Can anyone out there tell me,
What the OD of the rear spring shackle is on a 1923- 1927 Model T? I am finding used spring shackles at swap meets, and cannot tell how much wear is on them.
I don't have the data in front of me but I think it's 9/16". Look for wear on opposing sides that make it oval shape. That's the quickest way to tell. If you a small caliper, just rotate the caliper around the shaft. Worn shafts will be oval shaped.
That should read "If you HAVE a small caliper". Sorry.
9/16" it is Ken.
Allan from down under.
Thanks Allan. I have the specs out in the shop. I rebuild them. I should have it committed to memory but there's not enough room.
KEN --- Macs Auto specs. call to ream the shackle bushing to .587and 9/16 is .562 which leaves .025 clearance -- is Macs info correct because that a lot of slop !!! Thanks for any help --- Joe ----=email@example.com
I responded to your PM Joe.
I just went out to the shop and measured some. I got .565". Until somebody can prove otherwise, I'm calling BS on Mac's.
I just measured a NOS front and rear, and they are both 9/16. I wouldn't ever believe anything Macs says.
I'll bet that the value should have been .578 (1/64 oversize). Mac's sells drills as a cheaper (?) solution to a reamer and perhaps that's the size drill they're selling (?).
if...IF...that's the case, then for the casual driver that's a reasonable fit, particularly if the springs have any twist on the main leaf. For the work I do, I'd never use a drill where a reamer is called for, and don't, but wouldn't condemn a guy who does one in his life to using a drill. In any event, the reamer needed is either an expensive decimal reamer or an adjustable reamer (imports are cheap, but good ones are quite dear).
The bushing in the perch will definitely need adjusting (reaming or drilling), but you may well find that the one in the spring doesn't, as it won't squeeze the bushing nearly as much and it may retain it's original size (which is a sliding fit as made)
As I told Joe in a PM, these aren't precision bushings and I've never reamed them. The service manual doesn't call for reaming either. If you clean the rust/scale out of the perches and springs the bushings will press right in with a little oil (or hammer in). I use a busing installer that doesn't bugger-up the bushing from hammering.
All the weight is on one side so it's not like a spinning shaft application. If the shackle fits and it takes oil, you're good to go.
Agreed. The only thing that I would add is that (in my opinion, of course), one should try to keep the bushing sufficiently close to the shackle diameter to the extent that the oil used will stay put to some extent rather than immediately run out.
I've found that lathe way oil or chainsaw bar oil works very well in shackles that have some miles on them. If recently replaced, then 30wt is just fine.
I use brass bushings for my shackles. No sense wearing out shackles, especially when they are as nice as the ones Ken does.