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Okay, so I know that the L's usually vibrate in some way or other but:

At 100km/h on a smooth road I get a vibration that slowly comes, peaks at a niggling gentle vibration then goes. This could be over a 5 or 10 minute period, it will then come and go again so long as the road remains smooth. On bumpy road you won't notice a thing and on a smooth ride it can take a bump in the road to get rid of the vibration.

This also occurs with both the 27 inch tyres and the 23 inch tyres. I've removed the rear drive shafts and not had an issue. That got me thinking that it was the tail shaft - so I got a 192k km second hand unit and replaced my original one, put the drive shafts back in and its still there. This gets me thinking that it is the moustache bar which I've noticed is slightly bent:



^ That's the best pic I could get that shows the bend in the bar.

I'm thinking that this starts to wobble as the rear wheels drive the rear diff. The still conditions of a smooth road allow an oscillating vibration where I think the diff starts to wobble left to right due to the bend in the moustache bar.

Has anyone experienced something like this due to a bent moustache bar? This one will be getting a "treatment" when I get back to cobaw where there's a shed with a welder and some steel

Cheers

Bennie

Hey Bennie,

Is this the same thing you noticed when we were driving to Robe?

Not quite sure if you had anything done to your rear diff, but I would also check out your diff bearings, end-plays and pre-loads. I know it's strange that it comes and goes... Don't know, but I'd be having a good look at the diff before welding stuff.

Cheers,
Pedro.

pezimm wrote:Is this the same thing you noticed when we were driving to Robe?

Not quite sure if you had anything done to your rear diff, but I would also check out your diff bearings, end-plays and pre-loads. I know it's strange that it comes and goes... Don't know, but I'd be having a good look at the diff before welding stuff.

Yeah Pedro - same thing, just want to get to the bottom of the problem.

I don't think its the diff internals as there are no noises and I've not had a problem with it until the moustache bar appeared bent... Since I've eliminated everything else thats usually the culprit I'm now thinking that its the bent bar.

Cheers

Bennie

is it felt thru the steering wheel or the whole car?

Nothing through the steering wheel or whole car, just a niggling vibration that feels like its coming from the rear end. Its not violent just annoying! And it shouldn't be there!!

I spoke to a mate today about it and he said straight up it'll be the bent moustache bar.

It probably hasn't helped that I drove it to work on the black top in 4wd yesterday - I didn't mean to and didn't see the lights on the dash either...

Cheers

Bennie

Okay so this has become more of an issue now.

On the move from lakes back to home I removed the rear drive shafts to avoid the vibration that it caused. This was all good until the vibration came back again some time down the road. I thought it could have been the trailer I was towing but it was throughout the entire car, still felt like it came from the rear but I'm really unsure now.

I have felt it while accelerating from 60 to 80 and up to 100km/h, but it is different and drawn out in the "peaks" of the vibration, this gap sort of closes with speed but not as quickly as you would expect if it was a tyre or drive shaft. It also seems to change once the speed is settled to a "finer" vibration that can become "lightly violent" but not violent at the same time. It comes and goes but not in a pattern and a bump in the road no longer gets rid of it.

I have still not had time to fix the moustache bar, that will be done this week. I'm now thinking it could be gearbox mounts (they've got some tension on them) that need replacing or something very out there like a dying spark plug that isn't performing as well as the other plugs - or a set of plugs not doing as well as the other two as I found out that I've got two different brands/types of plugs and think this may be contributing - its an "out there" theory but if it gets rid of this vibration I'll be happy!

Any other thoughts or ideas that might help are greatly appreciated.

Also, I've started another thread about my gear stick is now "talking" at times. Its hard to describe but it sounds a bit like a straight cut gearset through the gear stick, but only in 2nd and 4th - it has been heard in 3rd and 5th on occasion too.

Cheers

Bennie

Tailshaft.

I say this because I now think you have something from the gearshifter rubbing on it. Look for signs of rubbing on the shaft and try and feel for dry uni-joints. Do you still have the L box in it? and have any troubles with hard knocks (rock climbing adventure kinda things) from hard surfaces underneath the car?

I've seen worse bend rear bars then yours on the rally cars but wouldn't rule it out as an contributing factor.

yep I second the rubbing on tailshaft theory. I had a bit of rubber from the shifter touching the tailshaft and it would only make noise in 1st,3rd and 5th, when I got rid of the offending rubber the noise went away.

