OK, not the gears. They're fine. I decided to pull the pinion support out today to replace the o-ring and fix the leak. I found I had a little bit of end play in the pinion so I removed one small shim from the solid crush sleeve. When I went to put the pinion back in, I noticed the bearing retainer for the rear bearing support was on the floor. I looked inside the diff to see the bearing support was cracked. Luckily I had a spare and spend the rest of the day swapping the gears over into it. It took me a couple of hours to get a perfect gear wear pattern before putting it all back together. I guess it's just about time to upgrade the third member to something better. I want the Moser aluminum bolt through third member. It'll go nicely with the aluminum spool and aluminum daytona support I already have waiting to be installed. When I installed my new 31 spline Moser axles at the beginning of last year, I used a straight edge and painted a line down the length of the axles. When I had the axles out, I can see a very slight twist along the line. It's roughly one spline out now. Maybe a little less. Maybe it's time to upgrade to 33 or 35 spline axles now. Then again, maybe my straight edge wasn't exactly straight down the axle. I'd be worried if the line had an obvious twist but you have to look down the length of the axle to see it.

yep, would have to say a stock type center section has no place on any car in the 10 and faster range, i cant count on all my fingers and toes the amount i've seen snap/crack/explode at the races...one of those "living on borrowed time deals"

I believe that's what happened to mine last year. It ended up blowing out the side of the case and broke both bearing caps. Lost the ring and pinion too. Mine just exploded on the starting line. Might as well move up to the 35 spline stuff and be done. Mine took out the drive shaft and tail housing on the trans with it.

i run the aluminum bolt-through housing and aluminum daytona support with 35 splines...if i break that thing i must be doing something right I think you'll really like them.

Thats where the stock castings are the weakest. Time for an upgrade.

If I recall Moser says that is perfectly normal and should be rotated from left to right. however you can't switch axles on a 9".. My 31 have some twist.
Have been on the car since about 1997.. But I do think one has a little runout now. Guess I can't complain about that though..

i have the strage alum carrier. ive broke 2 gears but never once did anything to the carrier. im supprised a tubbed car not already having a aftermarket housing and 35 spline axles.

be very suprised...standard/nodular factory housings run rampant at the drag strip in all sorts of stuff they should'nt be. sure they last for a long time, but eventually they will break, they're just not upto this kind of abuse all the time. Watched and helped push countless cars off the line due to this and each driver has ALWAYS stated, "i knew that was a weak link, and i guess it finally decided to go"

oh well, there's area's in my car i've not upgraded to best i could afford, but the drivetrain i made sure i did the best i could...dont need to be breaking on the line and sure the heck dont wanna have issues down track and lose the complete package.

as far as axle twist, i want to say i spoke with a moser rep at an event and he said either 2 or 3 spline twist is completely fine, and twisting 1-2 spliine on a heavy car, or car with lots of power is very common, esspecially with 31 spline axles. knock on wood, mine are still string straight, but they're only 4 years old and have may 4-5000 passes down race tracks plus street miles so we'll see what they look like in the next 4yrs, and then i'll judge'em.

my 35splines are straight as the day i bought them 10 years ago. lol

You need to understand how much torque is put through the axles. If I was running a 3 speed transmission, I would exceed the limits of these 31 spline axles but I only use a powerglide.

According to the Moser axle tech formula.

Torque x first gear x rear end gear x .9 gives a calculated torque that the axles need to absorb. One axle should be able to handle all the torque.

My car is putting out an estimated 770 pounds of torque however racing at altitude, that number will be lower probably by about a hundred foot pounds. 1.76 first gear and 4.86 gears.

770 x 1.76 x 4.86 x .9 = 5927 pounds of torque

Moser 31 spline axles can handle up to 7000 pounds per axle so I'm still below the safety limit. My race weight is 3042 which is a moderate weight.

Now lets say I was running a TH400

770 x 2.48 x 4.86 x .9 = 8352

33 spline axles are good to 8200 pounds so I would then need 35 spline axles which are good to 9600 pounds

Now yank out my engine and drop in a modest SBC with 550 pounds of torque with a TH400 behind it.

550 x 2.48 x 4.86 x .9 = 5966. It would only need 31 spline axles and would produce slightly more torque to the wheels as my current setup does.

From the Moser web site
Too many people think bigger is always better.

What sort of case was that, single or the double rib? I'm running a stock 9" as well with Currie 31 spline axles. Been worried about it breaking plus would like to shave some weight with the aluminum case.

Does'nt matter, i've seen plenty of "war cases"/ Nodular center sections give up the ghost as i have a plain jane factory case. Going aftermarket is just buying insurace...and as i seen last weekend, buying a cheap spool-even in a 2600lb car-is'nt the best decsion either, the entire right side of the spool that the axle slides into sheered off the center part of the spool

This one was the average, run of the mill, find them in everything, C7AW-E case. All factory cases including the N case is still weak around the bearing support.

