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front diff issues

Posted: Fri Jan 21, 2011 11:16 pm
by stahlhut
Hey guys

Recently i acquired a cheap GQ 4.2 Petrol. On driving in 2wd goes fine. i locked in the hubs and 4h and the patrol seemed very restrictive and the front end was constantly bouncing up and down, This also occured in 4L

I left the hubs locked in and placed transfer into 2wd, The patrol continued to have the same problem causing the front end to bounce and be restrictive, Once unlocking the hubs all returns to normal

Can somebody please help to narrow down my search as to what could be causing this problem

Re: front diff issues

Posted: Sat Jan 22, 2011 9:30 am
by RIZZO
has the front or rear diff been replaced, sounds like it might have different ratios between the front and rear diffs to be acting like that

Re: front diff issues

Posted: Sat Jan 22, 2011 10:14 am
by 351ciofgrunt
As above or could have a welded up front centre, check by:

Jack up the front wheels off the ground, put it in 2wd, lock the hubs in and spin one front wheel if the other wheel turns in the same direction ie. both spin forwards, then I'd say the front diff could be welded into a locker

not neccessarily a bad thing, just drive around with only one hub locked in until you find a hill you can't get up, then lock in the other hub

Re: front diff issues

Posted: Sat Jan 22, 2011 12:14 pm
by stahlhut
351 nah does have a locker checked that but it doesnt spin both, but will be checking to see if prehaps the ratios are different today

Re: front diff issues

Posted: Sat Jan 22, 2011 1:16 pm
by RED60
stahlhut wrote:351 nah does have a locker checked that but it doesnt spin both, but will be checking to see if prehaps the ratios are different today
Should that read DOESN'T have a locker....... How will you check ratios without pulling them apart.....

Re: front diff issues

Posted: Sat Jan 22, 2011 2:28 pm
by 351ciofgrunt
Yeah if it's the 3.9 and 4.1 it will be too close to tell the difference by the old trick of a chark mark on the tyre and counting the driveshaft revolutions, you will have to count the teeth on the crown wheel and divide by the pinion.

Re: front diff issues

Posted: Sat Jan 22, 2011 3:51 pm
by thehanko
351ciofgrunt wrote:Yeah if it's the 3.9 and 4.1 it will be too close to tell the difference by the old trick of a chark mark on the tyre and counting the driveshaft revolutions, you will have to count the teeth on the crown wheel and divide by the pinion.
simply multiply the number of rotations 2 or 3 fold and the gap will become obvious.

since one tyre is held static the ratio effectively doubles making it 7.8 compared to 8.2. so nearly half a drive shaft rotation different already?

it will be easy to tell.

Re: front diff issues

Posted: Sat Jan 22, 2011 4:26 pm
by oldmate
It won't be the ratios. Even if they were different there would be no issue when in 2wd hubs locked because the front and rear output flanges on the transfer can turn independantly.

Probably a busted CV or diff.

Re: front diff issues

Posted: Sat Jan 22, 2011 11:34 pm
by stahlhut
Hey guys, sorry that was ment to say doesn't have a locker. Tested the rear looks to have 3.9 tested the front with hubs locked turning one wheel only and did 2 turns of the drive shaft do u have to turn both wheels for this to work and if so at same time or one after the other because 2 revolutions of the drive shaft just doesn't add up

Re: front diff issues

Posted: Sat Jan 22, 2011 11:59 pm
by RED60
thehanko wrote:
351ciofgrunt wrote:Yeah if it's the 3.9 and 4.1 it will be too close to tell the difference by the old trick of a chark mark on the tyre and counting the driveshaft revolutions, you will have to count the teeth on the crown wheel and divide by the pinion.
simply multiply the number of rotations 2 or 3 fold and the gap will become obvious.

since one tyre is held static the ratio effectively doubles making it 7.8 compared to 8.2. so nearly half a drive shaft rotation different already?

it will be easy to tell.
Hanko is close in theory, but numbers are off..... the method... mark both tyres on same side of vehicle and floor with chalk alignment marks.... gearbox in neutral with transfer in 4wd...both front hubs locked... jack up both marked tyres.... rotate tailshaft by hand 3 or 4 revolutions... if the chalk marks on the tyres align simultaneously with those on the floor still you have the same diff ratios front and back... if they don't align simultaneously then you have different ratios...

Re: front diff issues

Posted: Sun Jan 23, 2011 12:05 am
by RED60
stahlhut wrote:Hey guys, sorry that was ment to say doesn't have a locker. Tested the rear looks to have 3.9 tested the front with hubs locked turning one wheel only and did 2 turns of the drive shaft do u have to turn both wheels for this to work and if so at same time or one after the other because 2 revolutions of the drive shaft just doesn't add up
This method won't work.... see my previous explanation....

Re: front diff issues

Posted: Sun Jan 23, 2011 11:36 am
by hokey
won't be different ratio's cause still does it with hubs locked but transfer in 2wd.

did it spin smoothly when you had front diff in air with hubs in? front driveshaft uni's stuffed maybe? buggered cv or maybe even stuffed cw and pinion?

just pull it apart and till you find te problem. not very complicated if you've got a manual

Re: front diff issues

Posted: Wed Jan 26, 2011 2:32 pm
by Z()LTAN
bent front driveshaft