Seeking some advice before ordering a Moser 12 Bolt

[IROCZman15]

SHORT VERSION:
I am buying a 12 bolt rear for the iroc and had a few questions that I was looking for some community input on before ordering it within the next few weeks. the plan currently is 12 bolt rear with new big ford ends. 1350 yoke, 33 spline (or 35 spline) TrueTrack, 33 spline axles, (full details below) and link is http://www.moserengineering.com/12-b...d-package.item
Questions:
- sealed ball bearings or a tapered roller bearing ?
- will these adaptor plates work for mounting my 12" rotor 2piston PBR caliper brake setup onto the rear axle? http://flynbye.com/catalog/i11.html and this is the brake kit I have now on my 10 bolt that I want to move to the new 12 bolt. http://flynbye.com/catalog/i11.html
- 3.55 or 3.73 gear ratio ? (it will be behind a highly beefed up 700R4)



LONG VERSION WITH DETAILS:
I apologize if this post is long, but I wanted to lay out all my thoughts and tech info as much as possible to give a clear picture of what my plan is....

As some of you may know, and for those that don't, my major winter upgrade to the car this year is a new rear axle and a driveshaft capable of handling 800 horsepower. I have anther thread going where I have information about the transmission (done), fuel system(done), suspension (done), engine (next winter) and chassis mods (next winter?). here is that link: http://www.njfboa.org/forums/showthread.php?t=68229 This car is and always will be a street car. I have autocrossed it, road track raced it, and done some drag racing. I plan on doing way more drag racing with the car's next engine but will also not shy away from autocross and a short road track event either. Yet, the car will remain a street car and will put down several thousand miles a year.
The engine will make around 525 hp NA and then I plan on spraying it with a 200 wet shot. I hope to run mid/low 11's NA and hopefully mid/low 10's with the nitrous. The car will need a cage, and currently weighs 3,400 pounds without me in it. If I only bolt on a set of rear slicks, and keep the rest of the car in street trim, I would love to run 10's so I need a rear end that can handle that task for years to come

I have been doing reading and research online for the better part of this past year and I am of the opinion that a new 12 bolt setup is what I want. Nothing against the 9", 8.8", or 60 rears, I just don't think that it is what I want. I know the 60 is the most severe duty use but also heavy, more expensive, and more for pure drag racing. the 9" and 8.8 were options, but I honestly don't think I'll ever be that super intensely competitive with drag racing or any racing (for this specific car) where I'll want to be changing out 3rd members based on what event I'm doing. They do eat a good amount of power too and are also heavier. I also don't want to deal with the extra bracket that would be needed to mount my S&W racing adjustable torque arm either.. and I have read that it is common for the torque arm/bracket assembly to bang into the transmission tunnel and cause interference while driving down the road. No thanks . Also, i don't like the way it looks from underneath the backside of the car.

Therefore, the 12 bolt is the answer. I am not going to spend a single penny beefing up my 10 bolt, as I know it will fail with the amount of power the next engine will be bringing. It has 3.73's and stock 26 spline axles. the posi unit has been on its last legs for several thousand miles, and one of the 5 fasteners that hold the diff case together is sheared off!

I have looked at Moser, Currie, Strange, Quick Performance, Mark Williams, Drivetrain Specialties and so forth. A moser seems like the best bet. Their website is simple and straightforward, unlike some of the others. I called Moser tech support today on the phone and went over basically everything that I am discussing here. They are also of the opinion that a 12 bolt will suit my intentions very well.

