Swap of a Later Transmission into an Early Car

This is the story of the swap of a later transmission and front part of the propshaft into a 1967 car, to replace the broken and bent ones resulting from an exploded flexdisk/giubo.

The problems I was facing at this point included:

-shifter platform destroyed (but bent back into shape)

-front part of the propshaft bent and flange distorted

-transmission flange distorted

-mounting point for shift platform broken off the transmission

-shift rod into the transmission was also bent

I could get the original transmission to shift into four gears, but could not find reverse.

I started out by buying a second hand, later propshaft, with two universal joints and four-bolt flanges. That cost me 15 euros, and the propshaft was in fantastic condition - good central bearing, no play in the joints. I lubricated them with fresh grease, and thought I'd be good to go.

It would be rather important that the front part of the propshaft would be of the correct length, because the earlier propshaft has no universal joint but yet another giubo, the center bearing is reportedly different and no longer available (bollocks, it turns out - the dimensions are exactly the same, and the later part should just press on), and the front giubo is thinner.

These are the front parts of the shafts - later one on top, earlier one below:

As you can see, the splines are the same, and the later front part fits together perfectly with the earlier rear part.

That is crucial, because the rear part of the shaft is of a different length due to the long nose differential in the early cars, and it has a four-bolt flange as well, while the early cars have yet another giubo at the back end, with a three bolt flange.

Early rear part (note the giubo in front of the differential):

Later rear part:

Four bolt flange and UJ at the back end of the later propshaft:

Since I now had a four bolt flange at the front of the propshaft, I also needed a four bolt flange at the transmission end. Since my transmission would need work anyway after the accident, I bought a second hand one from a nice guy in Germany who had five to choose from. I picked the one which didn't leak. I could shift it manually into four gears, but couldn't find reverse ... sounds familiar ?

This is it - '72 transmission, probably a Getrag 242, came complete with clutch slave cylinder, which was a bear to remove, even after I found the second circlip.

Rear end - note the longer shift rod, this is necessary to clear the larger 8-bolt giubo.

Front end - I was worrying about the splines, but there was no indication that the clutch splines had ever changed.

Some number stamped on top of the bell housing ...

The next step was to have the friendly neighbourhood garage exchange the transmissions and clutch mechanisms.

This is what came out - nice original Getrag 232 - unfortunately damaged. Note that it still has the course splines on the output shaft. This was another reason why I could not just buy another flange - new four bolt flanges have fine splines.

Input shaft splines are identical ...

And here the number is at the back end. I couldn't find a casting date, but it should be 1967 or 1966. The car first ran on May 22nd 1967, the build date cannot be found out, as it was a CKD car assembled in Kontich. Note how the shift rod is bent and the broken off shifter platform mount.

With the new transmission, you need a new shift rod between the shifter and the shift rod at the back of the transmission. The older ones were longer, as can be seen in the pictures below. Luckily, this was included with the transmission.

Both shifter platforms, which are otherwise identical:

Older:

Newer:- yes, obviously I changed the rest of the parts over to have a shiny shifter inside the car.

Make sure to renew the shifter bushes. I've never known the car other than shifting like stirring in a very large kettle of soup, and it's been 21 years since we own it. In fact my girlfriend called me at some point to ask me where reverse was. I told her "to the left and forward" - turned out she had shifted the seat towards the front to reach the pedals, and there was so much slop in the shifter it wouldn't go into reverse with the seat that close! The two plastic bushes where the shifter connects to the shift rod disintegrate, and the rod is loose. They cost something like 2 EUR from W&N - best upgrade ever - the shifting is now tight. I tried to look for them a few years ago, but got confused by all the rings and circlips and bushes in the parts diagram, none of which seemed available. Trust me, all you need is those two tiny plastic bushes at the end of the shift rod to make your car shift like new! The location is indicated by the shiny red arrow in the picture above.

