47 Plymouth Deluxe Special (new to me and drive shaft help)

[solar07]

Hello all, this is my first post. I was given a 47 deluxe special a few months back from my wife's uncle, and I have enjoyed taking it on. This car is very foreign to me but it's been fun. I consider myself good at working on cars boy I don't know a darn thing about this baby. 

 

Anyway, the car has a really bad vibration over 35/40 and after looking everything over, I see that the rear of the drive shaft has what I have researched and found to be a ball and trunion style. The boot is ripped and I can grab the drive shaft and wiggle it left to right a good 1/2". I'm guessing that's not how it should be unless I don't understand the design beyond the boot rip itself.

 

My question to you fine folks is what's the best method of attack? Should I try to find the parts to rebuild or is there an upgrade to a better ujoint style setup? I've looked around and can't really find anything online as far as parts so if you have a suggestion, if you'd be so kind as to let me know where and what to get I would greatly appreciate it. Thanks all! I spent the day cleaning her up and she came out really nice.

Edited September 7, 2019 by solar07
Title change

[greg g]

The parts are available to rebuild, getting new boots on without ripping is tricky.  Suggest you get a service manual, reprints are available on eBay.  The other option is having a new driveshaft with modern u joints.  I have heard prices range from 300 to 400 bucks depending on where you are. Modern stuff will give you piece of mind going down the road.  Nice looking car, they are welcome engineered and fairly basic to work on. Most parts are available with a bit of digging as these engines were used in a lot of applications like fork lifts airport ground support equipment, military and agricultural equipment well into the 70's with very few changes.  Most of the basic stuff has been covered many times and the search feature is good at digging out the answers to questions.  Welcome and good luck.

[solar07]

Thanks for the info. If I went with a new drive shaft, do I have to have one made somewhere or can you buy them somewhere?  Thank you.

[greg g]

Usually they are custom fabricated at specialty shops. Go to a cruise in or check with guys in your area with hot rods or race cars, they should be able to pass along info regarding who does that type of work in your area.  Then it just a matter of taking yours in for measurement and fabrication.

[Dodgeb4ya]

https://fortwayneclutch.com/product/1948-dodge-plymouth-d24-custom-replacement-rear-propeller-driveshaft-assembly-sku-1948_d24/

[Adam H P15 D30]

I had mine made at Denny’s Driveshafts for about 400.00, delivered. 

[Bbdakota]

I ordered mine from driveshaft specialist in Texas. I did change rear ends but they can supply you a bolt in driveshaft for your application with a few measurements. 

[Andydodge]

Due to the way these driveshafts were designed they used a sliding yoke or in your cars case a sliding trunion to allow forward and aft movement.......modern driveshafts use a yoke cast with the splines that slide in and out of the rear of the transmission.........mopars used a fixed flange held onto the rear mainshaft with a large centre nut then either the ball & trunion or sliding yoke universal joint..........personally I wouldn't bother with the ball & trunion and would chase up a replacement driveshaft with proper uni's at both ends....any competent shop that plays with trucks or a hotrod shop should be able to recommend some place to make a driveshaft .........tho' you MUST ensure that the front uni has some sort of sliding yoke arrangement where it bolts onto the flange on the handbrake drum............BTW welcome aboard from oz.......nice car also.................andyd    

[9 foot box]

solar07,  Type, servicing U-joints, in the search, on this Forum. 

[solar07]

Thanks all. I really appreciate the guidance. For those of you who mentioned you changed out the rear end, what was the gains there? Looking to hold cruise speeds easier ?  Mines a three on the tree. Not too sure how well she will drive at 55 yet until get the new shaft.

[Sam Buchanan]

5 minutes ago, solar07 said:

Thanks all. I really appreciate the guidance. For those of you who mentioned you changed out the rear end, what was the gains there? Looking to hold cruise speeds easier ?  Mines a three on the tree. Not too sure how well she will drive at 55 yet until get the new shaft.

 

My '48 P15 with the stock 3.91 rear ratio is very happy at 60 mph. The brakes keep me from cruising any faster. 

Edited September 13, 2019 by Sam Buchanan

[Merle Coggins]

I have 3.73 gears in my truck and cruise easily at 65 MPH. I can push it up to 80 when needed, but I don't like to push like that if I don't have to.

[Bbdakota]

I'm going to be the black sheep with most on this forum. I don't like twisting my 230 very high. I changed my rear from 4.11 to 3.55 using a 71 b body 8-3/4 and couldn't be happier with the cruise rpm now. I still won't go above 65, mostly under 60. With the 4.11, 52 mph is as high as I wanted to twist the 230. It would go there but seemed the engine rpm was to high for the load it was under. I like a nice low rpm putting along cruise vs a screaming engine building unnecessary heat. Just my 2 cents though.

[solar07]

How do I find out my gear ratio?

[Bbdakota]

If you know the options, ie. 4.11 or 3.73 or 3.5, etc. You can Jack up one rear tire, mark the position of the tire and driveshaft, rotate the tire 2 revolutions and count how many times the driveshaft rotates. If it rotates 3 and a half times, you got 3.5 gears. 4 and just a little, 4.11 gears.... at least that is the easiest way if there's no tag or stamping. Note,  positive traction rears, bring both rears off the ground and rotate the rears 1 revolution. There might be a stamp on these rears, Hopefully others with more knowledge about these cars can chime in.