Vibrating noise in 4th/5th - 1989 HJ75 (1 Viewer)

[Touz]

Hi,

I have this vibrating noise in my HJ75 Troopy between 80-100 km/h (50-60 mph). It is not consistent - comes and goes, and varies in intensity. There is no noticeable difference in performance and handling.

I recently used the old girl to tow a caravan 650 kms / 400 miles. It was on the first drive after that trip that I noticed the noise. Interestingly, I recently drove with the back filled with wooden pallets and other heavy stuff and for that drive the noise was absent. Could it be something to do with suspension? Only wear and tear I can see is one of my front leaf spring clamps is broken so some of the bars are slightly misaligned.

Another theory was the fan shroud. At first I thought the noise sounded like the fan hitting metal, and the shroud is pretty flimsy and some of the spot welds have come undone. But the fan doesn't have any chunks missing. So I thought maybe the fan shroud is rattling like crazy at certain speeds. I tried tightening it all up with extra screws but it didn't make a difference to the noise.

Originally I was convinced the noise was coming from the front, but last time I drove it I thought it could actually be coming from the back. It's hard to tell because the troopy is so noisey but maybe it could it be the rear differential? It previously had a constant perceptible whine at 80-100 km/h (50-60 mph) that my mechanic noticed. This is new noise though is way more dramatic and not consistent. Could my rear diff be about to give out?

The other potential is a 4th/5th gear bearing. But I notice the noise doesn't just occur under load, I can be coasting at 80-100 km/h (50-60 mph) and the vibrating noise is there. Also I recently had the gearbox reconditioned, so I'm assuming they would have replaced anything that was about done. But maybe they messed up and it still could be seomthing in gearbox?

Any suggestions or ideas would be much appreciated. Cheers

 

[Eurasiaoverland]

Noises at that speed are typically the driveline, propeller shaft (tailshaft in Australia) UJs would be my guess - they can be worn and create noise even without any obvious movement.

I seem to recall you had a loose pinion flange on the rear diff - this is a sign of trouble in the rear diff. Whining, howling on deceleration are also signs.

There is no such thing as a 4th/5th gear bearing. And contrary to popular belief, the bearing belonging to a particular gear is stationary when that gear is engaged, and moves at all other times. There is no 4th gear bearing as there is no 4th gear as such. A transfer case bearing is a more likely candidate for the noise.

If the noise was from the fan it would be engine speed specific. Your noise seems to be road-speed specific, so you can probably rule the fan out.

 

[Touz]

Noises at that speed are typically the driveline, propeller shaft (tailshaft in Australia) UJs would be my guess - they can be worn and create noise even without any obvious movement.

I seem to recall you had a loose pinion flange on the rear diff - this is a sign of trouble in the rear diff. Whining, howling on deceleration are also signs.

There is no such thing as a 4th/5th gear bearing. And contrary to popular belief, the bearing belonging to a particular gear is stationary when that gear is engaged, and moves at all other times. There is no 4th gear bearing as there is no 4th gear as such. A transfer case bearing is a more likely candidate for the noise.

If the noise was from the fan it would be engine speed specific. Your noise seems to be road-speed specific, so you can probably rule the fan out.

okay thanks for the reply, I'll check the prop shaft UJs tomorrow, anything in particular I should look for? Would any signs be present without having to pull anything apart?

Loose pinion flange was a hypothesis for the whining sound I had in 4th and 5th. This is a new sound, that is quite difference - more of pronounced vibration or rattle.

 

[Eurasiaoverland]

To check the UJs properly, the propeller shaft flanges need to be reemoved from the companion flanges on the diff / transfer case, so you can move the joint in both axes by hand. Any undue stiffnes or notchy movement suggests wear. The OEM UJs are in my opinion far superior to other Japanese brands such as GMB and definitely worth the money in my opinion.