Packard Forum Index » V-8 (1955-56)

My 1956 Patrician (with torsion level suspension) has a new problem. It seems that my rear differential has locked up. If I raise the car in the air, and set the gear into neutral, when I spin one rear wheel in any direction, the other rear wheel spins with it, as well as the drive shaft. If I drive straight, there doesn’t seem to be a problem, but if I turn, I hear a loud bang (since the left and right wheel can’t spin independently). I changed the rear diff fluid last year, and it still looks clear and at the right level. I am also getting excessive backlash when shifting into reverse or drive. It seems that I need to take apart my rear differential in order to see what is wrong.
In order to inspect what is going on, do I need to remove the complete rear axle as described in the “Rear Axle Removal” section of Sect15_RearAxle.pdf, or is it “possible” to inspect and possibly remove the assembly while the axle and differential carrier are still attached to the car?

Any advice is appreciated!

Thanks,
John

Chances are that you have the first-year Twin Traction rear which was an option. You first cure might be to get a bottle of positraction additive which will ease the operation of the clutches in the diff. If that is no help then I would recommend finding a regular rear axle assy and installing that. Since few of us are driving these cars in deep snow, that will be your easiest route. The posi parts are thin on the ground.

Yes, you can service the diff on the car just like any other Dana-Spicer rear: Pull the axles and the back cover and pop it out. But I don't recommend that struggle.

John, seeing you're in Finland it might be easier to try Ross's suggestion of a bottle of positraction additive first before a complete rear end swap is contemplated. Additionally if you do have to swap rear ends it would be helpful to know whether any other parts like a driveshaft, universal joint, etc are needed to make the swap as painless as possible.

There is a write up on how the Twin Traction operates in SC V0l 30 #4. No how to take it apart and repair info in the article but there is a reference that says it is serviced in the same way as the regular axle except that other than the ring gear the detail Twin Traction parts are NA and it is to be serviced as an assy. There is some additional info in a tech bulletin also mentioned in the article and available for download on this site.

Axles are described in the Rear Axle section of the Service Manual which can also be downloaded if you don't have a printed copy. The new to Packard 56 Dana axles are covered in the 56th series supplement at the rear of the section.

Hi,

I got myself a bottle of positraction additive. I removed some of the fluid from the diff and peaked in the fill hole. I noticed a bolt sticking out, which didn't look normal. Instead of putting in additive, I decided to drain the fluids and open the back cover with the rear axle still attached to the car. Just to see if there was something obviously wrong.

I can conclude that I have the twin traction safety differential, as shown in SC Vol 30 #4. However, it seems to be in kind of rough shape, since none of the bolts are attached.




Looks like I need to pull things out in order to see what can be salvaged.

John

ps. My brother is flying to visit in a week and a half, so I am able to order a suitcase of parts if needed for him to bring over.

I was able to get the rear axle out. I built a home made stand, and got the differential assembly out. All eight bolts holding the twin traction unit had sheered off. I think the bolts had loosened up, which eventually caused the failure. The failure also caused a failure in one of the parts inside the limited slip that holds the spider gears. I took the broken part to a machine shop, and am waiting for a quote. He said that he could make it from steel, but it would also need to be hardened. It sounds like it will be a while until he can do it, and he said it might be cheaper to get a used assembly.

If you know of someone with an assembly please let me know. I found the one on ebay, so I have one lead already. The car is a 1956 Patrician.

Here are some pictures for those that are interested.

John

I also wanted to ask, is there a way for me to "skip" the twin slip/positraction part? It seems difficult, because the inside gears are holding the outside gear in place.

Sorry for all the questions, but one more. The differential I found on ebay is from a 1956 Clipper Super Touring Sedan. Will that be compatible with my 56 Patrician? Since I'm in Finland, I would only get the differential assembly, so I would be fitting the Clipper differential assembly into the Patrician rear axel housing. I would also use my existing rear axles. Are they compatible?

The parts book would tell you compatibility but I expect the ratios and even the wheel bolt pattern may be different between a Packard and a Clipper. That said, have you checked with the dealers for the parts? Tucson Packards, Merritt, Gerry at Packards Southwest or one of the others should be able to help ger your posi-traction back on the road..

I doubt one out of a Clipper will work. The parts book lists many differences.

https://packardinfo.com/xoops/html/modules/partslist/platelist.php?cat=25&partslist=1955-1956