Trans input shaft strenth??

At what point do you absolutely have to go with the 1.25 shaft? Is it a torque or weight number? Combo is a D Screw @ 120 over 481x 3100#,Trying to run the outlaw 10.5 tire class for 2010. Duz it matter if 2 or 3 speed(More Stress on it ?) My trans is a Bruno w/400 shaft w/Lenco 3 speed,Just debateing wheather to change all this stuff now or see if it's gunna hold up: Anybody have real first hand experience w/turbo 400 shaft breakage? What happens if it does let go? Thanks,Joe Schroeder

 

Th 400

The best thing you can do is run the blower at 80 over or less (LOL)... make less power... LOL

We run a Rossler th400, he makes the best input out there.... the only thing we did is twist the shaft a little... never broke one...

See you on the starting line.

 

I ran a T400shaft on my car last year for about 4 races, (4.40's @ 3100 lbs) plus in my previous car with a screw at 3000 on 10.5's. the shaft had well over 200 runs on it and never broke. i upgraded to 1.25 when i changed converters. Accoriding to Chance the 400 shaft is actually a little more efficient. i'd say run it til you break it.

 

I have not run one personally but know several people who have had them go south on 10.5 cars with both big nitrous motors, so I am sure with a D rotor its only gonna be worse.

 

I broke a turbo input shaft this year leaving on the trans brake. It broke right at the hit. I bought the trans second hand so I don't know what material it was made of (I was told 300m). The input shaft sheared so clean it looked like it was cut with a band saw. I didn't create any internal damage to the trans I just disassembled and cleaned it. I bought a new high dollar shaft from Coan that is supposed to be as strong as you can get without going to the bigger shaft.

 

Thanks everybody for the replies,dont want to tear up parts if i can help it. Did your engine free wheel -Hit the rev limiter when your shaft broke? It sounds in your post like nothing else breaks when the shaft let go. Is that correct?

 

When they break, something in you tells you to get off the gas pedal immediatley - instinct, you wont over rev your engine.

 

When the car didn't launch I let off the pedal right away. The engine went up a bunch but I don't think it hit my 8600 chip. If it did, it wasn't for long enough for me to hear it.

In my situation it did not break anything else. However, I don't know if that is always the case.