Ford 9" information
http://www.kevinstang.com/Ninecase.htm

i ran a plain jane housing in mine for awhile before going to the aluminum. i am still running the standard pinion support, though.

i will say the usual cause of destruction like that is too much pinion angle. not saying that was your issue, but for most people thats the root cause.

im thinking it was just plain old fatigue. after thousands of passes, stuff just gets fatigued. thats why you can pick up all the used nascar engine parts for so cheap. lol

And just think of how old these things are and how many miles they have on them from previous service life

lol no kidding, the gears, limited slip and center section in mine have who knows how many miles on them. I have put new clutches in a couple times, 1st set burned up probably do to my fault or it may have happened when one tire didn't get wet in the burnout box. Yes a spool is in the plans and the limited slip will be retired to street duty with some 3.50 gears.

I broke a carrier bearing cap on my cast case last year. Thus ruining ring,pinion,carrier, ect.

The housing was rattling around in the back of my truck today. Me and the guys at work took a look at it this afternoon and once it was cleaned up a little more, we noticed another crack on the other side of the support. I gave it a tap with a hammer and it broke right off. No pic of the broken piece. So that's 2 potential major failures I found this month. The broken valve spring and the broken diff. Now everyone at work says I have a horseshoe shoved up...

That sucker was really ready to go.

I have seen cases crack in that area that have never been in a race car. Very common.

You just might have a golden horse shoe. You have saved yourself a bunch of money finding the problems. Most of use find out the hard way. I wish I could have seen the crack in my crank before it destroyed the block ect. The engine only had about 20 passes on it this season, on a freshen. At least you can buy a good case now with all the money you have saved.

LOL, I be hate'n da broken cranks...cost me lottsa muhla TWICE until i figured out what it was causing it...fricken alternator/factory steel pulley....$8000 later and the real fix woulda been $325 for the new alt/brckt/pulley i have now..hind sight and problem solving skills like a retard LOL!!!

I've paid my dues in major failures in the last 10 years of racing. I've gone through a few engine rebuilds. I'm due for some good luck.

It's a sore subject, but i agree 100% with ya

i know its an old post, but i didnt get so lucky.
1.36 short time and broke.
it was some banging and rattling ive never heard before.
trashed everything.

was that a stock case?

Had to of been, seen multiple center sections implode like this every season and in almost every case it's the pinion support that frags...and the #1 thing the guys all say back in the pits cooling down with a cold one-
"That was the one piece that i knew i was on borrowed time, figured if i could get through this season i'd upgrade it this winter"


Prolly broke right on the line either on the hit or a split second after the hit?

Hopefully nobody was hurt, sucks, but now's your excuse to upgrade

I got lucky when I discovered mine or the same thing would have happened. I finished off last year's season with a spare C7AW-E case that I had and last winter, put this into my car.

Moser bolt through aluminum center section. Aluminum Daytona pinion support. Aluminum 31 spline spool and 4.86 gears. I didn't think the cheaper Strange aluminum case would have been strong enough for me.



The 9" case design is still very strong but they're not indestructible, nodular or not.

yea, stock case. car was 1.361-1.366 all day. i think i made 8 passes ,then it broke RIGHT on the line. car was going to the sky and it broke.
stephen- your right about the strange, i was not comfortable with their aluminum unit either.

ended up with a moser aluminum thru bolt daytona support, spool, and a lightened and treated gear.
the rearend ended up killing my tranny yoke, or it may have been on the way out as well. i had to beat it off the transmssion with a sledge.
splines were seriously twisted.
so now i have a chromemoly yoke and a chromemoly driveshaft.
bad news is i think it broke the planetaries in my th350. when i got it back together, its still clunking, car doesnt want to move.
metal all in the pan. chunks, slivers, bits, pieces.
im test fitting a glide right now. friend of mine has an extra im going to try, but i think a 3spd might have an advantage at my weight and gear.
its a freebie, so its only my labor im out before i figure out which tranny i want to lay coin down on.
i shouldnt have any weak links left now, as long as i keep oil in the motor.

Sexy looking 3rd member


Yep, and that can pretty much be said about anything and everything we bolt in/on our cars...no matter how big and how much they cost

Well, what in a moser 12 bolt can break like that? I am sure only gears and axles, anyone disagree?

The 12 bolt won't break like that because of how they mount the pinion in the long snout of the case. The factory production 12 bolt case and side gear bearing caps can still flex and break. Your Moser case is a lot stronger than a factory case and you can see what kinds of limits the factory 9" case can take.

The 9" actually uses 3 bearings to support the pinion. The pinion support bearing is called the pilot bearing. The stronger setup is to use a Daytona support which has a larger inner bearing and can take more load.

Ok, glad to learn some infor like that.