TOONGA

Another kindof out-there theory that might be worth considering - does it do it on a completely different set of wheels/tyres?
I've experienced whole car vibrations that seemed very much mechanical before in my old Corona and it actually came down to both my front tyres being faulty - the radial metal meshing was separating from the rubber (they were quite old). Replaced them and everything was great again.

Ok I've swapped the tail shaft only to have the same issue arise. And this first showed its self on the trip to robe - removing the rear shafts did the trick. This vibration was apparent with the 23's AND the 27's. I'm currently back on the 23's but will go back to the 27's this week when I unpack them.

If it was a tyre I'm sure it would come and go in a pattern, this doesn't have a pattern - I didn't even feel the vibration on my way home from a mate's place tonight (15km at speed except for 2 towns). Got me stumped.

I'm going to weld my moustache bar during the week, just need to find some steel etc. I'll check for something rubbing on the tailshaft too - this could be enough to get a vibration worked up, but with this said I don't have any rear drive shafts in at the moment as this was my trick to avoid the vibration on my move back to cobaw It doesn't feel right without the rear shafts - no 4wd on the fly

Cheers

Bennie

ah crap, teach me for not reading things carefully, completely missed you said it was apparent with both sets of tyres! Scratch that then.
Engine mounts in good nick?

AndrewT wrote:ah crap, teach me for not reading things carefully, completely missed you said it was apparent with both sets of tyres! Scratch that then.
Engine mounts in good nick?

No worries AndyT - happens to the best of us!

I haven't looked at the engine mounts yet. But I have done that "trick" of moving the engine back a couple of mm by moving the gearbox mount further back and using EA engine mounts in the front hole of the EJ mounting plates. I really don't know if it actually worked but I left it as is since doing it. Hope it hasn't achieved anything as I'll be putting the EJ mounts back in and I've got about 10mm gap between crank pulley and the nearest thermo fan

Cheers

Bennie

Ahhhhh.. new evidence comes to light

I'm still going with tailshaft but this time it's due to the free play that has now been reduced by moving the engine/box backwards. I also agree with you that the diff bar is bent and because of both these things and the weight on the tow ball, then as the car is weighed down the tailshaft is pushing up (ever so slightly) against the back of the gearbox. Do you have another diff bar to try out?

Sorry.. but also check out your diff mount (rubber bit) on top of the diff.

RSR 555 wrote:Sorry.. but also check out your diff mount (rubber bit) on top of the diff.

I'll second this - good suggestion.
I had really bad vibrations in the RX at one point due to this bush flogging out. Although that was only under load and was there 100% of the time under load.

Ok, some progress - sort of:

New plugs installed, runs smoother now and less vibration but still there.

I dropped the rear diff and the rear section of the prop shaft out, vibration is still there same as after the new plugs were installed.

The mount above the diff is still holding well, hard to get movement out of it which I think is a good thing.

I'm now wondering if its either engine/gearbox mounts or as suggested by a mate on facebook - water inside a tyre - which could happen for two sets of tyres I guess... But that still stumps me. Anyway, just need to try and make some time between work to check out the mounts - probably with a lever.

Cheers

Bennie

Maybe take 1 set of wheels/tyres in to get them balanced up and see how they go.

Yeah andy T looks like it might be a tyre - after getting Ruby Scoo up on a hoist (it was hard work, very heavy :P) I noticed on the rear left that it looks like there should be another weight on there as there's an outline of where one used to be.

I'll be swapping the rear tyres for another set if the weather is wet tomorrow (no work!) and see what happens. I'll be pissed and happy at the same time!

Cheers

Bennie

Sheesh, didn't you say you ruled out tyres earlier? Sometimes get a weird uneven ply separation that leaves funny slight bubbling, or get odd wear marks, cause noise and vibration... good luck being happy

steptoe wrote:Sheesh, didn't you say you ruled out tyres earlier? Sometimes get a weird uneven ply separation that leaves funny slight bubbling, or get odd wear marks, cause noise and vibration... good luck being happy

Yeah I did - due to two sets of tyres doing the same thing.

Tyres on the rear are now swapped - vibration has so far been reduced futher but is still there I'm almost stuffed on this one. The other thing that is getting replaced this weekend is the front shafts - hopefully for another set that are in better condition, at least enough to get us through the snow season.

If its not the shafts or front wheels (relatively new but will be replaced with other rims and a new set of snow tyres) I'm thinking it could be something along the lines of either low compression as you've suggested Jonno or an issue with wear inside my gearbox

If its wear inside the box due to incorrect diff instalment or something I'm just going to have to put up with it until I get the other box done

Anyway we'll see next week what happens!

Cheers

Bennie