e220 auto 94 gear change jumpy.. new prop?

[jonnyb1]

Hi, ive noticed lately that the change up and down in gear on my 1994 e 220 is a little jumpy so i presume its propshaft linked. There is a grinding metallic sound when reversing off the drive.The problem is that i have been told there are no uj joints available so its a complete prop..... is this right or are there spare uj,s now available....assuming this is the problem.
Any advice would be helpful.
I dont know if it has any relevence,but this prob seemed to show itself after the RAC pulled a few wires etc to find the crank sensor,but as i say it may be coincidence ...cheers colin

 

[Bolide]

Jumpy changes

There are lots of potential causes for this, including a worn autobox, disconnected gearbox vacuum line, worn propshaft doughnuts, worn diff mounts, worn diff input bearings, worn gearbox or worn engine mounts. I'd suggest you take it to an experienced independent and get them to diagnose the fault

You don't say how many miles the car has on it but my money's on the prop doughnuts


Nick Froome
www.w124.co.uk

 

[tom7035]

Jonnyb1.
The 'doughnuts' Nick refers to are in fact your propshaft u/j's, but I agree a little further investigation is required.

 

[Bolide]

Doughnuts to you too!

The 'doughnuts' Nick refers to are in fact your propshaft u/j's, but I agree a little further investigation is required.

I wasn't referring to UJs. By doughnuts I mean the rubber disc that sits between the gearbox output and the prop, and between the prop and the diff. The drive is taken via a rubber doughnut to reduce vibration & shock. Over time the doughnuts break up and produce a nice clonking as drive is engaged. They're £50-£80 from Mercedes as I recall

If it is UJs then the bad UJ can be knocked out, new ones installed & staked and the prop rebalanced. You'd need a prop expert to do it


Nick Froome

 

[jonnyb1]

many thanks for info Iknow someone who worked at gkn so hopefully...... cheers

 

[tom7035]

That's right Nick - the 'doughnuts' do the job the old Hardy Spicer u/joints once did on each end the propshaft as well as in the centre, but much more smoothly.
As for the metal u/j in the centre bearing, any 'old-fashioned mechanic' (as opposed to a 'modern techy') should be able to replace this joint, staked or otherwise. Biggest hassle will probably getting hold of one in the first place. So long as the alignment of the shaft is properly noted at the start, it wouldnt have to be re-balanced.
Suspringly, pre-war (WW2) little Austins were fitted with a 'doughnut' too! (Though just a single one at the front).

 

[kth286]

Jonnyb1

I think you are correct that the RAC person pulled off a vacuum line.

The smoothness of the gearchanges rely on a good vacuum, and as the Crank Position sensor is on the bell housing near to vacuum pipe runs, that's likely what happened.

Look for disconnected vacuum tube, and reconnect it, and you will likely be sorted.

Regards

 

[jonnyb1]

Thanks Again Will Look When It Stops Snowing