Anyone With The Moser 12 Bolt, A Body Rear End? Thoughts
 

Time to address this last aspect of the car now that the engine is done and making 600tq.

I'll be selling my 8.2 "N" rear end with disk brakes and I'm really leaning towards the ..
Moser 12 bolt for A bodies
30 spline
Eaton posi
3.91 gears (30" Street R tire probably next)
11" rotor with Dynapro 4 piston
PC black gloss

They said the brakes have e brake function and lines.
The rear length is factory so wheels will be in the same spot.
All suspension points will line up
Driveshaft will bolt on without issue (3" steel)

Curious what you all that have one can comment on?

Thanks

Absolutely wonderful piece of equipment. Now that sucker wasn’t cheap though.
Wilwood discs.
3.42
No issues.

Won’t need the hop stop bars for the top. The casting is already modified 1.5” taller there to begin with.

Stout piece.

I have a Moser 12 in my 69 bird. It's a great piece. It was setup well from Moser. I haven't had a single issue with it.

I opted for the TruTrac instead of a traditional posi unit. I still like the trutrac better, especially for bigger power on the street.

The dynopro wilwood kit will have a drum in hat parking brake. You'll need to get their universal parking brake cable and adapt it into the factory cable.

Thanks guys...

With the 1.5" taller, I didn't have hop stop bars at $315 but I suspect my adjustable upper arms will just need to be tweaked to fit in this new raised position?

Trutrac (worm gear?) was only a $30 upgrade vs normal Eaton posi, it's with the upgrade?

When I put Stop Hop bars on my stock rear end I was able to use the same stock upper CAs. You should be fine with yours.

Thanks that solved that ?

The parking brake, since I'm auto its value decreases and mainly for emergency brake. Is this drum in hat thing worth it all, I'm leaning yes since I've needed the E brake 1x in my life and glad I had it.

Yes a TruTrac is a helical gear limited slip differential. It is not a clutch type "Posi-Traction" differential that acts as an open carrier until the clutch apply.

The TruTrac has no clutches to wear and differs in that it is torque splitting towards the loaded gear. It can sent around 70-75% of the available power to the tire with the most traction, while still allowing the wheels to rotate at varying speeds. On a dragstrip launch this means you'll typically torque split nearly evenly and the car should launch straight.

Powering out of a corner the outer wheel which has the traction will be receiving the brunt of the power. This is unlike powering out of a corner with a posi where the application of torque will begin to lock the two wheels together in rotation speed.

Anywhere you would use a Posi over something like a spool, the helical gear differential almost always works better, is stronger and has less maintenance. Plus no need for any friction modifiers. Just run straight 90 weight conventional gear oil.

I did the same in my 67 but went with the bigger 1350 yoke and 33 spline axles

Do you know the difference in price between the 12 bolt and a 9"? I bought the Ford only because I wanted to be able to change ratios quickly. Having spare center sections I can change ratios in a half hour. I also use the soft locker. Do you really need the rear disc brakes? Rear brakes really don't make a big difference.

I have a Moser 9" rear under my 64 GTO.

Very happy with the quality of the unit. Only thing I did was, years later, was shorten the rear end width so I could mount Ford Explorer rear disc brakes.

Those Moser rear axles are some hard to machine parts.

Very happy with their products. I run a steel Strange 9 inch 3rd member.

I was told that some of the Moser rears, 8.5" are very strong.

Tom V.

I have a Moser 9" rear under my 64 GTO.

Very happy with the quality of the unit. Only thing I did was, years later, was shorten the rear end width so I could mount Ford Explorer rear disc brakes.

Those Moser rear axles are some hard to machine parts.

Very happy with their products. I run a steel Strange 9 inch 3rd member.
33 spline axles.

I was told that some of the Moser rears, 8.5" are very strong. No info on the 12 bolt stuff.

Tom V.

I didn’t know Moser made an 8.5

Have a Moser 12 bolt Muscle Pak with the economy disc brakes with parking brake, Eaton posi 3.73. I had them make it 4 inches narrower so I could tuck my N50-15s underneath. Powder coated black, fit perfect. 70 Judge

It's been a long time, but I have had 2 Moser 12-bolts in the past and both were for the '67 Lamnas, behind the 535.

First one was a 3.55 True-Trac, but without brakes, 2nd one was a 3.90 Wave-trac. A bit of overkill, but nice peace of mind. IIRC, I had an 11X2 rear drum brake set-up on both.

Both had pinion seal leaks.....ugh!!,

I've got no iron in this fire so to speak happy with my 8.5" 10 bolt from a skylark, but looking at the Moser sight with a few little upgrades and unpainted this 12 bolt still comes in at $5000 you can but TWO very similarly built 9" rears from quick performance for this price point. I know some are purists and nothing but GM based in the car but I'd be hard pressed to pay twice as much to say it had a 12 bolt in it.

If you can get that done in 1/2 hour my compliments.

I found myself in a similar spot with my current project. The Moser rep I worked with pointed out that the cost of a 35 spline 9" with all the upgrades and a Truetrac diff was a bit less than the best 12 bolt they could build, while being far stronger and offering easier paths to good rear brakes. I have no regrets. If you can get past the appearance and/or stigma, go with a 9". Quick Performance would be a better budget option than Moser, but I've never dealt with them.

Ive delt with Moser, strange and quick performance. It's hard to beat bang for the buck on a 9 inch. Just don't get too hung up on the ability to swap pumpkins. It means nothing in the grand scheme. Once you set the car up with a proper gear for the combo you'll never touch it again. And if you want better highway cruising an overdrive fixes that then you have the best of both and wont have a need to touch it.

Honestly though since gear swaps mean nothing to me I'd just go with a 12 bolt.

Not sure where the guys comparing cost between the QP 9” and a 12 bolt Moser for an A body are getting their numbers. When I have compared the two combos equally set up the Moser is $700 to $900 more, not close to twice as much. I am apparently checking some extra options I think are necessary, which comes from all the stuff my friends and I have broke on 9” set ups. If you want to build the 9” with all the options, gusset’s, back braces, billet steel front bearing support, Moser 3rd member, there is hardly any difference in cost, I think the 9” may even cost a little more.

IMHO, the standard QP 9”, is not as strong as the 12 bolt Moser. The standard QP 9” is cheaper, and for mild street cars you can run some stock 9” parts to get the price down, but then it is a long ways from being as strong as the Moser 12 bolt. The 9” with all the options is an EXTREMELY nice piece, and about as bullet proof as you can get. It is not cheap to build though. JMHO…The Dana 60 is the best value for it’s stock strength with small bracing upgrades.

And neither is nearly as strong as the old 9.3 Pontiac /Olds rear with 35 spline axles…

The caps on the 9” or the 12 bolt, especially the 12 bolt are laughable.