[AROWHED]

Early this year I narrowed a 1963 Pontiac 9.3" by 2.5", and put a 31 spline spool in it with 3.42 gears. Vehicle is a 65 Grand Prix, about 600HP E-headed stroker 467, Viper six speed, and 30" tall street tires on rear. Probably 4500 lbs with me in it. Had Moser build me a pair of their $385 31-spline custom street axles. I had to send them back upon initial delivery, since they would not fit in my spool, nor a factory axle gear. They recut the splines but in process of doing also made them twice as long as they needed to be.

Got about 1000 miles on it this summer, and was gonna switch to 4.10 gears but upon disassembly found I have twisted the splines, and slightly bent my screw in 1/2" lug bolts. The splines and lug bolts are twisted in the direction you would expect from (possibly) excessive applied drivetrain torque. Pic shows Driver side axle on left, pass on right, and pass side lug bolts, driver side bolts bent the same.

Moser does not warranty their 31 or less splines axle shafts. They say my application exceeded the strength of 31 spline, the spool being the final straw. They say I need 35 spline.

So is there any 35 spline, 3-series posi differential option out there for a 9.3" rear, besides the Strange D1550 spool?

Do you think a street driven car with a spool should be able to twist a 31 spline axle and bend lug bolts like that? Are these shafts now useless for anything beyond a real grocery getter?

[Kevspontiacs@aol.com]

Possibly too much stag in the trailer?? Lol

That sucks Mike.

I'm wondering if the axles were heat treated after they resploned them.

[AROWHED]

That definitely crossed my mind. How could I tell if they weren't heat treated? Moser seemed adamant they splined them correctly, using an actual Pontiac axle shaft gear as their template of sorts...until I shipped a 1963 gear back with the mis-cut axles to prove they would not work. I think they had the pressure angle wrong, Fabcraft told me the angle changed from 30 to 45 degrees at some point, and maybe Moser used a later gear the first time. Either way, they doubled the length of the splines when re-cutting them....and the twisting is visibly all in the extended length, except right near where they taper off, going inwards.

[Richie Hoffman]

i just built s 62 catalina with 9.3 for a customer got axles from Fabcraft made by mark williams who i think makethe best stuff then strange Moser good for street stuff

[Richie Hoffman]

i also put 5/8 studs in axles these cars are heavy

[opeliac]

A couple things here...First off, if you twisted the studs, then obviously you are doing enough to break stuff, therefore a 31sp axle was not enough to start with...

Second...The comments were made about where the axles twisted, and hinted at the heat treating being the issue...Well, the axle twisted as soon as it left the gear in the posi, which is where damn near every one will twist...It CANT twist in the actual gear.

I have been a Moser dealer since the 80s, and we have had their stuff in BIG HP cars, that were also heavy...They have always held up great...With that said, I would've never recommended anything less than a 33sp for a heavy car making 600HP...

[tom s]

You have to remember on street driven spools everytime your turning a corner your dragging the opposite tire putting excess strain on that axle.Maybe have two 3rd members,a posi for street driving and a spool for racing.Not a huge job to swap out the pumpkin.Tom

[AROWHED]

I found that the tire on outside of turn dictated the speed for both tires..the tire on inside of turn does little wheels hops trying to keep up. Some guy in a grocery store parking lot says to me Nice Car, but there's something wrong with it, I've never seen a tire do that!
So am I SOL on trying to find a 35 spline, 3-series posi diff?

[tom s]

I Brads new posi does not come with that option yes your screwed.Tom

[Richie Hoffman]

we had a 65 catalina we put a 12 bolt chevy in 31 spline posi street strip car ran sticky tires never broke posi or axles

[Richie Hoffman]

30 spline

[opeliac]

Originally Posted by Richie Hoffman

we had a 65 catalina we put a 12 bolt chevy in 31 spline posi street strip car ran sticky tires never broke posi or axles

So you raced with 600hp and never broke a 30sp axle?

Thats impressive

[opeliac]

Also, to the OP...Just put a spool in it and be done with it...I put tons and tons of miles on my Lemans, in all types of weather, with a spool...

There are also a crap load of fast drag week cars with spools in them...

[JSPONT]

4000 lb Lemans with a turbo, putting 750+ to the ground, strange spool, 35 spline axles, slicks on the street. 2 years with a stick, 1 year with the auto. No issues yet.

[tom s]

He has a spool now!Tom

[Mike Davis]

Originally Posted by opeliac

So you raced with 600hp and never broke a 30sp axle?

Thats impressive

I ran 30 spline 12 bolt spool with Moser Axles for years in a low 10sec/high 9sec 3700lb car and never had a problem.

Ran the old stock 8.2 for 10 years running 10.60's with slicks.

Have since changed to a 33 spline set up. Just for a little insurance.

[Richie Hoffman]

65 catalina went 1200 full street trim

[Richie Hoffman]

i’ll let u know if i break the 9.3 in 62catalina 342 posi now with drag radial went 12.20 in heat 1.72 60 ft will run next week at track then i have another center section i will put together over winter with 31 spline spool and 4.10

[tom s]

Richie,if you have the dana style posi the weak link is the bolts.They stretch and allow the case to turn a touch.Then the mesh of the side gears go out and they break.Toms Differential some years ago when he was alive drilled the case a little over size and used the next larger bolts to hold it together.Never had a problem after that.Check them before its too late.Not sure if next grade bolts would be better.Tom went with larger.DONT break side gears!Pinions are easy to get but not side gears.I think the 64 style 1 piece case design might be stronger?
By the way he said that arma steel case was hell to drill and retap larger.Its still in my 421 63 Lemans for like 20 years now.Tom

[Richie Hoffman]

Tom thanks for info