12 bolt w/33 splines or 9in rearend with g-link

[Bonebuster29]

Which one should I buy if I am buying a brand new rearend? AND WHY

The cost is only a difference of like $150 and I had had mixed opinions...
My camaro will be pushing around 450-500hp

[ElkyZO6]

12 bolt all the way. It also takes less power to turn.

[Rybar]

I am in the exact same boat as you. Going with a Moser 12-bolt.

[ItDoRun]

I went with the Moser 12 bolt with 33 spline axles. Here's pictures after we welded the brackets on. it has since been painted.

http://carphotos.cardomain.com/ride_images/2/4568/2281/23918640302_large.jpg

[Rybar]

I went with the Moser 12 bolt with 33 spline axles. Here's pictures after we welded the brackets on. it has since been painted.

http://carphotos.cardomain.com/ride_images/2/4568/2281/23918640302_large.jpg

That looks sweet Chris, same is what I'm going with. What width did you go with what are your wheel specs?

[Vegas69]

33 splines for 450-500hp is more than plenty. I have a 12 bolt but I don't think it's an earth shattering decision. I've been happy with my true trac so far.

[ItDoRun]

That looks sweet Chris, same is what I'm going with. What width did you go with what are your wheel specs?

My wheels are 18x11.5 with 5.4" backspacing. My rearend width from axle flange to axle flange was 54".

I set my wheels and tires under the car and dropped a plumb bob from the 12 o'clock position on the wheel lip then set the outside edge of the tire 1/2" from the string. I have plenty of room on the backside...maybe 3/4"-1". I also trimmed the lips down to 5/8" wide for extra tire clearance. I may could have went 1/4" to 1/2" wider on the rear end, but everything seems to look dead on after mocking it up. I hope to have it on the ground next weekend (for the first time in 2-1/2 years), so I'll study it better then.

Remember, you can always add a small spacer, but it's a pain to cut the rear end again. Measure 50 times, then call Frank!

[ItDoRun]

I've been happy with my true trac so far.

Good to know. I was hesitant about the limited slip at first.

[67bird]

If your not set on changing the gears out, go with the 12 bolt.

[Vegas69]

Good to know. I was hesitant about the limited slip at first.

It's predictable in a racing enviroment. You'll be happy with it.

[BMR Tech]

An aluminum centered 9" is lighter overall, allows much easier gear and posi swaps, and doesn't rely on C-clips to retain the axles. The ring gear is slightly larger, pinion bearings are larger, and you just have more options for internals. I am a die hard Chevy fan but I would use a 9" over a 12 bolt everytime if I was starting without anything...

[Vegas69]

Most of us are referring to a 12 bolt with big ford ends and bolt in axles.

[Silver69Camaro]

An aluminum centered 9" is lighter overall, allows much easier gear and posi swaps, and doesn't rely on C-clips to retain the axles. The ring gear is slightly larger, pinion bearings are larger, and you just have more options for internals. I am a die hard Chevy fan but I would use a 9" over a 12 bolt everytime if I was starting without anything...

Same here. 9" housings are much more friendly for attaching suspension brackets. With power engines make nowdays, I wouldn't worry about the extra power needed for the 9".

[ProdigyCustoms]

Since we sell quite a few rears and suspension we run into this question everyday. A lot of old timers will tell you a 9" is stronger then a 12 bolt................... Welcome to 1987! Back in the day, if you was on the cheap, you could snag a 9" from a truck and it was strong as hell. There were not a real strong aftermarket for 12 bolts, only spools for a long time which are not real street friendly.

Now with the 33 and even 35 spline Tru Trac differentials, support covers, Ford 3.15 bearing ends, bolt in Ford style axle options. New 12 bolt housings that are stronger then the old original housings, the 33 spline 12 bolt is as strong or stronger then the 31 spline Ford 9". The difference in strength (if any) at our high horse street levels 500HP to 800HP, there is no real worries about either system holding up to the power

For me, the difference maker IF (Big I F) I can use a 12 bolt is keeping my car all GM and putting more power to the ground. Yes a 12 bolt has less power absorbtion and will put more power to the ground then a 9" Ford. By it's location, the pinion in the 9" Ford tries to climb the ring gear stealing power the 12 bolt does not give up. It is a small amount, maybe 10 to 15 horsepower, but at 300-500HP it could be 3 to 5 percent and we spend a lot for 10 or 15 horsepower at the flywheel only to give it up to the rear end.

Also from a cost perspective, the cost are almost identical for a double throw down, 33 spline, Performance Cover, Big Ford ended 12 bolt or a Nodular Center, 31 spline, Big Ford ended 9" Ford. So for me..........my choice is a 12 bolt....................IF I can use a 12 bolt!

