Slippage

[DMCMW Dave]

But I should take it to him, stick her on the hoist to take a look at the wiring to check it to be certain.

Have him at least run a line pressure test. Pretty simple and it's in the manual.

[SIMid]

Have him at least run a line pressure test. Pretty simple and it's in the manual.

It's funny you said that, I was browsing through the workshop manual and there's a bolt you remove to test the pressure in the box. I'll ask him if he's got the equipment.

[David T]

If it is slipping it has NOTHING to do with the shift computer. You have to check the line pressure. If it is low you have to find out why. It could be because of a dirty filter, a worn pump, or leaking internal seals. If the line pressure is good and you are slipping then you have worn-out clutch packs and there is nothing you can do except rebuild them.
David Teitelbaum

[SIMid]

If it is slipping it has NOTHING to do with the shift computer. You have to check the line pressure. If it is low you have to find out why. It could be because of a dirty filter, a worn pump, or leaking internal seals. If the line pressure is good and you are slipping then you have worn-out clutch packs and there is nothing you can do except rebuild them.
David Teitelbaum

Exactly what I thought about the computer. I have no experience with autos, so some Qs might sound a little noobish. Is it possible to repair the pump without dropping or opening the box? I'm guessing its the pump as the box is fine at the start, but longer in the drive, she starts to then slip.

I rang my mechanic and he's going to speak to his gearbox friend and see if he can get the equipment to pressure test it.

[Jimmyvonviggle]

One thing for sure, slippage is better than shrinkage.

[David T]

It is unlikely the pump. As the fluid gets hotter and hotter it gets thinner and thinner. If you have internal leaks as the fluid gets thinner and thinner it leaks faster and faster so the pressure gets lower. I question if you really took the filter all apart and cleaned it thoroughly. If you did, then to fix the slippage you are going to have to disassemble the box and replace the seals, steels, and frictions in the clutch packs. The pump CAN be opened without dropping the transmission. It is on the very front and is bolted on. Before doing the pump, do the filter again and fill correctly with the proper fluid. Then check the pressure.
David Teitelbaum

[SIMid]

It is unlikely the pump. As the fluid gets hotter and hotter it gets thinner and thinner. If you have internal leaks as the fluid gets thinner and thinner it leaks faster and faster so the pressure gets lower. I question if you really took the filter all apart and cleaned it thoroughly. If you did, then to fix the slippage you are going to have to disassemble the box and replace the seals, steels, and frictions in the clutch packs. The pump CAN be opened without dropping the transmission. It is on the very front and is bolted on. Before doing the pump, do the filter again and fill correctly with the proper fluid. Then check the pressure.
David Teitelbaum

Thanks for the reply David.

Maybe I need to retop up the second reservoir to the lip of the edge of the bolt, possibly not enough trans fluid? Also, I know that it should have Dex II, but what happens if my mechanic has put in Dex III by mistake? I know it's a no-no for these boxes.

[David T]

Dex III is supposed to be backwards compatible but it is always best to use the correct fluid. They have different friction modifiers in them and the wrong fluid won't work right. The transmission gets the Dexron, the final drive gets 85-90W Hypoid gear oil. It is also VERY important to fill the transmission to the correct level. You really should follow the procedure in the Workshop Manual. Do all of the external On-Car adjustments and check the line pressure.
David Teitelbaum

[SIMid]

Update: Me mechanic has advised me that i will need to go for a rebuild. Question i have, does the motor need to come out to remove the box? Surely it doesnt? Was watching Wheelers Dealers and they seperated the box (manual) from the engine which means they could drop the box? Is there anything else that should get looked at or replaced while shes going through this resto?

Thanks everyone.

[DMCMW Dave]

No. You can drop it from underneath. Replace the engine rear main too!