How to convert BN1 to later transmission

[BoyRacer]

My understanding has always been that to hook up one of the later 100-6 or 3000 transmissions to a BN1 you had to have a BN2 bellhousing , casting # 1B 3704. I just saw a 100-4 that has a later transmission but the bellhousing looks different than the 1B 3704 casting. Is there another bellhousing that will also work?

 

[Healeysince59]

The main issue is the clutch mechanism - mechanical on the 100, hydraulic on the 100-6 and 3000. I'm sure you could come up with an adapter plate to bolt a 100 block to a 100-6 or 3000 bell housing. I was told once that a 100-6 is easy but I don't know what (if any) the difference is for the 3000. In either case, you would have to rig a hydraulic master cylinder.

At one time, David Nock was selling a repro BN2 bell housing. I'm too lazy to see if they still list it. It was a little pricey but probably less and a lot easier than adapting a 6 cyl bell housing.

Marv J

 

[BoyRacer]

Marv,
Thanks for pointing out that mechanical linkage thing. It turns out that that 100-4 I saw .....the owner had changed the clutch linkage over to incorporate a hydraulic master cylinder, so that explains the later bellhousing. BTW, the bellhousings are the same for the 100-6 and all 3000s. So, it appears that any 3000 transmission can be directly bolted up to the 4 cylinder engine as long as you add a hydraulic master cylinder to the clutch linkage. Anyone else out there done this?

 

[John Turney]

Are you sure on the bell housings for the 100-6 and all 3000 are the same? If I had to guess, the one for side shift and center shift would be different. But looking at the Moss listings on-line, the 100-6 is different that the 3000 because the 3000 has a front seal. They also list the one for BJ8 as different.

 

[Keith_M]

The BN4 and BN6 used a smaller diameter clutch than the BT7's, BN7's and later cars. If you put an earlier transmission on a later engine (without swapping the flywheel and clutch), the clutch will hit the bell housing. You CAN however, use a later model bell housing on the older case, and it will all bolt up fine. All this I know from personal experience.

I think it will be OK to use the later transmission on the earlier engine. The bolt pattern to the engine should be identical.

Keith