driveline GRrrrrrrr

[Knucklehead]

Hi,

Hoping somebody has some suggestions on how to track down a fairly severe sounding driveline noise.

Fairly hard to describe, sort of like load groan/vibration from underneath but only when dropping below 10mph coming to a stop.

The noise will disappear when engage the clutch or accelerate. The truck drives fine rest of the time, it only shows up when coming to a halt. Will even show up if use the engine braking instead of the brakes and coast to a halt so not brake related.

Checked the usual stuff like UJs and changed the diff oil just in case but all seems fine.

Baffled by this one. Any thoughts guys?

Cheers,
Dave.

 

[clivehorridge]

I would still wager a (small) bet on the front prop front UJ.

I had exactly the same symptoms and spent a good half hour with a couple of bars trying to induce/detect some play in all of the 4 UJs. Nothing, all good and shipshape, so for good measure I greased them and the slips, and assumed it must be something else.

After driving it again, the noise had gone, so I then presumed one of the joints or slips had benefitted from the grease.

A short time later, somewhere on the motorway between Bucharest and Constanta (on our way for a week of beach holiday ) back came the noise with a vengeance. I ended up "driving" the truck very slowly along the emergency lane, with my head as far underneath the truck as possible

A bit of a daft thing to do, but in that position I could clearly identify the noise coming from the front prop front UJ.

I took it to service for their opinion, and although they admitted there was no play in it, and no visible signs of wear from the outside, they had removed the prop and he handed it to me and said "see?"

I could "see" bugger all wrong, but when I grabbed the diff flange of the UJ to rotate it to "feel the play" it was seized solid!

I couldn't move it at all by hand, but of course in situ, it was under loads of stress being forced to move.

My advice would be to drop the front prop off and check for seized bearings, which are just as likely (so I'm told) as bearings with excessive play. If it's not the front diff end UJ, try dropping the rear prop off, and checking it the same.

As I said, my money's on the front prop, diff end, UJ.

 

[Dave2000]

As per Clive's post IME. There may be no actual 'play' but release the flange and try to move it through all angles by hand. IME I have found the needle bearings often seize in one place. Another cause could be the sliding joint, but this normally makes a noise AFTER the car has been serviced, over zealous use of the grease gun causes the joint to apply pressure between the drive flanges, this prevents the propshaft contracting with axle movement.

Other causes are:

Tyre wall/tread faults, the steel banding can go out of shape, this causes irregular wear of the tyre surface and can set up all sorts of noises.

A faulty gearbox mount can allow the drivetrain to move out of line during acceleration/deceleration.

Broken antiroll bar bolts, antiroll bar hangs on bracket and hits the front propshaft but only at specific times, seen it on a 1990 model, along with the panhard rod pulled out of the chassis rail.

Rare but not unknown, the thrust washer in the front pinion fails, normally wet with oil around the pinion flange.

Also rare the bearing in the front transfer box output shaft.

And of course the usual suspects, weak engine mount allowing parts of the drive train to touch the bodywork, exhaust and so forth,

That's all I can think of at the moment mate.

regards

Dave

 

[Knucklehead]

Many thanks for replies.
Would a dodgy UJ only show up when coming to a stop at 10mph and under? There are no issues decelerating from faster speeds ie motorway speeds etc...

Sounds like worth removing the propshaft and have a proper poke around.
Will also look at some of Dave's suggestions as well.

Cheers,
Dave.

 

[Dave2000]

Just to help with the diagnosis, with the engine off and in quiet place, in neutral gently roll the car forwards and backwards, you often get a 'dry squeal' or 'groan' from an 'iffy' UJ.

Bad UJ's start giving issues when rolling slowly, then as you get faster the roughness smooth's out, eventually they wear oval and give up loads of bad vibes at speed.

regards

Dave

 

[Knucklehead]

Cheer Dave. Will give that a go. Pricing up some replacements as pretty sure these are originals and probably well past their best.

Dave.

 

[clivehorridge]

Many thanks for replies.
Would a dodgy UJ only show up when coming to a stop at 10mph and under? There are no issues decelerating from faster speeds ie motorway speeds etc... Sounds like worth removing the propshaft and have a proper poke around.
Will also look at some of Dave's suggestions as well. Cheers, Dave.

Dave, it was your description of the low speed grind noise and judder/vibration that prompted my reply. At speed there was no noise or vibration.

Having said that, I had 300+ km to get home, and by the time I did, the noises were notably worse and the vibes the same. I think that it was just about to let go when I had it changed.

 

[Knucklehead]

Cheers Clive,

I have decided to change out the UJs now anyhow as a bit of PM as thinking 200K miles on them is pushing my luck.
When I picked up my cruiser years ago they were badly neglected like the rest of the truck so will be interested to see what state they are in.

Hate having anybody else work on my truck but these sound a bit of a pain to change out so might need to leave in somewhere.

Dave.

 

[clivehorridge]

Cheers Clive,

I have decided to change out the UJs now anyhow as a bit of PM as thinking 200K miles on them is pushing my luck.
When I picked up my cruiser years ago they were badly neglected like the rest of the truck so will be interested to see what state they are in.

Hate having anybody else work on my truck but these sound a bit of a pain to change out so might need to leave in somewhere.

Dave.

They are a PITA to change and unless you've got a decent workshop with a press or a beautiful FO vice with parallel jaws, and some heat and drifts that are the right size and, and, and... I would suggest you have them fitted by someone with the right kit and knowledge. I've done many in my time, but it's easy to fcuk them up if you don't get them aligned properly or if the old ones are a bugger to shift.

Many's the time I've had a needle drop on assembly, and unless you have your wits about you, you can end up doing the job all over again a few days later.