Yes I know this is a crazy plan and that I should "run away" screaming in the opposite direction.
I am looking at rebuilding an early small drum ruckstell to large drum.
Our '27 coupe is heavy and slow and has a tough time navigating the hills that seem to be everywhere in town. Thus it doesn't get driven like it deserves.
What I know is that the rivets are not in the same place so the existing housing holes will need to be brazed and new holes made.
I am not really worried about the riveting process.
My biggest concern is that when I heat and press on the housing ends that the overall length is exactly the same as the original and of course that the shackle ends are precisely at the right position.
My thinking is that I will weld a metal "jig" that is precisely the right length from the original ruckstell to use as I put the new ends on to assure I press them on exactly far enough.
Is this a logical approach or do you have a better idea? Do you have a better one?
Many years ago I was faced with the same challenge. Fortunately I had access to a large lathe. I chucked both housings (one at a time of course) and cut them off and trued the bores to the same diameter inside. Then machined a sleeve to fit snugly inside and then once I bolted the left side to the right side and attached the radius rods I was satisfied that I had it reasonably lined up, just welded it. It is still running just fine after 40 years
Are you sure the engine is operating efficiently? Plugs, coils, timer all clean and in good shape?
Enough gas for adequate power?
I don't understand why you want to convert a small drum to a large drum? Both will work in a 27 and both, if original, have the same gear ratio.
If you have a small drum Ruckstell, you can convert the right side by installing an axle tube with backing plate to the right side. No changes would be needed for the right side. And The left side can remove the rivets from the Ruckstell side and cut and drill the large drum axle and rivet it to the Ruckstell. You will need to measure exactly the distance from the inside bearing to the outside bearing and make it the same length. This must be done to the thousandth of an inch.
Another thing which would be easier, if you don't care if it is completely stock, would be to install the small drum Ruckstell in the car and if you have wire wheels, you can use adaptor plates to fit the wire wheels to the small drum hubs.
I can certainly understand why you want a Ruckstell living in Casper Wyoming. High altitude robs the power and lots of hills to contend with and everything is probably 50 miles away (and throw in some significant wind). I live in similar conditions so I totally understand
I cut the axle tube on the small drum Ruckstell and made a matching cut on the axle on a large drum axle tube, beveled both tubes and welded the two halves back together. I built a fixture to position the parts for welding. If I were to do another one, I would build an internal sleeve to span the joint.
You could do like Ted said above, but using the way modern rear axles are narrowed for race cars. They use a centerless ground shaft (1.5" diameter I believe) and "pucks" or sleeves that slide over the bar at each end and the outside diameter matches the inside of the axle ends. This keeps it all in line and holds it all together for welding.
David. Is your goal to achieve better braking by having a large drum rear? If so, another approach to consider would be to install a disc brake setup on your small drum Rux. They look a lot better on a small drum than they do on the large drum rears.
David: PM sent check your email. Dan.
David, you might find someone who needs a small housing that would trade you. Having suggested that, I have converted a small to large by re-riveting a large backing plate end to a small tube. The shackle position is aligned with the radius rod and the end distance measured with a tape measure. Probably gets it within 1/16th of an inch, or better, which is close enough. I bucked the rivets by driving a tapered spud into the housing to back the rivet heads on the inside. This rear end has been in service in my car for 20 years and works perfectly and it is virtually impossible to tell that it has been converted.
Why not just buy 26-7 housings, and transfer the internal parts? Much easier.