Pros/Cons of 12 bolt/9 inch/8.8 inch ...
11-15-2003, 06:44 PM
#1
Pros/Cons of 12 bolt/9 inch/8.8 inch ... A few weeks ago, I snapped my driveshaft U-joint which made me start thinking about my rear end. I have searched this entire forum for good info on them and everyone seems to be very biased towards what they have.
Basically, I want a reliable rear-end, that will not be a huge PITA to install, and will withstand a 500+ rwhp car, with DR's. This will be going on my daily driver, but also brought to the track a few times per year.
What are the (unbiased) pro's/con's of each different type of rear end as far as reliability, strength, possible problems, cost, etc.
Thanks guys ...
Basically, I want a reliable rear-end, that will not be a huge PITA to install, and will withstand a 500+ rwhp car, with DR's. This will be going on my daily driver, but also brought to the track a few times per year.
What are the (unbiased) pro's/con's of each different type of rear end as far as reliability, strength, possible problems, cost, etc.
Thanks guys ...
Last edited by xphantomws6x; 11-17-2003 at 11:15 PM.
11-16-2003, 11:23 AM
#3
A very well traveled topic... 
12 bolt = Hey, it's Chevy! Strong enough for what you stated. More efficient than a Ford 9 inch due to the relative position of the pinion gear on the ring gear(chevy's is near/at middle, while the 9" is down lower on the ring gear)
Ford 9" = Strong as hell, not only because of the lower pinion gear placement(more tooth area is utilized when the gears mesh) but it also has a additional pinion support on the end of pinion. Normally slightly heavier than the normal 12 bolt. The *real* beauty/value of the 9" in my experience is the ability to swap out the third members for different tracks. Racing a quarter mile? Put in your 3rd member with the 4.10's. Racing at the 1/8th mile? Put in your 3rd member with the 5.13's! Going on that long trip to points far? Put in your 3rd member with the 2.73's!
Ford 8.8 = Strong as a 12 bolt, plentiful in the boneyards, proven in lots of 8 and 9 second mustangs(though they're probably lightened to a degree). Lots of choices for internals. Spools, lockers, posi's. Inexpensive components that can be had at most Ford dealerships. Stout aftermarket axles to allow you to mate your Fbody axle flanges to the ford 8.8 spline count are around low $200 for the pair. You can get it complete with installation cheaper than the other two cost for the units alone. This is for a bolt in version.
12 bolt = Hey, it's Chevy! Strong enough for what you stated. More efficient than a Ford 9 inch due to the relative position of the pinion gear on the ring gear(chevy's is near/at middle, while the 9" is down lower on the ring gear)
Ford 9" = Strong as hell, not only because of the lower pinion gear placement(more tooth area is utilized when the gears mesh) but it also has a additional pinion support on the end of pinion. Normally slightly heavier than the normal 12 bolt. The *real* beauty/value of the 9" in my experience is the ability to swap out the third members for different tracks. Racing a quarter mile? Put in your 3rd member with the 4.10's. Racing at the 1/8th mile? Put in your 3rd member with the 5.13's! Going on that long trip to points far? Put in your 3rd member with the 2.73's!
Ford 8.8 = Strong as a 12 bolt, plentiful in the boneyards, proven in lots of 8 and 9 second mustangs(though they're probably lightened to a degree). Lots of choices for internals. Spools, lockers, posi's. Inexpensive components that can be had at most Ford dealerships. Stout aftermarket axles to allow you to mate your Fbody axle flanges to the ford 8.8 spline count are around low $200 for the pair. You can get it complete with installation cheaper than the other two cost for the units alone. This is for a bolt in version.
11-16-2003, 06:23 PM
#7
LS1Tech Co-Founder
iTrader: (34)
Hey let me try:
12 bolt
-Lightest GM product
-Can be pricey with the 800lb steel clutches and other upgrades
Ford 9.0
-Budget builder can get a housing and axles for less than a $1000, and maybe do one up for less than you think.
-Makes the rear sit up higher you need to run lower springs or remove the spring cups to lower the car.
-Skews the tq arm over a bit.
-Will really make you understand the term 'stacking tolerances'
-Hard to break, never broke mine in four years
Ford 8.8
-Plentiful cores
-Ford 8.8 parts are everywhere, used stuff is cheap
-Not everyone can make you one cheap, needs to be redone with a jig
-I'm not a fan of cast parts
-One shop or so makes these, and they within 90% of the price of a Strange 12 bolt, and I am a personal friend of Geoff @ Strange, his stuff is great.
I have a Moser 9.0, got it in 2000. Has three hundred runs on it. No problems.
12 bolt
-Lightest GM product
-Can be pricey with the 800lb steel clutches and other upgrades
Ford 9.0
-Budget builder can get a housing and axles for less than a $1000, and maybe do one up for less than you think.
-Makes the rear sit up higher you need to run lower springs or remove the spring cups to lower the car.
-Skews the tq arm over a bit.
-Will really make you understand the term 'stacking tolerances'
-Hard to break, never broke mine in four years
Ford 8.8
-Plentiful cores
-Ford 8.8 parts are everywhere, used stuff is cheap
-Not everyone can make you one cheap, needs to be redone with a jig
-I'm not a fan of cast parts
-One shop or so makes these, and they within 90% of the price of a Strange 12 bolt, and I am a personal friend of Geoff @ Strange, his stuff is great.
