SlowProgress Project Introduction

[SlowProgress]

Yes it is. I think my problem is the last time I built the car was 25 years ago. There were 2-3 speed shops within a 15 minute drive of the house. Now everything is online. You can get anything now in 2-3 days, but there is no local backup up if you find you are missing something Friday evening.

[Vince@Meanstreets]

Sign of the times my friend. I remember when you use to shop at a place for the bond you made with the people that worked there. Now it's all about how much money you can save. Too bad you aren't local. I got a bunch of those parts on the shelf.

[SlowProgress]

I didn’t get finished with the diff., partly I didn’t have enough time and also I lost the locking pinion nut somewhere, probably at the hardware store. So I will post up what I have and finish the build this coming week hopefully. Here are a few things that may be helpful if you have never built up a 12-bolt.
First off I was surprised to find something I had forgotten. The 12-bolt pinion nut uses a 7/8-16 thread. So when I bought a fine thread nut from the store it would only spin on a couple of turns. You need (well it is nice to have) a free-running nut to set up the pinion depth so I cut off the first few threads of the 7/8-14 fine nut and it worked for my setup nut.



Then I sanded down my old pinion bearing with the dremel tool so it was a nice slip fit on the pinion gear. This worked great because I had the pinion out about 5 times tinkering with the best gear pattern and it would have been a pain to press the bearing on and off 5 times to adjust the depth shims! I don’t have a press.



I drove in the new races and once I had the pinion easy to take in and out of the housing I checked the radial and axial runout on the Wavetrack unit. Both radial and axial were about .0015 which I considered pretty good. Also I measured the height of the new bearing and race and the setup bearing and new race and they were within 1 tenth (.0001) so I knew my pinion depth measurements would be good.

Radial

Axial


I put the ring gear in the oven around 300F for a while and the diff. in the refrigerator. Everything slide together easily which was nice. I had a couple of old studs I used to line it all up. I had Moser press on the carrier bearings so I didn’t have to mess with that.



Then I got hungry



I started with the pinion shims from the previous rearend setup, adjusted the side clearance and backlash with the carrier shims as required.



It took several tries to get everything right. I bought some cheap brass drivers for putting in the races and also for taping in the shims. The differential needs a few extra thousands of preload during the last installation. I haven’t done that yet. I called Moser and they said they don’t usually use a case stretcher, just carefully tap in about .010 extra shims. I was going to make a case stretcher but figured if they don’t use one then I won’t. It is probably a good idea for high power applications. Some diffs. it is mandatory. Anyway the brass drifts work well – so far.



Lastly I messed with the pattern and used a prybar to load things up so I could get a good preload on the gearset.



I purchased this cool pinion holder from Raytech http://www.ratechmfg.com/toc.htm.



It came in really handy for checking the pattern and will be necessary during the final pinion nut torque. I am also going to bolt it to the differential stand to support the pinion, so I can remove the back brace and install the rear cover to button everything up.
I will try to finish up the rest this week and post the final images. It is taking too long for sure !!!

[Rick D]

Nice write up on the 12 bolt! I've done several rear ends and it always takes WAY longer then it should. Th least one I did was on my old daily Dodge Ram, wasn't to bad but only lasted two years then blow up again

[Sonar Chief]

Nice writeup for those that have never messed with the 12 bolt ... I hope my 12 bolt had this much attention put into the rebuild!



Michael

[SlowProgress]

I finally got some time to work on the differential this week. With all the clearances set I did a few pinion swaps changing the depth a few (too many) times to get the pattern I thought looked the best. This is a little tedious but I was happy with the final result.





I bought this inexpensive pinion checker from Raytech

https://www.ratechmfg.com/toc.htm.



I was a little skeptical about how accurate it would be. To be fair it did take me a while to get the hang of it. Since I was getting a slightly different reading each time I just set the pattern using the marking compound supplied by Moser and put the original shims in there. I saw somewhere online where it was suggested to start around .032 with the pinion shims. That’s exactly what was in the gearset I took out and the wear pattern was really pretty good. I only had to tweak it about .005 more. When I had a good pattern, I put the tool back on, took two readings and averaged them. The number came out exactly the pinion depth on the gear. So, I would have to say with a little practice this tool can get you pretty close!
Moser ships solid pinion bearing spacers with their 12-Bolt setup kit. That was fine with me because I hate the crush sleeves.



I installed the sleeve with a few shims and started making adjustments to get the proper drag. It took several installations, each taking out a few thousandths to get the bearing drag right.



The holding fixture worked well. I could just put a breaker bar against the cart and run the torque down to check the preload. Even though it took several installs, it went really fast. I used a modified nut with no locking feature so the pinion threads don't get worn out.



