differential gear ratio
differential gear ratio
I've learned AA's came with different gear ratio's in the differential. The higher speed rear ends were stamped on the outside. How does one find these stamps? I have three complete rear ends and two of them have stamps on the right side. I have included a picture of one of them. At this writing, I can not read the stamp, but believe that with some elbow grease, I can interpret what is stamped.
Can someone help me learn if this is the gear ratio stamp and what it means? My goal is to install a rear end in my
31 to obtain the maximum comfortable highway speed.
Can someone help me learn if this is the gear ratio stamp and what it means? My goal is to install a rear end in my
31 to obtain the maximum comfortable highway speed.
- Chris Haynes
- Posts: 2203
- Joined: September 7th, 2003, 5:18 pm
- Body Type: 82A
- Model Year: 1930
- Location: Camarillo, CA
Re: differential gear ratio
Easiest way is to remove the speedometer drive from the drive-line. The ratio will be stamped on the gear.
Re: differential gear ratio
Thanks Chris. Only one problem: the speedometer cables are gone. So not only do I need to know the gear ratios of the three rear ends so I can choose the two I will use (two trucks to rebuild), but I'm assuming I will need to know the ratios to order the correct speedometer cables.
Now what?
Now what?
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- Posts: 1442
- Joined: April 24th, 2003, 11:50 am
- Body Type: Mail truck, Stake tr
- Model Year: 1931
- Location: SO CAL
Re: differential gear ratio
Like Chris said you need to remove the driven speedometer gear from the torque tube not the speedometer cable.
Bob
Bob
- 1crosscut
- Posts: 877
- Joined: December 25th, 2010, 7:22 pm
- Body Type: 82-A
- Model Year: 1929
- Location: Lincoln, NE
Re: differential gear ratio
Block one drum / wheel from turning. Mark the other drum / wheel. Clamp a vise grip to the end of the drive shaft and see how many turns it takes to rotate the marked wheel one full rotation. You can compute the gear ratio from that.
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Dave
Dave
- Farrell In Vancouver
- Posts: 314
- Joined: February 23rd, 2011, 6:52 am
- Body Type: Deck
- Model Year: 1931
- Location: Vancouver BC Canada
Re: differential gear ratio
You are looking for a tag on one of the diff bolts that reads 7-36 which should denote the 5.14 gear set for high speed.
- Chris Haynes
- Posts: 2203
- Joined: September 7th, 2003, 5:18 pm
- Body Type: 82A
- Model Year: 1930
- Location: Camarillo, CA
Re: differential gear ratio
My Early 1930 has High Speed gears. But NO TAG on the rear axle. A tag is easily removed.Farrell In Vancouver wrote: ↑September 8th, 2017, 12:29 pmYou are looking for a tag on one of the diff bolts that reads 7-36 which should denote the 5.14 gear set for high speed.
Re: differential gear ratio
The images on the housing as shown above are hallmarks and will tell the restorer NOTHING. They may refer to suppliers of housings or they may indicate batches of stampings in case of defects; a mystery yet to be solved. Obviously not all AA housings were made in the same casting mold; maybe they indicate which mold in case of a problem.
Hayslip
- Neil Wilson
- Posts: 3062
- Joined: February 5th, 2003, 9:42 pm
- Body Type: 82-A/89-A
- Model Year: 1930
- Location: Boulder, CO
- Contact:
Re: differential gear ratio
FYI - You need to divide the number of drive shaft revolutions by 2 to determine the gear ratio.
Regards, Neil Wilson
______________________________________
aafords.com@gmail.com - use this email for contact
https://aafords.com/
______________________________________
aafords.com@gmail.com - use this email for contact
https://aafords.com/
- tiredtruckrestorer
- Posts: 338
- Joined: April 20th, 2003, 7:09 pm
- Model Year: 1931
- Location: Orwigsburg, PA
Re: differential gear ratio
The lower triangle in the picture (although upside down to read the letters in it) is the Timken trademark. The big "T" down the middle is for Timken, the "D" and "A" on either side of it is for Detroit Axles, and the "CO" beneath it is for Company. Can tell what the other triangle means.
Keith
Keith
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- Posts: 1223
- Joined: June 14th, 2007, 7:29 pm
- Body Type: Grainbox
- Model Year: 1929
- Location: Illinois
Re: differential gear ratio
So since its timken logo embossed does that mean its one of those Canuck rearends?tiredtruckrestorer wrote: ↑September 8th, 2017, 8:15 pmThe lower triangle in the picture (although upside down to read the letters in it) is the Timken trademark. The big "T" down the middle is for Timken, the "D" and "A" on either side of it is for Detroit Axles, and the "CO" beneath it is for Company. Can tell what the other triangle means.
Keith
- tiredtruckrestorer
- Posts: 338
- Joined: April 20th, 2003, 7:09 pm
- Model Year: 1931
- Location: Orwigsburg, PA
Re: differential gear ratio
No, the Canadian Timken rear is completely different than the '30-'31 "AA" Timken used in the trucks in the US.
Keith
Keith
- Chris Haynes
- Posts: 2203
- Joined: September 7th, 2003, 5:18 pm
- Body Type: 82A
- Model Year: 1930
- Location: Camarillo, CA
Re: differential gear ratio
Once again. Take a wrench and remove the speedometer drive. The gear ratio is stamped on it.