Strange noise and vibration

[EEED]

Hi All,

Since I had the engine rebuilt last year there has been an annoying, intermittent vibration / rumble when I change up to top gear. Other times it occurs at a cruise around 45/50 mph. On other occasions it has occurred downhill in top gear. During the rebuilt the diff mounts were tightened. When the noise/vibration first occurred I was advised that the mounts probably needed replacing. This wasn't the cure. I tried checking everything else that might be the cause, but a couple of weeks ago a drive on the motorway showed that at a steady 60 mph the vibration and noise became quite severe. Increased speed didn't help so I had to back off and drove rather cautiously. My passenger was convinced the problem was from the back end somewhere. Subsequently I 've been advised that following a close and thorough inspection of the whole transmission, it appears that the spacer under the gearbox mount was missing (a previous rebuild - the gearbox hasn't been out during my ownership).

Could this be the cause? I'd owned the car for four years prior to engine rebuild and hadn't experienced this problem all that time, including a long motorway drive when I first collected the car and another motorway trip just before the rebuild, plus regular use in Surrey and Sussex.

Has anyone experienced anything like this? Any ideas welcome!

Paul

[billwill]

On mine the exhaust pipes vibrate and at certain speeds, the vibrating pipe can just touch the gearbox making a loud vibration type noise. Could yours be the same?


An out-of-balance propshaft could probably produce your symptoms or a failing/failed universal joint on the propshaft.

[MickG]

Hi Paul,
Not experienced anything like your problem but I would:-
fit the spacers to the gearbox mount,
check the propshaft universal joints,
check the axle torque rod bushes.
If you have rubber rotoflex couplings or the solid drive shafts check those also.
Jack the rear and rotate the wheels each side and listen for any noise from the bearings in the rear hubs and diff.
You should be able to give each drive shaft a good shaking to see if any play is evident in the bearings.
Check to see if anything is loose that could rattle against the body.


Regards Mick G

[jimj]

I had something similar but only apparent when there was no load, neither accelerating not decelerating. I wasted hours checking allsorts but overlooked the obvious: The bolts between the diff. flange and prop. shaft flange were just less than tight. New nuts, bolts, spring washers and Loctite (to be extra sure) and all was well.
Jim

[peterexpart]

Paul
It may be worth checking that the Diff is not sitting on the Chassis Plate as there is very little adjustment and if the Rubber Mountings which the Diff hangs on have sagged it could just be touching

[EEED]

Hi all,

Thanks for the responses. I'm going to get the spacer fitted and have all the points suggested checked over again.

There did seem to be some resonance/harmonic vibration that contributed to the noise, so the exhaust mountings have been checked as they were changed to the correct set-up when the engine was rebuilt. In fact one of the new mounts that had been installed was removed, but it made no difference.

I'll post again when I discover the solution.

Paul

[EEED]

Hi all,

Thanks for the responses. I'm going to get the spacer fitted and have all the points suggested checked over again.

There did seem to be some resonance/harmonic vibration that contributed to the noise, so the exhaust mountings have been checked as they were changed to the correct set-up when the engine was rebuilt. In fact one of the new mounts that had been installed was removed, but it made no difference.

I'll post again when I discover the solution.

Paul

[sprintsoft]

Hello Paul,

I know it's been several years since you had this issue, I'm wondering if you can recall the solution?

I find myself with exactly the same symptoms, best described as an exhaust resonance that manages to resonate through the gearbox between 50-60 mph in 4th. It does not happen in any other gear at the same revs, and the sound originates from the gearbox area.

There is plenty of clearance between the exhaust system (new stainless) and the gearbox so no chance it's physically touching anywhere.

I have new engine mounts, new gearbox mount with correct spacers, new diff top mounts (frustacones), new torque rod bushes and correctly tightened torque rods onto the chassis, in short nothing is loose, or on old rubber mounts.

The gear lever nylon cap is tight with no slack, the noise is not affected by holding the gear lever.

When the car is cold you dont hear it, it's only when the car gets up to temp, and you've done 4-5 miles then it comes in. I have new EP80 in the gearbox.

I'm stumped on it, not really sure what to try next...

Regards
Iain

[1owner69Elan]

Have you checked the prop shaft u-joints?

[sprintsoft]

Yes, have had the drivers seat out to check the front prop shaft joint, the rear joint also is good with no play, and the rear flange bolts are tight.

[2cams70]

What were the circumstances leading up to the noise? Did you change anything or did it just appear during normal use, did it start small and then progressively get worse or did it just appear and stay the same?

[sprintsoft]

Hi,

The first time I noticed it was when I made a change to Redline MTL, that oil does improve the change slightly but has the effect of making the box more noisy, not happy with that, I ran it for less than 500 miles and swapped back to Castrol EP80.

The box works faultlessly otherwise.

Has anyone experienced the same resonance?

Thanks
Iain

[alan.barker]

I suggest you remove the prop shaft from the car and renew the uj's.
Sometimes you detect no play on the car but when they are dismantled you see they are worn.
Alan

[sprintsoft]

Thanks Alan, sound advice.

First job after Xmas I think... I?ll repost the results then.

Regards
Iain

[JonB]

Hi,

The first time I noticed it was when I made a change to Redline MTL, that oil does improve the change slightly but has the effect of making the box more noisy, not happy with that, I ran it for less than 500 miles and swapped back to Castrol EP80.

The box works faultlessly otherwise.

Has anyone experienced the same resonance?

Thanks
Iain

Yes. But dissing Redline is like heresy round here! I still have it in my box but it?s coming out soon!

Regarding the OP?s problem I have something similar and my diff and prop shaft have been overhauled professionally (although I am pretty sure the prop shaft wasn?t balanced). Sliding joint and both U/Js are new.