VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1938 Chevrolet Master 3:73 Rearend Available

About a three hour drive from where I live, there is a 1938 Master rearend for sale with the 41/11 , 3:73 gears. From what I have been told, it did sit outside some but the rear cover had not been removed and the torque tube is still attached. The individual selling it has moved it into his garage, removed the back cover and confirmed the number of teeth on the gear set. I was looking for one of these and now that it is available, I don't think I want to go to the bother of messing with mine to replace it. I am posting this here to get some exposure in the hopes that this rearend will not end up at the crusher.

Your 1938 Master would have come from the factory with the 3.73 ratio unless Canadian cars were different.

Canadian cars were different as they all had the 4:22 rearend. So this rearend that is for sale is not from a Canadian car.

They wanted you to be able to climb all of those mountains up there.

Haha. I must say the hill climbing ability of the little old Master is quite good.

Wouldn't you also have to change the speedo gear ratio on that too?? I'll be changing out the old hill climbing gears to, 3:73 on mine, once the weather warms up here. But I'm looking for the speedo gears on the u-joint and cable now. Mine is a 37 Chevy Master Delux that also has the 4;22 rear end, or would it make that much difference at the gauge if you didn't change them out?? Thanks,
Joes 37.

The speedometer and odometer will read 10 percent slow.
This is fairy easy to calculate when driveng or "marks" could be placed on the Speedo. face.
The correct speedo. gears for a 1937-1939 3.73 are difficult to find. To install will require removing the U joint and pressing the drive gear of the U joint yoke.....I just installed a new U joint at that time.
You can also purchase an external adaptor (goes between the cable and drive gear fitting) for around $50.

If I were to make the change, I would install the external adapter.

Gene, what are the chances of cracking the speedo gear when removing it off of another u-joint?

Depends how it is pressed or pulled of.

My thoughts are if you cruise at 55 MPH or less it is not worth the money and effort to make the change. With the 3.73 you increse the car speed 10 perent or raise it to 60 MPH, only 5 MPH.
I was very pleased making the Change to my '39 as I frequently traveled many miles on interstates and could run between 65 and 70 MPH....where as 60-65 was tops with the 4.22 before + the fuel milage increased by almost 10%.

Thanks Gene & Old 216 for all the info on this. I'll just have the wife drive in front of me and have her go at certain speeds and mark it on the speedo. face. Thanks agin, PS. where would I find this adapter ??
Joes37

I was lucky enough that Gene gave me a part# years ago and I found a set of trans gears on Ebay.

There are many companies that make the adapters as they are very common when rodding a car. A quick google should find someone close enough to you to give them a call.

You can easily get by until you get the adapter. I change tire sizes between winter and summer on several of our cars and have never found a need to label the cluster, even with differences up to 10%. The new inaccuracy will be greatest at the highest speed so all you need to do is test the highest speed and then remember that at say 60 you are really going 66ish.

At lower speeds the inaccuracy becomes almost irrelevant - at 30 you'd only be 2-3mph off.

I notice that Jim Carter carries an adapter that is stated to work for "all GMs' over a period of years. You order stating the correction you need and it is made to order. I checked my speedometers with my GPS.

I put 3:73 gears in one of my cars and 3:55 in the other. When driving the one with 3:73 just remember whatever MPH the speedometer says, you are really going 10% faster. 30MPH = 33Mph,50MPH= 55MPH, etc. When driving the other car the diff is close to 15%. I made a small chart starting at 30MPH and every 5MPH increments up to 60MPH It shows speedo MPH readings vs actual MPH for each increment (50 = 57.5 MPH etc). I then clipped it to my sun visor for quick reference. I find now I very seldom look at it and just enjoy the ride knowing the speedo is off.

Dick

Thanks agin guy's for all the info. Will definitely have to look into an adapter!!
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Joes37

I bought the torque tube with the 3.73 gearset today. It looks to be in pretty nice shape. The seller also has the independent suspension assembly for the 1937 Master Deluxe. It is still mounted to the frame crossmember and the crossmember is still attached to a short segment of the frame. It also has the tie rod and steering arm attached. I guess I will post in the parts for sale just to make it available. I did takes some photos of it. I would hate to see these parts go to the junk yard. The seller doesn't use a computer.

I hate to say this but the knee-action units ae most likely shot and just good for boat anchors....or will require rebuilding.

I recently installed a 3.73 in my 39 chevy Master delux,wow it isn't the same car thanks to the help of you guy's for some instructions.