Convert a Model A rear to open drive?

I've searched the archives and I think I understand the jist of a Banjo open drive conversion. Is there any reason why a Model A Banjo rear can't be converted. The A version is weaker they say. Is it lack of pinion support? I have a Model a rearend. Wondered if it would be worth messing-with for a B Banger-T5 combo, in a light '27 T modified.

 

I am doing a later banjo conversion right now..........mine is similar to Smokeys but kinda different and simple
I know the A banjo is different, havent looked into the details, will have an A Banjo here in the shop this weekend however............

 

Thanks for the quick response Tman. I have to admit, I thought Smokey's post was a bit hard to read. I think if had the parts in hand, it would make more sense. If you get a chance to look that a Banjo over, that would be great.

 

I will when I get it unloaded this weekend

 

Ihave a '29 A with a T-5 and B banger, and the drive is converted to open. I didn't do it, I bought it that way, iit was done in Southern Oregon, I think Rogue River area. It's an awesome combo - drives very nicely, and can out drive the mechanicla brakes with ease! I can try and run downt he place it was done if you want, The car was pretty well done when I got it, other than adding 16 inch bent spoke Kelseys and 5.50's/7.50's.

 

Sounds like HotRodWorks from Nampa Idaho.......they do good work and are on the HAMB. Many of us like to do it ourselves though. For the open drive conversion, I have $45 in parts and an hour of lathe time. the Conversions for later Banjos are $300 and a few bucks more for the As

 

Been searching archives without a definitive answer... Has anyone here ever done a home brew solution on converting a Model A banjo to open drive? Cutting down and using the original drive shaft/pinion?

 

Yes, there is a great thread today

 

http://www.jalopyjournal.com/forum/showthread.php?t=519343

 

thats not a model a rear axle. a model a axle has a one piece drive shaft. to make it work you would have to cut the drive shaft and drill a hole and possible weld/pin on the yoke. tk

 

The method is the same. Click on my thread linked into the other thread. I used off the shelf parts that would work with A or v8. All you are looking to do is mate a yoke to the rear splined, smooth same diff. whether you bolt/pin a splined yoke on or a smooth one.

 

Isn't the biggest problem (i.e. weakest link) with the Model A one, that there is no second bearing to support the pinion at the back, as there is on later banjo axles? At the front the conversion adds a seal, but no additional support.

 

Exactly, Is it possible to press fit a yoke over the smooth cut-down drive shaft and then drill and pin it? The shaft is only about 1" diameter, what size pin would you use? Maybe need two smaller ones? I'm sure the pin would have to be hardened. Would using a grade 8 bolt and nut (or two smaller ones) throw it out of balance enough to mess it up? Just looking for someone who has tested the waters using the A shaft.

 

Just as easy to add another bearing when you add the seal

Hot Rod Works bolts theirs on. I would do the same and add a keyway if I felt it needed more support.

 

can you bolt in a later center section?

 

Looks to me that their pinion shaft is splined for the yoke and I'm guessing the bolt/washer/lock washer to the right of the yoke threads in to the end of the pinio shaft to hold the yoke on. Looks like the use a whole new pinion shaft and not the original A shaft cut down. I'm still leaning towards your idea but it would be nice to know if someone has already had sucess going that route. I also like the idea of adding a bearing on the adapter for the upper end of the pinion shaft, I hadn't thought about that.

 

^^^^^^^^^^^^^I meant their v8 one is bolted. Never actually looked hard at their A conversion

 

This one?
Isn't the inside of that yoke splined to match the pinion shaft?

On an A there are no splines so all the torque would be on the bolt/cross shaft pin.

 

Yes.

 

I took the pinion out and welded a flange I made onto the pinion. I used the outer torque tube and welded a plate onto it. I turned a recess in it to take a seal. It has been on the car all year and has been driven e few thousand miles and it seems ok so far.

 

I know, thats why I mentioned a keyway.

 

Look at the other thread I linked from today. Similar to yours!

Deosn't anybody read these threads and follow the links anymore?

 

Here ya go...

 

Is that a Model A shaft cut down? If so did you key the shaft like Tman suggested or just put in the cross shaft? It looks like the hotrodworks V8 conversion kit to me. If that is home made it was done extremely well.

 

Sure, I've looked at a bunch of open drive conversion threads but they've all been on later splined pinion shafts, not on the Model A.

I might end up going with the keyed shaft but it would be easier if I could just use a cross shaft. I've found a should screw in the Grainger catalog that has a 84,000 psi shear rating but I can't remember my physics well enough to figure how much torque that would stand up to. I'll have to dig out some books and brush up to see if it will handle the power.

 

if youre worried about power blowing stuff up just get another rear end! model As are weak i hear. get a later banjo and put top spring mounts on it. then adapt that to open drive (or use a 46-48 truck rear)

 

I was referring to others.

 

i was just saying if you are going to do a "home brew" set up then the one piece drive shaft from a model a would have to be modified to work differently than its 32 and up counterparts. tk

 

Yes, thats what our discussion is about! Glad you are up to speed, now we can move on!

 

FYI people DO read links, unfortunately the link you posted was for a later banjo axle and NOT a model a one and the original question on this thread was regarding a Model A axle

If you did the conversion as you said with a key and a bolt then you would be relying on a single key to drive the car - not a good idea. The hubs in the end of the Model A axle also have keys, but it relies more on the taper fit of the hub to drive the car rather than just the key. My set up has been welded and pinned and it works fine.