I have a true 12 bolt in my 69 GS which was built in Canada. Has 3.07 non-posi right now. I purchased a used 3.55 ring and pinion and want to also install a good posi. Was thinking a truetrac. I don't have enough money to have someone else intall this stuff before spring musclepalooza and was wondering how hard it is for a mechanically incline person to install this stuff on their own. Any tips appreciated. Bear in mind, I've never been into a rear (in any way shape or form p ) so this is a first for me. I would need to know any tips and what tools I would need. Thanks.
Ken, all enthusiasm aside, I wouldn't try a new ring, pinion & carrier install without someone looking over your shoulder who's done it many times before. While with keeping the same gears but switching carriers you usually only have to worry about tooth backlash and carrier bearing preload, to do both carrier & gears throws in pinion depth as well. I'd at least look into DVD or other video tutorials available to see what you're up against and the tools needed. Devon
Thanks Devon. I think some online tutorials are definitely in order. And would I need to replace a carrier (what part exactly is that? o No: ) if I am putting gears from a 12 bolt into a 12 bolt?
Watch this video to see if you feel like taking on this project: http://smartflix.com/store/video/1356/Differential-Rebuilding Get in touch with Jim (Monzaz) for parts and questions too. Down here I'm hearing between $100-$150 to set up a rear-end package. Haven't decided yet, but it could be cheap insurance considering what could happen if I do it myself.
The carrier contains the differential spider gears, side gears, cross shaft and if posi, friction plates. It's the cast iron piece that the ring gear bolts to. If you replace the open carrier with a posi carrier and a different gearset, you have to treat everything as a fresh install due to machining tolerances between the one carrier and the other. Devon
Ahh, gotcha. This seems like something left to someone who's done this before I'm thinking? :idea2: So when I buy a posi for an open rear, what parts do I still need (gears aside if I were to change the gears)?
I'm not sure what all comes in kits these days, but you'll need new carrier and pinion bearings, crush sleeve, pinion seal, maybe a new pinion nut, carrier bearing shims to adjust bearing preload and backlash, pinion depth shims, new ring gear bolts are a plus, cover gasket, gear marking compound to check pattern, bearing assembly lube, posi additive. Specialty tools include pinion depth gage, dial indicator, inch-lb torque wrench, bearing race press & remover, and probably other stuff I can't remember at the moment. Devon
here in Canada,an overhaul kit (bearings,crush sleeve,shims,etc) is about $120.00.i like using ARP ring gear bolts for about $30.00.the proper tools are expensive. i usually charge $200.00 to assemble a bare housing.
I purchased a complets set of parts (kit) for the rear end from monzas for my '72 gs. I also bought a new eaton posi from him. I then paid a local tranny shop, that i trust, to overhaul the differential (no gear change). That included all the bearings, seals, races, etc., + universal joints. My cost for labour and shop supplies was $500 + tax. To me, it was money well spent.
Ken, if you are mechanically inclined, it is not that hard to do. Study up first. You will need the Posi carrier, and it will replace your "open" non posi carrier. the Ring gear bolts to the carrier. I just bought supplies from Jim (monzaz) for my 72 convertible I am building the rear for. He has a kit that has the carrier bearings/races, shims, crush sleeve and other stuff you need. There are a couple of tricky things in the set up, in my opinion. You have to set the backlash, and to do that correctly, you may have to change the shim on the pinion gear. Pinion bearings are pressed on, so I ground out an old pinion bearing so I could slip it on and off the pinion to get the correct shim. You have to measure your backlash and gear mesh pattern, and will use shims on both sides of the carrier bearing races to get the carrier in the proper position. You have to tighten the pinion gear nut down to crush the crush sleeve and that is tough to do. I use a plumbers wrench to hold the yoke, and a breakover bar with cheater to get it torqued down to proper resistance. You can do it, just read and study, ask, Monzaz is a bunch of help also. Good luck!
OK a few issue here with this video...lol. FIRST OFF NEVER DROP A CARRIER INTO THE HOUSING NEVER! They have just smashed the bearing into the races and dented them scratched them etc. BAD MOVE! ou: NEXT- YOU press on a pinion bearing you do not HAMMER IT WITH A DRIVE PIPE! another NOT SO GREAT IDEA more messed up parts coming right up!...lol. ou: ou: SAME deal with the outer bearing NO hammering use the yoke to pull the bearing in. ou: ou: ou: ANYWAY thye make it look so nice and clean and easy ion TV do not be fooled give your self plenty of time and space to do the job. YES you can do it but NEVER under estimate any JOB! Just my 2 cents so you can have a smooth rear diff set-up. Jim
Depending on the level of mechanically inclined you are, its pretty straight forward and logical. A rebuild kit is a must, as is a magnetic dial indicator. An extremely clean work place with a large enough area to work. You can't be too clean when it comes to rebuilding a differential. One grain of microscopic sand behind the ring gear, and you'll be rebuilding the diff again real soon. DVD's, books, and if you have a friend that is mechanically inclined is a great help too. When rebuilding a differential, you have to be exact. Close enough is not going to last. The rebuild kit will come with a new pinion nut that can only be used ONCE. If you torque that nut down and need to remove it, you need to buy a new one. I will use the old nut to find the correct clearances/backlash ect,but the new nut gets used once. Once you assemble the rear end and get it back into the car, you need to baby it for the first 500 miles and avoid hard accelerations and driving at a constant speed for more than 10 minutes at a time. I generally avoid the freeways for the first 350 to 400 miles and then change my speeds every 5 mins Like 5 miles per hour at a time and try to avoid 2 of the same speeds. I know tis sounds over the top, but it's a good practice. Lastly, once you get it back o the road, if you did it correctly, your diff should be very quite, no humming, clicking, banging (Unless you have a Detroit Locker...they seem to be the noisiest diffs out there. Well there's my two cents. Hope you end up wit a good first rebuild. My first didn't go all that well. I was young, knew everything, and was in a hurry. But you learn and the next one get easer and easier. Good luck!!
I can walk you through it. Since it is a factory posi,and it is a 12-bolt Chevy,I would keep the existing posi unit. That is an Eaton unit,which has clutches,and is rebuldable,and since it sounds like you are on a budget,you can save a lot without having to buy a new posi unit. You will need an install kit,with pinion shins,carrier shins,crush sleeve,nut,compound,etc. this is also the perfect time to rebuild the entire rearend,with all new bearings & seals. You will also want to check the axle shafts,where the bearings ride,to make sure that surface is still good. They can wear in that area,and either require a repair bearing,or a new shaft.
Glad you guys kept writing... I was able to get some good info from Mike and Brian.... Even if it was 4 years after the original post. Lol.
