M40 to M42

Post Tue May 28, 2013 10:33 am

Right guys, I now have the following parts ready for my swap:

Engine (E30)
Loom
ECU
Mounting arms and Mounts
Full exhaust

is there anything else M42 specific I need before I get started?

Post Tue May 28, 2013 11:28 am

coil pack and mounting arms if you can get them off a scrap 318iS - if not cable ties will do

pretty sure you need the M42 gearbox and

maybe a prop and radiator also. - worth checking

Post Tue May 28, 2013 11:41 am

got the coil pack and a lad who's handy with a welder for a bracket!

Post Tue May 28, 2013 11:42 am

reading on here the m40 Box and prop will be fine, are the clutches different between the models? think I may as well change that while the engines out!

which gaskets would be best changed while the engines out?

Post Tue May 28, 2013 12:30 pm

Post Tue May 28, 2013 1:20 pm

Rad will be fine but you might need the m42 top hose? m40 gearbox and prop combo is fine. Clutches are the same too. I'm only in Banbury if you need a hand gimmi a shout

Post Tue May 28, 2013 1:43 pm

TPS wrote:AFM?

Same, as long as it's from a 1.8 M40, and has a CO adjustment pot.

Post Tue May 28, 2013 2:16 pm

"1.8 M40, and has a CO adjustment pot. "

I had a late M40 with a 1.8 - it was a K reg cab - and it didn't have have a CO pot - was this because it had a lamda sensor ?

Post Tue May 28, 2013 2:47 pm

I was under the impression that the AFMs were the same, I've got one with the M42 anyway.

So I'll definitely need the top hose, if I'm going to use the M40 rad. I'm sure i did read somewhere, that the accelerator cables are different? I don't want to find myself screwing over one part to get finished

Post Tue May 28, 2013 7:10 pm

jimbom30cab wrote:"1.8 M40, and has a CO adjustment pot. "

I had a late M40 with a 1.8 - it was a K reg cab - and it didn't have have a CO pot - was this because it had a lamda sensor ?

Yes. With later cars, when all were supplied with cats. etc, the CO pot. on the AFM was superfluous, so an AFM was introduced without it.

Post Sat Jun 01, 2013 12:05 pm

baggimodo wrote:I was under the impression that the AFMs were the same, I've got one with the M42 anyway.

So I'll definitely need the top hose, if I'm going to use the M40 rad. I'm sure i did read somewhere, that the accelerator cables are different? I don't want to find myself screwing over one part to get finished

Yes to the M42 top hose, you cant get away with the M40 item (I tried when I did my M40 to M42).

I used the original throttle cable but had to modify it a bit, so an M42 cable would be better to have.

The other thing to check (or get in case) is a new spigot bearing to suit the M40 gearbox. My M42 lump had the smaller diameter bearing fitted and I couldn't get the M40 box on until I changed it.

Post Sun Jun 02, 2013 12:29 pm

Gizmo, that's brilliant thank you.

Hadnt considered the spigot bearing, so will grab one as well as a throttle cable.

Where did you buy your rad hose from?

Post Sun Jun 02, 2013 1:35 pm

Check the bore of what you have. Spigot bearing only needs changing if it's the wrong one.

Post Sun Jun 02, 2013 2:59 pm

Stupid question, but when people say spigot bearing, is that the bearing that sits in the end if the crank (also known as a pilot bearing)?
No.5 in the link....
http://bmwfans.info/parts/catalog/E30/2 ... _flywheel/

Post Sun Jun 02, 2013 8:22 pm

jmc330i wrote:Stupid question, but when people say spigot bearing, is that the bearing that sits in the end if the crank (also known as a pilot bearing)?
No.5 in the link....
http://bmwfans.info/parts/catalog/E30/2 ... _flywheel/

Yes. In the absence of a suitably sized internal bearing puller, remove it, if you have to, by packing the area behind the bearing with grease, making sure you don't trap any air, then find a piece of steel rod/bolt that's a tight sliding fit through the centre of the bearing, hold it in place and belt it with a large hammer. The rod will act like a small piston, the bearing like a larger one, the grease like hydraulic fluid, and the bearing will move outwards.

Post Sun Jun 02, 2013 9:05 pm

Cool, I thought that's what it was, but people call them different things.

I think the change over between the two bearings was Sept 90, so before that its the smaller and after its the larger. That applies to both the M40 and M42.

That's what I'm hoping anyway as I will be using an 89 M40 box on an engine with the larger bearing, so I've got a smaller one waiting to go on - good tip on removing it Brian