From what I can see there was no bushing used in the early Ruckstell Hall-Scott small drum backing plate. I can measure external diameter of a bushing but want to have the hole size correct for fit. What is the correct hole size in the backing plate?
I had the same problem and just took a die grinder and bit and ground the hole large enough to tap the bushing in. I put the bushing on the cam and used the cam to tap it in.
You are correct on the Hall Scott backing plates. I reamed mine out for a standard Ford bushing. If you have a later Eaton made housing, you won't have that problem. They bought their backing plates from Ford! BTW, the Ruckstell repair book completely overlooked this item.
Ford parts variations are endless. You can't cover them all in one book and the brake cam bushing has nothing to do with the Ruckstell. That is why it is not in the book.
I disagree. Ruckstell made the LH housing, and they made the backing plate too, so it should have been in the book since Hall Scott made it! I can't imagine rebuilding a Ruckstell rear end, and leaving the brake cam sloppy.
Anyone with any sense would re-bush the hole Larry but it has nothing to do with rebuilding the Ruckstell. If it bothers you I will include it in the next reprint along with welding and re-drilling the oblong shaped rear perch hanger holes.
Still does not answer my question of what is the correct size for the hole.
The hole is 0.004" lager than a new cam pin.
Never mind, I'll figure it out myself.
Measure a new or NOS brake cam bushing and add the approximate .0015-.0002 or what ever the appropriate "press fit" should be. If you don't have the bushing, I can go out in the shop in a bit and measure one for you.
I have a bushing. Thanks, I will try those clearances and see how that works. Gives me a place to start.
Mark -- I have some NOS Ford script brake cams in stock, and I measured them with a micrometer today. The shaft on those is 3 thou under a half-inch. (I don't have any repro's to measure.)
I'd say you could use a spindle reamer to ream the bushings and it would be about right. You can get 1/2-inch ID bushings of various OD's at any bearing store, and drill the backing plate to fit whatever size bushing you get.