Replacing overdrive inhibitor switch

[cullywoo]

Hi all,

My Mk2 is nearly finished after needing to be substantially rebuilt.

I ended up changing my old moss gear box for a newer all syncromesh box with o/d. This has turned out to be a costly process needing a heap of modifications to get it to fit. Anyway all installed and it turns out overdrive doesn't work.

This has been traced to a faulty switch (brand new!) on the box (the one that inhibits o/d when not in 4th). The mechanic has told me to replace this will need to take gear box tunnel/centre console out.

Is there not an easier way to do this? At a cost of £55/ hr plus vat this is starting to hurt. Doesn't help that the head gasket went while on the rolling road on Monday!

In all quoted 28hours to do both at a cost of £2k!

I'm guessing the head gasket is beyond me, but the switch must be easier?

Thanks in advance for any thoughts.

[piman]

Hello Culliwoo,

Could he not just undo the gearbox cross member and drop the gearbox a bit so as to gain access from underneath? It's possible that the switch needs shimming to get it to work correctly?

Far too late now but a simple test before the gearbox was installed would have proved the switch operation?

Alec

[cullywoo]

Bit annoyed the switch wasn't tested first. Sent as a newly refurbed unit direct to workshop.

Hey ho.

Thanks for suggestion will see if that's a go-er. Difficult when I don't have car.

[cullywoo]

Ps He did suggest he switch would need fettling to get it working properly. I presume that's the reason it needs to be in-situ.

[Martec]

Hi,

When I fitted my recon full synchro gearbox and overdrive in place of a 4 speed moss box (no Overdrive) only minor changes were needed, ie clutch release bearing, as it came with the propshaft as well.

A few months later the new overdrive switch ontop of the box failed (high resistance across the contacts). I fitted a new one and wired the operation via a relay so that the heavy current wasn't going through the column switch or the gearbox switch, only low operating current. It has been fine ever since.

I lifted the carpet, undid the screws holding the fibreglass tunnel top and VERY CAREFULLY levered up this casing and access was easy.

Put a multi meter (approx £10 from Maplin or similar) across the switch terminals and it should show a circuit when you engage 4th gear, and open circuit in other gears, check power supply and the other switches first before diving into the tunnel.

A few months later it failed again but that was due to the terminal wire on the solenoid being partially broken (not many strands left) a new wire soldered on has worked ever since ( over 10 years).

I do my own work so labour is free.

Best wishes

Brian