Following on from previous thread, I have just had a replacement (2nd Hand) 4x4 Autobox fitted. It has a large servo on the back of it that wasn't fitted to the old box. Can anyone tell me what it is for, and if this box is likely to work without it being connected?

Thanks

Tom

- (#9114) Tom Lister, 13 Jun 03 6:10

Tom. The CD shows this servo as " Diaphragm Cylinder and Transfer Vacuum Actuator". This is the device, presumably, which engages the transfer box to take power to the front axle. I had thought that this was solenoid actuated, via the 4WD button, on the dashboard, but, it may vary from model to model. If your previous gearbox did not have the vacuum unit, it might be a problem to engage 4WD and you should get it checked before fitting.
Of course, someone might comment here and advise more competently. Perhaps there is a solenoid AND a vacuum unit, though I don't seem to have one on my 4 x 4 Masterace.

- (#9115) John Davis, 13 Jun 03 7:24

Thanks John, I will pass that on to the garage and see what they think. I don't use 4x4 often but up here in the Highlands, when I do use it I really need it. If anyone else has any info on this I would be grateful...

Tom

- (#9116) Tom Lister, 13 Jun 03 7:39

Looks like early models selected 4x4 on the lever. Can you confirm this, Tom? If so, It's be a fair bit of work to get switches, solenoids etc configured to control the later box. Perhaps your mechanic can transfer the transfers? (sic) - they will unbolt from the end of the tranny, and should (but don't quote me) interchange...

- (#9117) david miller, 13 Jun 03 8:07

Tom. I really ought to get out a bit more !!!!
I have just done an inspection of my 1990 4 x 4 Masterace gearbox and, yes, I DO have the vacuum unit mounted on top of the transfer box casing but, in front of it there is a wired "plug". I now feel that this plug is a solenoid operated valve, ie, engaging the dashboard 4WD button, opens the valve and vacuum, through the diaphragm unit, does the work of pulling the engaging lever up. Unless someone can advise differently, I think that you do need the diaphragm and, also, the wired solenoid. Did you ever use 4WD on your old gearbox and, possibly, had the diaphragm unit been removed? Is David right, did some models have a pure electric solenoid actuator, operated from the gear lever?

- (#9118) John Davis, 13 Jun 03 8:30

Glad to hear that my query has enhanced your knowledge, John. I too am learning rapidly!

On my Aug '87 townie 4x4, the 4x4 is selected by a lever, no fancy switches on the dashboard for me! And it workded great before the box died. (David, could the broken plastic end of the kickdown cable have led to dirt in the box and the death of said box?)

Colin at the garage says that there is plenty of time to get the box working 4x4 before winter, but just now (having been up until 2:30 this morning working on the thing) he wants his ramp back!

Thanks for the help,

Tom

- (#9119) Tom Lister, 13 Jun 03 8:40

Anything that lets grot into the box will expedite it's demise...

I think the easiest way to sort your 4x4 issue would be to swap the transfers over- an hour or two and maybe a couple of gaskets ought to do it!

- (#9120) david miller, 13 Jun 03 9:28