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70 nova rear end upgrade???

9K views 9 replies 5 participants last post by  Big Dave 
#1 ·
have a 70 nova with inline6, want to start building the car starting with the rear end...then trans...then suspension then engine....it has a 8.2" 10 bolt...eventually i plan to put a 383 stroker or 350 looking to be making around 400hp. Is the 8.2" 10 bolt something i can work with??? i was thinking of one of those detroit locker or eaton differentials...but would that handle the power or do i need to change the whole rear end??? what rear end could i use that wouldn't require modifications, looking for a simple bolt on??? what vehicles can i find them on???
 
#2 ·
#4 ·
Aftermarket 28 spline axles and a 28 spline posi will get you to the max 400 horse capacity of this rear end. It will last forever with street tires, but when times comes for big slicks and a well preped track things could change. An 8.5" 10 bolt would be a better choice as the parts cost the same (aftermarket axles, rebuild kit, and posi), and it is bigger and stronger allowing a 30 spline count axle (about 550 horse when built up).

By the way horsepower is misleading, it is torque that breaks parts not horse power. If you look on line at many aftermarket sites you will see a calculator that you plug in your engine torque, and choice of first gear and final drive ratio to determine what level of spline count you actually need for those back bumper scraping wheelies.

Big Dave
 
#5 ·
oh did i mention i was going to be using a post 88 700r4??? i believe this is a 30 spline...so if the output shaft is 30 spline does that mean the rear end also needs to be 30 spline??? if so...do they have 30 spline axles and differentials for my 8.2" or do i need to step up to an 8.5"??? if so...where can i find one of there where i won't have to modify???? i plan to go from my stock monoleafs to some mulileafs also...
 
#6 · (Edited)
Different spline counts. One is the change in the number of splines were increased in the input shaft of the tranny. Earlier trannies were weak and broke until the modifications were made.

The splines I am talking about are on the ends of the axles were they slide into the differential spider gears. On a stock 8.2 rear end they are 28 splines. On the 12 bolt and the newer 8.5" 10 bolts they use a 30 spline axle which is bigger in diameter than the 28 spline axle. That added diameter increases the strength of the axle as the square of the radius. So a bigger axle is a stronger axle. Spicer 10 bolts use 28 splines, 12 bolts use 30 splines, but if you buy a nonstock aftermarket posi unit you can specify a larger spider gear that has a bigger hole to accommodate a bigger axle. So for the 12 bolt there is a 31 and a 33 spline axle (requires a spool) available as upgrades. But Spicer also built the Dana 60 and it has 35 spline axles stock, and they can be upgraded to 40 splines with a spool. So there are several choices available.


The transmission output yoke is for a TH350 or PowerGlide tranny. If you had either before it will fit into the end of your 700R4 transmission. You may have to modify the drive shaft for length but splines will have nothing to do with it. As to the springs you should buy multileaf brackets (available new from Currie or Moser) and weld them in place of the monoleaf brackets but that would be the only major change.

Big Dave
 
#7 ·
oh ok...so i can use my yoke out of my th350 or powerglide for the post 88 7000r4??? ok...so...do you think it's worth it to change to an 8.5" 10 bolt posi unit now or build my 8.2" 10 bolt??? also..can anyone tell me what cars i can find a 8.5" 10 bolt??? that has leaf springs??? i know the novas and camaros but what else??? would a rear end out of a truck work??? off topic but does anyone know if the crossmember for the powerglide is the same as the th350??? does it have to move at all or stays in the same place???
 
#9 ·
would a 10 bolt rear end out of a 71-81 camaro be a direct bolt in??? would it fit??? i found one with factory posi for $60 locally so...if this will work and is a direct bolt in i'll get it....what do you guys think???????????
No it is not a bolt in. The overall width is longer and the perches are spaced farther apart.
 
#10 ·
It is an almost fit. The perches are to far apart (but if you are going to cut off your old monoleaf pearches and weld on new multileaf perches you could move them inboard to the correct place at that time. That just leaves the one inch too wide part to deal with. That can be accomodated by buying wheels with much less offset (so they look more like modern Corvette wheels).

Big Dave
 
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