Drivetrain Issues

[Wilcey]

Morning all,

My FC ute has developed another noise, however this one is more concerning. I'm not particularly mechanically minded, but would love to have a go at fixing this myself before taking it to an expert.
It seems to be somewhere near the rear axle, when I go anywhere over about 40 MPH the car starts shaking (gets much more noticeable if I shift into Neutral and Roll at high speeds). In addition to this when turning corners (also over about 40MPH) there is a soft rumble coming from the rear that almost sounds like something rolling in the tray. I'm assuming its a bearing somewhere or the diff playing up but would love any tips or suggestions that you may have.

Thanks,

Wilcey

[Harv]

Probably either propshaft bearings, or rear wheel bearings.

If you are getting seat-of-the-pants vibration, its likely the prop shaft bearings. These are relatively easy to do, parts available via Rare Spares. Rear wheel bearings are slightly more difficult.

Cheers,
Harv

[ardiesse]

Wilcey,

You've just done the standard test for diagnosing an out-of-balance driveshaft: >40 mph in neutral.  As Harv suggests, examine your front and rear universals for looseness.  If your unis are not loose, then see whether you can wobble the driveshaft yoke in the gearbox.  Excessive play here will cause an out-of-balance condition; but is a pain to fix (new yoke, if they're even available, and replacement of the rear extension housing bushing).

Stubborn cases of driveshaft imbalance can only be cured by taking your driveshaft to a specialist, getting them to machine the uni-joint trunnions off, remove two heavy cardboard tubes from inside the driveshaft, re-weld the trunnions, and then balance the shaft.

The soft rumble is most likely shot rear wheel bearings.  You need a press to replace these.

Universal joint replacement is the only "do-it-yourself" job of all these.  Unless you have a 20-ton press in your garage.

Rob

[Wilcey]

Thanks Harv and Rob,

The universal joints don't seem to be loose, and what I thought was the yoke also seemed pretty tight. The rear wheels dont seem to have any play either but its likely that it could be them as I doubt they've been changed in the last 20 odd years. Sounds like I'll be taking her down to a specialist this week. I'll keep you updated.

Wilcey

[Wilcey]

So the rumble ended up being the 2 rear wheel bearings, after 20+ years of use I guess that's to be expected! Had the boys at Newcastle Gearbox and Diff change them out, cost me 280 bucks which I thought reasonable. (I also changed the front wheel bearings over the weekend myself as I felt like getting my hands dirty). I drove down to Sydney and back yesterday with the old man, and noticed a loud clunk when loading up the transmission and a very noticeable vibration when driving at around 50mph. Took back into Newy Gearbox and Diff this morning, they've confirmed its the rear uni joint playing up, and will change it this afternoon. Fingers crossed thats all she needs for now as I need to save up the dollars to cut more rust out!

Thanks again fellas