Justify a 9" rear end
Justify a 9" rear end I'm going back and forth about whether or not to get a built 9" for my Nova. Right now it's got an 8.5" in it that I'm going to have to put gears and a posi and probably axles in anyway. So with my potential power levels, would it be a necessary investment to get the 9" instead of even worrying about the 8.5"?
I won't be drag racing the car a lot, and I won't be running anything more than drag radials way down the road, and I'll never run a tranny-brake.
It's looking like either a $1000 investment or a ~$2500+ investment.
I won't be drag racing the car a lot, and I won't be running anything more than drag radials way down the road, and I'll never run a tranny-brake.
It's looking like either a $1000 investment or a ~$2500+ investment.
Teching In
Joined: May 2010
Posts: 21
Likes: 0
Since you mentioned drag radials I say spend the money and don't stress. "You'll never break a 7.25 Mopar rear with a little 318" they said. I broke 2 of them and upgraded to an 8.25. "You'll never break a 8.25 Mopar rear end with a mild 360" they say. I am suspicious and upgrading to a Mopar 8.75 before I blow up anything else. Consider it insurance against having to pay to have your car towed home.
See if Bruce can get you a factory 8.5 limited slip. They have steel clutches and are very strong. Don't run synthetic fluid with it.
BPonti442@aol.com
I have done several 6 second or 10 second passes with mine. I am going into the 9s so I will be upgrading to a nine inch. If I was staying with just 600 or so horsepower on radials with auto, I would be sticking with the 8.5. The 8.5 replaced the gm 12 bolt, and has many components just as strong. It is not the same as other gm 10 bolts. I'm also running a factory 3.42 ring and pinion which seems to be meant for the LS swap.
BPonti442@aol.com
I have done several 6 second or 10 second passes with mine. I am going into the 9s so I will be upgrading to a nine inch. If I was staying with just 600 or so horsepower on radials with auto, I would be sticking with the 8.5. The 8.5 replaced the gm 12 bolt, and has many components just as strong. It is not the same as other gm 10 bolts. I'm also running a factory 3.42 ring and pinion which seems to be meant for the LS swap.
Last edited by futureuser; Nov 18, 2014 at 11:35 PM.
If you going to rebuild and put new parts in the 8.5" .. use the 30 spline posi and axles and you should be good. Add a re-enforced cover.
Correctly build with the stronger 30 spline stuff.. cars have been known to dip into the 8's with the 8.5".
I have a 8.5" in my Nova, throw in a Eaton Posi, Richmond 3:73 gears and Stange HD 30 spline axles.. I am pertty sure it well handle what ever I will throw at it.. some 1/4 miles blasts at Sonoma, to Auto-Xing and canyon carving to long drives out of town. The light weight and less power to turn them can be a plus.
Don't dismiss the 8.5" if on a budget or for some heavy thrashing.
But if you need to step up.. yeah.. 12 bolt, Dana 60 or the ford 8.8" or 9" are all good.
I forget, but there is a Dana 60 from a donner that is the correct width as your Nova, got a buddy that put one in. If I can get a hold of him.. I will get the make and model of the Dana donner. It will be cheaper than a 9" setup.. and less of a power robber than the 9".
I have also read that you can pull the posi and gears out of a later model truck (S10 ?) and can fit into the older 8.5 housing. Can be an budget up grade.
BC
Correctly build with the stronger 30 spline stuff.. cars have been known to dip into the 8's with the 8.5".
I have a 8.5" in my Nova, throw in a Eaton Posi, Richmond 3:73 gears and Stange HD 30 spline axles.. I am pertty sure it well handle what ever I will throw at it.. some 1/4 miles blasts at Sonoma, to Auto-Xing and canyon carving to long drives out of town. The light weight and less power to turn them can be a plus.
Don't dismiss the 8.5" if on a budget or for some heavy thrashing.
But if you need to step up.. yeah.. 12 bolt, Dana 60 or the ford 8.8" or 9" are all good.
I forget, but there is a Dana 60 from a donner that is the correct width as your Nova, got a buddy that put one in. If I can get a hold of him.. I will get the make and model of the Dana donner. It will be cheaper than a 9" setup.. and less of a power robber than the 9".
I have also read that you can pull the posi and gears out of a later model truck (S10 ?) and can fit into the older 8.5 housing. Can be an budget up grade.
BC
Last edited by bczee; Nov 19, 2014 at 12:13 AM.
Not the S10, but the full size trucks. The problem is the limited slip or posi unit is not nearly as good as the 28 spline early unit. An aftermarket 30 spile unit might be better than the original early 28 spline units, certainly better than late models, but I'm not convinced, especially with composite clutches.
