IzaguirreZ28

im trying to gain more car knowledge..... and I wanted to know what is the point of going from a 10 bolt to a 12 bolt rear end ? What is the significance of it ?

FirstYrLS1Z

iTrader: (4)

a similar recent thread

https://ls1tech.com/forums/gears-axl...25-c-clip.html

01ssreda4

iTrader: (96)

12 bolt is bigger/stronger plain and simple. No other real reason.

BrntWS6

iTrader: (7)

Since GM was too f'ing cheap to put a decent rear in our cars we have to pay a lot of money to correct the problem. Especially if you modify your car. Great for the aftermarket but I would have loved to save 4k and put it toward coke and ho's.....or a turbo.

01ssreda4

iTrader: (96)

If GM was spending a fortune replacing 10 bolts under warranty, they would have given us something better.....but they weren't, so they didn't. Its a numbers game. They don't care that we have to upgrade the rear end if we want to mod the cars. At the end of the day if you're serious about modding, you'll replace most everything in your drivetrain anyway so its really a mute point.

Delfygo

iTrader: (2)

Not to thread jack but somewhat goes with this one, I'm looking at putting in some 3:73's in my stocker for now until a moser 12 bolt is saved for. Question I have was looking at motive gears and see summit has a street & strip set of their own make. any one have a preference on gear make for a 10 bolt? Looking for a quite dependable set of gears, and any experience with the summit brand

BrntWS6

iTrader: (7)

Of course they didn't care....they went with the cheapest rear they could throw in the car. All your points are obvious....just complaining Cruz I upgraded to a 9" recently and it was more then my entire H/C/I setup. The mod bug is a bitch.

JakeFusion

iTrader: (7)

Agreed. The aftermarket rears cost more than built shortblocks or upgraded transmissions. It's stupid. On a Vette you can get an upgraded IRS for less. Ugh.

01ssreda4

iTrader: (96)

I've installed one set. They whined like hell. Every set of motives I've put in have been silent or near silent. Word around the campfire years ago were they were reboxed Richmond's, Richmond known for being a little noisy so it made perfect sense. Now, the word is motive purchased Richmond and moved production to the motive plant. So, what are you buying when you buy summit gears? New motives or old stock Richmond's? Who knows. Not worth the gamble to me.

01ssreda4

iTrader: (96)

Oh BTW, you have two options for your car from Motive. GM75373 is their blue box street gear, should setup very quiet and I've always had good luck with them. G875373 is their orange box performance gear and are known to be more picky as to how they are setup. The alloy (harder and more prone to noise) and the gear cut (more aggressive cut and more prone to noise) may be different as well. I've run and still run the orange box motives. They have slight whine from the 45-55mph range but I don't care.

1 FMF

iTrader: (1)

first understand that "10-bolt" is a slang term referring to the small solid rear axle used in the 4th gen f-bodies, the s-10 pickup, and i assume a few other gm platforms going back into the 1980's. It's called that because there are 10 bolts holding the differential cover on. There are many other axles out there having only 10 bolts holding the differential cover on. so....

the gm 10-bolt has a 7.5" or 7.625" ring gear size. It's mainly the size of the ring gear which determines the strength of rear axle. The larger the ring gear, the more steel, the stronger it is, along with a similar increase in pinion gear size. I believe the 7.5" gm 10-bolt is the smallest axle out there, but i could be wrong.
Some other axles:
- the ford 8.8" in ford explorers, 8.8" ring gear. you'll see some posts in here about converting them to work in the f-body.
- the gm corporate rear axle in 2500/3500 trucks, have a 10.5" ring gear and are known as the 14-bolt.
- the AAM 11.5" ring gear in the 2500/3500 gm trucks with diesel engine or 8.1L gas engine. have it in my truck, forget how many bolts on diff cover but i believe it's less than 14. so don't go by the number of bolts on the diff cover as a way of determining axle strength.
- there's also the ford 9", and then Strange Engineering has their S60 axle which is a direct drop in axle for the 4th gen f-body which uses a 9.75" ring gear and i believe the S60 has 10 bolts on its differential cover.

i honestly forget the specs on the gm 12-bolt. it is however better than the gm 10-bolt. my suggestion is google some of the terms above,

http://www.chevyhiperformance.com/te...nd_comparison/

the purpose of going away from the gm 10-bolt, basically to any other axle which is bigger, is for strength. the gm 10-bolt because of it's crush collar pinion sleeve setup is notorious for not last lasting over 100k miles especially if it sees any power put through it. the pinion seals often leak, and because the ring gear is so small is generally noisy even when new gear sets are installed. a lot of people have problems even putting a new 7.5" gear set into the 10-bolt and not getting them quiet. the 10-bolt also has smaller axles which is another weak point.

attached is a pic of the pinion gear which sheared in the rear of my '99 camaro. i still have it sitting on my desk at work.

1 FMF

iTrader: (1)

i think it's safe to assume gm designed this axle way back when engine horsepower/tq ratings were fairly low, under 300 hp on a good day. the gm 10-bolt was used all through the 3rd gen f-bodies with the LT1 engine, not sure what it's track record on that platform was compared to the 4th gen fbody with LS1 engines. but with the 300hp rating of the LS1 on pretty much any day, the 10-bolt axle became too weak in general for the 4th gen fbody application. add to that people take these cars to the strip and launch them on good tires you're simply going to break the rear axle.

looking at it objectively: was gm too cheap to put a good axle in the 4th gen? sure, but they're a company making money so what do you expect. under "normal" driving conditions the 10-bolt will last 3yr/36k miles so why bother design or even try to use a different axle in the 4th gen f-body from 1998 when it was basically known that platform had it's last model year slated for 2002.

murphinator

iTrader: (2)

to expand a bit more on the "10 bolt" , back in the 60's through I believe 1972 the 10 bolt rear was 8.2" , then in 73 instead of offering the 8.2" 10 bolt and the 12 bolt GM came up with the "corporate" 10 bolt that was 8.5" ring gear and came in variations with c clips or with bolt in axles to replace both the 10 & 12 bolt , they were in everything from f bodies to chevelles , to full size cars and 1/2 ton full size trucks they could take a pretty good pounding , the corporate 8.5 is what the grand nationals had in them and many of those cars retained the 8.5 10 bolt right down into the 9's & 10's. The 3rd gen fbodies had the 7.5 or 7 5/8 as well as s10 trucks , monte carlos including ss and many other cars - too bad gm didnt put the 8.5 recast for a torque arm provision in the 4th gens with bolt in axles....

1981TA

iTrader: (7)

1981 was the last year an 8.5" 10-bolt came in an F-body, and like Murphinator says, it came in a bunch of stuff after that. Too bad, not the 3rd and 4th gens though. If memory serves me right, I think they were all C-Clip style axle retention, unless you modded them to take bolt-in axles.

Bob@BruteSpeed

iTrader: (16)

http://shop.brutespeed.com/Brute-Spe...nformation.htm

I have put together a lot of info at the link here that may help you out. Bob

MikeWS6

I really like the Mid West 9". Looks like they shed off a bit of weight. What did you pay like $3000??