The Ford Barn

Tom Walker · 04-01-2013, 12:40 PM

I come from just round the corner at the V8 place (boo hiss), but would like to ask you guys about the rear end gear. Specifically, the over-hung pinion. As you know, if you have an early '32 V8, it has a ring and pinion very like the A/B set-up, with the pinion only supported in one place.

I would like to know if you have trouble with the pinion breaking out of the axle housing, or more likely, the bearing gradually becoming loose.

The reason I ask is that I am going for a little more power on my otherwise very standard 32 Tudor, and wondered if I need to put the later V8 rear end in to avoid trouble down the line.

Thanks, Tom.

1931 flamingo · 04-01-2013, 12:48 PM

Depending on how much more power I'd think you'd be ok. If you're going to swap to a later r/end be careful of spring/placement.
Paul in CT

Tom Endy · 04-01-2013, 01:22 PM

The V8 Rear axle assembly has an additional pinion bearing behind the pinion gear mounted in a boss in the banjo. The Model A does not have this extra bearing.

The early Model A cars had a banjo that did not have support gussets around the flange for the pinion bearings. Sometime later, I believe in early 29 they added the support gussets. I have never seen a later banjo cracked, but I have seen the early ones cracked. Just about every 28 banjo will have four very small cracks from the four holes (two on each side) right next to the pinion flange where the axle housings bolt on. The cracks are hard to see, but they are usually there. They start at bolt hole and run to the edge, which is a nominal 1\16". I have gone ahead and used them in this condition when the owner was building a 28 show car and wanted it correct. In most other cases I recommend to the owner we switch out the banjo with one that has support gussets.

I imagine there were more severe break ups of the banjo with these eary ones when a ring & pinion failed and locked up. I have a dandy example of one that should be in a museum. It came off an early car that came up from Argentina. Someone had welded re-bar around the backside of the flange, extending it several inches onto the banjo in four places. It is a work of art and it came off a running car.

Tom Endy

MikeK · 04-01-2013, 02:11 PM

The very short 6-splined 32-34 pinion shaft would allow twisting torque deflections within the single back-to-back bearing set if there were no bearing at the front of the pinion.

The A rear pinion needed no bearing other than one double-back-to-back set because the A pinion was mounted to a very long drive shaft with no coupling near the banjo. With no moveable spline on the shaft near the banjo, the A pinion did not need the pilot bearing to control deflection.

Simply put, the second pinion torque deflection control point on a 32-34 rear is the pinion pilot bearing, the second pinion torque deflection control point on an A is the drive shaft bearing at the front of the torque tube, a much longer lever.

The design change was made to accommodate and simplify manufacturing assembly and service. There is no history of A axles (other than early '28 as explained by Tom) blowing out rear ends, even when coupled to OHV bangers that would smoke any stock EV8.

There is often an unfounded conclusion that 'the manufacturer changed the design to address a mechanical weakness'. The mid'32 Ford rear changed for other reasons.

Tom Walker · 04-01-2013, 03:46 PM

Thank you for those interesting replies.
Mike K, if I read your post correctly, the Model A pinion is simply an extension of the prop shaft? Does that mean that to change the ratio in the rear, you have to change the whole prop shaft to change the pinion ?!

George Miller · 04-01-2013, 04:20 PM

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My blue roadster with a 455 olds head did many hill climbs. Has way more power than a flathead V8. The only rear end problem was I lost the bolts out of the torque tube one time. clamped it back together with vise grips and won king of the hill. I would not worry about the real end it will take it if it is in good shape.

Tom Walker · 04-01-2013, 04:43 PM

sorry, being stupid. I see now, the pinion gear is bolted to the end of the prop shaft and presumably on a taper with key.

So the design was changed to a separate short pinion shaft during 1932. My car will have the long prop shaft.

thanks, Tom.

MikeK · 04-01-2013, 04:48 PM

Quote:

Originally Posted by Tom Walker

. . . you have to change the whole prop shaft to change the pinion ?!

Yes. The end of the prop shaft is tapered with a keyway and the gear is locked on with a nut. A real bummer, huh?

