55 roadmaster rear axle questions

thegnu

Member
I have this idea in my head that I can swap the rear end in my 55 to something more modern , an im not absolutely positive if it will work so this may be lengthy any input is very much appreciated. I will start at the beginning. I would love to retain the dynaflow transmission,{ I still have the oem nailhead an a conversion kit that will accept any gm transmission is fairly expensive} an this is where it gets complicated.
1. I understand there is first the torque ball an u joint to deal with an that I would need a slip shaft to account for the rears movement . the oem ujoint assembly is bolted to the output shaft . I assume that by removing the tourqe ball an installing a hybrid u joint assembly with a slip yoke on the driveshaft side I could effectively account for the movement of the rear axle as the shaft lengthens an shortens as it moves up an down with the rear axel. what possible issues could I have here an is the tourqe ball the transmissions "rear seal" essentialy?
2. drive shaft , would have to be custom made similar to one from a 4x4 with a slip yoke at the front an matching rear as the rear end of choice. here the queston is would vibration be a serious issue on the transmission?
3. rear axel an suspension, clearly a 4 link an panhard install makes the most sence with coilover shocks , or possibly retaining my coils an adding shocks. (a) whats a good gear ratio to look for in that rear axel ? an the dynaflow is a 2 speed. (b) rear axle width ? recommendations or best donor axels?
any out side input or issues I have overlooked is very much appreciated before I start spending cash on something that may not work .
 
You should crawl under your car and get familiar with how the rear end and transmission are connected. There is an enclosed drive shaft. The rear end is held in location by the drive shaft tube. You will have to change your transmission and rear end if you want an open drive shaft. It will get real expensive real fast if you have hire this done.
 

thegnu

Member
You should crawl under your car and get familiar with how the rear end and transmission are connected. There is an enclosed drive shaft. The rear end is held in location by the drive shaft tube. You will have to change your transmission and rear end if you want an open drive shaft. It will get real expensive real fast if you have hire this done.
i learned that on some caddys they had an open drive shaft but will have to change the tail shaft an tailshaft housing on my car . either way I have decided not to go with this swap until after I repaint the car .
 
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