Why Moser?

**Bouvers** · 10-16-2007, 02:17 PM

Hey I have a question it seems everybody goes to a 12 bolt moser when ever they upgrade from their stock 10 bolt... why is that... is it simply because its the easiest one to put in. or is it truly the strongest... I've heard that a ford 9" is actually stronger then the moser 12 bolt true or false? whats the most bulletproof rear end out there?

**Jays00ss** · 10-16-2007, 05:16 PM

I just bought a custom Brand new 9" rear end. I got the Moser case and 35 spline axles. I then added the Strange Pro Nodular case with Motive Performance 4.30 Gears and a Detroit locker. I think Moser has the better case and axles but Strange make a better 3rd member.
Strange makes a Dana 60 for the fbody, They are Ideally the best rear end you can get however, I have researched that the torque arm mount is not that good on the strange housing and the rear end housing is tweaking under extreme conditions. + you have to do a few more things to get them to fit (shorten the drive line, send in your backing plates to get welded to the axles or purchase new ones), And they have a back order of 4-5 weeks.
Unless you have over 1000 hp which I highly doubt, the moser 9" with 35 spline axles is more than enough. They have been around long enough to prove themselves. I would not recommend a 12 bolt with a 6 speed the 9" has a much better torque arm design and the gears will remain quiet. + the 12 bolt has a 8.75 ring gear and the 9" has a 9" ring gear. They are the industry standard for racing.

**Bouvers** · 10-16-2007, 06:12 PM

i have a question as to why you said you wouldn't recomend a 12 bolt with a 6 speed... ?

nevermind re-ready the post makes sense to me now... :P

**astyles** · 10-16-2007, 06:24 PM

Originally Posted by Bouvs

i have a question as to why you said you wouldn't recomend a 12 bolt with a 6 speed... ?

thay dont take the beating from the launches as well......a4 is not as harsh

**Bouvers** · 10-16-2007, 07:00 PM

so does moser make a 9" rear end or just the 8.75" 12 bolt? Also you said you changed out your ring to a 9"... does this mean you have to change out your whole guts like the ring AND pinion? or can you just change out the ring end of story?
One last question (for now) if you upgraded your axles to 35 spline what did it come with originally?

**Jays00ss** · 10-16-2007, 07:28 PM

Originally Posted by Bouvs

so does moser make a 9" rear end or just the 8.75" 12 bolt? Also you said you changed out your ring to a 9"... does this mean you have to change out your whole guts like the ring AND pinion? or can you just change out the ring end of story?
One last question (for now) if you upgraded your axles to 35 spline what did it come with originally?

Moser makes them both, A GM 12 bolt (It has 12 bolts holding the rearend cover on and it has a 8.75" ring gear) and the Ford 9" (It does not have a rear cover, and has a 9" ring gear). I changed (removed) my complete 10 bolt rear end (Housing and all) and replaced (installed) it with a New moser Ford 9" housing, New moser 35 spline axles and a Strange 3rd member "Pumpkin" with the detroit locker and new gears installed.
35 spline axles are about the strongest you can buy. You can also buy through moser a 28, 31, or 33 spline axles. They make a 40 spline but typically for extremely High horsepower pro mod type cars and are very expensive. Without getting to technical,the more splines you have, the stonger the axle is.
The stock 10 bolt (It has 10 bolts holding the rear cover on) in our cars has a 28 spline axle and a 7.5" ring gear. You can not change the size of the gears (ring gear, Its always going to be 7.5") in the 10 bolt, but you can change the gear ratio (3.73, 3.90, 4.10's etc....).
In order to "upgrade" axle's to more splines, you also have to change your posi unit to accomodate the different size splines. In my new rear end, I got a 35 spline detroit locker to accomodate the 35 spline axles. Make sense?

