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Joined: Jul 2014
Posts: 31
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jul 2014
Posts: 31 |
Hello. My Master 85 parts car which I am parting out has the more desireable 3.7 rear axle gear ratio vs the 4.1 in my SD
Can I swap one for the other ( entire rear axle and torque tube) or is there a difference.
Also curious why Chevrolet would put the higher speed rear axle in the lower priced model, seems strange to me.
Thank You for your help.
Grant
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
All parts are te same except for the ring gear and pinion. A perfect swap.
Why did Chevrolet do that? For increased gas mileage for the economy car.
The 4.11 was the "performance" ratio and the 3.73 the "economy" ratio. Also happened to be the high speed ratio. The 3.73 was a factory option for the Special and Master Deluxe.
Gene Schneider
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Joined: Jul 2014
Posts: 31
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jul 2014
Posts: 31 |
Thank You
Makes sense now.
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Joined: Dec 2001
Posts: 2,037 Likes: 5
ChatMaster - 2,000
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ChatMaster - 2,000
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For many of us, the 3:73 Master 85 rear end is the preferred rear end for a 1940 Master Deluxe or Special Deluxe passenger car. The 3:73 was a factory option for the MD & SD. I run the 3:73 gears in my Master Deluxe and it is excellent except for steep mountain driving in West Virginia. At those times, I wish that I was running 4:11's.
dtm
the toolman
60th Anniversary Meet Chairperson
Dave
VCCA # L 28873
VCCA #83 Tool Technical Advisor for 1914-1966
VCCA #83 1940 Chevrolet Technical Advisor
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Joined: Jul 2014
Posts: 31
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jul 2014
Posts: 31 |
I have just removed the 3.73 rear axle from the Master 85. All went well.
My question is this. Is there a way to hold the U joint in place to make the install easier? It seems difficult to get your hand in there to line the joint up while someone is pushing the axle forward.Thank You
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Joined: Apr 2008
Posts: 1,194
ChatMaster - 1,000
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ChatMaster - 1,000
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You should be able to move the ball socket back on the torque tube.
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Joined: Jul 2014
Posts: 31
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jul 2014
Posts: 31 |
So I tried to determine if I do indeed have the 3.73 ratio now that the axle is out. My concern is that it appears to be something less. The casting number on the carrier is GM 593021
and the only stamped numbers I can find are right beside the casting number and says E 606
Does this make sense?
Thanks for your help
Grant
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Joined: Apr 2008
Posts: 1,194
ChatMaster - 1,000
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ChatMaster - 1,000
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Take the rear cover off and count the number of teeth on the ring gear and pinion gear.
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
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The rear axle serial number should be a 7 diget number begining with a letter possibly and the first two numbers will be 22.
If you remove the rear cover you will see 11-41 stamped on the back of the pinion gear and may find it on the side of the ring gear. The casting number you mentioned means nothing as far as the ratio is concerned.
Gene Schneider
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