1934 Plymouth PE Deluxe 4 Door Sedan - Rear End Help

[Guest Lownslo]

I recently bought a 1934 Plymouth PE. The previous owner was the son of the man (now deceased) who modified the rear end. I believe the goal was to make the car into a street rod or resto rod. The problem is the current gear ratio is way to low! Starting off is like starting off in 2nd gear. The problem is I don't know and have no way to find out (since the guy is dead) what was changed. Did he change the gears inside? Did he change the gear carrier with different gears inside? Did he change the entire rear end with housing, axles, brakes and all? I don't know. Here is a picture of the current rear end:

I believe this is probably not the original housing or gear carrier, but I don't know that for sure. Does anyone recognize this rear end? Does anyone have a correct rear end? First I think I need to know what I have, then decide how to proceed, but if you have a correct rear end then please let me know price and location. Thanks, Bud Silvers - Lownslo in the Black Forest of Colorado....

[ply33]

Definitely not a '34 Plymouth rear end. From the location of the input shaft it looks like a hypoid rear end. The '33 through, I think, '35 (or maybe '36) rear ends were spiral bevel. If no one else comes up with a photo, I'll crawl under my '33 and get a photo ('33 and '34 rear ends look basically the same).

[keiser31]

That rear end looks like a Ford 9".

[ply33]

I recently bought a 1934 Plymouth PE. The previous owner was the son of the man (now deceased) who modified the rear end. . . The problem is I don't know and have no way to find out (since the guy is dead) what was changed. Did he change the gears inside? Did he change the gear carrier with different gears inside? Did he change the entire rear end with housing, axles, brakes and all? I don't know. . . .

Off topic, but this is one of my big objections to modifying vehicles away from stock. I suppose in a perfect world anyone who did that would create a binder with all the documentation of what was done, part numbers, etc. And in a perfect world that binder would stay with the car under all conditions and events. But in this imperfect world a few people create such documentation and even if they do their heirs may not know about it and send it on with the vehicle. At least with stock you know what you have or should have. And you can, for cars built in the last 80 or so years, access the manufacturer's documentation.

Another big objection is that changes away from stock are not always well advised. Generally a manufacture does a reasonable job of balancing out the total package. Changing a rear axle for an increase in cruising speed may make starting or hill climbing a problem. And you may be tempted then to run faster than the brakes or suspension can safely handle. Etc.

Sorry about the OT post, and I'll get off my soap box now.

And I am encouraged by the original poster's request for information about getting the correct rear axle.

[Guest Lownslo]

Hello all, and Thank you all! I have located a complete rear end (brake drum to brake drum) for a 1936 Plymouth. The seller says that it is the same rear end and has a 4:30 ratio. I believe that I should have a 4:375 and suspect that is what the one for sale actually is. My question is if $350 plus $119 shipping sounds like a good price and if there is any difference between the '36 and '34 rear ends. As ply33 says in the last post this could create a problem for some future owner. I agree with his post and would not have bought this car, but the rest is so clean. Here is a picture of it: Thanks again. Bud

[ply33]

That car does look nice!

With respect to the '36 rear end, you might want to check the distance between brake backing plates. I am fuzzy on my memory of this, but sometime around '36 or '37 they redesigned the rear axle and among other things went to a hypoid gear set. But they also made the axle wider when they did that. From your photo, either the previous owner cut the axle or he managed to find one close to the correct width. At least the rear wheels look to be in about the right place. If the '36 axle is wider you may have an issue with the wheel being a bit too far out.

There are detail differences between the '33 through '35 or '36 (or whatever the last year before redesign was). The width of the brake drums was one item I think. But, again IIRC, the ring and pinion sets can be swapped. Apparently in '35 or so they had a 3.9 ratio available on coupes. I know a fellow with a '34 engine in his '33 who installed that ring and pinion and says it is a good match for the engine and weight of the car. I have the stock 4.375 rear in mine and it works for me (500+ miles at a time at 60 MPH and also reasonable pulling on steeper hills) but a lot of people prefer taller gears.

[Guest Lownslo]

I spent some time last night trying to identity my existing rear end. I now believe it to be an 8" Ford. Probably from a Mustang or Cougar. I have other projects for this winter so am going to continue to look for a '34 rear end. If I am going to fix this, I may as well fix it right! IF I can find a '34 rear end. Does any one have a lead? Thanks again for your help so far. I am going to post another thread under "parts wanted".

[Dave Mellor NJ]

The 8" Ford rear is square compared to the 9" which is round. I agree this is an 8".

[Hudsy Wudsy]

The '36 parts book indicates that the standard rear axle ratio is 4.125 to 1. The coupes, however, came with 3.7 to 1 ratios. A Hollanders Interchange manual says that '33 to '36 differentials interchange, but shows some differences in axles. I can't tell what those differences are, but they might be about axle length or rear wheel bearing issues. If it's about axle length, there might be some small differences in over all width of the rear axle assembly, but, if that's the case, I'm guessing that the differences might be negligible. If you are looking for an exact bolt-in replacement, I suppose that you might want to look for any differences in the distances between the spring mount pads and the width of the pads themselves. It appears that you'll want to get an original unmodified driveshaft, as well.

[Guest Lownslo]

Hello all; I have found an axle from a 1934 PF which I believe has a slightly different ratio than the PE. I have bought the axle and am now trying to figure out the cheapest way to ship it from New York to Colorado. Thanks to everyone for your help. I think my next project may be a street rod so the 8" Ford axle may come in handy. Have a great day and thanks again for all the help. Bud Silvers

[ply33]

Hello all; I have found an axle from a 1934 PF which I believe has a slightly different ratio than the PE. I have bought the axle and am now trying to figure out the cheapest way to ship it from New York to Colorado. Thanks to everyone for your help. I think my next project may be a street rod so the 8" Ford axle may come in handy. Have a great day and thanks again for all the help. Bud Silvers

IIRC, the PF sedans typically had a 4.11 while the PE had a 4.375. Should be "close enough". With an engine in good shape and cruising at 3300 RPM (reasonable for this engine design) that is a difference of 4 MPH (63 MPH for the 4.375 vs 67 MPH for the 4.11). See: http://www.ply33.com/Misc/speed#calc

Or you could also get the '36 coupe 3.7 ring and pinion mentioned elsewhere in this thread and put it in the PF axle if you wanted a taller rear end ratio.

I'd have to check the books, but the PF might have pressed steel brake drums and the PE Centrifuse. And the PE drums might be slightly wider. Should work as I think the PF and PE have very close if not the same track, but your brake parts might be a little different.

Edited November 20, 2013 by ply33 (see edit history)

[Hudsy Wudsy]

Here's a '35 Coupe rear end for sale I came across on Craigslist - Austin TX. If it is, in fact, out of a coupe, it should offer the 3.70 gearing that's so desirable for one of you who have followed this thread with interest. It seems like shame to suggest this, but maybe, for shipping purposes, the seller could have the pumpkin torched out of it.

http://austin.craigslist.org/pts/4176131637.html

[Steve9]

Here's a '35 Coupe rear end for sale I came across on Craigslist - Austin TX. If it is, in fact, out of a coupe, it should offer the 3.70 gearing that's so desirable for one of you who have followed this thread with interest. It seems like shame to suggest this, but maybe, for shipping purposes, the seller could have the pumpkin torched out of it.

http://austin.craigslist.org/pts/4176131637.html

I vote for this coupe rear end for your car. My car has a swapped-in coupe rear end and for motoring in today's world, your engine will thank you for not working it so hard.