Transmission rumble

[T100SS]

Grasping at straws I realise here but for one thing - since I don't know the cause of this problem I cannot categorise it.

At around twenty and forty mph, both under power and on run-over, I get a vibration that starts as a rumble and eventually shakes something around like it was going to drop off or disintegrate. I've taken a passenger out to listen but they could not discern the exact location/source of the vibration.

I've recently rebuilt the back axle and this made no difference beyond making the car drivable (half shaft gone). The axle is not loose, skewiff, tight or anything else I can think of - and the problem had been slight before the axle build anyway. When I say build, I mean diff and half shaft swap, new seals & gaskets. It has the correct new oil in it.

The prop shaft joints at both ends are firm - no play whatsoever. It has not been rotated on installation.

I have just replaced the gearbox rubber mounts and checked general security whilst under there. This too has oil of correct grade. This has made no difference and a cursory look at the engine rubbers shows no sign of any problem.

There has been some clutch judder since that was replaced, however it could be avoided by not slipping for too long and the judder/rumble of which I now speak was faintly discernible prior to any work I have done on the car - I just presumed I'd be doing the prop shaft sooner than later but how wrong can you be?

It is a standard 71 traveller, 1098, drums etc etc all original. A servo has been fitted but this was subsequent to the rumble. Ideas please, on a fifty pound note...[frame][/frame]

[bmcecosse]

Are the rear hubs secure on the axle? New gearbox mounts may be too hard...... Are you absolutely sure the axle perches are good - and U bolts all fully tight?

[Gilesv]

Hi

This may have nothing to do with it, but I changed the engine mounts on a convertible nearly two years ago for some new ones purchased from a respected parts supplier. This was the first time that the car had had a clutch change since it left the factory and there was no vibration before it came off the road.

After fitting the new mounts, the car had so much vibration that it was undriveable. I replaced them with good second hand mounts and the problem was solved. An identical thing happened to a friend who bought a newly restored Traveller, so he changed them for some new-old-stock ones that I found at an autojumble, and again the car was transformed.

The newly made mounts were made of a rubber material that is far too hard and therefore inflexible.

Maybe you have a similar problem with the gearbox mounts?

Hope this helps..

[T100SS]

Hi
Thank you all. I think I've got it - rechecked prop shaft with a soft mallet and found movement at both ends (urgh) so have ordered new ones.

Yep, everything on axle tight - I'd only just had that apart and checked anyway. There was a smidgen of slack on the cross member but only needing one good heave, not enough to let things flap around like chickens in a Laurel and Hardy film:)

[bmcecosse]

There's always a little movement on the prop shaft - don't be too hasty there......... If you run the rear wheels off the ground (well propped...) do the wheels run straight and true ?

[T100SS]

Hee Hee - I have a knack for doing things while people advise me not too:)

But we're all wrong re prop shaft

The UJs felt fairly tight to me (given the tolerances the likes of Morris and Triumph (mcycles) will run OK in). But I changed them anyway. Given the state of things mechanical on this car, I'm resigned to eventually doing everything...

Prop shaft back in - it does have the original balance weight by the way - and it still clunks at road speed.

Thinking I might be to blame on a previous repair when I rebuilt the back axle, I examined the wheel bearings. The nearside, which had been a problem, seemed to have worked very slightly loose. But there was no more play than on the old bearing on another axle I have. I removed it anyway and it was still good - actually I seem to remember I bought new.

So I cleaned it all up and refitted it, having examined the half shaft whilst I had it apart. The left hand thread which I'd thought to be dodgy tightened up (axle/wheel bearing nut) and stayed tight with as much heave as I could give it.

It still bumps along, and turning right seemed to set it off although said right turn is also up hill.

Next thing might be to run it on stands, but as the noise matches road speed the symptoms it might only occur under load. It also happens clutch in, rolling backwards.

So I could get my assistant to use the brakes; but meanwhile - notwistanding everything mentioned previously - the only fault I can see is a damp damper. But it is securely mounted as is every thing else (yes the exhaust etc etc etc).

I suspect maybe the drive joint where the propshaft fits, or maybe something inside the diff. But Bemcosse's remark re perches has me wondering - even if the ubolts are tight, the axle could still perhaps rock about if the perches have somehow failed. It seems a slim chance given that there has always been a faint rumble however the logic of all old parts break the same way suggests I should investigate. Oh lovely, axle orff again.

But I wonder if anyone else has gone down this road? I'm also thinking about getting the chassis and engine from something famed for reliability and longevity (no not a bloody beetle) and dropping the traveller shell on that:)

[T100SS]

With a spanner (not a local, a tool; no not a scroat either) in hand I began dismantling the axle for examination. As I slackened the last few nuts off on the 'u' bolt it just schlocked into place. That is to say, I'd noticed it was not perpendicular to the floor and was suspicious. What had happened is that the threads on the 'u' bolts don't go very far up. So despite the nuts being tightened, the axle was not gripped firmly and twisted - causing a knocking as if to say 'can I come in?' and thankfully it didn't. Just as this chapter closes, I notice a leaf-cutter bee trying to get into the garage. I wafted but it insisted, so I watched. There is a hole where a Yale lock used to sit. I'd patched it from outside. The bee went over the door, down the inside thencely into the other side of the hole. So it is not longer a garage door, it is a leaf-cutter bee's nest. PS I fitted fat washers to the U-bolts:)