High speed rear axle

AA Ford Discussion Group relating to the repair and restoration of your AA Ford.
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Rumbler
Posts: 64
Joined: May 21st, 2017, 4:27 pm
Body Type: 82-A Closed Cab
Model Year: 1928
Location: Illinois

High speed rear axle

Post by Rumbler » January 14th, 2019, 11:36 am

Hello Bud-
My April28 truck has no high/low speed markings that I can find on the rear axle, so I believe this indicates an early high speed. I hope to be taking it apart soon to verify.

Brian
Last edited by Rumbler on January 21st, 2019, 5:25 pm, edited 1 time in total.

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1crosscut
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Joined: December 25th, 2010, 7:22 pm
Body Type: 82-A
Model Year: 1929
Location: Lincoln, NE

Re: high speed rear ends

Post by 1crosscut » January 14th, 2019, 4:08 pm

Brian, you can jack up one rear wheel, put it in third gear and using the hand crank turn the engine over by hand. Count the number of rotations of the engine needed to make the wheel in the air go one full revolution. Just a little over 3 1/2 turns of the engine to one wheel rotation is good news. Any more turns than that and you got yourself a low speed rear end.
If the rear end is out of the truck just grip the end of the driveshaft with a vice grip and turn it that way. One wheel needs to be held stationary for this to work. If your rear end turns out to be a high speed it would still be a good idea to open it up to make sure all is well.
------------
Dave

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Rumbler
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Joined: May 21st, 2017, 4:27 pm
Body Type: 82-A Closed Cab
Model Year: 1928
Location: Illinois

Re: high speed rear ends

Post by Rumbler » January 14th, 2019, 8:03 pm

Thanks, Dave. I'm going to give that a try.

Brian

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Chris Haynes
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Model Year: 1930
Location: North Hills, CA/ Pine Grove, CA

Re: high speed rear ends

Post by Chris Haynes » January 14th, 2019, 9:15 pm

My Early 1930 has the gear ratio stamped on the speedometer drive gear.

bud valerius
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Model Year: 1930
Location: Manhattan , Kansas

Re: high speed rear ends

Post by bud valerius » January 15th, 2019, 5:43 am

with one wheel on the ground a little more than 2.5 turns of the drive shaft turns the wheel one time with the 5:17 a little more than 3.5 turns of the drive shaft is a 7:25

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Rumbler
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Joined: May 21st, 2017, 4:27 pm
Body Type: 82-A Closed Cab
Model Year: 1928
Location: Illinois

Re: high speed rear ends

Post by Rumbler » January 15th, 2019, 4:03 pm

I've completed the test. Only difference is that I'm turning the input shaft of the dual-high since the engine & tranny are out of the truck. The dual high is in 1:1 mode (shift lever position is to the rear). I get about 2-2/3 revolutions of the input shaft to turn the free axle 1 revolution.

So good news, according to Bud's numbers it looks to be confirmed that I've got the high speed 5:17 axle.

Next step: Clean off the mass of dirt and oil from the differential housings, remove the axle from the frame and begin to take in apart. Fingers crossed that things are ok on the inside :)

Brian

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Rumbler
Posts: 64
Joined: May 21st, 2017, 4:27 pm
Body Type: 82-A Closed Cab
Model Year: 1928
Location: Illinois

Re: high speed rear ends

Post by Rumbler » January 15th, 2019, 4:10 pm

FYI, for jollies I just completed the same test but with the dual-high in low mode. It took about 3-3/4 revolutions to turn the free axle 1 revolution.

Brian

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1crosscut
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Re: high speed rear ends

Post by 1crosscut » January 15th, 2019, 6:59 pm

Looks like I got my numbers mixed up. Glad you have a high speed.
------------
Dave

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Rumbler
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Re: high speed rear ends

Post by Rumbler » January 19th, 2019, 1:39 pm

I've cracked open my worm drive axle housing and fortunately have found it to be in great shape. Worm drive and gear look very good, as do the planet (spider) gears and axle gears. Only trouble area appears to be the seals, which I would have expected to replace anyway. So I have some questions:

-Each axle housing has two seals, one inner seal (near the differential) and an outer seal (about 4 inches in from the end of the housing). I think I've found the outer seal on Bert's website (same as the driveshaft seal), but I'm not so sure about the inner seal. The inner seal appears to be a cup shape which contains a felt seal. Should I be able to find a supplier for the inner seal? Photograph of the inner seal is attached.

-Before taking the differential planet gear assembly apart, I measured the total axial movement (clearance) of the axle shafts to be 0.015 inches. Do we know of a spec for this...does this seem acceptable? The AA Supplement to Model A Shop Manual doesn't go to this detail.

Going forward, from a Fine Point perspective is all the hardware for the axle and springs unfinished? Ref: Axle housing bolts, worm cap bolts, torque tube to housing bolts, radius arm bolts (front and rear). Also the axle/spring mounting cap bolts, all the various spring pivot bolts?

Thanks,
Brian
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dhetch
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Location: Lakeville, MN

Re: high speed rear ends

Post by dhetch » January 19th, 2019, 10:05 pm

Brian, I have never seen seals there. They are to be pushed through from the diff side out almost to the brake end of the housing. Use a piece of 1" pipe and a set of Harbor Freight seal installers and a good LED flashlight. First make sure you have the old seals out before you try to install the new ones. I use a AA4245 or a CR16118 seal and you might want to have a spare or two because it is easy to bend them until you have done a few.
Just a suggestion, before you get too happy with this axle, look very carefully at the bottom of the surface where the wheel bearing rides on the housing. If it is damaged here, it could have also damaged the wheel bearing and hub bearing surface. While it is apart, you might want to spin the axle shafts to check for straightness and matching lengths. FYI the 28 and 29 have different wheel bearing, hub bearing length, and axle shaft and housing lengths. Any of these worm gear axles I have run into use a CR27471 hub seal. This axle also requires a special gear lube which is explained on page 23 of the April 2017 Double A'er.
Dave

Bob C
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Model Year: 1931
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Re: high speed rear ends

Post by Bob C » January 20th, 2019, 1:11 pm

I think that the inner seal may be a carry over from the TT. Snyders shows one that may replace the felt one, may be call them
and get dimensions. https://www.snydersantiqueauto.com/inner-seal-kit.
I think it would help if this thread was moved to the Discussion Forum.

Bob
worm axle-2.jpg
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Rumbler
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Body Type: 82-A Closed Cab
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Re: high speed rear ends

Post by Rumbler » January 20th, 2019, 2:35 pm

Bob, thanks for the diagram and yes, my apologies to Bud for hijacking his "for sale" post.

How do we move this to the discussion forum?

Brian

Bob C
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Re: high speed rear ends

Post by Bob C » January 20th, 2019, 3:36 pm

"How do we move this to the discussion forum?"
I think you could go to the link and request that they move it. memberlist.php?mode=contactadmin

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1crosscut
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Re: high speed rear ends

Post by 1crosscut » January 20th, 2019, 4:50 pm

I think that you have a very early rear axle assembly. What does the speedometer housing on the drive shaft look like?
------------
Dave

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Rumbler
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Joined: May 21st, 2017, 4:27 pm
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Re: high speed rear ends

Post by Rumbler » January 20th, 2019, 5:00 pm

=========================
Re: high speed rear ends
by Bob C » January 20th, 2019, 5:36 pm

"How do we move this to the discussion forum?"
I think you could go to the link and request that they move it. memberlist.php?mode=contactadmin
=========================
Thanks, Bob I have made this request.

Brian

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