Then I bought some more new parts - apart from the bushes, I bought a new 8-hole guibo and bolts (another reason to upgrade - the old propshaft would have needed 3 6-hole giubo's at 105 EUR each - the 8 bolt giubo costs 70 EUR, and you only need one ...luckily the 6-hole one in the rear part of the old propshaft seems OK for now), a transmission support rubber, and the rubber thingies to connect the exhaust. All of those had definitively perished.

The time to reassemble came and I'm happy to report that I didn't make any mistakes that required me to undo things and start over in a different order. I started with mounting the later shifter platform onto the later transmission. This is almost impossible with the transmission in the car, while the older shifter platform can be mounted and dismounted at liberty. However, it can be done, if you rotate the shifter 180 degrees, and then you can just get it through the hole in the bottom of the car while moving the shifter platform past the (longer) shift rod from the transmission. The next step was to hook everything up and see whether the transmission shifted. That it did, like butter, also into reverse. Good!

I unbolted the transmission support beam to drop the transmission at the rear, replace the broken transmission mount and give me somewhat easier access to the flange. I started by bolting on the giubo, nuts on the transmission side.

Then I slid the front part of the propshaft into the rear part, and moved it forward until it connected with the transmission. I jacked up the rear of the car and undid the hand brake, in order to be able to rotate the propshaft and connect up the four remaining giubo bolts - again, nuts on the transmission side. I put the transmission support beam back, lowered the rear of the car, jacked up the transmission and using a bit uf muscle and a choice selection of swear words, bolted the support beam back in place. Then I bolted the propshaft center bearing back in place. Make sure it is above the support before bolting the transmission support back in place ...

This is what it looks like when done. Since the whole thing had fallen apart already when I started taking it to pieces further, I have no idea how far a correct propshaft front would protrude. It doesn't seem too dramatic like this though.

Finally, I changed the oil in the new transmission - always undo the filler plug first to avoid being stranded... What came out was gold in colour and smelled like hypoid oil - good. The magnetic plug had a substantial amount of metal deposits, but all fine and nothing gritty to the touch. Good so far.

I still have to discover a sensible way of filling these transmissions with oil - using a funnel and a long tube from the engine compartment somehow seems less than ideal, especially if the only way to know it's full is by it overflowing through the filler hole, coating the undersigned with a nice smelly layer of GL4 hypoid oil while trying to do the filler plug back up.

I had drilled two large holes in the exhaust downpipe to hammer out the dents caused by the propshaft, and bandaged those up with a tin can and exhaust bandage. Of course it still leaks - I have a new downpipe on the way now. I mounted back the exhaust manifold and downpipe (use copper grease on all the studs for future disassembly!). It turns out the exhaust studs were where all the oil over the right side of the engine was coming from. I put them back in with loctite, and hope that that will stop the leaking. Reassembling the exhaust manifold is a fiddly job, topped only by reassembling the downpipe, where the German engineers specifically designed the bolts so they can never be reached, let alone tightened, by a mere human.

Still, I managed to get it done, lowered the car off the stands, started the engine, shifted into gear, and went for a drive around the block, testing all gears - all good! Yay!

Still to do:

-remove steel band from giubo

-replace clutch spring, which went missing in action

-replace exhaust downpipe to get rid of throaty sound

-double check snugness of giubo nuts in a few 100 km

-replace and connect wire for back-up light

The result of all that can be seen in the two pictures below - new (correct, early) exhaust, which needs the exhaust support in a different position than the later system, steel band around giubo removed, back up light wires replaced and heat shrinked (in green) ...

... and finally the clutch spring:

And that's it - she's back on the road!

One issue remains, and that is the balancing of the propshaft. I've been mucking around with a hose clamp all the way up front, but that does not seem to be where the problem is located. I have the impression that the middle of the propshaft, where it is supported by the rubber-mounted central bearing, goes into a harmonic vibration at about 35 kph, in a very narrow speed range. It is probably out of balance, but the question now is whether it is the front or the rear part that is out of balance , and by how much. I'm sure a competent driveshaft shop could look at it and balance it, but that means taking the whole thing back out, which I am not looking forward to. Well, at least I know how to by now!

If you made it all the way down here, congratulations - and thanks for reading!

Cris