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Installing the drivetrain in my 1937 R12

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broughit
Posts: 2
Joined: Tue Jan 30, 2018 9:28 pm

Installing the drivetrain in my 1937 R12

Post by broughit »

Hi all,
I'm in the process of doing the final assembly on my R12.
I have the engine and gearbox installed and bolted in the frame.
Please forgive my ignorance, as I purchased it as a rolling basket case.
How do I get the diff in? The driveshaft obviously doesn't allow clearance.
Do I remove the shaft and install it as a last step?
Puzzled in CA.

cwf
Posts: 155
Joined: Sat May 15, 2021 5:52 am
Location: London, UK
Been thanked: 2 times

Re: Installing the drivetrain in my 1937 R12

Post by cwf »

Hello,

If it's like my R 35, single cylinder in a star frame, designed in the 30's, it's a bit of a struggle. I checked with a German website and they confirmed I was doing it right and, when I got it together, I found my frame is a bit bent. The drive shaft should leave the final drive and engage with the gearbox output at 90 degrees, horizontally and vertically. Mine is 2 or 3 degrees out vertically (seen from above),which is too much.

So, I fitted the Hardy disc (rubber shock absorber) and put some sort of fluid on it to help it engage with the output flange. It was then a matter of pushing and swearing, while you support the heavy final drive, until it was far enough in for the bolts to fit the frame. Some damage to the paint is likely. It's a tight fit. On mine, the centre of the gearbox mainshaft fits inside the driveshaft flange.

I've repeated the process about eight times, while I worked out that the replacement final drive housing was different and was fouling the frame. It becomes a little easier but not much.

One of those occasions when you have to sit back occasionally and think of something soothing, and then try again.

Good luck,

Charlie.
75/7+ offroad sidecar; 50/2; R 35; XR125V; XR200A; Solex; 1939 Hillman Minx DHC.

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