here is a link to the part of their website where I can piece together the rear:
http://www.moserengineering.com/12-b...d-package.item


and here is the rundown of my selections in each category:
- Diff fluid : Motul 75-90
- Truck Freight: Residential liftgate required
- Axle type: Bolt in
- Year/Make/Model: 1982-92 camaro/firebird * can-NOT use stock brakes
- Custom width and pinion offset: none needed ??
- Axle spline count: 33 spline (bolt in axles)
- Differential: 33 spline TrueTrac
- Gear Ratio: 3.55 or 3.73 (still undecided now but will be one of those)
- Pinion Yoke: 1350 series
- Rear cover: aluminum girdle
- Bolt pattern: 5 on 4 3/4"
- Bearing type: Tapered roller bearing (see my comments below though)
- Stud type: 12mm x 2.5" (I actually have to check my measurements and make sure I get long enough studs to be legal at the track and probably get longer lug nuts to work with them accordingly)
- ABS: None
- BRAKE OPTIONS: OTHER (I will need to write a detailed description of the 12" PBR setup and probably describe to them the brackets I plan to use; maybe I'll send them a link or photo ?)??
- Additional Brake options: None
- Additional Options: 1982-02 Fbody sway bar mounts, 1982-02 Fbody lower control arm mounts, and flange access holes
- Powdercoat options: semi-gloss black powdercoat




I currently have a 12"PBR brake package (from when I converted my old drum brake 10 bolt to a disc brake setup) from Ed Miller at FlyNBye performance ( http://flynbye.com/catalog/i11.html ). Since I already own the 12" rotor and PBR kit, I wouldn't want/need to buy a rear axle from Moser that has a brake package pre-installed on it.. I would want to use what I have since they work great and I already have it here.

My major questions are:

1. what would be the best way possible to mount the kit to the new Moser 12 bolt rear end, which will have the NEW style Big ford ends. I found this bracket on Ed's website, Item #BFNew12 ( http://flynbye.com/catalog/i73.html ) and unless I am missing something, it looks like that would be all I need ?? .... I just got off the phone with Moser technical assistance and they looked at the bracket and agree that it should work and be able to slide on later/after they press on their bearings etc. they did request that I ask Ed about two things though:
- I sent Ed an email as well and hope to hear his thoughts on this, but also figured I would ask you guys too
a: on his website it says that those caliper brackets work but give the 2.75" offset...however Moser says that they typically build their ends to be spec'd to the 2.5" offset. they recommend a 2.5" offset, but if needed they would possibly make adjustments for a 2.75" offset? thoughts/input?
b. should I go with a 'sealed ball bearing" or "tapered roller bearing" setup ? they have a note on their website that the tapered roller will not work with 93-97 fbody brakes, but I do not believe that the 12" PBR disc setup is similar to the LT1 fbody brakes?? if it is, or if the tapered roller bearing setup will not work, please let me know so I do not make a mistake when ordering. Moser suggested tapered roller bearing because the car is mostly a street car that sees about 3,000 miles a year and will later see 8-10 drag-strip days as well as some autocross and aggressive street driving.


Anyways, sorry for the extra long post. I want to make sure that I order this rear axle once and have it done and only need fluid changes every so often for many many years to come.

Once the rear is here and in the car, I will have to measure for a driveshaft and order one. It should be exactly the same measurements as a stock length 3rd gen auto-trans driveshaft, but just in case something is a small amount of difference, I am going to hold off on ordering the driveshaft until the rear is actually in the car and set.

Thanks for the advice and any positive/negative feedback will be listened to.

[Blackbirdws6]

Sounds like you have your mind made up. What are you asking?

[IROCZman15]

sorry, I wrote half the text in the post and needed a break so I just quickly posted what I had written halfway.
full (long) post is complete now.

[Blackbirdws6]

I can't help you much on the brake questions as you will need to rely on the various parties to determine if their parts will bolt up. That will be tricky but hopefully it will all work out in the end.

Gearing: Determine your RPM at normal cruising speed and determine which gearset works better for you. Also determine if for that gearing, what MPH that puts you at in the 1/4 mile to give you enough room for your goals. In hindsight for my build, I would have gone with a 3.54 (lowest offered for S60) to give me some headroom.

