Vibrations - propshaft?

Post by **garyd** » 15 Apr 2007, 19:45

OK, gradually working through a seemingly endless list of issues to tie down noises on my syncro.

NSF top ball joint and both track rods replaced this weekend to keep the front wheels pointing in the right direction once the tracking is adjusted anyway.

Now I have realised that there is a severe vibration between about 35 and 45mph. This is much worse when trying to accelerate through it than when cruising at 40mph say. Up around 50mph it smoothes out again.

From reading past posts it seems almost certain that the vibration originates from the propshaft. Can anyone confirm that diagnosis or offer any others? Having check it with two wheels in the air, I can see no obvious deformation or misalignment.

If it is the prop, what can be done about it? Is it likely to be a UJ problem or one of balance?

thanks
Gary

Post by **toomanytoys** » 15 Apr 2007, 20:12

If its happaening under load then I would say its more likely to be a CV joint rather than the prop..
I have a similar vibration (now I have jacked the rear end up a tad) and I know I have a worn CV joint, my prop is good.. a full set of CV joints are on the "to order" list for me..

Post by **blurb55** » 15 Apr 2007, 21:59

Had similar, but seems it is a wheel bearing. Symptoms sound identical, but if I weave down a quiet road the noise abates when the inside wheel lifts a little.
May be worth a go.
Cheers, Paul.

Post by **HarryMann** » 17 Apr 2007, 06:44

If the UJs on the prop really do feel completely without wear or play, and the prop hasn't taken a knock, then a new one or a balance often doesn't cure this... they'll often do it under load a bit worse than on a neutral throttle and at a slightly different speed on the overrun, particvularly the diesels (torque impulses)

CVJs need to be perfect to eliminate them from equation (the inners for sure) as they can definitely exacerbate it. Some find that shifting the gearbox about on its front mountings or the diff on its rears can eliminate prop-vibration - as its often really the whole drive-line that 'gets going'.

Equally it's often an engine or box going back in slightly different to when it came out that can trigger it - just being disturbed a bit - so check those CVJs first and then try loosening and levering the box one side or the other before nipping them back up.

Post by **Mudlark** » 18 Apr 2007, 08:48

I had bad 45-55mph vibrations on the Tristar; eventually a UJ failed and I had a new prop built which improved things but did not cure them.

When I lost reverse gear last year I had the gearbox overhauled and all the vibrations went

so possibly reseating the gearbox on its mountings was all that it took; but i really could not say for certain as there are so many other variables.

Some people have reportedly been successful in 'balancing' the prop by adding a jubilee clip or two and altering the rotational position of the screw head.

Post by **HarryMann** » 18 Apr 2007, 09:04

The other thing that has been suspect, or doesn't help, is possibly minimal wear in the transaxle output shaft or front-diff input shaft bearings... however, expensive and a pain to repair, ousually on if rebuilding anyway.

As Mark says, start with checking the prop for any sign of wear, lever the box and diff about a bit to see if mounts are really soft, but a common cure more and more seems to be 'adjusting' the posituion of one or the other slightly - and a dead straight-line of components is not what you are necessarily looking for.

Post by **garyd** » 20 Apr 2007, 06:48

Next update.
Propshaft removed and gearbox and front diff sprung apart as bolts released. Prop 'dropped' out unlike in someones earlier thread. Will ease off diff mountings and adjust before refitting.

Two of the UJ movements were slightly tight and have been eased by re-setting the bearing cups against the circlips.

Now, another question. Working on my memories from earlier syncro encounters (10-15 years ago) I recall that the prop varies with engine type. I believe it is as follows:

1.9DG - no rubber doughnut
2.1DJ - doughnut at one end
1.6TD - doughnut at other end

OK - can anyone confirm this please? More importantly, can anyone confirm which way round the prop goes on the 1.6 ? Doughnut to front or rear?

thanks
Gary

Post by **HarryMann** » 20 Apr 2007, 07:36

To front I think, but the Dodoka has it to rear with no vibration, but that's got a weird engine petrol engine now.

Think you may have discovered one problem then, as prop normally just about 'clips' into place.

I have a spare good prop just to try, if you need to after trying other things, but loan only, think you have my home number or mob.

Post by **dave friday** » 21 Apr 2007, 12:11

why can't prop shaft u j be replaced[they look replaceable],i replaced one on a ford van by the side of the road!.
sunny spain? its still raining here!!

Post by **HarryMann** » 21 Apr 2007, 13:40

This is not a Ford van

They can be replaced but not on the side of the road, AFAIK

They are also hard to get I believe. And as some have said, prop vibrations are not always caused by the prop, but by the installation as a whole.

Post by **dave friday** » 21 Apr 2007, 14:47

well it did look a bit like a type 2 [thames 1500cwt 1962].
point's taken.i'm looking for solutions without having to pay lots of carridge back and forth.the prop does have some play on one the uj's[the front one], and i get lots of rattles and ringing at low speeds very loud when on full lock in second gear, all of the inner cv's have some play so i'll start with them.