**Hamrhead** · 10-16-2007, 10:50 PM

A Strange S60 is the strongest but not always the best. Being new it is limited by gear choices. The 9" is made by several companies out there. Moser is the most common then there is Currie, Billingsley(not anymore) and some others. The 9" will not fit as well as a 12 bolt but will withstand a lot more. By not fitting I mean it will take some effort, not that it won't fit! The Currie 9" is nice but require LT1 brakes for fitment. If you are N/A then the S60 isworth looking at but if you are FI then look at the 9"! If you plan on staying around 400 then just go with a 12 bolt. Most people go with Moser because it is the most common and usually the most affordable. Just a note, the Billingsley uses a Strange center section.

**Firebirdjones** · 10-17-2007, 05:45 PM

I avoid Moser like the plague. Had to many problems with their housings. Not to mention other issues,,,,long story I can't simply explain.

Moser cast their housings in house,,,where as Strange and Currie both have another company cast their housings (outside supplier) and I have found them to be better quality.

I prefer to deal with Strange. I also prefer the 12 bolt, I just like to keep it all GM. But I have built 12 bolts for 6 speed cars that run well into the 10's and last just fine. They can take the abuse if built "properly."

Eaton makes a nice clutch style posi unit that is rebuildable and stout, with 33 spline axles, C-clip eliminator axles etc...

12 bolts rob less HP than the 9 inch due to the placement of the pinion gear in relation to the ring gear,,,this give the 9 inch a slight strength advantage at the cost of robbing some HP to the wheels.
I like the 9 inch, they have their place, but the only use I have for them is in a full blown race car, dirt modified car, Nascar, etc,,,,,where gear changes are an every weekend endeaver.

**Wesman** · 10-17-2007, 06:09 PM

Everyone always says the Ford 9" is definitely stronger than the 12 bolt, but has anyone on here actually broken a 12 bolt with bolt ons or H/C?? Can't say I recall anyone saying they've broken one, I think the 9" is just overkill unless you're running a fully built motor or FI/Nitrous.

**Firebirdjones** · 10-17-2007, 06:23 PM

I have broken a stock 12 bolt in my chevelle, but thats a different beast all together, with a 4,108 lbs. race weight and a BBC with alot of grunt,,,after building the 12 bolt to take the punishment, it has lasted for the last 12 years of racing just fine.

As far as an LS1 with just heads and cam,,,,even a small shot of nitrous,,,,if built properly it would take alot of doing to break it,,,like I said, my buddy has his going high 10's, in a full weight 4'th gen, and it's living fine.

If you think about it,,,,all the high HP chevrolet's that came out of Detroit during the musclecar heyday used the 12 bolt,,,and alot of these cars were converted to Stock Eliminator and Super Stock NHRA class racing using the 12 bolts, these cars dipped into the 10 second range back then, and they weren't feather weights,,,we are talking about some heavy cars.

I run the 12 bolt in 4 different cars and don't have a problem with it at all. But I do like a few things about the 9 inch,,,,just don't have a use for it in a street car though.

**Jays00ss** · 10-17-2007, 08:23 PM

Originally Posted by Firebirdjones

I have broken a stock 12 bolt in my chevelle, but thats a different beast all together, with a 4,108 lbs. race weight and a BBC with alot of grunt,,,after building the 12 bolt to take the punishment, it has lasted for the last 12 years of racing just fine.

As far as an LS1 with just heads and cam,,,,even a small shot of nitrous,,,,if built properly it would take alot of doing to break it,,,like I said, my buddy has his going high 10's, in a full weight 4'th gen, and it's living fine.

If you think about it,,,,all the high HP chevrolet's that came out of Detroit during the musclecar heyday used the 12 bolt,,,and alot of these cars were converted to Stock Eliminator and Super Stock NHRA class racing using the 12 bolts, these cars dipped into the 10 second range back then, and they weren't feather weights,,,we are talking about some heavy cars.

I run the 12 bolt in 4 different cars and don't have a problem with it at all. But I do like a few things about the 9 inch,,,,just don't have a use for it in a street car though.

I have nothing against the 12 bolt at all. In fact I have had many and still do in my Big block powered 71 SS El Camino. All I was trying to point out is the 12 bolt torque arm mount in our f-body is not as good as the 9" and the six speed puts more abuse on it makeing the gears whine. The auto does not beat up the rear as bad and the gears remain quiet.
I will quote Bob at EPP.