Studs: See if they can offer axles with larger studs (screw-in or press-in, I prefer screw-in). 1/2" should work fine with your factory wheels. It's best to make this decision now vs having to pull axles and have them drilled to accommodate larger studs. My axles came with the smaller 12mm but had provisions for the larger 1/2". If you put a sticky tire on your car, it will be good assurance you don't bend or break the smaller units. Ask me how I know.

Other: I assume the cover has a fill hole?

[Joey D]

Originally Posted by Blackbirdws6

I can't help you much on the brake questions as you will need to rely on the various parties to determine if their parts will bolt up. That will be tricky but hopefully it will all work out in the end.

Gearing: Determine your RPM at normal cruising speed and determine which gearset works better for you. Also determine if for that gearing, what MPH that puts you at in the 1/4 mile to give you enough room for your goals. In hindsight for my build, I would have gone with a 3.54 (lowest offered for S60) to give me some headroom.

Studs: See if they can offer axles with larger studs (screw-in or press-in, I prefer screw-in). 1/2" should work fine with your factory wheels. It's best to make this decision now vs having to pull axles and have them drilled to accommodate larger studs. My axles came with the smaller 12mm but had provisions for the larger 1/2". If you put a sticky tire on your car, it will be good assurance you don't bend or break the smaller units. Ask me how I know.

Other: I assume the cover has a fill hole?

How do you know?

[Blackbirdws6]

Originally Posted by Joey D

How do you know?

New S60, didn't select upgraded studs, ran at track with sticky tire and twisted all studs on both sides.

[IROCZman15]

Originally Posted by Blackbirdws6

New S60, didn't select upgraded studs, ran at track with sticky tire and twisted all studs on both sides.

WHEW!! thats intense!!




yea, moser (and most of the other companies listed above) allow me to choose which size studs I want. diameter and length.

mosers options:
STUD TYPE:
7/16 x 20 -x1 1/4" (.480" Knurl)
7/16" x 20 x 2 7/8" (.480" Knurl)
12mm x 1 1/2" (.505" Knurl)
12mm x 2 1/2" (.505" Knurl)
1/2" x 20 x 1 1/2" (.620" Knurl)
1/2" x 20 x 3" (.620" Knurl)
1/2" x 20 x 2" (Screw-In)
1/2" x 20 x 3" (Screw-In)
5/8" x 18 x 2" (Screw-In) (Add $65.00)
5/8" x 18 x 3" (Screw-In) (Add $65.00)
7/16" x 20 x 1 3/4" (.480" Knurl/ Disc Brake Stud)
1/2" x 20 x 1 3/4" (.620 Knurl/Disc Brake Stud)
14mm x 1 11/16" (.620" Knurl)

--so I will just have to take a few minutes out to determine which length will be best for me, ensuring that they are long enough to pass tech at island dragway etc. will go with the 1/2" diameter too.. unless i should just go total overkill and get 5/8" ??! . i will eventually get a second set of wheels to mount slicks onto, so I want to make sure the studs are up to the task of a hard launch, and hopefully some wheels up action.

I currently run 3.73 rear ratio, and I'm happy with it, but I have no idea what the real world power chart of the next engine will put me at when coupled with the 700R4 and whatever height tires I end up with. I am probably deciding between a 3.55 or a 3.73 final ratio.

i reached out to the brake guy, but haven't heard back yet. If he says those brackets are what I need that will be great.. I am still unsure about the 2.5" offset moser recommends, vs the 2.75" offset that the brackets are advertised as giving


I will be going with the tapered bearing setup as was suggested to me by several guru's on thirdgen.org .. since my car will be doing more than just straight line racing the tapered bearings are highly recommended


thanks for the input fellas, keep it coming !

[Blackbirdws6]

No need to go 5/8" on the studs. That's overkill and will not work with most wheels. 1/2" will be fine for whatever you are doing. If you don't plan on running a dedicated drag wheel with shanks at the strip, grab some acorn, extended shank lugs. I'm fairly convinced my stud bending wasn't helped by the fact my car is heavy with a good amount of power running acorn lugs. Billet specialities makes them and I have a set in my garage if I decide to just run the car with street tires.