04-01-2013, 12:40 PM	#1
Tom Walker Senior Member Join Date: Aug 2012 Location: Leicester. UK Posts: 404	pinion support I come from just round the corner at the V8 place (boo hiss), but would like to ask you guys about the rear end gear. Specifically, the over-hung pinion. As you know, if you have an early '32 V8, it has a ring and pinion very like the A/B set-up, with the pinion only supported in one place. I would like to know if you have trouble with the pinion breaking out of the axle housing, or more likely, the bearing gradually becoming loose. The reason I ask is that I am going for a little more power on my otherwise very standard 32 Tudor, and wondered if I need to put the later V8 rear end in to avoid trouble down the line. Thanks, Tom.

04-01-2013, 12:48 PM	#2
1931 flamingo Senior Member Join Date: May 2010 Location: new britain,ct 06052 Posts: 9,390	Re: pinion support Depending on how much more power I'd think you'd be ok. If you're going to swap to a later r/end be careful of spring/placement. Paul in CT

04-01-2013, 01:22 PM	#3
Tom Endy Senior Member Join Date: May 2010 Location: Southern California Posts: 3,131	Re: pinion support The V8 Rear axle assembly has an additional pinion bearing behind the pinion gear mounted in a boss in the banjo. The Model A does not have this extra bearing. The early Model A cars had a banjo that did not have support gussets around the flange for the pinion bearings. Sometime later, I believe in early 29 they added the support gussets. I have never seen a later banjo cracked, but I have seen the early ones cracked. Just about every 28 banjo will have four very small cracks from the four holes (two on each side) right next to the pinion flange where the axle housings bolt on. The cracks are hard to see, but they are usually there. They start at bolt hole and run to the edge, which is a nominal 1\16". I have gone ahead and used them in this condition when the owner was building a 28 show car and wanted it correct. In most other cases I recommend to the owner we switch out the banjo with one that has support gussets. I imagine there were more severe break ups of the banjo with these eary ones when a ring & pinion failed and locked up. I have a dandy example of one that should be in a museum. It came off an early car that came up from Argentina. Someone had welded re-bar around the backside of the flange, extending it several inches onto the banjo in four places. It is a work of art and it came off a running car. Tom Endy

04-01-2013, 02:11 PM	#4
MikeK Senior Member Join Date: May 2010 Location: Windy City Posts: 2,919	Re: pinion support The very short 6-splined 32-34 pinion shaft would allow twisting torque deflections within the single back-to-back bearing set if there were no bearing at the front of the pinion. The A rear pinion needed no bearing other than one double-back-to-back set because the A pinion was mounted to a very long drive shaft with no coupling near the banjo. With no moveable spline on the shaft near the banjo, the A pinion did not need the pilot bearing to control deflection. Simply put, the second pinion torque deflection control point on a 32-34 rear is the pinion pilot bearing, the second pinion torque deflection control point on an A is the drive shaft bearing at the front of the torque tube, a much longer lever. The design change was made to accommodate and simplify manufacturing assembly and service. There is no history of A axles (other than early '28 as explained by Tom) blowing out rear ends, even when coupled to OHV bangers that would smoke any stock EV8. There is often an unfounded conclusion that 'the manufacturer changed the design to address a mechanical weakness'. The mid'32 Ford rear changed for other reasons.

04-01-2013, 03:46 PM	#5
Tom Walker Senior Member Join Date: Aug 2012 Location: Leicester. UK Posts: 404	Re: pinion support Thank you for those interesting replies. Mike K, if I read your post correctly, the Model A pinion is simply an extension of the prop shaft? Does that mean that to change the ratio in the rear, you have to change the whole prop shaft to change the pinion ?! Last edited by Tom Walker; 04-01-2013 at 03:47 PM. Reason: Spelling

04-01-2013, 04:20 PM	#6
George Miller Senior Member Join Date: May 2010 Location: NC Posts: 2,975	Re: pinion support Sponsored Links (Register now to hide all advertisements) My blue roadster with a 455 olds head did many hill climbs. Has way more power than a flathead V8. The only rear end problem was I lost the bolts out of the torque tube one time. clamped it back together with vise grips and won king of the hill. I would not worry about the real end it will take it if it is in good shape.

04-01-2013, 04:43 PM	#7
Tom Walker Senior Member Join Date: Aug 2012 Location: Leicester. UK Posts: 404	Re: pinion support sorry, being stupid. I see now, the pinion gear is bolted to the end of the prop shaft and presumably on a taper with key. So the design was changed to a separate short pinion shaft during 1932. My car will have the long prop shaft. thanks, Tom.