I have a stock 79' Monted Carlo rear end in my 80' Regal drag car right now with 3.42 gears and a locker(no posi). I know it isn't going to last much longer so my question is whether you can build up a 10 bolt or they just aren't very strong. I have a 455 big block punched .60 over with a built th400 and I am already running over 6k at the end of the quarter so I don't know if I can go to much hight in gears? What do you guys think?
Contact Monzaz on the board ..he is the rearend guru ...I believe there is some sort of problem getting the gearsets - ......Strength: I have heard the 10 bolts will hang in there awhile so they arent as wimpy as you would think.... J.
yes, the 68-70 8.2 rears are what has the gear problem. he stateed he had a chevy rear, so he'll have no problems! but still conatac monzaz as he has good prices :beer do you know if that monte rear is a 7.5 or an 8.5?
I believe a stock 79 Monte has a 7.5 in it......J . Off the net ... "7.5" GM 10 bolt- stock specs: 7.5" ring gear, 1.438" dia. pinion shaft, 26 spline axles. This rear is the most common housing to be found under any GM G-body car. The rear is called a 7.5 " in reference to its ring gear diameter. For street usage, this rear will hold up just fine. Also, the 7.5 10 bolt can be used for limited drag racing use. Street tires are recommended to limit stress on the "weak" internals. Slicks can be used with a 7.5, but just don't expect it to last very long. A heavy car and a sticky tire are just asking for breakage problems when using the stock 7.5" 10 bolt. The only major aftermarket parts available for this rear are an Auburn posi unit and a limited selection of gears. For this reason, it makes the most sense to not invest allot of money in this rear. If you plan to visit the drag strip on any regular basis, I would consider upgrading the rear with a heavier duty unit. J.
That is what I figured, and by the way it is a 7.5". So what would be the way to go then, find a 12 bolt or go to a 9 inch?
You can bolt in the 8.5 corporate rear from any 71-2 Cutlass/Skylark provided you buy new trailing arms. A 12 bolt Chevy will require the same arms and a Ford 9" will be even more money. The company below carries the correct t-arms for the 8.5" rear installation: http://www.umiperformance.com/
The info on the 7.5 is a bit off. There are many many posi units for the 7.5 rear Eaton, Auburn HP or Pro series. true trac, T2 (torsen posi), Power tracs, lock right, mini spools even detroit locker sell a unit for them. Now onto the gears. they sell 3 series gear from 3.23 - 4.56 and 2 series gear from 2.73-4.56 also and there are TONS of companies making them out there motive Yukon Richmond Accu gear strange and on and on. So I would say parts are not the problem. The only delema is where to spend your money wisely for what your going to do. Like stated drag rear rear it is not. It will perform well for hot rodding around town and limited drag action as long as you stay away from high stall over 3000 grand and clutch dumping standeard shift trannies. Best upgrade if you are having to keep your car 7.5 is to increase the axle shaft diameter from 26 splinr to 28 and get a posi unit with bigger and better designed spider gear cluster like eaton dura grip or use a power trax type unit that eliminates the spiders all togehter...BUT please buy the power trax lock right etc units NEW and installthem with the instuctions given. I see more of those unit used and they are junk buy misinstallation. THEY work great when install correct for drag racing. I am also working on custom build 8.5 rears if I can get someone to build my upper control arms I need. trying to build units we all can afford these days right under a grand for a super strong 30 spline posi rear for a g-body car. 1978-1987. Jim
Appreciate all the info, I decided to go with a custom 9". It is expensive but it will probably be the most indestructible rear that I can put in it.
I hope you go with a after market center section too or the 9" a'int gonna be any stronger than that 7.5. Hope you do your home work before buying. Jim
