Banishing The Dreaded Donut

[Guest rossmundo]

i m sure this topic has been covered a million times before , but can anyone tell me what propshaft i will need to replace the nasty vibrating donut item fitted to my s7? im just in the process of swapping the standard pinto for a 180bhp ish one so it would seem like a good idea to replace it now before mr prop makes abid for freedom!

[Big Jim]

I think that you need to get an answer from someone with an earlier car that has done it, but I would suggest getting a propshaft from a sierra, taking it, along with your 'doughnut' propshaft to a firm that specialise in shortening propshafts, and getting them to alter the sierra shaft to suite.

look in Yellow pages. we have such a place about 3 miles away.

[Mat-Moo]

I would think the RH one would be a suitable replacement as well?

[Big Jim]

That's if it's still the correct length, we are now about 6 models on. it certainly couldn't hurt to ask.

[Guest chris]

Re doughnut.How can I identify which propshaft I have.This would help to answer

a question I posted some days ago.Car is an S7 mk1

regards chris

[Peter Bell]

Chris look down the tunnel at the propshaft, yes I know it is tricky on a Mk1 it may be easy to see from the gear stick hole. The joint at the gearbox end should be a conventional universal joint to be really safe. If you can see a hexagonal rubber doughnut or a small flywheel (vibration damper) with the doughnut bolted to it (like the one on my car!) then think about changing it. Although they were used to good effect on the Lotus Elan driveshafts and had to take axial loads as well.

Peter

 

ps. look at chapter 8 in the Sierra haynes book (903) lots of pictures of them there!

[Big Jim]

I once had them on a 2.8i Granada, had to change it every year for a new one as they cracked up something terrible (mind you, I was pulling some BIG caravans in those days!)

[Guest nippykev]

If you want a first class prop try this place.

 

GKN Driveline Ltd

Unit 5, Kingsbury Business Park Kingsbury Rd Minworth

Sutton Coldfield West Midlands

B76 9DL

 

Tel: 0121 313 1661

 

They are GKN,s specialist 4x4 division. They will make any type or size of one off prop out of new components. They quoted me £100 + Vat for a locost prop.

 

Kevin

2b june 2003

[Guest chris]

Thanks for the tips chaps.After posting the question I put brain in gear and looked at the haynes manual,now I know what youre on about!The dreaded Item is indeed there,however It seems to be in good condition at the moment as far as I can see.I am considerinf changing diff to LSD at some point after finishing planned upgrade to my pinto top end,it would seem to be sensible to change the prop then.

regards chris

[geoff shep]

I had one of these - same car too. On the sierra, the drive runs from the gearbox via the rubber coupling to a fixed bearing so there is no bending at the donut - its just a shock absorber. You would probably find - if you could look along the tunnel - that the gearbox-to-diff run is not in line so the donut is taking a lot of bending. I lowered my gearbox rear mount to get the run as straight as poss but still soon got rid of the rubber.

 

There were horror stories at the time of donuts failing at high speed and in one case the flailing end of the propshaft bashed the tunnel sides out until they were almost circular in section - right by the bloke's knees!

 

As I remember, the front ends to get were off transit vans or cortinas and then get them mated to your own rear end. Anything with a live axle should have UJs. The front ends were different sizes also depending on whether they went into a 2 litre or 1600.

 

Robin Hood certainly used to make up prop shafts if you produced the bits - you just had to specify the required length.