9 inch, S60, or 10 bolt?

[JoeliusZ28]

So with the imminent death of my stock posi on the horizon, ive been doing my homework on a new rear end. It seems like there is a TON to consider when setting one of these axles up for taking corners, which virtually no one seems to do and there arent many options that can handle power and still behave on the street/twisties.

I've done a fair amount of research but still feel like ive only scratched the surface. So far it seems like the S60 with a true trac and either a 3.73/4.10 gear is going to be the winner.

I like the 9" but there downsides:
1) the 9" true trac has a history of problems ever since eaton bought detroit locker out, S60 doesnt seem to have this issue
2) the alternative "wave track" is super expensive and supposed to be better, but it seems like road racers actually kill wavetracs easily and instead prefer true tracs and lockers.
3) price... not sure when a decent 9" axle started costing $4000
4) 2.25" pinion offset vs the S60s 1.25" --- From what I can tell the offset pinion is responsible for robbing power in the 9" whereas the weight of components is the issue with the S60. Which leads me to believe they will perform similarly at WOT, but at a cruise the 9" will probably be more parasitic. (hotrod article below has some good info on this).

A couple plus's to the 9" is 3.90 gears which would be my preference, and lightweight fabricated housings which im not really interested in spending money on

My car is an all purpose car, and always will be. My objective is to have fun at the drag strip, autox, and road course and never have to worry about the axle. I typically only run street tires but I drive the car hard. (powershift, etc). My car is currently making 370rwhp, and the 10 bolt has survived at least 5 years of abuse with no gear whine or signs of failure (besides the posi). This leads me to believe nothing more than a 10 bolt is necessary, but it also doesnt give me any room to grow and doesnt give me an ideal gear ratio. My next build when that time comes will probably be somewhere in the mid 400 rwhp range. I have not changed the 3.42 gears in my 10 bolt because anything bigger is too small of a pinion IMO. If i were to rebuild the 10 bolt, it would be with a 3.42 gear. I am pretty confident my driving style would snap a 4.10 gearset in a 10 bolt.

My friend Jon is also looking to do the same upgrade in a higher powered LS car. Same goals but he's a little more concerned with the weight than i am. Or maybe im just a cheap ass. I'll tag him here but he probably won't chime in much because hes busy or just a jerk [MENTION=297]pHEnomIC[/MENTION]

Some reads on the topic:
http://www.hotrod.com/how-to/transmi...ear-axle-swap/
http://www.pro-touring.com/threads/1...ime-comparison

[zeeman]

I seam to recall reading about guys using 8.8 's too. But I don't know squat about it. I know we used to use em in Jeeps when I did that. Just throwing another option out there for ya to wade through.

[JoeliusZ28]

I seam to recall reading about guys using 8.8 's too. But I don't know squat about it. I know we used to use em in Jeeps when I did that. Just throwing another option out there for ya to wade through.

Thats correct, that is an option but they need to be fabricated I'd rather just bolt something in at this point, not only for time savings but peace of mind as well. Jeff (DetroitMuscle) fabbed one up for his car a few years back and it did seem to work quite well.

[ryanwarby01]

I think you lose more rwhp with a 9" too. I lost 26 rwhp going from my 10 bolt to a 9".

[JoeliusZ28]

I think you lose more rwhp with a 9" too. I lost 26 rwhp going from my 10 bolt to a 9".

Ive read a lot of conflicting opinions but it seems like consensus is the 9" robs more than the S60. Honestly, I think its a "luxury" of the 10 bolt we take for granted. The narrow pinion offset makes it a very efficient axle and a small offset is the opposite of what you want for strength.

[OVRKILL]

Well....you are a cheap ass soooo

9" is over kill for your needs, imo. S60 with a tru or wave should be all you need. Remember tho, the wave has a lifetime warranty.

[birdie2000]

For mid-400's rwhp as your goal, would a 12 bolt with an Eaton HD posi (or equivalent) give you what you need? A little more efficient, a little more street friendly, and at those power levels I wouldn't think strength is an issue. Plus you can usually find used ones fairly cheap if memory serves me.

[hoogiesngrinderz]

I've seen a 9" pop on a 12 second LT1 car Then again, that car was cursed. I'd vote 12 bolt if you are really concerned about it.

I never put a sticky tire on the rear for good reason, much like I put a weaker clutch on the manual cars I've done. I'd rather spin the tires or slip the clutch...call it a "fusible link" as I'm not interested in track times or dead hooking.

