Centre diff issue and questions

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El_Freddo
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Centre diff issue and questions

Post by El_Freddo » Fri Oct 04, 2019 11:46 pm

The patient: 1999/2000 RX Liberty wagon (EJ251) 5spd manual - aka, Basil

Issue: swapped in second hand gearbox (pick a part special!) only to find the vehicle now has a wobble like feeling from the front left when under acceleration, becomes worse with heavier acceleration. All other times the vehicle generally feels unsettled.
The other issue is that I have that totally awesome catch-let go-catch-let go feeling or experience when turning tight such as when performing a U turn.

Questions:
1) can a stuffed centre diff create the issue with the front end that I’m experiencing?

2) can the viscous gel stuff leak from the viscous LSD housing, and if so, what does it look like?

Question 2 was asked because after stripping down the old box that was replaced, Ive found a ball of what looks like silicone near the front diff area, grey in colour I think, and in between the drive and output of the centre diff is the same sort of material. It does seem like silicone but its just a real odd place to find it!

This gearbox has presumably done over 400k km now - if it hasnt been changed at some point. It was swapped because of a bearing noise and it was slipping out of gear (possibly due to shot pitch stopper rod and gearbox mount).

Upon rotating the centre diff it seems the noise is in the rear bearing. This centre diff is good so it’ll end up in the wagon either way - unless that grey material is the viscous gel stuff, then I don’t know what we’ll do...

Cheers

Bennie
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TOONGA
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Re: Centre diff issue and questions

Post by TOONGA » Sun Oct 06, 2019 9:29 am

Bennie not sure about the front end issue it could be torque bind or it could be a worn CV.

As for the centre diff they are full of silicone oil and it is possible it is leaking or has leaked.

TOONGA
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El_Freddo
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Re: Centre diff issue and questions

Post by El_Freddo » Sun Oct 06, 2019 5:47 pm

Thanks for the reply Toonga.

The issue with the front end could be on the money - it didn’t do this prior to pulling the engine and box out.

With a replacement (second hand, condition unknown) gearbox, we now have this “wobble”, only when under load. When coasting the vehicle feels unsettled in general. Before hand it felt firm on the road and loose in the gearbox.

I replaced the rear gearbox mount as the old one was completely shot. Turns out I replaced it with a group N mount (solid rubber, not the three individual sections moulded in). The LHS engine mount has evidence of cracking in it but not enough to warrant being stressed about it. The pitch stopper rod was replaced as well. Last one was cactus.

So the gearbox mount will be replaced with a standard unit that’s in good condition. The group N one will go to the RS if I ever get it going.

Now I’ve got the two gearboxes out. Gearbox “A” was the old one, gearbox “B” the replacement with the shot centre diff.

Gearbox A has a dead bearing on the rear upper lay shaft, between 4th and 5th. Probably the reason why it would slip out of 3rd and 4th, and why I could hear noises I didn’t like. It has a good centre diff - and was the one with the silicone like stuff in it. AFAIK this box since we’ve had it did not display any signs or symptoms of a dead centre diff.

Gearbox B is clean inside, the oil that came out was clean before I replaced it with new stuff. I don’t think this box was opened up previously, if it has someone did an awesome job.

Plan is gearbox A centre diff into gearbox B. Replace front diff bearings and reseal the box ready for install.

Now to order all the parts in half a week while organising the final parts of a school trip later this week. Fun fun.

Cheers

Bennie
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El_Freddo
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Re: Centre diff issue and questions

Post by El_Freddo » Sun Oct 06, 2019 10:28 pm

Thinking about your CV comment Toonga, I’m going to swap the shafts left to right etc and see if the issue swaps sides with the shafts.

Cheers

Bennie
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RSR 555
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Re: Centre diff issue and questions

Post by RSR 555 » Thu Oct 10, 2019 8:03 am

Hey Bennie,

Have you confirmed that you are running the correct rear diff? This unsettling feeling when just driving straight is common for incorrect rear diff ratio and this would get worse when turning. It takes a lot of heat to make the viscous coupling to let go, but with the wrong ratios, this will happen very quickly. I've also seen this happen with mixed match tyres.

If you can take the car for a 15min drive (the longer the better) with lots of cornering, then pull up home on a set of ramps, then put your hand on all driveline components and feel for hotter than normal temps. This might help pin point where things might be grabbing.

Cheers,
Paul

Edit: not to state the obvious but keep your hands away from the hot exhaust system ;)

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