MTFCA Forum

I will be replacing the drums in my transmission shortly and will need to re-bush them. Can someone steer me toward the appropriate reamer set for those large bushings? Getting new drums from Dave and Ben Notling and having them install my existing gears.

I used a cylinder hone on my big ones.

Worked perfectly.

Do not hand ream them. The drums should be squared up on the gear shaft in a lathe & bored. Outside surface @ the same time.This will center the hole perfectly to the drum. Optional is to bore close & finish hone. Hand reaming will follow the new bushing hole which is not going to be centered.

I would ask Dave Nolting if he would install & bore/ream the bushings for you. Since he's already installing your gears, it seems like a small addition to complete the process. I'm certain he can do it, but not certain if he offers it as a service.

I really like the idea of having Nolting install the bushings. Thanks guys.

Dave

You might want to consider finding someone who has a Dearborn Model T ford transmission drum bushing reamer. and know how to use it. The benefit is the drums are indexed to the newly installed gear pitch circle to ream the new bushings. And if you think about what is going on insdie the transmission that way makes more sense than indexing to any other surface.
Ron Patterson

The “simplicity” of the time never ceases to amaze me, Ron. Thank you for that. That is a method I was totally unaware of.

Cylender hone some cutting oil in a drill press
Slow but works well

NV Bob
Indexed to what??
Ron Patterson

I think the idea of the reaming fixture is to ensure the bore is concentric (indexed) with the pitch circle of the gear teeth and parallel to the gear axis. Neat idea plus it holds the drum assembly secure while reaming. Although quality machining will achieve this and all surfaces will run true and straight. Dave’s parts will be spot on. If it was me, and it was a couple of times, I would rather bore them in a lathe. That way everything can be checked for runout. Especially if a person was using old worn gears.

Brian

greenacres36 wrote: ↑

Mon Jan 03, 2022 7:23 am

I think the idea of the reaming fixture is to ensure the bore is concentric (indexed) with the pitch circle of the gear teeth and parallel to the gear axis. Neat idea plus it holds the drum assembly secure while reaming. Although quality machining will achieve this and all surfaces will run true and straight. Dave’s parts will be spot on. If it was me, and it was a couple of times, I would rather bore them in a lathe. That way everything can be checked for runout. Especially if a person was using old worn gears.

Brian

I believe the lath method is as perfect as possible. This fixture(never seen one before) may be second best.
The slightest bit of wear/slop is bound to skew the results. Not to say it could be good enough.

Until someone shows me the fixture for reaming OR boring the new drum bushings on a lathe while indexing the cutting tools to the gear pitch circle I am not convinced.
Can someone show me this fixture?
Ron Patterson

Ron Patterson wrote: ↑

Mon Jan 03, 2022 10:22 am

Until someone shows me the fixture for reaming OR boring the new drum bushings on a lathe while indexing the cutting tools to the gear pitch circle I am not convinced.
Can someone show me this fixture?
Ron Patterson

Very accurate 3 jaw chuck. .001 max indicated run out. All gear teeth are multiple of 3's. Remove burs from gear teeth. No fixture necessary.

Well, I decided to send the whole drum set, including the driven plate, out to Dave Nolting to install new reverse and low speed drums onto my gears. He's re-bushing everything and sending me a new main shaft.

Jim Guinn is putting wood bands onto my metal at his shop. Magnets are re-charged. Tearing apart the Ruckstell shortly. Getting a nice frame from Charlie Gagel next weekend. It's all coming together!

I wonder how Ford did it in the factory? Anyone know? besides quickly.

New assemblies should he made quite concentric. Literally, if the bushings were made correctly you should be able to indicate the face of the drum hub that is machined and the outside diameter of the drum then check the bore to be sure. Bushings of any quality should be finished on the OD and ID at the same time when manufactured. Provided the bore in the gear is round. There’s a lot of factors in that transmission that can have run out. I would imagine a couple thousands wouldn’t matter a whole bunch. All being said, if I had to choose between two, a little run out in the gear or the outside diameter of a new drum I would lean towards having the drum run true. That would affect balance the most I would say.

I suppose if a person wanted to indicate to the pitch circle of the gear it could be indicated over pins of the correct size laid into the teeth of the gear.

I’m certainly not claiming I’m the best and know it all but I’ve been machining for 34 years including four years cutting gear teeth full-time.

Not being ornery but I just checked the unused portion of a low speed gear that I have. The teeth were not cut on a hob machine. Meaning they are not generated they are single indexed which is a less accurate method of cutting gears. The cord length over several teeth varied by about .008”. I’m actually surprised at that a little bit. Either it was a lack of accuracy in machining or distortion during heat treat.
New gears are generated. An extremely accurate way of producing a consistent pitch and tooth form.

greenacres36 wrote: ↑

Mon Jan 03, 2022 11:31 am

Not being ornery but I just checked the unused portion of a low speed gear that I have. The teeth were not cut on a hob machine. Meaning they are not generated they are single indexed which is a less accurate method of cutting gears. The cord length over several teeth varied by about .008”. I’m actually surprised at that a little bit. Either it was a lack of accuracy in machining or distortion during heat treat.
New gears are generated. An extremely accurate way of producing a consistent pitch and tooth form.

Please explain how these are not generated gear teeth. Are you really suggesting that Ford cut these gears one tooth space at a time with a form cutter and not on a Barber Coleman or some similar machine?

Ron Patterson wrote: ↑

Wed Dec 29, 2021 10:11 am

Dave

You might want to consider finding someone who has a Dearborn Model T ford transmission drum bushing reamer. and know how to use it.DSCN2006.JPG The benefit is the drums are indexed to the newly installed gear pitch circle to ream the new bushings. And if you think about what is going on insdie the transmission that way makes more sense than indexing to any other surface.
Ron Patterson

Ron,

That's a wonderful looking fixture. I must say however, that in manufacturing, it's very poor practice to modify/correct the location of a bore with a reamer. Reamers are notorious for following the bore they are enlarging. How well is the reamer supported by the fixture? How close a fit is the reamer shank to the fixture? Not trying to be contrary. Wish I had one of those!

Jerry

this will answer all of your questions: http://www.mtfca.com/discus/messages/17 ... 1325030711

Scott_Conger wrote: ↑

Mon Jan 03, 2022 8:32 pm

Jerry

this will answer all of your questions: http://www.mtfca.com/discus/messages/17 ... 1325030711

It did!!

Yup, that's a great fixture and those reamers should indeed recenter the bore. Not your garden variety reamers to be sure!

Thanks!

It appears by the tooling marks and the inconsistency among the teeth I believe they were not hobbed. It appears they may have been indeed cut with a form cutter. That sounds crude and inefficient but that is what I am seeing on the low speed gear that I have. Typically what I have seen in the past with gears that were cut with a gear hobb there tends to be a chiseled or shimmering appearance on the flanks of the gear teeth. The teeth that I am looking at on my gear have linear marks or tears which indicates to me they were cut with a form cutter. However in efficient that seems to be.