steveplym Posted August 7, 2011 Report Share Posted August 7, 2011 After having a noise problem with my car and slight vibration I had been chasing for a couple of years, I decided it was time for a swap. I had changed basically the entire driveline and all wheels and tires. So I figured I needed to rebuilt the rear end, but instead of rebuilding the one I have I decided I might upgrade a bit. I discussed it with several forum members and appreciate the help from James Curl as he did the same swap on his P-15. With the 218 and R-10 OD I was concerned about getting too high a gear ratio, and started looking for a 3.90. That was an option for the '87-'90 Dakotas and was not easy to find. So I found a 3.55 locally and I got it fairly cheap. With reservations about how my car would handle with that setup I went ahead and purchased it and hauled it home. This is what I started with. Had to cut off the shock brackets and then I removed the spring perches. Quote Link to comment Share on other sites More sharing options...
steveplym Posted August 7, 2011 Author Report Share Posted August 7, 2011 (edited) I removed the cover and made sure all the gears were in good shape and no issues with any leaks. This one is out of a 1990. The guy said he had recently got this truck in and the guy drove it to him. The motor blew up so he basically sold it to him for scrap. Checked the seals and bearings and all was good. Next up I replaced all the brakes and bought new drums. Went ahead and painted it about halfway as I was taking it out to a friends house to weld on the new perches I purchased from Northern tool. I used an angle finder and set the pinion angle the same as the old one. Put them side to side and did a lot of measuring to make sure. Edited August 7, 2011 by steveplym Quote Link to comment Share on other sites More sharing options...
james curl Posted August 7, 2011 Report Share Posted August 7, 2011 (edited) I am curious about how well the 218 will pull the 3.55:1 rear end ratio in overdrive. Be sure to let us know after you have driven it for a while, especially if you take a trip longer than 50 to 100 miles. You should be OK because you should be running 70 mph at 2230 RPM which is up on the high side of torque scale. Edited August 7, 2011 by james curl addition Quote Link to comment Share on other sites More sharing options...
steveplym Posted August 7, 2011 Author Report Share Posted August 7, 2011 (edited) With the old rear end out of the way and the new perches welded on. I finished painting it on last Tuesday night and installed it on Wednesday. I spent about a month or so cleaning it up and replacing the parts I needed to. I pulled the old rear out Tuesday night and had the perches welded on and all of it pretty much done on Wednesday night. All lined up well and I didn't have any clearance issues with the wheels and tires either. Then the hiccup came. I had a new driveshaft made about two years ago and thought I could remove the end piece that went from the u-joint to the pinion flange and the u-joint would go right into the new one. It all worked great and the u-joint fit perfectly. Only issue was the driveshaft was too short now. Wasn't real happy until the next day I took it to a local machine shop and they added about two inches to it for around $100 bucks. I had thought about that being an issue, but with the slip joint I figured it would be fine. It worked out anyways. Got off cheaper than I thought I would. I finished putting the car back together on Friday and went cruising. Bled the brakes and all seems to great. The OD does great with the 3.55 so far. I drove it about 25 miles or so. It goes up modest hills pretty well. I just have to kick it out of OD now a little sooner than I did before. RPMs do not get as high in the lower gears which I like and I took it up to 65-70 and no noise or vibration. I think I'm ready to get it back on the interstate soon. I'm going to try to drive it more this week as the weather is supposed to be much cooler by Wednesday. Here's the photobucket album with all the pics I took of the project. http://s167.photobucket.com/albums/u122/siufan6/Rear%20Differential%20swap/ Edited August 7, 2011 by steveplym Quote Link to comment Share on other sites More sharing options...
steveplym Posted August 7, 2011 Author Report Share Posted August 7, 2011 I am curious about how well the 218 will pull the 3.55:1 rear end ratio in overdrive. Be sure to let us know after you have driven it for a while, especially if you take a trip longer than 50 to 100 miles. It did great so far James. I am interested to see how it will do with larger hills and more highway driving. Quote Link to comment Share on other sites More sharing options...
greg g Posted August 7, 2011 Report Share Posted August 7, 2011 You can probably afford to run some shorter tires to get around having to do the kick out thing so often. Do't know what you are running, but something like 205 70 or 75 15 would work out with that rear set up. Quote Link to comment Share on other sites More sharing options...
