940 m46 to m90 conversion

[knuckledragger]

Well the overdrive isn’t working on the m46, and the clutch bite point is jolly high too...

[classicswede]

sounds like gearbox off anyway. It not a huge amount extra to do the swap.

Get the M90 off the donor car first.

My tip with the M90 is to remove the gear linkages and then drop the box

The M46 you only need to remove the gearlever

[Laird Scooby]

Originally Posted by knuckledragger

Well the overdrive isn’t working on the m46, and the clutch bite point is jolly high too...

Have you checked the fuse and the oil level? Also the interlock switch and main on/off switch. The clutch might need renewal if it's high mileage but from what i understand, it's substantially cheaper for a clutch on an M46/47 than it is for the M90 clutch, even with the mods you're apparently planning if you go down the M90 route.

[knuckledragger]

I have tried removing the relay and bridging 15 and 87 but nothing happens. Also checked the switch at the lever for continuity when pressed and it works fine, although can’t seem to measure a voltage to the solenoid with the car running. I couldn’t get a continuity bleep between the solenoid terminals either, or get any “clonk” from it when I ran a 12v feed directly from the battery to the solenoid positive terminal. The cars been sat for 5 years by the way...

[knuckledragger]

Any other simple checks I can do to ascertain if if it’s solenoid, relay, wiring?
No I’ve not checked the fuse, which is it? Is it shared with anything else? I couldn’t find it in the fuse box chart

[360beast]

If you decide to keep the m46 and fix it then I have an m46 in the for sale section, I doubt it will sell so if it is any use to you you can have it and canabilise bits off it. I'm heading over your way 14th June so if you wanted it and Dave is happy to have a gearbox at his then maybe you could collect it from his place in Lakenheath?

[Laird Scooby]

Originally Posted by knuckledragger

Any other simple checks I can do to ascertain if if it’s solenoid, relay, wiring?
No I’ve not checked the fuse, which is it? Is it shared with anything else? I couldn’t find it in the fuse box chart

According to the diagram i have, it's fuse #12, not sure at the moment what, if anything else, shares it.

If you get a test lamp and wire it across the solenoid terminals with long enough leads so you can view the lamp from the drivers seat, take it for a test drive and hit the overdrive button. If the lamp lights you know the electrics are good but from the wiring diagram, it appears that you have to be above a certain speed to engage the overdrive.

If the lamp lights, i would suggest removing the solenoid, cleaning the plunger so it moves in and out easily, cleaning the terminals on the solenoid with a small rotary wire brush and then bench test it using a battery to provide the power, +12V to the main terminal, 0V to the solenoid body or earth terminal. If it's simply a matter of dirty terminals you should have it working by now. Refit (and as you've already tested the electrics above) the overdrive should work.

Also check the oil level in the gearbox and top (or maybe even change) the oil as needed.

Originally Posted by 360beast

If you decide to keep the m46 and fix it then I have an m46 in the for sale section, I doubt it will sell so if it is any use to you you can have it and canabilise bits off it. I'm heading over your way 14th June so if you wanted it and Dave is happy to have a gearbox at his then maybe you could collect it from his place in Lakenheath?

I don't mind Luke but he's in Yeovil so he's probably closer to you than he is to me.

[knuckledragger]

Originally Posted by 360beast

If you decide to keep the m46 and fix it then I have an m46 in the for sale section, I doubt it will sell so if it is any use to you you can have it and canabilise bits off it. I'm heading over your way 14th June so if you wanted it and Dave is happy to have a gearbox at his then maybe you could collect it from his place in Lakenheath?

Thanks for the kind offer. I saw your advert, but with my box having an inoperative overdrive too, I wouldn't be improving much by swapping it for yours.

As for the fuse, I have had a quick look at wiring diagrams and am I correct in saying its fuse 12, which is also the reverse light fuse? As I understand it, with the ignition on I need to check for 12v to 15 terminal, and if ok there then 12v to the hot side of the switch?

[knuckledragger]

Oopps double post, sorry

[knuckledragger]

The light doesn't come on at all; never seen it on