[B4C]

I had the tapered roller bearings in my Jeep and they leaked non stop, the sealed ball bearings Moser sends have a nice o-rings machined into them and they seal nicely as long as you don't roll the o-ring when you install the axles.

[SS Performance]

this link has lots of automotive related programs and calculators. You can use it to help determine the best rear gear;


http://www.bgsoflex.com/auto.html

I prefer the roller bearings for road racing, drag racers tend to like the ball bearings.

[IROCZman15]

So as this stands, I spoke to Scott a bit and to Moser about re-working my existing drum-to-disc conversion brackets. While it is totally possible, it would cost a bit of $. Again, much thanks to Scott for being very helpful.

Then, the day before I was going to place the order with Moser, I decided to try calling Ed again. (Ed owns www.flynbye.com performance and is the one who sells/makes the brake package that I have on the rear and front of the car. he does great work, but it is VERY difficult to get in contact with because he has a demanding full time job and does brake kits on the side).
Out of pure luck he answered the phone and apologized for not getting back to me. He agreed that my exising plates could be machined, but instead offered that he would mail me a set of the proper (10/12 bolt style plates for 12" rotor w/ PBR caliper) if I sent him back my old plates. All I had to do was pay shipping. This was AWESOME. I shipped my plates out and about a week later I got these in the mail from him (photos attached). these look like exactly what I need to make my existing brakes work on the new rear

Next, I am going to ship these to Moser, and if they say "ok, yes we can use these and they will be compatible with the proper end/bearing/seal combination" .. I will then place the order. I will ensure that they know to use a 2.75" offset for my Gm style C4 corvette brake kit, but I think that they will be able to just install these plates before pressing on the bearing/seal to each axle right?. then when it all arrives at my house, I will bolt in the axles, mount-up the rear, and bolt on the brakes. I think I'll have to run new brake lines, or reconfigure my current ones

I think I am going to go with 3.73 gear ratio. I run a Nitto 555 street tire, which is 26.97" tall if I go with a taller slick, or drag radial or something similar the 3.73's might be better than the 3.55's. I also wont have to swap out the plastic speedo gear either.


i will get screw in studs. 1/2" diameter. i think 2" on the length. will figure out lug nuts later...


here are some photos. The rear gear oil was only put into the axle back in march 2018, and has only 2,200 miles on it. jeeeezzz

[Blackbirdws6]

That T1000 terminator oil doesn't look much different than what came out of my Z.

Congrats on all the purchases.

[IROCZman15]

The rear arrived on Monday afternoon. I knew it was coming so I finished pulling out the old 10 bolt that morning. Installed the axles and my brakes (with the new plates from Ed Miller) on Monday. Tuesday, spent a bunch of time making trips to various autoparts stores for brake fittings etc. Ran my own 3/16" brake lines on the axle housing. (Next year when the engine is out, I will be completely eliminating the combination valve/prop valve and running all new brake lines from the master cylinder to both front wheels, and then from the master cylinder back to the ones I just did at the axle). Mounted the axle in the car Tuesday afternoon and got it all squared up with the various adjustable suspension parts from UMI, that made things VERY easy! Sat the car up in the air at it's ride height today and took measurements for a driveshaft. Ordered the driveshaft tonight


The rear was built by Moser. I had dozens and dozens of conversations with people in person and online about specs, power levels, street-ability, part compatability, etc. Ed Miller got me the set of brake backing plates I needed to run my 1LE style PBR brake setup. I shipped these to Moser and after they gave the "ok" we placed the order.