"Put a 12 bolt into a early Chevelle, Nova, Camaro, etc and you can beat the crap out of it, and not hurt anything. Put one into one of our cars with a torque arm, make a couple 4000 to 5000 dragstrip launches, and I can just about guarantee you'll pick up gear noise. If it is a drag only car, you'll never know or care about the gear noise. Drive your car home from the track, and the noise will drive you nuts. I feel the torque arm stresses the 12 bolt housing, causing distortion. We have never seen this happen with the 9 inch housing.
Exotic Performance Plus strongly recommends the Moser nine inch. This rear is even tougher than the Moser 12 bolt, and the horsepower of the late model F Body cars keeps escalating every year, which requires a very strong rear. With the recent introduction of the 6.2L GM aluminum block and the excellent flowing 6.2 litre heads, the horsepower of these cars is going to just keep climbing at a very fast pace.The nine inch will handle the power, plus we prefer the way the torque arm is bolted to the nine inch in the same way the oem rear-end is attached. (This is the only good thing about the stock 10 bolt...) The Moser 12 bolt uses four short bolts to attach the torque arm, and they have a habit of loosening up, even when loc-tite is used. Why the nine inch is stronger than the 12 bolt. The 9-inch has an internal rear-pinion support that also supports the gear end of the pinion to limit gear deflection under high torque loads. This seems to be the major reason why the 9 inch doesn't start whining after high rpm clutch dumps, when the 12 bolt will pick up noise.The 9-inch locates its pinion gear lower on the ring gear to improve tooth contact, than the 12 bolt does.The 9-inch has a 0.125-inch larger ring-gear diameter and internal pinion support than the 12 bolt does. This is not much of a difference, but it is worth noting."
That is all I was trying to point out.

**Jays00ss** · 10-17-2007, 08:56 PM

Regarding the statement above. My car is a street/strip car. I will keep modding it to go faster. I have a 6 speed and I believe the 9" is a better rear end for our f-body. I can't stand gear whine, and That is why I went with the 9". They are cheaper, Easier to work on and change 3rd members out.
Yes, the 12 bolt will probably not break, They are great rear ends. However I have researched this topic endlessly and I think the 9" is a better choice for our cars for the reasons outlined above in my previous post(s).

**Firebirdjones** · 10-18-2007, 04:08 AM

Originally Posted by Jays00ss

Regarding the statement above. My car is a street/strip car. I will keep modding it to go faster. I have a 6 speed and I believe the 9" is a better rear end for our f-body. I can't stand gear whine, and That is why I went with the 9". They are cheaper, Easier to work on and change 3rd members out.
Yes, the 12 bolt will probably not break, They are great rear ends. However I have researched this topic endlessly and I think the 9" is a better choice for our cars for the reasons outlined above in my previous post(s).

Well we were talking about breakage possibilites, but if you want to switch the subject to gear noise, here is what I have found.
If you are having gear whine it's more than likely due to improper setup. Mine have been quiet since I switched to strange housings. The moser housings were not square on a Jig, causing misalignment. Go to a Strange and the problem is solved, this explaination can get involved so I won't go into detail.

The torque arm is a source of noise transfer no matter which rearend you use. I find that most people go to an aftermarket torque arm and thats where some problems start. As these are generally installed with poly mounts, or even a more solid heim jount,,,such a solid connection will transfer noise no matter what rearend or transmission you have. Some assemblers, and even moser themselves believe that using a Motive gear set is the solution because they run quieter,,,,but this is only a bandaid for the real problem. Motive gears are made of a softer material and make less noise,,,,,so why put an insuperior gear set in the car when the real problem is either the housing or torque arm setup being used.
I use nothing but Richmond gears,,,mine are all quiet, even in the 12 bolts we have done for the 4th gens.
They can be quiet if done properly. Simply slapping a gear set in there and checking gear patterns with marking compound does not get it done. This is the way most shops will do it,,,because they do not want to take the time to use a pinion depth gauge and set things up accoring to the gear manufacture specs. Then when you get a moser housing that isn't square it only compounds the problem.

