Rebuilding Rear Uprights and rear discs

They are torque distribution plates and are intended to be used with Schnoor single use lock washers.  The M10 10.9 allen head bolts should be of the length where a few threads extend out of the CV joint.  This helps maximize strength of the joint.   The bolts are then torqued to 62 pounds.  You can get the M10 Schnoor washers at McMaster.  These bolts have not come loose on my car.

The bolts and torque plates are reusable to a point.  The Schnoor lock washers are single use.

Using the Schnoor washers without the the thick plates would quickly tear up the thin sheetmetal cover.  The washers make a serrated imprint on the metal they are torqued onto.

They use Porsche 930 CV axles quite a bit in the off-road world and this seems to be their standard setup.

Links to these parts are below.  I got the allen head bolts at McMaster as well.

https://www.mcmaster.com/produ...rs/?s=safety-washers

https://dunebuggywarehouse.com...6ZRtASnMUyPltvAfx-Nr

Also, the allen head bolts are actually 12.9 tensile strength, not 10.9.   That's why they can be torqued to 62 pounds.

Disassembled the rear uprights from the car and I could clearly hear bearing noise. Oddly enough the bearings were louder from the driver side of the car on the bench. To a lesser degree on the passenger side even though on the road the passenger side was noticeable loader. Clearly these have been replaced before.

Digging deeper today and removing the axles (impact wrench and proper socket used; they were damn tight) there is noticeable wear on the mating surface at the outer bearing on the driver side. This axle also appears to be the newer design with a full thickness front flange and a shallow rear hole. The passenger side is of the original design and showed no signs of damage. The spacer tubes had light compression on them from the bearing retainer plates and were able to be pushed around after the screws were removed. There was also no interference between any of the bearing ID’s and any of the axles (slide right apart).

The lower bronze bushings were a mess although they had installed grease fittings a poor job of drilling them through to the shafts didn’t help much. Getting the bearings removed at the shop and start the rebuilding process next.

With the bearings out you could plainly hear the rumble noise in the outer driver side bearing! Cleaned up everything will be replacing the expendables. Have a question about axle diameter. It looks to me that the non contact area of the axle measures 1.5743 inch on both my new and OEM style axles. Does anyone know the target diameter for the proper running fit to the bearing ( 40mm x .03937 =1.5748 )? Our driver side axle at the front bearing measures 1.5702 and is grooved and will need replacing. My concern is the passenger side axle. The rear bearing interface measures 1.5742 ish (great!) but the front area interface measures 1.5726 no galling or tracks. I’m inclined to replace that axle as well or does this still have life left in it?  

For reassembly I found an old infopop that talked about after installing the bearing in the upright first then placing the upright in the oven at 150 degrees for 30 minutes and the axle in the freezer. Pressing them together with the help of expansion/contraction. Is this the best way or has someone come up with something better?

Finally back to this project with the two new axles and necessary parts. We cold pressed everything together and the Uprights with the axles are back together with stock replacement bearings; but not without some issues. Our uprights had been apart before for bearing replacement. The shields were not reinstalled which is common today but someone put a .032 inch shim to help take up the missing outer shield space. Does someone know how thick the outer shield is? Knowing this thickness would help with getting the caliper centered over the disc. During disassembly I noticed I small contact gouge from the rotation of the back side of the disc/stud area in the bearing retaining plate on one upright. Nothing much just a scrape thru the retaining screw faces. We corrected the depths of the counterbores and used flat head cap screws to secure the bearing retainer plates. However we had a few original wheel studs that had goofy threads and new studs were installed. When pressed it all together everything bound up! We found that the heels on the new studs (with the flat on the diameter) were approximately .016 inch taller than the production wheel studs. We had new spacing shims made from hardened blue tempered flat stock at .026 inch thick. We installed two shims per side (.052 total) and removed the original shim of .032. We now have full rotation with the bearings fully seated. On to the lower shaft assembly.

Ken - Sounds like you know more about this than 99% of the rest of us Pantera Owner’s, because you’re elbow deep in it!

Keep up the great work!

Rocky

Just goes to prove that there is no such thing as a bolt on? Granted, the Pantera rear is just a little bit unique.

Personally I like making everything work like you have to.

Just an after thought, are you sure that the noise when turning isn't from the limited slip unit itself?

Hi, yes my first thought was “oh Lord not the gearbox”! Thinking maybe the diff clutches started acting up with the new pressures from spirited corners after years of not being used. I knew the bearings in the uprights had no movement while doing the classic 6/12 and 9/3 o’clock pull testing by heavy hands. So before I started tearing the uprights out I spoke with Dennis Q. We did a couple of tests Dennis suggested (they all showed a worn but fully functional diff section) and he said without opening it up he strongly suggested the bearings in the uprights. Another friend ex-Porsche racer turned early 911 restorer also strongly suggested the bearings in the uprights. Knowing our OEM rear discs were at the low limit we decided to go in and replace axles, bearings, discs to eliminate that concern and hopefully clear up the issue. I’m not holding my breath because further inspection of the old bearings showed no rust, dirt or damage with the shields removed. However as above one of the axles was badly beaten up and the other showed minimal wear/damage.

@KR500 posted:

Hi, yes my first thought was “oh Lord not the gearbox”! Thinking maybe the diff clutches started acting up with the new pressures from spirited corners after years of not being used. I knew the bearings in the uprights had no movement while doing the classic 6/12 and 9/3 o’clock pull testing by heavy hands. So before I started tearing the uprights out I spoke with Dennis Q. We did a couple of tests Dennis suggested (they all showed a worn but fully functional diff section) and he said without opening it up he strongly suggested the bearings in the uprights. Another friend ex-Porsche racer turned early 911 restorer also strongly suggested the bearings in the uprights. Knowing our OEM rear discs were at the low limit we decided to go in and replace axles, bearings, discs to eliminate that concern and hopefully clear up the issue. I’m not holding my breath because further inspection of the old bearings showed no rust, dirt or damage with the shields removed. However as above one of the axles was badly beaten up and the other showed minimal wear/damage.

What rear discs did you use?

Are they dimensionally a substitute for the originals?

The discs came from Larry at Pantera Parts Connection in Carson City NV. Larry sells these as the stock disc replacements. I checked a few dimensions and they look to fit nicely. I wanted stock size discs for the rear in case maybe someday I would go with stock wheels for the full restored look. We also installed (earlier this year) Wilwood six piston calipers all around which also clear stock wheels from SACC.