12 bolt axle housing.
33 spline axle shafts
1/2" x 20 x 2" studs (screw in so I can run longer ones If I ever put on some slicks)
Eaton Detroit TrueTrac diff
3.55 gear ratio
1350 series yoke ChromeMoly
aluminum cover
f-body suspension mounts
powdercoated black
sealed ball bearings
bolt in axles
3" axle tubes fully welded


I am very happy. I can't believe how massive these 33 spline axle shafts are !! The axle with my brakes on it (but without fluid) weighed 210 pounds and is a beast! I know it will rob a lot of horsepower to turn this(and I don't have much currently), but it is worth it in the long run for the strength. The next engine coming will work out just fine with this setup.
I wanted to simply do this once and do it right. I was told by Moser that this axle combination is good to hold about 900 hp on a street type surface, but a little less for any type of transbrake launches on a prepped track with a sticky tire. I forgot to think ahead and buy larger U-bolts for my sway bar mounts (larger 3" axle tube) so those have been ordered.

Driveshaft should be here in a few weeks. Then we can break this in properly and hit the road.

photo album link:
https://www.flickr.com/photos/iroczm...57706981674364


photos of the old 10 bolt and new 12 bolt

[IROCZman15]

photos:


old stock 26 spline axle shaft vs new 33 spline

[ThoR294]

awesome. this is on my list when my rear blows again lol

[ar0ck]

That is a beautiful piece of machinery right there.

[Blackbirdws6]

Love the pics and details as always. I'm sure the rear end will serve you well and looks like you are taking the time to do all of it the right way. I'm glad you went to the 1/2" screw-in studs.

[sweetbmxrider]

I agree with Bls, always enjoy your updates. You are probably one of the few people to put a 10 bolt on rolled out carpet

[IROCZman15]

haha,I cracked up laughing about your comment of the 10 bolt on the carpet. ha.

driveshaft arrived. it is a very nice piece. weighed in just around 21 lbs. 3" tube. fully welded. 1350 U-joints, Sonnax chrome-moly slip yoke, super high speed balanced. free lifetime replacement if I ever break it. Denny's rates this driveshaft as capable of handling 1,500 horsepower and hardcore trans-brake launches. I will NEVER have tht much horsepower and probably won't ever have a transbrake in this car anyways, but its nice to know that this thing is stout.


Installed it with no problems. Checked my driveline angle and it was pretty good for now. I will be dialing it in after I go get a 4wheel alignment in the next few weeks.

Took the car on a road test after doing the recommended break-in session as per moser...which was to put car up on jackstands and let rear axle turn for 2 minutes in Drive, and then 2 minutes in reverse....followed by some road time with moderate driving for 15 minutes. .

the tru-track is niiiiiiiiiiice. I have no gear whine noise at all(my old worn out 10 bolt howled and screamed). the rear feels pretty squared up going down the road too. an alignment will perfect this, but it didn't crabwalk or anything weird. I know I have to move the rear about 1/2" to the drivers side now via the panhard bar adjustment but I couldn't get it this set precise when the car was up on jackstands before.

hmmm, speedometer isn't working at all though. despite me buying a new black colored driven gear, and a whole metal new speedometer gear housing for the 700r4, so I will take it apart and see what is happening. maybe the teeth/splines just aren't engaging.

didn't get enough speed or heavy footed driving to feel any difference between the new 3.55 ratio vs the 3.73 ratio of the 10 bolt. I'm sure this beefy rear setup is robbing me of some power due to driveline loss too. oh well

all in all, project is basically complete and working great so far.

I have been sorting out an ignition issue that Polar Bear has been super helpful with recently and I think i have it somewhat figured out. Also, installed an adjustable proportioning valve for the rear brakes and gutted the current combination valve out. new Hawks HPS front pads too. some other minor things too. hoping to have a good year with the car this 2019 before the engine comes out in the winter.










]

[Blackbirdws6]

I will remember you said this. "Denny's rates this driveshaft as capable of handling 1,500 horsepower and hardcore trans-brake launches. I will NEVER have that much horsepower and probably won't ever have a transbrake in this car anyways, but its nice to know that this thing is stout. "

Parts and install look nice. I always love new things!