Now, with all the said, I just got my new suspension yesterday for our next shop project...........and it is a Fabricated 9"! But it also runs a watts link and that is another subject entirely! (no watts link with a 12 bolt). And at our horsepower levels, we will be giving up less then 1% power (you do the math) because of the 9", so we have 10 to 15 horsepower to give up.

Now how was that for making a strong arguement for 12 bolts and then muddying things up at the last second!

[Vegas69]

Hey Frank, bring that 9" Ford out for an ass whippin.:D

[JRouche]

Now, with all the said, I just got my new suspension yesterday for our next shop project...........and it is a Fabricated 9"! But it also runs a watts link and that is another subject entirely! (no watts link with a 12 bolt).

I agree with you all the way, mostly. Yup, the ford 9" got its rep from the days when a guy could go to the scrap yard and pull a truck rear end out and go for it. Man!! I wished I was part of those days. When garage racers and car builders did what they could to make fast cars. Before all of the aftermarket suppliers made it so you can get ANYTHING. Dont get me wrong. I love the fact that we can buy anything now. Im just thinking about the nostalgic part of it. Back when buddies and neighbors got together and got greasy working with scrap yard parts to build some fun rides. Now its all clean and sterile. Now I look up and down my street of 20 houses and not one guy has any grease under his finger nails or permanently implanted in his finger prints. I may be living in the wrong part of town.

I went with a 9" for only one reason. At the time, 1996, I didnt have enough faith in my ability to set up the gears in the rear end. The gear mesh and tolerances. And I didnt have a means for transporting a rear end to the mechanic. But I could have reider racing set up a nice 9" center section and mail it to me. Convenience is what did it for me. And Im sure for some racers that is a plus. To be able to have two or three centers sitting around with different ratios. For what ever track they are gonna run. Quick easy gear changes. Almost a cartridge setup.

Oh, but as far as the watts link and a 12 bolt go. Ummm, yes, they can live together. Here is mine that will work with a 12 bolt. Its on a ford 9". But I can make it work with the 12 bolt just the same. :) JR

http://img.photobucket.com/albums/v366/Jrouche/Steves%20Nova/Rear%20rebuild/Final%20pics/c.jpg

[JRouche]

Hey Frank, bring that 9" Ford out for an ass whippin.:D

;) Now, I see all the posts here about racing. Man!!! Gets me itching :unibrow: I always said I wont race this pathetic nova. But just for fun Id love to track it just to see. For my own enjoyment. I know it wont even come close to the camaros that are around here :_paranoid But.... I have a feeling it would be a lil surprising. Why are all the tracks so far away :mad: JR

[Vegas69]

I only got Frank by 32 seconds in his 2010 SS on the road course at RTTC. (I've took shorter naps)I'm sure that 9 inch parasitic drain will only take him back to 33 seconds or so. :rofl: :rofl: :rofl: :rofl: :rofl: I can't wait for this response!

[deuce_454]

i have the 33 spline moser12 bolt, and it is a stout piece.. fro me the decider was the lower paracitic drag of the 12 bolt.. it might just be 4% difference but at 500 rwhp thats 20 free rwhp.... I ordered the housing ends as big ford.. so thats one c-clip arguement down the drain...

just be sure to get it with screw in studs, mine is press in and it was a bit of a biatch finding the right knurl for the longer studs

if you really want the option of fast diff chance i would go with a currie track 9 housing and a richmond alluminum 12 bolt ring and pinion / 9 inch drop out centersection.. but when was the last time you changed diff at the track? (and if you actually need to do that often.. then you should propably get a champ car quick change)

[Rybar]

My wheels are 18x11.5 with 5.4" backspacing. My rearend width from axle flange to axle flange was 54".

I set my wheels and tires under the car and dropped a plumb bob from the 12 o'clock position on the wheel lip then set the outside edge of the tire 1/2" from the string. I have plenty of room on the backside...maybe 3/4"-1". I also trimmed the lips down to 5/8" wide for extra tire clearance. I may could have went 1/4" to 1/2" wider on the rear end, but everything seems to look dead on after mocking it up. I hope to have it on the ground next weekend (for the first time in 2-1/2 years), so I'll study it better then.

Remember, you can always add a small spacer, but it's a pain to cut the rear end again. Measure 50 times, then call Frank!

Thanks Chris. :cheers:

[ProdigyCustoms]

I only got Frank by 32 seconds in his 2010 SS on the road course at RTTC. (I've took shorter naps)I'm sure that 9 inch parasitic drain will only take him back to 33 seconds or so. :rofl: :rofl: :rofl: :rofl: :rofl: I can't wait for this response!

I was writing a order will driving.

