Outer Limits 4x4 Board

Hi all, have what i believe to be something seriously wrong in the front end of my MQ SWB diesel.
Was driving down the street a couple a days ago in 4L testing it out after a partial resto when i started turning left or right the front started grinding/crunching away.The manual hubs were AMV brand at the time,believing they may be faulty due to broken locking springs i fitted another set of original hubs i had laying around,using both shim/spacer cones (almost 4got the two in each side)i thought this should do the job,but still no good.
I had the MQ on stands testing it in 4L seems ok (no noise) with the wheels straight and applying the brakes to load it up,if you turn the wheels either way and load it up by braking it starts crunching/grinding and bangin like crazy.
Im stumped,if it was the diff why not do it at any time and i find it hard to believe that a sd33 power house could brake the front diff in any way.
Any idea or previous experience on this would be much appreciated.
cheers
jnr

First thing, I hope you were driving in 4L with the hubs unlocked on hard surface. You may have some broken CV fragments in the knuckles - I would pull the cvs out, check all the wheel bearings, rotor, spindle and the inside of the knuckle and kingpin bearings. Messy work, but ya gotta find out.

Yeah, its a big no no to drive in hi or low 4 with locked hubs on hard surfaces, unless ur going in a dead straight line then its ok.
The moment u turn the wheels u get one front wheel travelling a longer distance to the other and because there is too much traction the other cant comensate, so u brake CV's and twist diff centres.
This may be something to do with ur problem. check the cv's then the centre.
Remember if its the centre it will onlt do it when in low with locked hubs not in hi 2 on the road.

HTH.

Screwy

Area54 wrote:First thing, I hope you were driving in 4L with the hubs unlocked on hard surface. You may have some broken CV fragments in the knuckles - I would pull the cvs out, check all the wheel bearings, rotor, spindle and the inside of the knuckle and kingpin bearings. Messy work, but ya gotta find out.

yep....................... what Area 54 said... ( "extreamly" good call " )

also will create a heap more dammage if ya keep driving it with the front locked in

Ok ,i had a busy week with this and this is what i have found.
I removed every thing bar the diff centre which looked a ok once the cover was removed.The passenger side cv appeared to be a little knotchy and the stub axle had no bearing.Thats the small needle roller bearing that seats against the brass shim on the axle.No cage no needles nadda,all gone.So i started to destroy a spare i had and that also was missing from passenger side.Then i moved to drivers side which was in better condition with all bearings and shims in ok condition,and this was the case with the spare also.Is this a common fault with these,both diffs in the same condition on both sides.(strange)
Dont go genuine for these little bearings,$65 for bearing and $35 for the brass shim.
Anyway,fitted the cv's from the spare diff and the stub axles that had the bearings still present and in good nik.All done and re assembled but on stands in the garage im still getting that slight crunch once applying the brakes alittle to load it up with the wheels turned left/right.
I will go for a spin down the street to park land and check again on softer ground but from the way it is in the shed,it dosnt look good.
The only thing left is the front drive shaft,uni's,and slip joint has very little movement so im fucked if i know gents.
Will let ya's know once i drive it .
Thanx to all for ya advise
cheers

Ok gents, tested and im gettn nasty noises from the front still.
I get a bangn clunkn noise when turning but not as bad when straight .
I have now found that the front tail shaft is badly worn,this rig was sitting for years and when i checked it must have rusted tight but since driving its freed up.Im geting it fixed locally for roughly $300.I hope this fixes the problem cos every thing else has been done.(unless transfer is rooted)
Ill let you know
jnr

Check all ball joints for play/looseness and Steering box mounting bolts, pitman arm nut, box play, did you inspect the kingpin bearings and the knuckle seals for debris/needle bearing material (totally remove the knuckles and degrease everything)

Thanx for ya help area54,yeh ive done/checked all of those things .I had a little play in the king pin bearings but they werent to bad,I adjusted the pre load on them and removed some shims on em.All moves nice and smooth.The only thing that hasn,t been done is the front drive shaft which gets done this week (fingers crossed)
I had lot of crap on the knukles and cv,s all cleaned and re greased,both cv,s replaced with spare set due to one of the old ones being notchy,replaced stob axle bearings the lot.Its hard to explain the type of noise it has (here goes) it has a bang/crunch when turning in 4x4 every second or so,Like its binding up then releases,it dosnt bang going straight but does make some noise.I was told to check that i dont have to different diff ratios front/rear by marking the tyres,but i think i did it wrong.I marked the tyre and the tailshafts then turned the tailshafts one turn and compared the marks on the tyres (is this correct)
They were very close (within an inch)

One good idea might be to try to isolate components a bit.

For example if you disconnect the front driveshaft from the transfer case (just tie it up with wire out of the way) and go for a little spin in 4WD (hubs unlocked!), the only front-drive component running will be the transfer case. No noise? It's probably not the transfer case then.

Then disconnect the front driveshaft from the front diff. Now go for a spin with the hubs unlocked. No noise? It's not the front wheel bearings or anything on the out side of the locking hubs.

So now lock the hubs and go for a spin. Noise? It's somewhere between the two front locking hubs - maybe the diff, maybe the CVs.

Well, that's how I'd do it. You may not narrow things down enough unless you can start crossing possibilities off the list.

Good luck.

Jason

Screwy_ScrewBall wrote:Yeah, its a big no no to drive in hi or low 4 with locked hubs on hard surfaces, unless ur going in a dead straight line then its ok.

The moment u turn the wheels u get one front wheel travelling a longer distance to the other and because there is too much traction the other cant comensate, so u brake CV's and twist diff centres.

I don't mean to nitpick, but I believe that's not quite correct. The problem is not one front wheel travelling further than the other front wheel - the front diff can handle that just like a rear diff does all the time (rear wheels travel different distances in a turn too.)

The problem is front axle vs rear axle; there is no diff between the two axles so they can bind up. That is, left vs right is okay because of a diff at each axle; front vs rear is no good because they are locked together by the transfer case.

The other possible problem with locking hubs and using 4WD on tarmac is understeer; there is no problem with having hubs locked while driving in 2WD other than extra wear and reduced fuel economy due to more parts turning.

Jason

chimpboy wrote:

Screwy_ScrewBall wrote:Yeah, its a big no no to drive in hi or low 4 with locked hubs on hard surfaces, unless ur going in a dead straight line then its ok.

The moment u turn the wheels u get one front wheel travelling a longer distance to the other and because there is too much traction the other cant comensate, so u brake CV's and twist diff centres.

I don't mean to nitpick, but I believe that's not quite correct. The problem is not one front wheel travelling further than the other front wheel - the front diff can handle that just like a rear diff does all the time (rear wheels travel different distances in a turn too.)

The problem is front axle vs rear axle; there is no diff between the two axles so they can bind up. That is, left vs right is okay because of a diff at each axle; front vs rear is no good because they are locked together by the transfer case.

The other possible problem with locking hubs and using 4WD on tarmac is understeer; there is no problem with having hubs locked while driving in 2WD other than extra wear and reduced fuel economy due to more parts turning.

Jason

This is also why full time 4wd i.e. GXL Cruiser, Cross8, discovery, etc. all run centre diffs... this eliminates the possibility of windup on the road