That is why i asked about the Moser 12, the GM unit was just not made for the abuse and had too many casing flaws, although there are some stockers that have more borrowed time and others, the 12 bolt stock is not on par with a stock 9 inch.

Thanks Steven.

while the 12 bolt is a good piece, the f body version lacks a great way to mount the torque arm.
youve got to keep an eye on the mounting bolts, as several issues can occur when the bolts loosen or come all the way out.
broken torque arm, twisted driveshaft, transmission trouble, body damage, etc...

That is what i have had people say, but it is to each his own, myself and several other have never had an issue. I check mine, but i have a friend with a 427 LS in his 02 TA, beats the snot out of it and never checks it. 4 or 5 years now.

Guy I know wadded up a 12 bolt couple months ago when the torque arm mount broke. Doesn't help he launches his stick car at 7200 rpm lol. He had a 4 link installed after that happened.

Was this a stock TQ arm? Or did the bolts back out? I have seen them not have an issue and then i have had people bitch about having to check them.

Don't let that Moser guide fool you. It told me that my 31 spline was fine with a 1.80 gear Powerglide and 1200hp. They guy on the phone laughed at me and said 35-40 spline son is what you need.

And my 31 spline axles are fine. Estimated dyno corrected, I'm only a little over 800 HP. Somewhere around 830. According to DD2000, torque is slightly under that. Of course, racing at altitude, I'm not making that much power. I estimate I'm making less than 750 HP so less torque also. Based on those numbers, my 31 spline axles should still survive with a 1.76 glide.

After all those wheels up launches late in the season, I will still pull the axles to see if they're twisting or not. I can easily upgrade to 33 spline with the 9" case I have. It is possible to upgrade to 35 spline with a special spool that will fit into a small bearing case but I don't know if I would trust the small bearings with such a large axle shaft.

i ran my stock case for 10 years street/strip.
i was fortunate, sounds like your buddy is beating the odds too.
im not saying all of them have issues, but even with red loctite ive seen the bolts back out.
read where a few guys will just put a lil tack weld on the bolt just to keep it in place.

Aftermarket torque arm kinda like a Jegster short arm. He's been running the same setup for who knows how long till this happened.

LOL, my stock 2.73 10 bolt is still in one piece for some reason, i beat the snot out of it, now it is sitting waiting for a gear swap so it can go in my new 89 T top car.

I was actually wanting to see if i could make a plate that could secure the bolts in place, but i might wels a thin piece of metal to them, i think that is the best bet.

Never ran that, heard they are not that great too.

Found another one. Every 9" failure looks the same. Pilot bearing support breaks and the pinion goes out the side. This looks like one I saw last year at the track.

there is a plus side to that picture above.
you wont need a 9/16 wrench to get the bottom bolt out.
looks like a socket might clear it now.
haha!

Guessing the trans was fine before, you likely took out the low roller support. - That's what I did when I munched the driveshaft with my TH400, but I knew it was possible, so I pulled the trans down to check; thus saving everything else(another hit would have slaughtered it). - I'm no th350 guy, but I know they are similiar in design to the 400.

I'll stick with the fact that if a name brand, top of the line glide was given to me I would just pass the deal along to someone else. F* 2-speeds in a heavy car, there's a reason they make bolt-on carry handles and quick detach trans cooler lines.....

I was thinking the same thing when I saw the pic

got the call from PTC. i EXPLODED it. in his terms.
he doesnt think the rearend killed it, but it could have helped.
clutches were all burnt, steels were scarred and he couldnt find the sprag in the tranny, it was in pieces.
odd. i had an aftermarket deal in there.
600 to replenish mine, or they will upgrade me to a glide for 300 bucks(900 total)
mentioned about having to put an aftermarket set of planetaries in it at my weight and 60ft to lessen trouble, but all are 2.75 1st gear for a 350. thats just too much.
also be a good idea to upgrade to a hardened shaft, but to do that in a 350, you have to run a aftermarket set of planetaries. back to square one.
waiting till after the points race next week and then gonna toss it in.
ill report back with some accurate info.

th400..................at least 6 glides got swaped between Friday and Sat evening that I know of at the ORTC race, and I was suprised to see a lot more Rossler stickers than there used-to be on radial cars.

rosslers 400 is becoming more popular.
id like to have one, but my current situation wont support it.
i might see if ptc will work a deal with me on a upgrade to a 400 if the glide doesnt work out for me.
i dont see why not.

An otherwise stock TH400 will handle 800hp all day long with nothing more than the 34 element sprag, decent clutches and proper prep/set-up. Upgrade the fwd hub and that number goes to 1k hp. North of 1k, the stock input shaft and intermediate shaft become unreliable.

As soon as I freshen it I will be getting rid of one of my 400's. I've yet to need my spare, so I deffinitely don't need to keep two spares around.