centre support question

[straylight]

The time has come to refit the prop shaft and I dutifully grabbed the SPRINTPARTS PDF of the service instruction, remembering I had a vibration in my shaft last time I fitted it.

http://sprintparts.triumphowners.com/up ... pshaft.pdf

The service bulletin shows three variations, A is for Dolomite, B is for Sprints and C is for autogearbox.

Problem is, the support I have appears to be variant A, not B as it should be for my sprint. The two lugs are definitely opposite each other, not like the offset lugs in B (and C) where the left lug is higher than the one on the right.

So, knowing I replaced the centre support back in around 1988 and would not have noticed whether the lugs were different from the old one, should I:

Buy a new centre support and ensure it is the sprint version

(my parts book doesn't distinguish between them anyway, simply has part 21H5632 for the sprint)

Put the existing one back in following the instructions for variation A (the way it was fitted)

The vibration which occured after I replaced the support last time could be down to a number of things, not just the centre support bearing, but alignment of the front and rear shafts and alignment of the fore and aft connections.

meanwhile, I'll continue fitting up the steering wheel and column.

stu

propshaft centre bearing fitting (sprint is Var B).jpg (53.42 KiB) Viewed 2390 times

[SprintMWU773V]

As a slight aside I wonder if it would be possible to make up the centre bearing doughnut out of polybush material? Original items seem expensive and not always in the best condition.

[straylight]

hmmm, looking at this after an afternoon of thought, is the centre support bearing actually different, or is it just mounted differently ? Why would the Sprint need to have it twisted clockwise (looking from the rear) ?

stu

[SPRINTPARTS]

Hi Stu,
The bearing is the same it is the mounting that is different as per the drawings.
Cheers
Philip

[straylight]

Thanks Philip. It is going in as per diagram B.

stu

[jeroensprint]

As a slight aside I wonder if it would be possible to make up the centre bearing doughnut out of polybush material? Original items seem expensive and not always in the best condition.

They become too hard and the prop will vibrate. I did some expirimenting on this. I had a new carrier and filled it with silicone kit on both sides. You get a solid carrier. When driving it did vibrate a lot. Then I made 12 10mm holes in it so it could flex a little. Then it was ok, no vibrations and no more tramping under the car when taking off.

Jeroen

[straylight]

fitted the shaft up yesterday, following the instructions for diagram B.

But it doesn't look right


the prop shaft, to my eye, has a definite bend.



the right side is mounted up to the two bolts as shown above.


This means that the only hole that lines up on the LHS is the end or inboard hole.

What does this look like to everyone else ? I don't think the shaft should kink like that. There is some room for play in the large mounting hole between the bearing carrier and the body support bracket, on the diagrams above. The hole is much larger than is required by the bolt (set screw) and the carrier could be moved around.

I'm still not certain why the sprint would need to have the carrier rotated clockwise. This seems to lower it and kink it to the left a smidge.

thanks for the help.

stu

[straylight]

can anyone confirm whether the prop shaft will be okay left like this or have I got a problem with alignment ?

thanks

stu

[MIG Wielder]

Hi Stu, this is an interesting question. I had a look at my 1850 (same centre bearing, same mounting bracketry ) and mine is fitted according to diagram " A" . And yes, I hadn't realised this before but the brackets have 2 bolts one side and one bolt on the other. This is quite correct according to the Dolomite parts manual. The brackets ( 156985 ) look O.K. as well, i.e they are not handed. Now I had a read of the official workshop manual and the fitting instructions run along the lines of loosely bolting everything up, and then moving the brackets and centre bearing carrier around to get the propshaft as straight as possible, before final tightening. And yes, the straighter the better, as the 3 joints will have more work to do if it is out of line. Does the rear half of the prop run centrally down the transmission tunnel ? If the diff; was offset one way or the other this would show up under the wheel arches / tyres. That should be pretty obvious though. That would just leave the engine mounts to check at the front then.
HTH. Cheers for now, Tony TDC 0091.

[straylight]

thanks tony, appreciate the help. With fitting B the centre bearing shifts a bit clockwise, this drops the prop centreline a tad and moves it to the left, not sure why this is needed. The prop shaft is centrally located in the tunnel and when it spins there is no wobble. I can see this when I line up a point on the tunnel and turn the shaft.

Thinking a bit more on this, there is so much movement up and down in the normal course of driving, that vertical position isn't that critical, but left-right positioning is more important.

Has anyone got a sprint that can confirm the single body mounting bolt goes through the inboard hole in the mounting plate on the LHS ?

thanks again tony

stu

[Stevecox]

Hi Stu
Left hand bracket on my sprint is Bolted through the center hole.

Cheers Steve

[straylight]

thanks steve, I'll see if I can loosen it all up and shift it across 1/2".

how's it going up there anyway ?

should be visiting my parents up on the sunshine coast in middle of january.

stu

[Stevecox]

Stu
All Good with the Sprint and Life in General Thank You
Will try to get a Photo of the Prop Shaft , from front to back
At least give you something to compare with (Alignment wise)
If you have any spare time on your trip up here , Your welcome to visit.
Will post as soon as

Steve