**Jays00ss** · 10-18-2007, 08:34 AM

This whole thread stared out in wanting to know the best or most bulletproof rear end. I have run the Ford 9" in all of my race cars (drag racing). They are proven to be a stronger rear end. In my experience being around racing, about 20 years or so,
I would say of the local racers I have been around, at least 85% of circle track and 75% of the drag racers have the 9". That must say something about them. Look at top fuel, funny cars, pro stock cars. They all have derivatives of the ford 9".
Like I said before, I have nothing against the 12 bolt. I have had and continue to have them. I am a GM, Chevy guy, through and through. I have had over 20 muscle cars from big and small block Chevelles, Novas, Camaros, chevy 2's, and Elcaminos. Most of them have had a 12 bolts. However, the 9" is just a better rear-end.
If we get down to it, the Dana 60 is even better. It has a 9.75" ring gear. They are in all the 1 ton trucks (must say something about their durability). alot of my buddies run them in their drag cars.
Yes, I am new to the 4th generation f-bodys. I am more of an old school 60's-and 70's muscle car guy. I have asked around at the track, Read numorous Internet articles, talked at the car cruise scenes, asked different manufactures, Talked to rear end and differential shops and the consensus among every group of people is to run the 9" in the 4th gen f-body because of the torque arm mount.
Don't want to piss you off, We just have different opinions on this subject.

**Firebirdjones** · 10-18-2007, 08:45 AM

You're not upsetting anyone that I know of. But as far as the torque arm mount is concerned they both are mounted in a similar fassion, no difference there really. They both mount to the center section, making the torque arm capable of transfering noise in either case.

I was never disputing the point that the 9 inch is or isn't stronger,,,,I just stated that for a street car it's probably overkill and it robs HP.

Whether that makes it better is just a matter of opinion. I don't hate the 9 inch,,,I currently run one in my 56 Nomad.

But for a simple street car that runs in the 10's a 12 bolt will get it done fine, been there and done that.

**Jays00ss** · 10-18-2007, 09:46 AM

Me too, Been there and done that as well. Like I said I have had many 12 bolts in my older muscle cars. 9" is just better suited for a m-6 F-body.

**Firebirdjones** · 10-18-2007, 01:09 PM

Originally Posted by Jays00ss

Me too, Been there and done that as well. Like I said I have had many 12 bolts in my older muscle cars. 9" is just better suited for a m-6 F-body.

I still don't see how you figure that last statement. It's really personal preference I guess.

**Firebirdjones** · 10-18-2007, 01:19 PM

What I do like seeing is more people asking about them for these F-bodies, since the factory 7.5 inch 10 bolt is inadequat for even a stocker.

GM really dropped the ball in that area. What I see alot of is 600 HP 4th gens forsale that are still running the stock 10 bolt. Seems most people start these serious builds on the wrong end of the car.

If some of these people ever experienced a rearend explosion at speed they may think twice about that decision.

**Zboner** · 10-18-2007, 01:35 PM

i bought moser cause Strange had a 3-4 week back order.

**Jays00ss** · 10-18-2007, 01:54 PM

Originally Posted by Firebirdjones

What I do like seeing is more people asking about them for these F-bodies, since the factory 7.5 inch 10 bolt is inadequat for even a stocker.

GM really dropped the ball in that area. What I see alot of is 600 HP 4th gens forsale that are still running the stock 10 bolt. Seems most people start these serious builds on the wrong end of the car.

If some of these people ever experienced a rear end explosion at speed they may think twice about that decision.

I totally agree with this. Everyone wants the high hp, but they don't take the time to build the drive train to support it. I have always built the drive train first, then did all the go fast goodies to the engine. Then you never have to worry about it again. I have personally seen at least 3 people with 10 bolts grenade theirs on the starting line at the track. They insist on getting the cam, heads, etc... then leaving their 10 bolt in there with 4.11 gears and then run DOT slicks. It is Not a good combination and just a matter of time and inconvenience when it does break.
The 10 bolt is an adequate rear end for stock street use, but if you like to go to the local strip every now and then you better know a buddy with a truck and trailer.