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TECH Regular
Joined: Oct 2011
Posts: 408
Likes: 4
Ford explorer 8.8 is your answer , for a nova or camaro , 1st gen that is ,while you are at it grab an additional passenger side axil ,I think its 3 inches shorter than the drivers side , cut and paste the drivers side tube of the diff , and you have a perfect length rear for a mini tubbed car , that is 2 inches on each side , allowing for 315 tires in the rear [easly] , total cost involved is where I got the kit for my 68 camaro , I 4 linked mine , you can use your leafs with some modification .
The 8.8 in an explorer comes 2 basic ways 373s on a 2 wheel drive , or 411s on a 4 wheel drive , make sure there is an L on the diff tag , that stands for locker ,, its about the only good part on an explorer , yards are full of them ,, you get 31 spline axils ,bigger gears than a 12 bolt gm ,and disc brakes if its 96 or newer , I paid 115 for the one I put in the camaro with complete brakes and the axil I needed
The 8.8 in an explorer comes 2 basic ways 373s on a 2 wheel drive , or 411s on a 4 wheel drive , make sure there is an L on the diff tag , that stands for locker ,, its about the only good part on an explorer , yards are full of them ,, you get 31 spline axils ,bigger gears than a 12 bolt gm ,and disc brakes if its 96 or newer , I paid 115 for the one I put in the camaro with complete brakes and the axil I needed
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Verdad Gallardo This is all a lot of really good insight.
My car is turbocharged, so gear ratio is important.
Also, I'm probably only going to be running around 400-500 hp (I think) for the time being, with a maximum of 800 in the end.
The plan is for the car to be more of a pro-touring car rather than a drag car. I want just a great driving car for the street.
What I'm also worried about is the posi-trac. How durable are these units and what brand do you buy?
I've run two Powertrax No-slip lockers "soft-lockers" in two different g-bodies, and I really like them, as long as they don't end up on ice on an incline.
I've just never run a posi before, so I figured I'd give it a try.
Right now I've got a shortened stock driveshaft and a stock 8.5". I feel like a decently built 8.5 will handle all the street abuse I want to throw at it with the few strip passes also.
I'm figuring a girdle cover, axles, gears, bearings, "posi", and maybe an axle tube brace like this and I feel like it will be fine.
Is this wrong?
My car is turbocharged, so gear ratio is important.
Also, I'm probably only going to be running around 400-500 hp (I think) for the time being, with a maximum of 800 in the end.
The plan is for the car to be more of a pro-touring car rather than a drag car. I want just a great driving car for the street.
What I'm also worried about is the posi-trac. How durable are these units and what brand do you buy?
I've run two Powertrax No-slip lockers "soft-lockers" in two different g-bodies, and I really like them, as long as they don't end up on ice on an incline.
I've just never run a posi before, so I figured I'd give it a try.
Right now I've got a shortened stock driveshaft and a stock 8.5". I feel like a decently built 8.5 will handle all the street abuse I want to throw at it with the few strip passes also.
I'm figuring a girdle cover, axles, gears, bearings, "posi", and maybe an axle tube brace like this and I feel like it will be fine.
Is this wrong?
TECH Apprentice
Joined: May 2010
Posts: 372
Likes: 8
From: So. WIS
Broke my 8.5 in an El Camino SS w/ a built LT-1 small block. Separated the axle tube from the carrier casting. Was pushing about 400 hp. This is the same rear as in the Nova. Upgraded to the 12 bolt unit from a Chevelle.
Your best bet is a 9". Tons of aftermarket support, and still millions in the junkyards and farms. Next would be the 8.8 Explorer previously discussed. If you go the built route, be sure to have the axle tubes fully welded to the carrier.
You are somewhat limited on gear ratios. Most Nova's came with 3.08 or 2.73 ratios (assuming V8). The I-6 cars had steeper ratios, but tend to be weaker.\
BTW - Drag Radials will hook up. I broke a Muncie 4 speed on my Stage 1 GS when the car hooked up. HP is addicticting, so build something stronger to save the aggravation of a busted car on the flatbed!
Your best bet is a 9". Tons of aftermarket support, and still millions in the junkyards and farms. Next would be the 8.8 Explorer previously discussed. If you go the built route, be sure to have the axle tubes fully welded to the carrier.
You are somewhat limited on gear ratios. Most Nova's came with 3.08 or 2.73 ratios (assuming V8). The I-6 cars had steeper ratios, but tend to be weaker.\
BTW - Drag Radials will hook up. I broke a Muncie 4 speed on my Stage 1 GS when the car hooked up. HP is addicticting, so build something stronger to save the aggravation of a busted car on the flatbed!
On The Tree
Joined: Sep 2012
Posts: 184
Likes: 0
If you decide on a 9in, call JD race and restoration. Ask for Jim. Fantastic prices and customer service. Just ordered my Moser 9in, 35 spline axles, spool, nodular iron case, 350 gear. This is going in my street strip 64 Belair turbo build. 9in= a piece of mind....
Thanks. I've already got a good contact to build my 9". I'm just trying to justify the 2-1/2 times as much money for it.
