them stock cases are junk. good for 4 wheeling but serious drag racing no way. they were never made for it. i love when guys get 9" rear,upragde everythng but a $200 strange c section. weakest link people.

maybe im a tool but why are you thinking 33-35 splines will stop axle twist? arent them axles going to be the same thickness therefore the same twisting strength? isnt the spline count more or less just a stronger link between axle and diff? again i dont see how splie count helps twist. 31- 0r 35 spline your still dumping the same torque.load threw the same axle. i read the above post with the math formulas but that tells me the spline section can handle more power not the axle portion...if im wrong somebody explain it to me like a 5 year old.

 

Depends on whose axles they are. Strange axles have a slight taper and the splines are a larger diameter than the axle. All GM factory axles are weak because they have a taper. Some but not all Ford factory axles are non tapered. I use Moser axles. Technically I can get the axles shortened and resplined because the axle diameter is the same diameter as the splines.

Spline shape and size is uniform no matter what the spline count of the axles are. Going from a 31 to 33 or 35 spline axle means the axle shaft needs to be larger in diameter to add in the extra splines. You can't take a 31 spline axle, cut it shorter and cut 35 splines into it. The smaller size of the splines won't fit into anything.

It takes a lot more torque to twist a larger diameter shaft. Grab a pencil and twist it. Now grab a broom handle the same length and twist it. Both can twist but it takes a lot more effort, torque, to twist the larger diameter broom handle. The Moser axle calculator can tell you how large an axle you need for your car. There's always a safety margin allowed in the calculations and if you stay below the rating of the axle, you should never break one.

Going above 35 spline axles and sometimes even 35 spline axles, are usually gundrilled. Technically, the axles are hollow but not all the way through. This doesn't reduce the strength of the larger diameter axle but it does greatly reduce the weight of these large axles.

There are a handful of aftermarket axles available. Some are good, some are not much better than a factory replacement. Many racers use Moser or Mark Williams axles.

 

improper burnouts and spinning off the line(or playing on the street) can still kill a sprag in the 400. youve got to have some HP to do it, but it will happen if you dont take care of the parts.
they are some stout buggers.
ive got 113K on my truck and i give the 4L80 hell pulling a trailer everyday, and to the racetrack on the weekends.
it will prolly go out tomorrow, but its been a good one.

 

very true. I may go with the griner spragless set-up for the blower motor.

 

Biggest common TH400 killer/sprag killer is the guys who roll out of the burnout in 1st/2nd gear..esspecially 2nd gear since that is sending all that shock of the dead hook directly to the sprag, vs coming out n high gear where everything internally is essentially "locked together" and transmit the shock through ALL components vs just the sprag only.

 

while we are on the suject of trannys, whats in your ride?
rear gear?

 

9" BTE pro mod convertor....seriously LOL!! All the other 8"ers just flared/flashed waaaay to much and nobody could get one tight enough for my tank and the combo i had...but it's awesome since even on the nitrous it's tight with a free replacement garuntee saying i'll never be able to hurt/break it with anything that'll be in this car..through my personal dealer/freind, not through BTE...kinda of a dare to spray the snot out of it i guess, but i aint goin there.

TH400, all JW guts

ford 9", strange center section/richmond 4.11 pro gear/richmond full spool/moser 31 spline axles

hooiser 29x9 slicks 15psi