vibration from 40mph to about 80mph

[smchris]

So i've been looking round the forum extensively the past month or so, and I cant seem to find an answer to this problem. I have a 1.4 340dl with a welder

I've done all the usual stuff. tried different wheels, had all wheels rebalanced about 3 times, put in a new steering rack, wheels have been laser aligned twice, geometry checked, driveshafts checked and I still can't find the problem. searching for this led me to BMW e30 forums where a lot of people were describing my exact problem..except with bimmers. Ive been ploughing money at the car left right and center to sort this out, and its getting ridiculous so any help would be appreciated, or anyone that lives near swindon area, i would be greatful if you could check it out.

I've come to the conclusion it could be one of the following...which are all expensive so I need to preferably get it right first time :/

either:

prop shaft is bent or out of balance
cv joints and boots are gone
clutch and/or flywheel, ( i do get a clunking noise when I engage and disengage the clutch, which i believe means it is getting to the end of its days) it doesnt slip at all though, its got a pretty good bite aswell.
engine mounts (my last MOT got an advisory on these)
gearbox/ diff problems?
some other driveline problem

it sometimes seems to directly effect the power of the engine ( not that it has much power, obviously) but it's almost as if it chokes the car a bit..once you sail passed 80 though it seems to get better or go completely. the whole car shakes quite aggressively. its seems to oscillate, i.e it goes and comes back in a wave .

I'm so frustrated and desperate now, any advice would be a godsend, preferably I'd happily travel for one of you who really know these cars to have a look at it..as I said it can't be far from swindon, its just damn scary on the motorway, and if it is the prop i dont fancy that breaking, could be catastrophic. It really grounds me so I cant travel anywhere outside of swindon.

I've tried sitting on a motorway at under 60mph aswell to lessen it, but thats also very dangerous, Ive had some large lorries try to overtake me and nearly miss their junction when I do this, and its dangerous for people coming out of the fast lane aswell as I essentially turn into a moving wall at that speed :/

call or text me anytime on 07769177358 or respond on here with information and guidance, as you can tell im desperate and the car doesnt feel safe, and its incredibly frustrating

[Hell Driver]

Have you tried jacking up the rear of the car and getting someone to 'drive' it and watching the prop/half shafts/wheels/gearbox/diff etc. for vibration? I used to do this witch the CVT when I had problems to access where the vibration was coming from. At least you will know which end of the car it's coming from. If it stops you know it's the front, if not you know it's the back. Just be carefull and don't fall off the axle stands! Sounds pretty bad so it should show up.

[smchris]

.. now you mention it, when we first done the diff, had the car up on axle stands to check everything was ok and there was ever such a slight wobble then, but thought nothing of it because it was around the time i had a damaged steering rack anyway, how do i diagnose it? I recently got new diff mountings aswell because the originals were knackerred..tht wasnt the prob either

[pettaw]

Silly question but you haven't mentioned it so here goes. Have you checked the wheel bearings? Both front and rear. Hopefully its a front one cos they're easy to change but if its a rear one then its a PITA, When I had a rear wheel bearing go it had a knocking/vibration but only at certain speeds, and would come and go depending on whether you went round a left hand or right hand corner.

Hope that helps.

[Ride_on]

Since its speed related and not engine speed I doubt its anything to do with clutch/propshafts/gearbox etc, but do lift the back wheel and check out the final drive parts. Also the final drive parts are too small diameter to affect balance IMO. If you had joint problems it would not go away at certain at certain speeds.

General vibration Tests - remember the gearbox is at the back, there is very little of the parts rotating at road speed, its all faster and geared down for the wheels.
1. In neutral rev the engine
2. With clutch in rev the engine

This won't really simulate if its a load related problem but worth trying.

Wheel bearings are a definite port of call, lift the wheels and check for movement. Fronts are adjustable or otherwise easy to sort, but wear is usually noticeable on cornering. Rears are easy enough for a mechanic with a press.

The wheels are usually the main issue, but since you have changed those it must not be the problem, that pretty much leaves the bearings, or possibly (unlikely) stub/short axles.

Wheel Nuts ok?

Some tyre places can balance wheels on the car, get them to run it up and check which wheel is the problem.

[smchris]

thanks pettaw and Ride_on for your feedback.

