GM 7.5 10 bolt Questions.

[MrSony]

Yep you should check them out. Any thing you need to build a race car he has or can get for you. Doug was a huge help in us building dad's prostreet big block vega. A lot of custom parts went into that build. There usaly some neat projects sitting around his place. I have not been to his new location in town yet. Not open on the weekends though. If you you do build a rearend and run into trouble I can come down and give you a hand if needed. I have rebuilt quite a few differentials, from 10 bolts to Cat payloaders.

Cool man I'll keep that in mind.

 

[Bonnewagon]

Chris- very generous move posting that manual download! Now THAT'S a moderator! I have my own theory about the 7.5" rear. It is not as weak as people think. I have found that every rear I know of that failed, it was because we were trying to push dead gears with a big motor. That goes for the 8.2" and 8.5" rears as well. By that I mean we stuff a big huge motor with all sorts of hot rod parts into a car and then fail to put better gears out back. Mostly because it's expensive and a big job. Lots of cars come with 2:41 gears stock and those are the worst of all. Just changing to 3:08, 3:23, or 3:42 gears takes a tremendous strain off the rear and allows the car to accelerate properly. Imagine you are riding a bicycle up a hill. In first gear you can pedal effortlessly. In tenth gear you can't hardly move at all. The more you grunt and groan against the pedals, all you will do is break spokes. Same logic works with the car. As for strength, I had an '81 Malibu wagon that I swapped a Pontiac GTO 400 w/4 speed manual into. I had 3:23 gears and a Guv Lock carrier 7.5" rear. Weak, right? Wrong. That set up lasted 10 years of my abuse and I was not easy on it at all. That same rear is in my 301 powered Bonnewagon right now. It is dead stock, but the 3:23's take all the strain off the rear and it revs effortlessly. Would I drag race a 7.5"? NO! As always- fit the punishment to the crime.

 

[Opie Knievel]

Chris- very generous move posting that manual download! Now THAT'S a moderator! I have my own theory about the 7.5" rear. It is not as weak as people think. I have found that every rear I know of that failed, it was because we were trying to push dead gears with a big motor. That goes for the 8.2" and 8.5" rears as well. By that I mean we stuff a big huge motor with all sorts of hot rod parts into a car and then fail to put better gears out back. Mostly because it's expensive and a big job. Lots of cars come with 2:41 gears stock and those are the worst of all. Just changing to 3:08, 3:23, or 3:42 gears takes a tremendous strain off the rear and allows the car to accelerate properly. Imagine you are riding a bicycle up a hill. In first gear you can pedal effortlessly. In tenth gear you can't hardly move at all. The more you grunt and groan against the pedals, all you will do is break spokes. Same logic works with the car. As for strength, I had an '81 Malibu wagon that I swapped a Pontiac GTO 400 w/4 speed manual into. I had 3:23 gears and a Guv Lock carrier 7.5" rear. Weak, right? Wrong. That set up lasted 10 years of my abuse and I was not easy on it at all. That same rear is in my 301 powered Bonnewagon right now. It is dead stock, but the 3:23's take all the strain off the rear and it revs effortlessly. Would I drag race a 7.5"? NO! As always- fit the punishment to the crime.

Thanks Mark. No problem. I figured it would help some people out. I know it's been pretty handy having a full service manual on my phone. It's a lot easier to carry than the real one! There are a lot of people on here who would have done the same for me.