steveplym Posted August 7, 2011 Author Report Share Posted August 7, 2011 Right now Greg I am running 205 75 15's. I was impressed about how much clearance I had between the tires and fenders on both sides. It seemed a little close before on the left side, but wasn't much closer with this swap. Another note on the swap, it was pretty straightforward, I used the brake lines off my old rear end as I had just purchased them a year or so ago and the brake hose hooked right up with no problems. Since this rear end is only an inch longer than the original, I shouldn't have been surprised about the clearance issues I guess. Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted August 8, 2011 Report Share Posted August 8, 2011 Looks good! I am happy with the 3.55/1 gears in my car but I have a few more cubes in my engine. The locating hole in your new perches (for the pin on your spring) looks a little big. I had to add a 1/4" plate with the correct sized hole to my perches. If this pin is not snug in the hole you could get some movement and this could sheer the pin. Dont ask how I know this:eek: Quote Link to comment Share on other sites More sharing options...
48ply1stcar Posted August 8, 2011 Report Share Posted August 8, 2011 This past Saturday I spent some time thinking about this exact swap. Except I have considing a 3.21 ratio that I understand comes with the V-6 Dakota. I don't have a tach installed, but my car I allways feels like I need another gear. I can't imagine doing 70 mph, I would just like to do 60 without the engine sounding like it max out. Anyone have any comments about a 3.21 ratio rear. Harold Quote Link to comment Share on other sites More sharing options...
greg g Posted August 8, 2011 Report Share Posted August 8, 2011 probably wear your clutch out. I believe that anything under 3.55 is a bit to tall for these engines to pull, especially if you have any hills to contend with. with 27.5 in diameter tires, you would be running about 64 mph at 2500 rpm. But you would likely need 2nd gear to pull hils of any kind Quote Link to comment Share on other sites More sharing options...
oldodge41 Posted August 8, 2011 Report Share Posted August 8, 2011 "Anyone have any comments about a 3.21 ratio rear. Harold" I am running a 3.27 rear from an explorer in my 41 Dodge Cpe. I like it alot better than the original. I am running a stock '48 230 and a fluid drive three speed. I believe it is a bit under powered to truly pull this gear on steep grades in high gear if it were not for the fluid drive. I also believe the fluid drive is a saving grace for my clutch although 1st gear seems plenty low enough. It was alot cheaper than an overdrive tranny, but I feel I could use another gear between second and third for climbing hills. It is not fast but will cruise at 60mph no problem and is a more relaxed ride than before. I would like to try a 3.55 someday but have no desire to go back to 4.11 Quote Link to comment Share on other sites More sharing options...
greg g Posted August 9, 2011 Report Share Posted August 9, 2011 Fluid drive will ameliorate some of the issues, especially at start, and up hills. Quote Link to comment Share on other sites More sharing options...
Cpt.Fred Posted August 9, 2011 Report Share Posted August 9, 2011 hmm... how about this 3.55 rear end behind a 201 with 3speed and 6.00x16" tires? i'd like to get rid of the 4.11 one day as well, but maybe i should wait until a nice 230 crosses my path... oh, and thanks a lot for sharing the pics and describing the project so well, Steve. really answered a lot of questions here. Quote Link to comment Share on other sites More sharing options...
55 Fargo Posted August 9, 2011 Report Share Posted August 9, 2011 I have a 3.73 in my 47 Chrysler, the stock diff, was sually 3.90 or 3.54 for the 48 Chrysler. I do not have a fluid drive coupler. I would not might trying up to the 3.27 range, as we do not have any hills around here. I do find with my tired 228, a 3.73 is about right for my heavy old boat, especially on windy days. I can cruise comfortably at 55-60 mph, I worry more about the steering than the engine blowing at higher speeds....... Quote Link to comment Share on other sites More sharing options...
steveplym Posted August 10, 2011 Author Report Share Posted August 10, 2011 Thanks for the comments. I have been driving the car the last few days. Speedo is about 8mph slow. No wonder I was passing all that traffic at 65mph. Checked it with my GPS. It handles pretty good, and the OD works pretty well over 50mph. Anything less than that I try to stay in 3rd w/o od. Only had to kick it out of OD to get up one hill coming up to a stop. Mostly because I was going to slow once I hit the hill. Gonna keep driving it to make sure all the bugs are worked out. Heading to Evansville, IN for a trip at the end of the month for Frog Follies. Gotta have it ready for that. Quote Link to comment Share on other sites More sharing options...