I have a Moser 9.0, got it in 2000. Has three hundred runs on it. No problems.
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11-16-2003, 07:00 PM
#9
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I am thinking of tossing the stock axle aside this winter. I had always planned on the 12 bolt, but now I'm not really 100% sure what one I want to go with. Sounds that there are a couple of fittment issues with the ford 9, but it looks like it's the way to go for absolute strength.
11-16-2003, 07:09 PM
#10
So far from what I am seeing ... it seems the 12 bolt is the most costly, but is the best "bolt-in" replacement, requiring the least amount of modification..
The 9 inch seems to be the strongest, but require the most modification, and like prostockjohn said ... make your car sit high up and throw off your tq arm.
The 8.8 seems to sit somewhere in the middle ... and while not being a direct bolt in ... is relatively easy to get in there, doesn't screw up much, and is in the middle of the cost and reliability range ...
this all sound right?
The 9 inch seems to be the strongest, but require the most modification, and like prostockjohn said ... make your car sit high up and throw off your tq arm.
The 8.8 seems to sit somewhere in the middle ... and while not being a direct bolt in ... is relatively easy to get in there, doesn't screw up much, and is in the middle of the cost and reliability range ...
this all sound right?
Last edited by xphantomws6x; 11-17-2003 at 11:16 PM.
11-16-2003, 07:38 PM
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I have an auto, heads/cam/bolt-ons. I'm probably going to be sub-1.5 sixtys once I get some tires that really hook. I'm getting 1.5s with ET streets that are still spinning a bit. I don't know for sure, but I probably won't really need the additional strength of the ford 9 over the others with my setup, you think?
11-17-2003, 05:27 AM
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Originally Posted by xphantomws6x
So far from what I am seeing ... it seems the 12 bolt is the most costly, but is the best "bolt-in" replacement, requiring the least amount of modification..
The 9 inch seems to be the strongest, but require the most modification, and like prostockjohn said ... make your car sit high up and throw off your tq arm.
The 8.8 seems to sit somewhere in the middle ... and while not being a direct bolt in ... is relatively easy to get in there, doesn't screw up much, and is in the middle of the cost and reliability range ...
this all sound right?
The 9 inch seems to be the strongest, but require the most modification, and like prostockjohn said ... make your car sit high up and throw off your tq arm.
The 8.8 seems to sit somewhere in the middle ... and while not being a direct bolt in ... is relatively easy to get in there, doesn't screw up much, and is in the middle of the cost and reliability range ...
this all sound right?
my moser 9 inch went in without any modification. the car sits the same as it did on the 12 bolt. if you are planningon making 500 rwhp and ever run it on any kind of et streets, the 12 bolts is gonna whine after. yes, the 9 inch with a locker is clunky, but mine doesnt whine anymore, and to me thats the most important thing!
11-17-2003, 11:01 AM
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You think the 12 bolt is gonna get noisy from 500 rwhp and ET drags, huh? I have heads/cam and am looking into N2O as a winter project. First off, I'm gonna upgrade the axle, though. I don't want to get a 12 bolt if it's gonna get beat up from quickly from abuse.
11-17-2003, 11:48 AM
#16
Originally Posted by Jorday
You think the 12 bolt is gonna get noisy from 500 rwhp and ET drags, huh? I have heads/cam and am looking into N2O as a winter project. First off, I'm gonna upgrade the axle, though. I don't want to get a 12 bolt if it's gonna get beat up from quickly from abuse.
Trust me on this one. I have gone through 3 sets of gears in my Strange 12 bolt. They have all been setup by someone that knows what they are doing. They start out quiet, and after you beat on them at the track with tires, they get louder and louder. I have many buddies with the exact same problem. 
A4 cars seem to do OK with a 12 bolt, but around here the strong M6 cars have killed a bunch of them. Do yourself a favor and get a 9" with a locker. I have driven Evils car and I would rather deal with a bit of popping from the 9" going around tight turns, than the whine of a 12 bolt. Don't say you weren't warned if you go with a 12 bolt. I don't think it makes a difference if its Strange or Moser. 
Bruce
11-17-2003, 12:44 PM
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Well, my car is an A4, but you sound like you think the ford 9 is better regardless. I've rode in cars with detroit lockers, and the noise wouldn't bother me. I will probably be spraying out of the hole, so maybe the 9 inch would be best.
11-17-2003, 03:57 PM
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i broke my 12 bolt 4 times. the 9 inch after launching on the jug is stone silent.
as for spraying out the hole, i always do, and the 12 bolt will be quiet until i spray it, then it howls like a beat dog.
as for spraying out the hole, i always do, and the 12 bolt will be quiet until i spray it, then it howls like a beat dog.
11-17-2003, 04:39 PM
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You broke your 12 bolt FOUR times? 
I'm going to be launching on the bottle. Even though I have the auto, I leaning toward getting the ford 9 after reading that.
I'm going to be launching on the bottle. Even though I have the auto, I leaning toward getting the ford 9 after reading that.