NorthCoastal
New member
1999 FG637 (150000k)
Just chasing a drivetrain noise, its gets a raspy hum up coming off load driving downhill at around 85-95 kph. Noise goes away when throttle is re-applied to load the drivetrain up again.
Looking at the diff, centre bearing, tailshaft slip joint, tailshaft universal joints and the transfer case as possible culprits.
So far I have found
diff has about 2mm of lash measured at the input flange circumference when the rear wheels are fixed. (not sure if this is normal)
Rear Uni has slight tight areas in one axis. (will replace anyway)
Tailshaft splines are slightly worn can feel the play if you twist or push the tailshaft.
Diff sounds a little noisy (but it is a truck)
Centre Bearing seems a little noisy when vehicle run whilst rear is elevated on stands, using a rod as a stethoscope. It also gets warmer than I thought it should just driving the rear whilst it was up on stands (think I shall change this as a service issue regardless)
Re the transfer case, I have been advised that one of the carrier shafts can wear in the case housing and loose its preload causing it to shimmy in the case. (I'll probably pop the cover and have an inspection of this)
I would be interested to know part numbers of centre bearing, and the rear universal joint.
Any advice from other users that have had a similar issue would be appreciated
Also is there a site with service info online or a parts breakdown
The vehicle is a single cab but has had the chassis lengthened to crew cab specs eg 2 piece tailshaft and centre bearing.