Finally all the shims are selected and everything is setup. I took a few minutes to think about how cold/hot I needed to get everything to slide the real bearing on the pinion, since I don’t have a press. I looked up the expansion coefficients online and figured out that I should be able to put the bearing in the oven at 300F and cool the pinion down with some dry ice. I wasn’t sure how cold I could get the pinion, so I just assumed around -30F. Should be possible to get it colder but I was just guessing a little. Sorry about the geek stuff but here is the spreadsheet I used. Actually it was a fun learning refresher and I realized I need to ask for an infrared thermometer for Christmas so I don’t have to guess at temperatures!



The bearing in the oven and the pinion in with the dry ice.




The bearing slipped right on. I just held it down with some pressure until the temperatures started to equalize. We do this at work with liquid nitrogen so you don’t have to heat the other part. But I don’t have any liquid nitrogen at home.



I cleaned up the housing really well prior to assembling it for the last time. There was some loose scale inside the tubes from welding on the outside. I ran a hone inside the tubes just to break all the loose stuff off and then hosed it down with mineral spirits and hot water to clean everything.




The last little bit of work was to shorten one axle. I knew from pre-assembly that it was just a touch too long. Moser suggests using a chop saw. I taped up the bearings really well and then cut it off carefully with a .040 cutoff and the Makita. It only took a few minutes.



I forget to plug the gun-drilled hole and made a real mess inside. I ran some rags and mineral spirits inside and finally got it clean. Lots of junk came out. I realized that I really hadn’t checked the other axle and it had quite a few metal chips inside from gun drilling. So I am glad I looked them both over before slamming it together. This is just some of the junk that came out.



It was really nice to have the whole thing done. No part of this is particularly hard it just takes a lot of steps to get there.



I decided to put it back in the car. The dolly worked out well by positioning it close. I still had to move stuff around with the floor jack but it was an easy one man job. It looks pretty nice in there!




Overall, I was able to re-learn some things I hadn’t done since the 80s. I am happy I did it but if I ever blow this one up, I will probably buy the next one to save some time!!

Here is just a short refresher on how to setup the 12-bolt in case you are reading this to get some setup ideas.

1. If you don’t have a really accurate depth tool, I suggest to make a setup pinion bearing. Sand the inside to get a slip fit but not too loose. Grind evenly so it is centered. There are videos online where people show how to do this properly. Use either a new bearing, or lightly used bearing so the height is the same as your new pinion bearing. Measure to be sure so the setup distance is the same.
2. Start with the shims from the old gear set, or something around .032.
3. Check the pinion depth
4. Set in the differential and adjust the shims where it taps in with medium effort.
5. Check the pattern. If it is close then set the backlash and recheck.
6. Adjust pinion depth as needed. Each pinion depth change means re-shim the differential.
7. When it is all final then press on (or use temperature) to put the new pinion bearing on for the last time. Don’t use a really high temperature or the bearing hardness will be affected.
8. Set up the pinion bearing preload and install the seal and torque the pinion flange nut.
9. Double check the pinion drag.
10. Add about .010 to .012 extra differential shims (split evenly on each side) and tap in the differential. It will take some effort this time and you won’t be able to easily pull it back out.
11. Double check the gear pattern and backlash. Nothing should have changed.
12. Button it all up.
13. Have a beer !

[waynieZ]

Nice !

[SlowProgress]

I finally got out in the garage after a couple months off. Home repair projects are the worst hobby killers. Ramping up slow but made some progress on raising the tunnel. Took a while to find my build thread for the small update because it was so many pages back. I need to remember to keep it fresh the rest of this year.
I had 1.5 inch strips tacked on but substituted 2-inch strips and I think the height is closer to what I need.



I used my poor man bead roller to sort of match the original factory bead near the floor seam.





I trimmed the edges clean to line it up on the welding table and tacked it on.





Did the same thing on the other side. It went pretty fast.



I plan to use the original style console so I set my beat up old console in there to make sure it all fits.



Now I need to do the hard stuff, work on the rear transition back down to the original tunnel height and the front transition into the firewall. I will also cut a larger hole in the top to be able to access the shifter cover. There is still a lot to do but it was a good few hours of easy work to get me fired up again.

[KPC67]

Great update! what about raising the remainder of the drive shaft tunnel? You would have to think about your rear seat of course if going with one.
just a thought you might already have a way, and a better one to boot.
I enjoy your build progress!

[SlowProgress]

Yes, I am keeping the back seat. I have seen this done many different ways so my approach was to start with dirt simple and see if that works. If it tilts down front-to-rear it could make the console look funny, so keeping the original angle seemed best with a stock console. I still may need to split and widen the tunnel at the rear to ease the transition. It is probably time for some paper templates and try to figure out what looks the best. I am probably more worried about the front bell area due to all the compound angles and difficult access.