48ply1stcar Posted November 9, 2011 Report Share Posted November 9, 2011 I just did a search and refreshed my memory. I'm still hoping to do the same. Are you still happy with the results? Is there any issuses that you would like to share? Quote Link to comment Share on other sites More sharing options...
old stovebolt Posted November 9, 2011 Report Share Posted November 9, 2011 Thanks for the comments. I have been driving the car the last few days. Speedo is about 8mph slow. No wonder I was passing all that traffic at 65mph. Checked it with my GPS. It handles pretty good, and the OD works pretty well over 50mph. Anything less than that I try to stay in 3rd w/o od. Only had to kick it out of OD to get up one hill coming up to a stop. Mostly because I was going to slow once I hit the hill. Gonna keep driving it to make sure all the bugs are worked out. Heading to Evansville, IN for a trip at the end of the month for Frog Follies. Gotta have it ready for that. Thank you for all the photos and information, very nice job... Quote Link to comment Share on other sites More sharing options...
falconvan Posted November 9, 2011 Report Share Posted November 9, 2011 Nice swap; exact same thing I did in my 48 Plymouth except I've got a 5.3 Chevy and a 700R4 in front of it. Quote Link to comment Share on other sites More sharing options...
deathbound Posted November 13, 2011 Report Share Posted November 13, 2011 hmm...how about this 3.55 rear end behind a 201 with 3speed and 6.00x16" tires? i'd like to get rid of the 4.11 one day as well, but maybe i should wait until a nice 230 crosses my path... oh, and thanks a lot for sharing the pics and describing the project so well, Steve. really answered a lot of questions here. Anybody have any comments on this, I was wondering the same thing. Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted November 13, 2011 Report Share Posted November 13, 2011 Anybody have any comments on this, I was wondering the same thing. This link will take you to the web page of forum member Tod Fitch. Plug in your numbers and use the speed calculator to figure out your speed at any given engine RPM. http://www.ply33.com/Misc/speed Quote Link to comment Share on other sites More sharing options...
steveplym Posted November 13, 2011 Author Report Share Posted November 13, 2011 Well after driving it quite a bit this fall I am satisfied with the swap. I can run the car at 65-70mph in od and it cruises right along nicely. If I am in city traffic I just pull out the OD cable and it pulls just fine. Usually wait to push it back in until I am on the highway. I drove it to Evansville, IN and all over Southern Illinois the last two months. I am really pleased with it. Next big trip will be Jackson, TN in April. Quote Link to comment Share on other sites More sharing options...
BruceR&C Posted November 22, 2011 Report Share Posted November 22, 2011 Thanks for the info on this swap. Looks like a good option instead of trying to locate an affordable 9". I imagine this would work on a coupe also. Quote Link to comment Share on other sites More sharing options...
Robert Horne Posted December 5, 2011 Report Share Posted December 5, 2011 Well after driving it quite a bit this fall I am satisfied with the swap. I can run the car at 65-70mph in od and it cruises right along nicely. If I am in city traffic I just pull out the OD cable and it pulls just fine. Usually wait to push it back in until I am on the highway. I drove it to Evansville, IN and all over Southern Illinois the last two months. I am really pleased with it. Next big trip will be Jackson, TN in April. Glad the Dakoto rear works for you. Can you tell us the Dakota measurement, backing plate to backing plate? My Plymouth Coupe is about 56 1/2", and the Ranger rear I was trying to use, is shorter by about 3 inchs. Quote Link to comment Share on other sites More sharing options...
steveplym Posted December 7, 2011 Author Report Share Posted December 7, 2011 This rear end is 1" wider the the original. I don't know the exact measurement as I didn't write it down. Quote Link to comment Share on other sites More sharing options...
Robert Horne Posted December 7, 2011 Report Share Posted December 7, 2011 Thanks for the info Steve. The link that "Wayfarer" posted has 37 to 48 have a 60 inch rearend. My 38 measures 61 on the outside drum to drum. I will check my 48 Dodge tomorrow. Quote Link to comment Share on other sites More sharing options...
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