Jim Yergin Posted June 2, 2013 Report Posted June 2, 2013 The differential in my 1941 Plymouth has gone "south" (locked up). Based on what I have read on this forum, I decided to replace it with a rear end from a Ford Explorer. Today I found one at the pick-a-part yard for $79.00. I know I have to change the spring perches but I am not sure how I handle the lower shock absorber mounts. I did a search but was unable to come up with specific information. Do I use the Explorer mounting plates but then the U-bolts won't sit against the narrower leaf springs. Do I use the Plymouth lower mounts and alter the Explorer U-bolts so that they are narrow enough to fit the Plymouth plate but remain wide enough to fit around the wider axle tube? Or do I need to fabricate a new mount? Any guidance would be greatly appreciated. Jim Yergin Quote
Plymouthy Adams Posted June 2, 2013 Report Posted June 2, 2013 Jim take a look at our lower plates...on mine I was able to use the stock lower mounting plates..the ones the u-bolts go through... is not the shock mount on this plate for 41? it is for the other years 48-48..if not there I know later they were part of the actual spring perch.. Quote
Don Coatney Posted June 2, 2013 Report Posted June 2, 2013 Pictured is what I did. I used the original shock mount plate. I heated and bent the (new and longer) U-bolts. What is the gear ratio in the new differential? Quote
Plymouthy Adams Posted June 2, 2013 Report Posted June 2, 2013 IF you want to use new perches and not have to go the trouble of removing them from your original axle..Summit Racing has the size you need...order toll free and have them in 2-3 days as they ship from one of the three distribution areas that most likely close to you... Quote
Don Coatney Posted June 2, 2013 Report Posted June 2, 2013 On the few things I have bought from Summit Racing I have found them to be excellent vendors. Fair price, fast shipping, and a very good return policy. On my way to Buffalo while driving through Northern Ohio I glanced to the left and spotted there store. Big place. Quote
Plymouthy Adams Posted June 2, 2013 Report Posted June 2, 2013 I stop in at the one in McDonough GA as I run to A-town and back...lots of goodies to get you drooling... Quote
Jim Yergin Posted June 2, 2013 Author Report Posted June 2, 2013 (edited) Thanks Don and Tim. I actually found new perches at my local Tractor Supply. Thanks to Don's pictures I took another look at my original lower spring mounts and see that they will work with the wider Explorer U-bolts. At most I may just have to elongate the holes in the plates. I chose to buy an Explorer rear end with a 4:1 ratio to replace my original 4:3. I found the ratio worked very well in combination with my O/D transmission. The Explorer rear end also has rear disc brakes. That means, once I get the parts cleaned up, I will be offering for sale my AAJ rear disc brake parts. Jim Yergin Thanks Don and Tim. I actually found new perches at my local Tractor Supply. Thanks to Don's pictures I took another look at my original lower spring mounts and see that they will work with the wider Explorer U-bolts. At most I may just have to elongate the holes in the plates. I chose to buy an Explorer rear end with a 4:1 ratio to replace my original 4:3. I found the ratio worked very well in combination with my O/D transmission. The Explorer rear end also has rear disc brakes. That means, once I get the parts cleaned up, I will be offering for sale my AAJ rear disc brake parts. Jim Yergin Edited June 2, 2013 by Jim Yergin 1 Quote
oldodge41 Posted June 2, 2013 Report Posted June 2, 2013 (edited) Jim, I made this swap on my '41 Dodge coupe. I am attaching a word document of my notes from the installation. Not much, just some notes I made. I did make new shock mounts as explained in my notes due to the shocks hitting the larger diameter axle housing..............Tim Rear Diff Swap.doc Edited June 2, 2013 by oldodge41 Quote
Jim Yergin Posted June 2, 2013 Author Report Posted June 2, 2013 Jim, I made this swap on my '41 Dodge coupe. I am attaching a word document of my notes from the installation. Not much, just some notes I made. I did make new shock mounts as explained in my notes due to the shocks hitting the larger diameter axle housing..............Tim Quote
Jim Yergin Posted June 2, 2013 Author Report Posted June 2, 2013 Thanks Tim. Do you have a picture of the shock mount you fabricated or more information on how and what you used to make it? Jim Yergin Quote
oldodge41 Posted June 3, 2013 Report Posted June 3, 2013 I believe they are made of 1/4" or 5/16" steel. Can't remember exactly but I can measure if necessary. Using the old ones as a pattern we cut them out 2" longer, drilled them, bent them and welded a grade 8 bolt in the hole we drilled for the shock mount. I had already bought my u-bolts planning to use the old ones that were thicker by elongating the holes for the u-bolts before finding out the shocks contacted the axle tubes. I decided a little extra thickness couldn't hurt so I added the 3/16" spacers under the mounts so I didn't run out of threads on the u-bolts. Quote
Jim Yergin Posted June 3, 2013 Author Report Posted June 3, 2013 Thanks Tim. That is a big help. Jim Yergin 1 Quote
Jim Yergin Posted June 17, 2013 Author Report Posted June 17, 2013 (edited) Here is an update on my Ford Explorer rear end installation in my 1941 Plymouth wagon. I purchased the rear end assembly out of a 1997 Explorer from a local pick-a-part for $79.00. It had the 4.1 ratio I wanted to use with my overdrive transmission and it also happened to be a limited slip unit. After cutting off the original spring perches I tacked welded new narrower perches that I got from Tractor Supply for $10.00. I located them 47" a part with the same pinion angle that the original axle had. I found somebody in town who TIG welded the perches for me for $40.00. I then fabricated some plates that I welded onto the ends of the new perches to which I could attach the Explorer caliper brake lines (using passenger side lines for both sides since I couldn't use the driver's side line with its junction box). I knew from olddodge41 that my original lower shock mounts wouldn't work with the larger diameter Explorer axle but I did not feel accomplished enough to fabricate the mounts that he built. Thanks to a tip from Tim Adams, I was able to use the Explorer lower mounts by installing 2" angle 1/4" steel pieces to retain the narrower Plymouth springs. I powdered coated the lower mounts and the angle pieces. I did have to enlarge the shock mount holes on the Explorer mounts to fit a 5/8" bolt. I already had converted my drive shaft to spicer joints but I had to have the shaft lengthened 2" and have the Explorer drive shaft rear flange installed. That cost $139.00. I mounted the Plymouth rear brake line junction on the top of the Explorer differential but that meant my flexible rear brake line was not long enough. I fabricated a bracket that I attached to the bottom of the car to extend the solid brake line far enough to connect to the flexible line. The one unexpected problem I encountered was the interference between the Explorer brake calipers and the 15" Plymouth wheels on my car. I had to grind down the highpoints on the calipers to get the wheels to turn. But once I did, the car was back on the road. Once again I am grateful for all the help this forum has provided me in keeping my car on the road. Jim Yergin Edited June 17, 2013 by Jim Yergin 1 Quote
greg g Posted June 18, 2013 Report Posted June 18, 2013 You know for a Barrister, the guy's a pretty good mechanician. Nice Job Jim. So you took it to Sully, how did it drive? Quote
Guest bewillie Posted June 18, 2013 Report Posted June 18, 2013 Great job but, I would like to see a little longer U bolt and nut or two nuts. Just me! Quote
Plymouthy Adams Posted June 18, 2013 Report Posted June 18, 2013 I agree that by looking it appears it may be a bit lacking but close look at the nut on the other u-bolt does show it extends through..could well just be the angle of the picture...full clamping force of the nut exist if any of the threads extend beyond the nut and torqued to the proper specification.. Quote
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