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Wobbly Prop Shaft
gingerprince - 17/2/13 at 07:24 PM

So whilst I had my engine out over winter (replace gearbox in 'blade) I took my prop out and took it to Dunning & Fairbank for a treat. It's been TRT'd, all UJ's replaced (I think they said with Freelander UJ's as they're stronger for track use), worn slider replaced and balanced.

Got it all fitted and run up on axle stands today, but the prop seems to "move". Pretty much the full length seems to "wobble" by roughly 1mm (not measured with a gauge - just hold screwdriver next to it to see gap size, so not accurate at all).

There's a video of the rear section here: -

http://youtu.be/UGHE6noOftg

Doing the similar "screwdriver" test on the prop/sprocket adaptor, and at the diff end, there doesn't seem to be an issue there, so I don't think it's being introduced by runout at the diff or gearbox, but again not accurately measured. I'm also assuming that the prop is straight given it's just returned from the professionals.

Is this sort of movement normal and a trait of the rubber mounted centre bearing flexing? Or is it something to do with angles of mount? I know from reading that the diff end and the gearbox end should be as parallel as possible, but in a BEC that's physically not possible due to the orientation of the engine.

Did a quick road test and it "felt" okay, and this sort of wobble was one of the reasons I took it to D&F in the first place, just wondered whether it was normal, or if not, what to investigate?

Thanks, Simon


madteg - 17/2/13 at 09:42 PM

Sounds like the ujs are not seated properly, would send it back as it can only create vibration because it can not be in balance.


jeffw - 18/2/13 at 06:55 AM

I would be on the phone to D&F to discuss.


adithorp - 18/2/13 at 08:22 AM

quote:
Originally posted by jeffw
I would be on the phone to D&F to discuss.


Agree with Jeff.


gingerprince - 18/2/13 at 08:27 AM

Thanks all. Bit of a pain in the ass, pretty sure prop wont come out without removing the engine again


scudderfish - 18/2/13 at 12:23 PM

quote:
Originally posted by gingerprince
Thanks all. Bit of a pain in the ass, pretty sure prop wont come out without removing the engine again


Better it comes out whilst the car is stationary in the garage than it comes out through the tunnel wall at 90mph.