Does any1 know a source for these. Im trying to protect my blackbird gearbox from showk loads down the driveline.

try yellow pages under bearing suppliers, they usually sell that sort of thing, but they are really meant as a sort of universal joint so shafts dont have to be exactly inline. from what you are saying you really want some form of slip clutch.

seirra has a donut on the front of its prop

Rear wheel drive Alfas have them on the prop, Triumph used them on their swing axles, as mentioned Sierras have them on the g/box output and many others.

Have a look here for a large selection, they're under propshafts and rotoflex couplings.

I havea friend who used the rubber donut off a sierra on their blackbird westfield. I don't think it was a good job, I'm pretty sure it started to vibrate badly and they had to remove it. Mind you these lads are on their 4th engine as well, so I reckon it held up OK!
What I did was have a layer of rubber placed between the inner and outer of my propshaft. That way the drive goes through a rubber stage, but it won't vibrate or go off centre.
My propshaft was custom made for me by Gregory Propshafts of Newry (NI) and cost 200 quid.

[Edited on 16/9/04 by alister667]

I am nearing this stage of my Blade locost build. I'm having a hard time visualizing these rubber doughnuts I suppose I will need. Does anyone have pics?

Also, can someone take the time to explain what it does? Does it just limit propshaft vibration? No excessive drivetrain lash?

--Thanks, Chris

Same issue confronts me - except the engine/propshaft is in!
Try this lot - they are top notch engineers: http://www.allensperformance.co.uk/gearboxes-and-couplings.htm

I think lots of folk don't bother with any "softness" in the drivetrain, I'd imagine it will be slightly less "clangy" with a bit of resilience. The sierra donut has a locating pilot bush in the middle to be failsafe and reduce vibration, I think the alfa is the same. The sierra donut is incredibly stiff so might not work so well as an original rotoflex. These were used in the driveshafts of imps and fwd triumphs. Lotus elans had a couple in each driveshaft but they were later replaced by a much harder donut in the sprints, effectively increasing the spring rate at the rear considerably!
Bob C

GKN make that sort of thing for 4x4's try there web site might have what ya looking for. andy