Outer Limits 4x4 Board

A couple of days ago we had the clutch in the 80 (`91 1HD-T) replaced, after 200k the old one was on the way out. Anyway, a heavy duty one was put in, I don't know what brand or the like, but part of the process involved machining the fly-wheel.

The problem now is there is a heavy vibration coming through the entire vehicle, it's apparenty while idling all the way up to and over highway speeds. The people who put it in couldn't think of anything right away, and if it has to come out they'd have to send it to be balanced - would this be the only way of eliminating the new clutch from the problem?

Why does it matter the arse that done the work has to warrant it.
Take it straight back at his expense.

Coighty wrote:Why does it matter the arse that done the work has to warrant it.
Take it straight back at his expense.

I never said they were not going to be paying for it. It does matter, it is nice to know what's going on and perhaps hypothesize as to what is wrong - it won't be looked at until next week now.

some times clutch plates can be worped slightly or out of balance or if the flywheel wasn't machined properly (mechanics aren't machinists) that will leave more wieght on one side of the flywheel

the amount of material removed when machining a flywheel should only be a couple of grams, not nearly enough to cause a noticable vibration even if it all came off the same spot. it is very very unlikely that the clutch itself is at fault, the quality control on components like that is always excellent because of the high penalty for failure.

now to the questions: is the vibration noticable when the vehicle is standing, with the engine idling, or only when it's moving? if only when it's moving, it's possible that the shop has accidentaly separated one of your driveshafts and put it back together incorrectly. The joints in the rear shaft have to be in phase, but the joints in the front shaft have to be 90 degrees out of phase. Some shops, when dropping the gearbox, will just let the front shaft slip joint separate to "save time" rather than undoing 4 bolts. This vibration will be proportional to vehicle speed.

is the shop experienced with and equipped to work on large vehicles? if the gearbox was allowed to 'hang' off the input shaft at any time, it is possible that the clutch driven plate (friction plate) is warped/damaged, this can cause signifcant vibration, proportional to engine rpm.

it is also possible that the flywheel bolts were not done up tightly enough, this can cause some nasty vibes and very bad 'knocking' noises, and the longer it is driven in this condition the worse the damage will become. it can destroy the crankshaft and the flywheel necessitating a complete engine overhaul/replacement. With a direct injection motor, the torque delivery to the crank is very staccato until the turbo comes on boost, and if the bolts aren't tight enough they loosen fairly easily.


hope you get it sorted easily!

cheers

Brian

Thanks for the replies guys.

The vibration is apparent at idle while stationary, and it doesn't really increase proportionally with the engine or drive speed - but it is there all the time.

You're definately right with the front drive shaft, it was put back incorrectly, we're just going to unbolt it now and fix it up. This is probably what is apparent at around 95km/hr.

D_Web wrote:Thanks for the replies guys.

The vibration is apparent at idle while stationary, and it doesn't really increase proportionally with the engine or drive speed - but it is there all the time.

You're definately right with the front drive shaft, it was put back incorrectly, we're just going to unbolt it now and fix it up. This is probably what is apparent at around 95km/hr.

hmm that's a bit strange - vibes are usualy started by the engine or driveline so are usually in synch with one or the other. broken off fan blade(s)? broken engine mount? broken exhaust flexible joint? all could potentially be caused by carelessness when dropping the gearbox.

dumbdunce wrote:
hmm that's a bit strange - vibes are usualy started by the engine or driveline so are usually in synch with one or the other. broken off fan blade(s)? broken engine mount? broken exhaust flexible joint? all could potentially be caused by carelessness when dropping the gearbox.

We went and had a look at the front drive shaft and it seems it was put back correctly. I also checked the fan, engine mounts, exhaust and a had a general sticky beek, it all looks to be ok.

I guess we'll find out when it comes out.

if the vibration is there at idle and continues when driving it is a possibilty the exhaust has been bent ,it has to be removed or loosened to allow the gearbox to drop far enough to be removed,they sometimes crack at the flexible joint if not released and pressure levered down on the engine to get it low enough to get the gearbox out,also recheck the engine mounts by trying to jack the engine up 1 side at a time.

Just thought I'd follow this up. We didn't have the clutch removed to check, partly because it was probably our imagination and we also had to go away. Anyway, after 2400km, it appears that everything is pretty fine, so there probably wasn't a problem in the first place.