[Vegas69]

That wouldn't surprise me.:D

[XLexusTech]

An aluminum centered 9" is lighter overall, allows much easier gear and posi swaps, and doesn't rely on C-clips to retain the axles. The ring gear is slightly larger, pinion bearings are larger, and you just have more options for internals. I am a die hard Chevy fan but I would use a 9" over a 12 bolt everytime if I was starting without anything...


Yes exactly the reasons I voted 9 inch over 12 bolt :thumbsup:

[lil427z]

call kyle at dse . go with the 9 . quada link.
rick k

[Roadrage David]

Moser 12 bold 33 spline eaton posi http://www.youtube.com/watch?v=zn3K6d_e7bw
http://www.youtube.com/watch?v=7Dp0PngisVI
do road racing high speed runs had it up to 190mph!! beating a Aston Martin Vantage. never scipt a beat nore thuse it makes noice hell done 5000 ml of trashing didnt even changed the oil. ones. il buy another one for my 69GTO :thumbsup:

[brans72]

I think it is odd but when I got my Chevelle couple years ago I thought about a 9 inch rear axle but went with factory 12 bolt and 33 splined axles like a year ago. Now this post pops up and guess I made right choice!!!!

[XLexusTech]

Franks post about Power loss in the 9 inch is real great info!....

Another thing I read somewhere is the position of the 9 inch yoke can cause some Driveline angle issues when doing LS/t56 swaps....

Any truth to that? :question:

[ProdigyCustoms]

Actually in some super low cars the lower pinion location can be you friend. But in a stock height car it can increase the driveshaft angle a bit. Probably not enough to cause a issue though

[Vegas69]

Like every car on this board. A lower pinion means less working angle and a smaller breach of the tunnel. I'll still take my 12 bolt. Me want as few Ferd parts as possible. :unibrow:

[davey]

I choose 9" because parts are easier to find (when in need), more race cars use them so more development on things occur for them meaning more options in the future, more options on brakes, rotors, axles, etc, and most of the parts for them do cost less in the end.

Sure there are a few companies that specialize in GM rear parts that are as good or maybe even better than the Ford 9", but they are just that - specialized parts.

Coming from a racing background, I know I would much rather have parts available from the local parts truck, or a good probability someone else there has spare parts that will work. That's just how I think.

[BBPanel]

...if you really want the option of fast diff chance i would go with a currie track 9 housing and a richmond aluminum 12 bolt ring and pinion / 9 inch drop out center section...

So would this be the best of both worlds? Axle housing you can weld on, big bearings, no c-clip and 12-bolt center-section. How do the aluminum center sections hold up?

[scherp69]

There's nothing like seeing the look on someone's face though when they see the fabricated 9" housing though. They are so cool looking.

http://i222.photobucket.com/albums/dd68/scherp69/PICT00293.jpg

[cspecken]

I am in the process of building a 64 GTO. Plans are to use a LS3 / 480 hp should be more with a few other bolt on goodies. I am thinking about going with the TKO 600 transmission. The car will be use mainly for spirited driving and maybe a road course or two!

I was looking at the Currie Ultimate Track 9 rear end, but it sounds like the 12 bolt maybe the way to go? I tried to configure the 12 bolt at Moser website but did not know if I was looking at the correct rear end. Are there any recommendations on vendors that I should talk to more? I also need to determine the best gear set for what I am trying to accomplish, any recommendation in this area?

I have talk with Mark over at SC&C vaguely about the rear end when I recently purchased my front suspension components. His vote was the Currie Ultimate Track 9, to get away from the C Clip issue (but this sounds resolved when going with Ford 9" axle tubes on the 12" rear end).



Thanks in Advance, Chris


1964 - 1972 Pontiac GTO's
1967 Buick GS 400 Convertible
1970 Buick GS 455
1970 Olds 442 W30
1962 - Corvette

[ProdigyCustoms]

Fist off I would recomend a T56 Magnum over the TKO 600 everytime, especially behid a LS motor that is born for a T56. The T56 Magnum shifts SO much nicer then a TKO 600. Both T56 and TKO kits require the tunnel be cut and raised, the T56 a bit more then the TKO, but once you cut, what does it matter if you raise 1" or 2"? The stock console will still fit.

Our T56 Magnum kit with equal parts components specs is only $400 more then a TKO 600 kit.

As for the rear, for you car, a Bolt in A body 30 spline Tru Track 12 bolt with Big Ford end and 3.15 bearings is right at $2250. If you have not ordered your wheels yet, we can also shorten the rear a bit, make it a little shorter to get you a deeper lip on you wheels without mini tubing.

Feel free to call me, we have it all from the transmission out to the tires.

[TheJDMan]

I actually had a 12bolt under the car but it was cheaper to buy a new Moser 9" with floating hubs than it was going to be to rebuild the 12bolt. The 9" is small block chevy of rear ends. Parts can be found everywhere for not a lot of money.