[Lucky SOB]

I like Brent's fab-9 cause it looks cool

[hoogiesngrinderz]

I like Brent's fab-9 cause it looks cool

That it does, and he has a justifiable need for one

I've never spent more than $300 to rebuild a 10 bolt. I've done 5 now in various vehicles, they always let loose because the spider gear thrust washers wore out.

[1BADAIR]

12 bolt would work. Locker,no. If mine didn't have a spool I would sell it to yA lol

[WMCCjames]

I wouldn't put a 12 bolt in your car knowing how you drive and like to hit the shifts hard. My vote will always be for a 9" rear because they are the best all around rear. Just be sure and get one set up with the set20 bearings (tapered) so it will handle the side loading for street and autox. Be prepared, you will have gear noise...it's just a fact of life with a 9" rear. That is the only drawback. All the aftermarket gears now come from 1 of 2 sources. An OEM quality gearset cannot be bought for a 9" rear anymore unfortunately. As far as a posi goes...I have had great luck with both the Ford trac-loc and Yukon's billet Trac-loc. They are both the "clutch style" posi's. They never gave me a bit of problems in my set-up.

[nascarnate326]

Im going to be the odd duck and say rebuild the 10 bolt. Its made it 20 years in that car, surly a properly rebuilt rear end could make it another 20. And with your current clutch it doesnt seem to be as hard on the drive line as the Spec was.

There was a place you could but a 8.8 for under $2,000 but I don't remember where that was.

[JoeliusZ28]

For mid-400's rwhp as your goal, would a 12 bolt with an Eaton HD posi (or equivalent) give you what you need? A little more efficient, a little more street friendly, and at those power levels I wouldn't think strength is an issue. Plus you can usually find used ones fairly cheap if memory serves me.

My concern with the 12 bolt is the torque arm mount, the housing isn't made to handle the load and they tend to break in 6 speed cars. Considering the nature of my driving style and the fact that I actually stretched the bolt holes in the stock torque arm to the point I blew a u-joint before i noticed it ... I don't that one is a good choice for me.

I never put a sticky tire on the rear for good reason, much like I put a weaker clutch on the manual cars I've done. I'd rather spin the tires or slip the clutch...call it a "fusible link" as I'm not interested in track times or dead hooking.

I agree, I've only had sticky tires on my car for a total of 2 weeks since ive owned it... more or less realized it was a bad idea as soon as I did it. But i let the tires entirely be the "fuse." I've had 2 strong clutches in my car now, the 10 bolt has been chirping 4th gear for nearly 10 seasons now . That being said, if I upgrade the rear end and driveshaft I would probably run slicks at the track. 13.0 at 113 MPH tends to point to some traction issues

That it does, and he has a justifiable need for one

I've never spent more than $300 to rebuild a 10 bolt. I've done 5 now in various vehicles, they always let loose because the spider gear thrust washers wore out.

Where do you source your parts and how does a newbie with no tools go about aligning/shimming things properly? I honestly trust my own work more than anyone but that doesnt mean i want to practice this 2 or 3 times before I get it right. But for $300 i could justify rebuilding mine.

Im going to be the odd duck and say rebuild the 10 bolt. Its made it 20 years in that car, surly a properly rebuilt rear end could make it another 20. And with your current clutch it doesnt seem to be as hard on the drive line as the Spec was.

There was a place you could but a 8.8 for under $2,000 but I don't remember where that was.

I don't intend on keeping my current clutch long term, but changing it out isn't a priority now. Even though its a really good clutch that grabs every bit as hard as the spec, the full brass disc was a mistake. Its not as fun to drive as the 6 puck and I have every intention of going back to a 6 puck (maybe even a 4 puck) once the time and funds are available. Once you have a taste of slamming gears like a built automatic, its hard to forget how fun that was

[JoeliusZ28]

I wouldn't put a 12 bolt in your car knowing how you drive and like to hit the shifts hard. My vote will always be for a 9" rear because they are the best all around rear. Just be sure and get one set up with the set20 bearings (tapered) so it will handle the side loading for street and autox. Be prepared, you will have gear noise...it's just a fact of life with a 9" rear. That is the only drawback. All the aftermarket gears now come from 1 of 2 sources. An OEM quality gearset cannot be bought for a 9" rear anymore unfortunately. As far as a posi goes...I have had great luck with both the Ford trac-loc and Yukon's billet Trac-loc. They are both the "clutch style" posi's. They never gave me a bit of problems in my set-up.

Good to know about those options for the diff, a stock behaving posi is what im looking for and it doesnt seem like theres much out there that offers that. Gear noise wont bother me within reason, already got dumped exhaust and its a purpose built car.