Rear end gears

[37 Cab]

My 37 runs at 3000 rpm at 60. Looking to change rear end gears. I believe it has 3.78 in it now. Want to go to 3.54. Looking for someone local to me that has experience doing these rears. I could probably get through it but I would probably make more of a project out of it than need be. I would rather have someone do it that has the tools and experience to knock it out. I am in northeast Oklahoma. Any help would be appreciated.

 

[rotorwrench]

The Early Ford V8 Club has a yearly roster of members and member services. There is bound to be someone that can help you out between Tulsa OK and Springfield MO there somewhere.

 

[Charlie Stephens]

First check and be sure what you have. If the existing rear end is in good shape I don't think the change from 3.78 to 3.54 would be worth while, but that is based on my use of my car and I don't know how you are using yours.

Charlie Stephens

 

[DavidG]

Sounds like a 4:11 rear end with that rpm at 60 mph.

 

[Tim Ayers]

First check and be sure what you have. If the existing rear end is in good shape I don't think the change from 3.78 to 3.54 would be worth while, but that is based on my use of my car and I don't know how you are using yours.

Charlie Stephens

This is good advice. May be hard to check with everything together, but by taking off the turtle and using a paint pen to mark the driveshaft and then chalk the tire at 12:00 o'clock.

Count the rotations. A little more than 4 spins of the drive shaft and one of the tire are 4.11's and just over 3 3/4's rotations of the driveshaft and one of tire you have 3.78's.

 

[deuce lover]

Taking off the turtle can a pain.Look under the web of the banjo center section.There are numbers stamped, 9-34 is 3.78, 9-37 is 4.11.Its a good chance it was never changed from new.

 

[Andy]

You should have 10 spline female end on the driveshaft. You would need to get a 40 or so driveshaft with the 6 spline male end. Your d/s could be cut and a coupling installed but it is a tricky job. The length is critical and it must be straight and centered. I did mine on a lathe.
I really like the 3.25 gears.

 

[Steve in Denver]

I have 3.54s in my '36 5 window and, as I have an 8BA motor, I was able to hook a Tach up and it shows 3000 at 60 mph.
I have considered going with a Columbia but everyone says that with a 3.54, it will lug the motor down too much except at very high speeds, that being over 65 mph. And even with a completely rebuilt front end, it shakes over 65.
Anyway, if you do have 3.78s you might consider going with a Columbia.

 

[JSeery]

Might check with Sid's. Not sure they do this type of work, but if they don't they could probably tell you who does.

https://droppedaxles.com/

 

[deuce lover]

It shouldn't shake even at 65 if all is done right.

 

[rotorwrench]

A Mitchel overdrive might also do the trick. With that, you buy the kit and replace the torque tube with the parts in the kit and install the control. I don't think the 37 has problems with body clearance like the some of the early V8 cars do.

http://mitchelloverdrivemfg.com/products/ford-v-8-overdrive/

 

[37 Cab]

Good information guys.. Thank you. I had thought about a Mitchell but my car is lowered and not much room under there. I did not know about the driveshaft issues so that adds a little to that idea. A Columbia would work I suppose... Is there anyone that supplies everything to do one?

 

[Seth Swoboda]

I just installed 3.54 gears in place of 3.78s in a 47 tudor. The difference in rpm is noticeably better at 60 mph with 3.54s. I do not regret the work involved in rebuilding the rear end. Michael Driskell at Third Gen Automotive helped me with my rebuild.

 

[drolston]

I went to 3.25 gears in my '41 coupe to get reasonable RPM for interstate driving. I love them, but I have 284 cubic inches with a ton of torque, so even starting on a hill is not a problem. A lot cheaper and more reliable than going to a Columbia.

 

[Mart]

My 41 pickup has 3.54s. It drives nice. I don't drive fast though. 50 mph gets me where I want to go. I did offset the taller rear gears by using a 15/29 gearset in the trans when I rebuilt it. It pulls away nicely.

 

[gwmartin55]

Rex Gardner is in Grove, Oklahoma. Flatmotor research is his business. I have 2 of his engines. Great work.

 

[larrys40]

I’m up St. Louis way and have done hundreds of rear axle rebuilds. You could also ask Eric at model a medic in Whichita or look up the v8 clubs in the neighboring areas. I know they are shrinking. My vote to you would be that the Columbia albeit the most expensive option would give you the best of all. I’ve seen some Columbia’s go cheap lately,(1500 on eBay broken down with controls ) . The need Bullet proofing and work over but that’s just part of it. My 40 has a Columbia and I can’t imagine without it. If you are interested in a Columbia I can probably help.

 

[Tim Ayers]

I’m up St. Louis way and have done hundreds of rear axle rebuilds. You could also ask Eric at model a medic in Whichita or look up the v8 clubs in the neighboring areas. I know they are shrinking. My vote to you would be that the Columbia albeit the most expensive option would give you the best of all. I’ve seen some Columbia’s go cheap lately,(1500 on eBay broken down with controls ) . The need Bullet proofing and work over but that’s just part of it. My 40 has a Columbia and I can’t imagine without it. If you are interested in a Columbia I can probably help.

I really wish I went with one two. I love the idea of having the O/D when you want.

I'm certainly on the hunt for one.

 

[37 Cab]

Decided to go with a Mitchell. Talked to Steve today and they are about 12 weeks out. I like the idea it can be removed if wanted and he thinks I will not need to modify my floor even with a reversed spring. Since my rpm is close to 3000 at 60 I went with the 36% unit. I will post an update when I get it installed. (May be a while depending on my need for space)