Change an M45 to an M47

[CaptainAhab]

Has anyone done this? I could use the following pointers;

Are the bell housings interchangable?
Can I change the box without removing the bell housing?
I'll need a new portion of prop shaft and the gear stick, anything else need changed?

Would appreciate any help.

Cap

[Clifford Pope]

It's quite straightforwards and pretty obvious, as long as your car is the later kind that has the speedo pick-up on the back axle not on th gearbox.

The bell housing is the same, just treat it as part of the gearbox, and bolt it on.

As you say, you will need the prop shaft, as I think all (?) M47s use the rubber front joint, and all (?) M45s use the traditional H/S joint.

I can't remember whether you need to move the gearbox cross member to its alternative position - that may only be a M46 feature.

Watch out when releasing the clutch slave cylinder from the bell housing. It may slide out easily, but I have had two stubborn ones. On one I broke the bell housing by using too much force, on the second I had to cut the cylinder into pieces and carefully chisel each segment free - it seemed to have welded itself into the hole.

Depending on which model you have you may find the gearing very high, as I think the axle ratio often reflected the gearbox.
I know that putting a M47 into a 1989 DL four-speed produced a top-gear ratio of about 30mph per 1000 revs. Fantastic for cruising, but 2nd gear lost its low-speed flexibility for crawling along.

[mylittletony]

I have had this done, but using a donor car (as you know!)

The safest way is to get the box, cross-member and complete prop as a package, then there should be no compatibility issues. I can't comment on joint types, but the front section at least is different due to the boxes being different lengths. Hence easiest to get the whole caboodle.

Mine needed a new slave cylinder in the end, so may be worth factoring this in at the start. Also a new clutch while it's apart is sensible!

The ratios should be ok, the 5th (or OD on M46) is in addition to the original 4 gears. i.e. 1-4 have the same ratio whichever box you get (there are some short 1st gears as the exception to the rule)

As Clifford also says, the speedo pickup is important:- rear axle sensor was introduced in '85. There are ways around this (obviously including an axle with a sensor), 81-85 you can swap instrument clusters and pre 81 you can build a hybrid cluster but it's quite involved, I'll create a thread once I've finished mine.

[heckflosse]

Four speed 230KH usually has the tall 3.3 diff.
Five speed is often a 3.5 on 230E s etc.
2 litre ones are usually a 3.9
3.7 is rarer- some automatics?
there was a 4.1 listed but no idea about them-possibly some obscure B19 LHD thing?

tall gearing plus good torque is the way to go, unless you live in Snowdonia.

[CaptainAhab]

Thanks lads, the speedo sender is in the diff so no worries there.

If the bell housings match that's fine, I'll just do a straight swap. From the list in Haynes the M47 1st gear is 4.03 verses the 3.71 in the M45, 2nd, 3rd and 4th are the same, so a bit more pick up off the line!

I am getting the box, housing and the prop shaft (need the whole one as they are balanced as a unit) from Phil127, maybe I should ask for the crossmember as well? Didn't know they varied (or that there was an alternate postion).

I was contemplating a new clutch and throw out when I was in there. the bearing is no bother, does anyone know a good supplier for the clutch?

Thanks again lads.

[Clifford Pope]

You don't need a new cross member, they are all the same (or differences if any don't matter). The only possible point is that there is an alternative position on the chassis to accommodate different gearbox length. I'm not sure it's even needed on this swap, but if it is the tapped holes are already there.

The gearbox ratios may all be the same, my point and heckflosse's was that the axle ratios varied. I think the point was that when the 2.3 engine only had a 4-speed gearbox, they fitted a higher (or lower, which ever way it is, if you see what I mean?) ratio at the back to give a more relaxed cruising speed.
So if you have one of those axles, as I had, then in 5th gear you will be getting a kind of double-overdrive effect. Nice, but you pay for it at the bottom end.

Definitely get a new clutch, and a new release bearing. Look very carefully at the release lever for incipient cracking.

If the clutch slave cylinder is loose, then you can simply release the circlip and hang it up out of the way - no need to disconnect or bleed.
But if it's stuck and you have to chose, sacrifice the cylinder not the bell housing

Just another thought - take care with the crank position sensor and its cable.
Remove it first before dragging the wires.
Some cars had a different mounting, and bolted to the engine block not the bell housing. There is a cut-away at the top of the bell housing and the sensor stays on the engine.
I'm not sure what would happen if you wanted to fit a later sensor type gearbox to an earlier type one. Somewhere I think I've read about having to cut out a notch for it.

[heckflosse]

All the bell housings I have seen have the shape of the cut out precast in.
If you need to use a TDC sensor, just cut to the line.
230K sensors are more sturdy than the LH type but be careful.
Clutches can vary in diameter- get the right one!

[CaptainAhab]

Good info again lads, thanks.

I had trouble with my clutch a while ago and when poking about found that the slave looked fairly new, so I live in hope there!

I have been talkind to TJ Stones about the swap, he reckons a possible problem might exist with the postion of the bearing mounting half way down the propshaft. It seems a bit odd to me that Volvo would change tooling for something like that given that the rear sections are all the same, but I will wait for him to come back to me.

I've been trying to get a clutch kit off ebay, but a lot of listings are specifying for year and engine size rather than using the gearbox code. I think getting the M47 clutch part number would be the best way to go.

Thanks again.

[Clifford Pope]

I am reasonably sure that the type of clutch depends on the flywheel, not the gearbox.
I have done two trans-gearbox swaps:
M45 to M47 - B230K 1989 DL.
M47 to M46 - B200K 1992 Torslanda.

In each case I just replaced the old clutch like for like. Each gearbox fitted fine.

(The only exception, which I have had experience of, is if fitting a later gearbox to a very early car which had the smaller number of splines on the gearbox input shaft, therefore needed a later clutch plate to match the new gearbox)


Further thought: I do know that release levers vary - there are two kinds, not sure if interchangeable. So it might mean getting a clutch kit for the engine, but a release lever plus thrust bearing for the gearbox ?
I've no experience of actually replacing those - I just used the ones already on each new gearbox.

[heckflosse]

The prop centre bearing is always the same.
It is the length of the front shaft that varies.
If it all comes from a donor car you won't have much bother.
Sometimes there are two aluminium plate washers that go between the chassis and gearbox x member.
I think these are for earlier cars, but am not certain.
Really not a big deal. A 200 clutch is a relatively pleasant job (try an 850!)