wilmacmike Posted November 11, 2014 Share Posted November 11, 2014 Hello there everyone,Here is what I have going on at the moment. My rear end is a 4.10 ratio. My S3 has a manual overdrive with a 3 speed. I have been looking for rear drums (10") and hubs. My rear end has one bad hub, which is worn down where it goes into the grease seal. The other drum had sheared off at the outer diameter of the drum. Some one welded it back together a long time ago. Needless to say it is way out of round and does not run true. This hub is also bent up.So I found and bought another rear end. The fellow I purchased it from said it was a 1943. It is indentical to the one in my car with a couple exceptions.For one, it has 11" brakes, which I will swap over to my rear end. It has the same size stepped wheel cylinders.Now here is the real difference which I am confused about. When I looked at it with the seller, he did not know the ratio. The drums were frozen solid, so I could not turn it to figure out the ratio. I was hoping it was a 3.90, which would most likely go well with my overdrive. Once I got it home and taken the drums off (what a job that was), I was able to turn the pinion and count the turns. It is somewhere around 2.25 turns of the pinion shaft to 1 turn of the axle.Heres my questions: What would this rear end ratio be used for/with? When was this ratio used?On the big flat spot on the housing underneath the unit is the number "43". I think this is where the PO thought it was a 1943 unit. My rear end has the same exact number "43" in the same area. Does any one know what this number represents? The pictures I have here are of the different numbers and letters on the rear end that I purchased. They are as follows:43 and 15. "K", "F" or a "P", and then the series of numbers. I guess I will swap out the backing plates and drums, rather than swapping out the whole rear end. Having extra parts is always good.Thank you all for any help you can provide.Keep on MoParing....Mike Link to comment Share on other sites More sharing options...
countrytravler Posted November 11, 2014 Share Posted November 11, 2014 No such gear ratio. You have to turn both axles at the same time one revolution and count how many times the pinion turns. Because the way the spider gears function, you will get a false reading by turning one axle. Or pull the rear. The ring will have the ratio stamped on it most of the time. Also by counting the teeth on the ring and pinion the divide. Example, ring-38 teeth-pinion-10= 3.80. Hope this helps. Link to comment Share on other sites More sharing options...
JACK M Posted November 11, 2014 Share Posted November 11, 2014 (edited) It might take two people to do an accurate check. But Dave is right, have a guy on each wheel end and turn them in sync while counting the pinion revs. If you are turning only one side you may have a 4:10 gear, as your number is approx half, (4:50?)My Plymouth has a 4:10 axle and it works well with the overdrive at 65 mph.I hope there are no differences in the axle tapers, or backing plate mounting. Edited November 11, 2014 by JACK M (see edit history) Link to comment Share on other sites More sharing options...
wilmacmike Posted November 12, 2014 Author Share Posted November 12, 2014 Thanks guys, I will try it with two people. The backing plate layout looks to be the same. I'll measure the backing plates and the axle tapers before I use any of the parts.Again, thanks for the help...Keep on MoParing,,,Mike Link to comment Share on other sites More sharing options...
countrytravler Posted November 12, 2014 Share Posted November 12, 2014 One guy can check with the axle on the ground. Mark the drum at the top and the pinion. Have the axle off the ground on stands and turn the drums at the same time and watch the pinion. Link to comment Share on other sites More sharing options...
c49er Posted November 12, 2014 Share Posted November 12, 2014 Why don't you believe the 4.3 ratio stamped on the housing?The picture I have posted is out of a MoPar parts list showing where the ratio # is stamped on the differential housing. Link to comment Share on other sites More sharing options...
countrytravler Posted November 12, 2014 Share Posted November 12, 2014 Why don't you believe the 4.3 ratio stamped on the housing?The picture I have posted is out of a MoPar parts list showing where the ratio # is stamped on the differential housing.49erWhat book is this in? Didn't know. Makes it a lot easier unless it has been changed. Have about 30 rear ends to ID.Thanks for sharing.Dave Link to comment Share on other sites More sharing options...
Guest 33DOdodge Posted November 14, 2014 Share Posted November 14, 2014 Hello there everyone,Here is what I have going on at the moment. My rear end is a 4.10 ratio. My S3 has a manual overdrive with a 3 speed. I have been looking for rear drums (10") and hubs. My rear end has one bad hub, which is worn down where it goes into the grease seal. The other drum had sheared off at the outer diameter of the drum. Some one welded it back together a long time ago. Needless to say it is way out of round and does not run true. This hub is also bent up.So I found and bought another rear end. The fellow I purchased it from said it was a 1943. It is indentical to the one in my car with a couple exceptions.For one, it has 11" brakes, which I will swap over to my rear end. It has the same size stepped wheel cylinders.Now here is the real difference which I am confused about. When I looked at it with the seller, he did not know the ratio. The drums were frozen solid, so I could not turn it to figure out the ratio. I was hoping it was a 3.90, which would most likely go well with my overdrive. Once I got it home and taken the drums off (what a job that was), I was able to turn the pinion and count the turns. It is somewhere around 2.25 turns of the pinion shaft to 1 turn of the axle.Heres my questions: What would this rear end ratio be used for/with? When was this ratio used?On the big flat spot on the housing underneath the unit is the number "43". I think this is where the PO thought it was a 1943 unit. My rear end has the same exact number "43" in the same area. Does any one know what this number represents? The pictures I have here are of the different numbers and letters on the rear end that I purchased. They are as follows:43 and 15. "K", "F" or a "P", and then the series of numbers. I guess I will swap out the backing plates and drums, rather than swapping out the whole rear end. Having extra parts is always good.Thank you all for any help you can provide.Keep on MoParing....MikeI used to have a 1938 DeSoto Custom Touring Sedan (sold) which had a manual overdrive and I believe those parts are the same. I still have the rearend ring and pinion assy, driveshaft, extra high compression head, the rear axles with bearings, the brake drums with hubs, slave cylinders, new brake shoes, misc....maybe the backing plates. All that is available. I also have several large original parts manuals for the 1937/1938 DeSoto. I'm looking for 1933 Dodge DO hubcaps. Link to comment Share on other sites More sharing options...
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