MTFCA Forum

Iam trying to confirm that the 26-brake drum had only one bushing and not two.
I remember reading it somewhere before but can't find it again and all the diagram pictures I find have the early brake drums.
any guidance is appreciated.
Bryant

See "March 17"

http://www.mtfca.com/encyclo/doc25.htm

Thanks Scott, that’s the proof I need. I always seem to forget about the encyclopedia.
Bryant

There is another extensive article in the Service Bulletins stating how to "index" the driving plate to the brake drum when reaming and a special double reamer that was put out by Ford.

RajoRacer wrote: ↑

Sun Jan 22, 2023 8:25 pm

There is another extensive article in the Service Bulletins stating how to "index" the driving plate to the brake drum when reaming and a special double reamer that was put out by Ford.

Thanks I will check that out.
I’ve been a fan of the Model T tips videos
They have some good videos on the alignment processes.
Bryant

While the drum may have only had 1 from the factory, 2 will give better support.

Mark Gregush wrote: ↑

Sun Jan 22, 2023 9:55 pm

While the drum may have only had 1 from the factory, 2 will give better support.

I was pondering that myself. I wonder the reason for them removing it.
Bryant

Saving time & money! I do use 2 in any rebuild. Just asking where exactly would you locate the one bushing? I guess at the top of the brake drum shaft close to the clutch basket?

No, at the fly wheel end, the drive plate bush carries the other end.

The Service Bulletin about this explains the why.

Has anyone come up with a reproduction of the reamer?
Would be quite helpful for setting the drum and drive plate up so everything runs true

Cheers
Glen

The best way to explain is to watch the model t tips videos on brake drum and drive plate alignment. No reamer necessary. Apparently they had reamed in the past but have built many transmissions and refined the processes to boring and finishing with Timesaver. Good videos. Someone here might know how to post the link.
Bryant

Bryant wrote: ↑

Sun Jan 22, 2023 11:15 pm

Mark Gregush wrote: ↑

Sun Jan 22, 2023 9:55 pm

While the drum may have only had 1 from the factory, 2 will give better support.

I was pondering that myself. I wonder the reason for them removing it.
Bryant

To save a penny or 2 on each unit.
I have seen quite a few with only one bushing. The smaller drive plate bushing takes all that rear load. They are usually very/excessively worn. I ALWAYS put in that second bushing. I see no advantage to leaving it out. I dont ream the bushings, I bore them for precise alignment & fit. Everything fits properly with no misalignment bind.

John

I, too, have bored and fit them. But really, 3 bushings spread across 2 semi-precise parts creating a 3-bushing assembly is not a really great design. I don't think they saved 2 cents on a bushing, I think they saved 50 cents in farting around and making sure the 3 were all in a line. I don't know your exact method, but mine takes time, time, time.

Since it took so long for them to adopt this change, I would not be surprised if this was not something in common practice in repair shops which gravitated back to the factory.

You have a bushing in the driving plate, so you don't really need the extra bushing in the brake drum.

Scott_Conger wrote: ↑

Mon Jan 23, 2023 9:50 am

John

I, too, have bored and fit them. But really, 3 bushings spread across 2 semi-precise parts creating a 3-bushing assembly is not a really great design. I don't think they saved 2 cents on a bushing, I think they saved 50 cents in farting around and making sure the 3 were all in a line. I don't know your exact method, but mine takes time, time, time.

Since it took so long for them to adopt this change, I would not be surprised if this was not something in common practice in repair shops which gravitated back to the factory.

Scott, I use a long boring bar on a lathe. All the drive plate mating surfaces get a clean up cut. Drums typically have some warp & run out.
The drive plate bushing is also bored & mating surfaces cleaned with a minimum cut. As a check, the drum goes on the transmission center shaft with the output plate bolted together. There is no extra rotational friction. That confirms the 3 bushings are all aligned. The procedure doesnt seem to take any extra time since I not using reamers & its optimal for bushing fit & finish. I doubt this operation could create close enough alignment to not have added rotational friction or lock up with reamers following the slightly off center nature of bushings. Yes, you have to be right on to get 3 bushings in 2 different mating parts to align. I rather prefer the extra support of the 3rd bushing.
I would think Ford had their machine processes down where everything assembled reasonably close. There may have been less than perfect alignment, but it would have been "good enough" for a model T. Run in would have "fixed" things.