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[rowleav]

Hi everyone, I am a newbie here but this is my second WJ.
My previous was a 60th anniversary 4.7 and it was the mutts nuts. Sold it for a silly reason, but today purchased a 2002 4.7 Overland.
Great car and only 35k miles but it seems to have transmission wind up!
On full lock at low speeds you can hear a groaning from the back of the car.
Also, if you drive straight on tick over and then turn full lock, the car will slow and then stop altogether and you can feel the tyres scuffing.
Alos, when moving the steering from straight ahear, you can feel it suddenly go light. It just wants to go straight and not turn.
Anyone offer me any advice as to what could be causing this?
I thought the Quadradrive thing was all hydraulic.
Does it operate on viscous couplings that might have seized?

Best regards,
Andy

[scrw]

Sounds like the centre diff is locked up.

Are the tyres all worn evenly?

I know on ours the fronts wear out faster and it can be a PITA getting out of 4lo due to transfer case windup (they only needs to be 1mm difference front/rear to cause problems)

[rowleav]

Thank you for the  response!
Sorry,  but being a newbie means I don't understand what PITA means.
Also, the rear tyres are considerably newer than the front pair.
I didn't think that it mattered with the viscous coupling system.
I can get 4 lo no problems but only ever tried it when stationary.
When in normal 4 all time hi, this is when the problem occurs.
Only on really tight turns (full lock) do you feel the car slow and find it hard to move off.

Can you tell me what the likely cost of a repair of this kind might cost me?

Thanks again.

Andy

[rowleav]

Sorry, forgot to say I'm in the UK (if that matters)

Cheers.

Andy

[MOCAJ]

pita = pain in the  arse

im sure someone will help with the other bits as im not sure on your truck  

[Mike Pavelin]

You need to get 4 tyres with the same amount of tread first so all wheels are rotating at the same speed.

[rowleav]

Ok, thank you all again.
Wife managed to work out the PITA just after i'd posted it, sorry for being so dumb!

I will arrange to get the tyres replaced asap and see where that goes.
I'm also considering getting a Tesco warranty just in case this beast turns out to be a trouble causer.
Their warranties look good and are priced excellently for this car.

All the best and thanks again.

[Mike Pavelin]

I would also ensure that the axles and transfer case have the correct oils in them.

[rowleav]

Oh, OK, I will do that also.
Can you tell me please, if the transfer case had either the wrong oil in it or not enough oil in it, would it cause this behaviour, and if it then had the correct oil in it, or had more put in to the correct level, would it be likely to rectify the problem?

Anyone have an idea what it might cost to have the PC replaced, or any recommendations to anywhere that sells these PC's or rebuilt transfer boxes in case the worst comes to the worst?

Thanks again

[tim_aka_tim]

PC?

[rowleav]

PC = Progressive Coupling aka viscous coupling.
Its what the Jeep bods call it in their workshop manual.

I have an update though.....
I lifted the 4 wheels and went into neutral with the handbrake off and I can turn the back wheels independantly of the front. They do try to turn but you can hold it back and then the rear prop turns when you turn the rear wheel/s. It stiffens up a bit but it turns. So I escalated the test a little by running the engine and selected a low gear in 4-hi. Releasing the footbrake slowly and with just a tiny bit of gas, the rear wheels both turned easily but the front stayed still. I guess that gets the PC/viscous coupling/centre diff off the hook?

So I turned my attention to the wheel alignment and looking down vertically, you can see they are a mile out! So, I adjusted them is as best as I could by eye and it has made an improvement.
On full lock, there is less wind up and rightly so I would think) but there is still an occasional clunk from the back. Some say that 4wd vehicles do tend to do this skipping thing but I'm not at all convinced.

Anyone able to offer any suggestions as to what the rearward clunking might be?

[Mike Pavelin]

There are no viscous couplings in the system. The differentials and the transfer case have multi disc clutch packs which are engaged hydraulically if one side of the output starts to rotate at a different speed to the other. If incorrect lubricant is used it can cause shuddering or groaning as the clutch packs do not slip smoothly, in a similar way to the shudder you get from a Trac-Loc LSD without the friction modifier in the oil. There shouldn't be any noticable hopping from a WG with Quadradrive. I would change the oil in the rear diff first of all. You might want to check all the rear suspension bushes and the ball joint on top of the diff for wear.

[rowleav]

Mike, you are a star sir!

I will be doing all of these things over the next weekend.
Everything you are saying makes perfect sense to me now.
I'll grab the owners manual and go get the oil.

I'm sure I read somewhere also that the transfer box oil should be sourced from the main dealer and not a motor store.
Should I get all of the oils from the main dealer to be totally safe?

[rowleav]

And once again, I'm hoping Mike might come to my rescue!

I have purchased the required oils and friction modifier and sealer to do all the oils under the car.
Today though I had a VERY different problem!!
I drove for about 30 miles and the car seemed a bit hesitant. You might say it slowed down quicker than expected when off the gas.
I was on the motorway so didn't stop as the car seemed to go OK on acceleration.
When I got home, I could smell the burning really bad!
The nearside rear disk was almost glowing and there was a fair amount of smoke emanating from the caliper/pads area.
So, I let it cool thoroughly and set about stripping the caliper to free the suspected seized piston or caliper slide.
When I put a screwdriver in to prise the caliper back  to force the pistons in, I could pull it with one finger!!!
The caliper slides beautifully and the pistons went in dead easy.
The handbrake isn't binding, so I cannot understand why the heck the brake was on so very hard.
This could have been the groaning we've been hearing too.

Can anyone explain this strange behaviour? Could the excessive heat have freed it all up or is there a system somewhere that puts the brakes on in a given set of circumstances?

Hope someone can advise.

All the best.

Andy

[scrw]

any play in the wheel bearing?

[TJMart]

Had the rear brake problem on a mates 1999 Grand cherry i cleaned it up twice and the problem still came back after a week or so.Every time i went to check the piston when it had been binding i could push it back no problem.So i put in a new piston and seal kit in the caliper and the problem was fixed, hope this helps.

[rowleav]

Not that I can feel.
Knocked wheel in and out at top, bottom, left and right and no sign of play at all.
Just come back from a 10 mile drive since last post and tried braking hard a couple of times to see if it might induce the sticking bake but it hasn't.
All 4 wheels same temperature (well, fronts a tad warmer as I'd expect) but absolutely no overheating.

Odd things!
Just got to get the low speed turning sorted now. Hopefully the oils will do it/

Has anyone on the forum had their 4.7wj remapped by the way?
Something I'm thinking of having done when other problems are sorted.

ALso considering a powerflow exhaust (quad pipe if they can fit it) and a K&N filter.
Wondering what difference all this would make.

Cheers again.

Andy

[scrw]

Have a powerflow on my XJ, nice rumble and an extra 1 MPG !  

[rowleav]

OK, an update for you.
Have changed the oils and put a 75-140 and modifier in both front and back axles and changed transfer box oil also.
A few figure of 8's later and the groaning has stopped.

Thank you to everyone for their advice with this.
Also. rear brake problem has not happened again since.

Anyone know of any Jeep breakers in the UK?
I now need a rear wiper motor.