I havent checked if its wheel bearings or not, the car has only 60,000 miles on it so I would be surprised, going by what you said about cornering it doesnt come up then..i guess its another avenue to check though! :/ theres no whining or weird noises from the wheels either. Ive double checked all the nuts on the wheels, I was hoping it was as simple as that! lol

I drove the car up to motorway speeds yesterday and tried the clutch thing, letting it roll at 60 odd with the clutch engaged, and the engine idling it made no difference to the vibration, same when I took it up past 80 where it mellows out a bit. it was still there. when the car is at a standstill, revving the engine doesnt cause the vibration either with clutch in or out.

I did have a problem with one of the driveshafts popping out occasionally when tight cornering, but it wasnt bad enough to effect rear drive and that was related to the diff mountings.

I'm going to try and get the car up on axle stands or a ramp this weekend, what should i be looking for? is there any specific areas or components I should focus on?

thanks chaps

[Ride_on]

You still havn't said if the steering wheel is shaking badly or not. If so I'd stick with bearings+stubaxles for now.

With each wheel off the ground try rotating it and listen for grindy noises (that isn't the disk/drum). Also grab the wheel top and bottom and give it a good shake in and out to rock the bearing, it should not move atall except through the suspension/steering. Also spin the wheel and look for run out on the rim (moving in and out with respect to a rigidly placed finger or tool).

Its pretty easy to inspect the front outer bearing, (cap off, undo big nut, remove bearing + inspect) but you should have a Haynes manual for the reassembly + adjustment procedure. The inner bearing is much bigger and longer lasting, I've never seen a knackered one.

Could it be just an isolation problem? If the exhaust touches the body it sounds aweful. Perhaps the gearbox is touching something if the mounts are bad, or stressing the drive shaft.. did you replace all of them?

Half shafts popping out is pretty unusual, mounts must have been really bad. I've no idea what damage that could do. The tuned up guys can expect to shread propshafts if the mounts are just tired, nevermind hanging off.

[smchris]

I forgot to mention that, yes the steering wheel does vibrate quite alot, i think its because the whole car vibrates around that speed it makes it harder to pinpoint the problem. around the town its perfect though.

ive had a new exhaust and mountings, went to longlife at bristol, and i must say, its been fantastic!

not touched anything at the back apart from diff mountings and lowering blocks since I've had the car. I want to avoid replacing everything due to expense but its looking like I might have to go through that.

I'm wondering if driving round with the old diff mountings might of messed up or damaged the prop U joints? (i wasnt aware the diff mountings were gone for a while)

[bogbasic]

Hello, just curious.... did it vibrate before you did the diff? I'm not a drifter so I have no idea what is involved and whether 'welding' the box could have caused this e.g. if the rear wheels are now slightly out of synch somehow?? I had similar problems that were partly cured by replacing the front rack but if you've already done the steering rack, it sounds like something with the final drive. I did have some vibration (but not at speed) due to a knackered half shaft spline which caused a major jolt on moving away. Front bearings is a good idea.... you can check the tightness quite easily and you need to peen over the nut as per Haynes. I do still have a similar vibration problem but mine starts above 80 and only when steering in one direction.... which is a good deterrent for going too fast - indeed for anyone approaching their twilight years that is probably a good thing.... ;-

[smchris]

Hey bog basic, manged to get the car up and have a look atound, i initially thought it might be diff, i was told if it wasnt welded propery this vibration could be a side effect, but its all sound, upon closer inspection of some of the front suspension components, some are reLly perished, the ant roll bar appears to be sagging slightly on the front right, so i think thats the last cheapest route to go! :/ lol i think its cos these cars are old now, your going to always get some vibration or rattling somewhere, after driving new cars, these are somethin else lol, the problem now is where can i buy all the suspension bushes from?

[tim-andre]

Hey bog basic, manged to get the car up and have a look atound, i initially thought it might be diff, i was told if it wasnt welded propery this vibration could be a side effect, but its all sound, upon closer inspection of some of the front suspension components, some are reLly perished, the ant roll bar appears to be sagging slightly on the front right, so i think thats the last cheapest route to go! :/ lol i think its cos these cars are old now, your going to always get some vibration or rattling somewhere, after driving new cars, these are somethin else lol, the problem now is where can i buy all the suspension bushes from?

Dai, poly bushes ftw!

[smchris]

cheers tim! thats what ive ended up doing! getting everything on front done lol the last thing after that is a "prop donut" ? not sure entirely what this is to be honest, but i know its very important with regards to stopping the propr flailing around

[Ride_on]

No prop donut on the 340 AFIAK. Sounds like the mid bearing you get on a front gearbox car like a 940.

Gearbox and engine should be fixed in place by by the mounts nothing should move (much), but the mounts can be tired as you have found.

Anti roll bar only comes into play around corners, should not cause the steering wheel to vibrate.