noise in 4wd

[crackatinny]

Latley My 87 sierra has been making a strange noise when in 4wd. it is mailnley in hi at high speeds.
basically, when fanging along 80 kays +. whenever i back off the go-pedal i get a deep crunching sound. it is almost like something is loose and is vibrating.
i only noticed it the other weekend while camping. scince then i have changed the transfer case oil and added some nulon G/B additive

any suggestions appreciated.

Jake

[Pep]

Latley My 87 sierra has been making a strange noise when in 4wd. it is mailnley in hi at high speeds.
basically, when fanging along 80 kays +. whenever i back off the go-pedal i get a deep crunching sound. it is almost like something is loose and is vibrating.
i only noticed it the other weekend while camping. scince then i have changed the transfer case oil and added some nulon G/B additive

any suggestions appreciated.

Jake

Does it do it at all in 2wd or at lower speeds in 4wd,
cause (in my opinion) you shouldn't be really "fanging along at 80 kays" in 4wd anyway,

[chops_Drover]

I'm with PEP,
I have only been driving 4wds for a few years, but normally if you are doing 80klms/hr i'm sure it would be enough traction to have it in 2 wheel. And it would also be putting a hell of alot of extra wear on the cars drivetrain. Im having your hubs locked(presumed) & being in 4wd on high traction surfaxces is a big no no! Hopefully someone with a bit more knowledge will shed the light on this for you...

[nicbeer]

80 in 4wd, do it often on the sand tracks asin 2wd it kicks all over the shop.

does it when slower speeds or in 2wd?

sounds like a bearing has gone in there. mine has a noise when backing off from the front input shaft bearing as there is 5mm slack there.

Nic

[chops_Drover]

Sand...Don't see too much soft stuff in Nth Qld. Didn't realise. Most of the stuff up here i drive the Isuzu mu round in 2wd & when in 4wd we may get up to 40klm max. Most sand tracks up here is fairly couse stuff & you don't really get the chance to go much faster without running the risk of hitting a tree or rocks. Don't do any beach driving .

[crackatinny]

nicbeer, i am thinking the same way as you (bearing) do you mean the input shaft in the front diff?
it is only in 4 hi that i notice. and i cant seem to pick it at low speed.

yes i often cruise around 80 to 130 kays in 4wd. when going through the pine plantations the roads will be excellent, then go round a corner and about 2 inches of loose crap. but on the straights i put 'er back in 2 wd.
doing this has saved my life a number of times

(old man says: if you wearnt going so fast you wouldnt need 4wd to make the corner)

there you go ill flame myself.

[Big D]

Iv just wasted 5 mins of my life reading through this thread

[nicbeer]

nicbeer, i am thinking the same way as you (bearing) do you mean the input shaft in the front diff?
it is only in 4 hi that i notice. and i cant seem to pick it at low speed.

nah in the front of the transfer.

u could try taking off the rubber boot and when decel and accel on the trakcs see if there is movement of the input shaft to the transfer.

otherwise could be output bearing on the transfer end or even diff bearing.