What are you guys doing for a posi unit if you are keeping the 7.5 inch 10 bolt? Looking for something to use in my Skyhawk.
Cheapest thing I found was a powertrax http://www.powertrax.com/ I use it in my 350 4-speed Sunbird,very strong unit,snapped an axle off drag racing and it didn't even scratch it
Here is what I did to my Monte Carlo SS: My car is not a foctory "posi" (g-80) car. But I have found, as well as others, that many s-10 trucks and Blazers have the same rear end as the Monte, only for leaf spings. Being fed-up with loosing traction because of an "open" rear, I decided to look for the code "G-80" in the Blazers and s-10 pickups. I have found about 60% of them have a posi. Late 80's seem to be the best bet for them. They have the same 7.5/7.625 26 spline carrier as the g-body, so it was no trouble for me to find one. I spent sunday morning scouring Copher Bros. u-pull it in Tampa and found an 88 s-10, four banger with automatic trans, with the "G-80" code on the s.p.i.d. sticker in the glove box. Who would have thought? Rotating the drum did not tell anything because one wheel spun forward, and the other spun backwards. I thought that was odd, but decided to remove the cover and investigate futher. Don't be fooled if both wheels don't spin the same direction because the Gov-Lok unit installed in some vehicals do not have pre-load on the cluthes. After removing the cover I found this unit had the 3.73 gears (what I have) and it was also a 26 spline, (what I have),It was also a GM Gov-lok unit with little wear because it was only behind a 4cyl. There was still plenty of pre-load on the carrier bearings which required me to use an axle to pry the thing out. It's very important to save all the pieces such as the carrier bearing races, and pre-load shims, and keep them on thier same side as they will be needed later for the re-install. There was very little wear on the bearing races, the ring gear was of no use to me, because I would be using the one out of my car, so it was good to go. I paid $60 including thier stupid core charge, not bad I thought. The install Monday afternoon I put the back half of the Monte on jackstands, and pulled the cover on my original rear-end. Fluid was ok, I think it was orig., with 158k miles. Next was to remove the retaining bolt for the cross pin. Easy I thought, since the one from the salvage yard came out like a piece of cake. On tug, two tug, three tug and SNAP! The cross pin retaining bolt that should take less than a min. to remove, snapped half way in it's bore with 2 threads still holding it. &$#@! were my words of choice! Now I'm already past the point of no return, it's going to take some destruction to get the retaining bolt out so I can remove the cross pin, Because I can't put it back together now with half a retaining bolt, should I have chosen not to go further. I have found a very clever way to get it out. Drill a hole trough the carrier 90 degrees directly above the retaining bolt to get access to the threads. I used a 3/8 drill bit, and driled till I hit the retaining bolt and kept going half way through the retaining bolt. I could now rotate the retaining bolt with a screw driver and remove. The prosses took about 30 min. The rest of the removel went without a glitch. After cleaning out the metal shavings in the housing. I did a "mock-up" install of the posi unit without the ring gear so I could measure the carrier bearing pre-load. I decided to first try the shims that came with the Gov-Lok from the s-10. Tight it was to slide in, but took about the same amount of force to push into the saddles as it did to slide out of the s-10. Good, now I tourqed the caps on and spun the carrier by hand, it rotated smooth, with some resisance, I have no tools measure this resisance, but it felt "right-on" to me. Back out it came, installed the ring gear from the Monte on to it, and re-install into the saddles to check the backlash. Carefully tapping the unit into place with a wooden happer handle, and being carfull as not to bind the pinion with the ring gear, it slid back into place. Torque the caps, put some precsion blue (machine dye) on the ring gear, and rotate to check the contact pattern. Son of a Gun! it was dead on where it was before, I could hardly believe it, but was thankful no adjustments were needed. My theory is that GM must pay close attention when maching the diff housings. Dean
Power Trax and Gov Lok Thanks Harry. I had no idea that the power trax was so strong. I only know one person who has used one and he was not happy with his. Dean, quite a story! Do you race the Monte? How has the Gov-Lok performed? Anybody out there using the Auburn posi?
i have heard that the auburn isn't that strong. i don't think the gov lock is a good race choice based on what i have read in different places. i think that eaton makes a "posi unit" for the 7.5. also usually you re use the stock shims that are from the rear end housing in your vehicle. the machining tollerances are usually off in the housing. the carriers are usually right on especially if they are both gm (old one and replacement one) always check the backlash reading with a dial indicator. spec can be found in a gm manual. if getting a used carrier always keep the side bearing shims. you can get a service pack of shims but they aren't as good and nice to work with as the factory ones. and it is always a good idea to run a pattern after rear end work. gm sells gear marking compound to brush on. the manuals have a diagram of what the contact pattern should look like. usually not effected unless you mess with the pinion gear. it can get complicated but i worked for chevy for 2.5 years and that is one thing i made sure i learned. good luck.
Thanks for the reply, Paul. I guess nothing for the 7.5 is really that strong. The Eaton unit is only available in a 3 series carrier. I plan to run a 2 series. Matter of fact, i just won a 2 series Auburn with a 3.08 gear on Ebay. We will see what it looks like when it gets here. I am also planning on running a rear end girdle. Hope it holds up! Thanks to all for your replies and experiences.
cacmanjr, I have raced the SS on the track with the Gov-lock many times, it does a great burnout all the time. And traction is super compared to no "posi" at all. I drive it on the street hard too. Just one thing to remember with the Gov-lock is don't throttle real hard if one tire is on very slippery surface, it could break the lock mechanizm in the diff. Heck, for the money I ahve in it, if it breaks, I'll just go get another one for the junk yard again. Dean
I can appreciate the thought, Dean. The 7.5 stock type stuff is cheaper because most people move up to something stronger. In my case, there is no direct replacement for the 7.5 in the Skyhawk. The torque arm Camaro stuff comes close but still requires a lot of mods. Hopefully with the girdle and a decent set of axles, it will suit my needs. Thanks again for the reply!
7 1/2 rear I have used a Alburn Posi in my S-10 for 98,000+ miles, and have one in a Regal with sbb. No problems to this point. I like it that both wheels move from the getgo. 88 plus S-10 use a 28 spline axle which will slide right in your Skyhawk rear and also give you a 5 bolt pattern. For more look at MonzaV8/com. Diver
