Kilgore47 Posted February 8 Report Posted February 8 I like to do several easy projects in between the hard projects. Now it's time for a hard project. The 3.90 pumpkin in the P15 needs to be re built. There is a lot of slack in the gears. When I first got the car the pumpkin was pulled to check everything. Removing it and putting it back in was difficult under the car by myself. This time I'm thinking about pulling the entire rear end so I can work on it on the ground. I'll pull the axels first to make it easier to handle. The 3.90 that's in the car would probably last as long as I will own it but I want to change it to a 3.54. I have a 3.54 pumpkin but the housings don't match. From what I have read the gears should be the same so I will remove the gears from the 3.54 housing and attempt to install them in the 3.90 housing. I'll probably take it to the local shop I use for final set up. Not sure my shade tree skills are good enough to get the set up correct. I guess the worst that could happen is that I'll have to put the 3.90 back together and use it. As long as I don't break something. Remember - shade tree skills - I've been known to break things while trying to fix them. I can fix that - I think Quote
kencombs Posted February 8 Report Posted February 8 Most of the 'pumpkin's will interchange. I seem to recall that one can count the studs/nuts attaching it to the housing and if they are the same, they interchange. The axle spline count may be different but that can be remedied by changing axle gears in the dif. Changing the pumpkin and/or changing the axle gears require any gear setup. Simple unbolt and reverse to install. I'm confused with the 'housings don't match' comment. If you mean whole housing that icncludes the axles and center section, that isn't an issue if you're only swapping the pumpkin. If you mean the pumpkin housing, I doubt that the internal gears will interchange if the casting is different. If you can provide the source of the replacement, I can look up the ring and pinion interchange in my old Hollander to determine for sure. Quote
Kilgore47 Posted February 9 Author Report Posted February 9 I am talking about the pumpkin housing. Sorry for the confusion. The 3.54 pumpkin I got is from a 1956 V8 Desoto. Quote
Booger Posted February 10 Report Posted February 10 This I'm interested in. Take us along on your journey Quote
kencombs Posted February 14 Report Posted February 14 On 2/9/2024 at 11:26 AM, Kilgore47 said: I am talking about the pumpkin housing. Sorry for the confusion. The 3.54 pumpkin I got is from a 1956 V8 Desoto. I replied to your PM. My old Hollander is kind of spotty in coverage of pre 50 Mopar stuff. But as best I can tell the V8s may be different. Sixes seem to be the same from 50 on. Probably earlier to but it doesn't cover them. Quote
Kilgore47 Posted February 15 Author Report Posted February 15 Thanks for the PM kencombs. I haven't worked up the nerve to tackle the rear end yet. May do a few more easy jobs first. Both the P15 and the 56 DeSoto have eleven bolts but I ordered gaskets for both and they don't match. I would like to drive the car to an eclipse viewing get together on April 8. Where we are the eclipse would be about 95 to 98%. If we travel about 40 miles west we would be in the 100% zone. So I'll probably do the rear end work after that. The shop that I will use to do the final set up on the pumpkin after I switch the gears is really slow but very reasonable, I'm slow also so I don't think the car would be ready in time. More news later Quote
nonstop Posted February 16 Report Posted February 16 On 2/14/2024 at 7:57 AM, kencombs said: I replied to your PM. My old Hollander is kind of spotty in coverage of pre 50 Mopar stuff. But as best I can tell the V8s may be different. Sixes seem to be the same from 50 on. Probably earlier to but it doesn't cover them. From what I read, the V8s used a carrier with 4 spider gears instead of 2 like in the 6 cylinders. Last year I put in a 3.73 pumpkin out of a 1954-56 DeSoto into my truck. The only changes needed were to the side gears. It is pretty straightforward and should fit. Quote
FarmerJon Posted February 16 Report Posted February 16 I am interested in how it goes and, more importantly, how it drives once completed. Just last night I had 3 other adults in my coupe and had to take off from a stop, up a hill. I personally wouldn't want less gear than the stock 3.9, unless I had a fair bit more power. Quote
Kilgore47 Posted February 17 Author Report Posted February 17 19 hours ago, FarmerJon said: Just last night I had 3 other adults in my coupe and had to take off from a stop, up a hill. I personally wouldn't want less gear than the stock 3.9, unless I had a fair bit more power. I thought about that part but where I live is mostly flat. And if that is a problem then I'll put the 3.90 back in. 22 hours ago, nonstop said: From what I read, the V8s used a carrier with 4 spider gears instead of 2 like in the 6 cylinders. I'm aware of the spider gear difference but I also heard that if the splines are the same then it may work. Quote
moparfun Posted February 17 Report Posted February 17 I did this same swap a while back. Sorry I could't figure out how to bring the post up, maybe some knowledgable tech can help. The post is, Rear Axle Help, Dec. 27, 2022. I hope it helps. Quote
Sam Buchanan Posted February 17 Report Posted February 17 37 minutes ago, moparfun said: I did this same swap a while back. Sorry I could't figure out how to bring the post up, maybe some knowledgable tech can help. The post is, Rear Axle Help, Dec. 27, 2022. I hope it helps. https://p15-d24.com/topic/59124-rear-axle-help/#comment-635519 1 Quote
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