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Strength/Limits of stock input shaft? When to switch to billet?

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818GN

Banned
Joined
Feb 6, 2010
Messages
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Currently I have a built trans, but a stock input shaft.

I have been told that the input shaft is the weak link.

At what point should you replace the stock input shaft with a billet piece?

Just added ported heads/intake and about to order a PTC converter real soon, then getting tuned.

Would like to know what the limits of the stock input shaft are, before I find out the hard way.:eek:
 
I shattered my stock input shaft while running low 12's with the stock turbo! I had a transmission built MINUS the billet input shaft because I didn't want to spend the extra couple hundred bucks and I didnt think I needed it yet. Then after about 3-400 miles on the new trans I exploded the stock shaft and send metal chips all through the new trans.:( I then paid to have it all redone PLUS a billet shaft. It really would have been cheaper to do it right the first time.
 
I shattered my stock input shaft while running low 12's with the stock turbo! I had a transmission built MINUS the billet input shaft because I didn't want to spend the extra couple hundred bucks and I didnt think I needed it yet. Then after about 3-400 miles on the new trans I exploded the stock shaft and send metal chips all through the new trans.:( I then paid to have it all redone PLUS a billet shaft. It really would have been cheaper to do it right the first time.

I would call that the exception, no billet input here and this car has been beat on with a transbrake for YEARS.
 
I would be more concerned about the forward drum shaft. That's the weak link in these transmissions. I'm running high 10's on a stock input shaft but have a billet forward drum.
 
If your car has mid 9 sec power and is capable of 60's in the 1.30's I'd replace the shaft. I've never broken a stock one and have only known of 2 that failed. Both were 9 sec cars
 
I've been low 10's at 133 with the stock shaft and 60' in the 1.4X's without any problem. AC Non-Lockup converter.
B.
 
I'd have to agree with the others. The input shaft should be of no concern until you get DEEP into the 9's on a regular basis.
It's the forward drum shaft that's the problem, get that one "billet'd" as soon as you can.
 
Very tough call. Stock input will handle good power in a Non-Lock application I would say low 10s. Lock-up app. I would say mid to low 11s.
 
Very tough call. Stock input will handle good power in a Non-Lock application I would say low 10s. Lock-up app. I would say mid to low 11s.

we broke one in a high 11 Limited stocker years ago.. BUT to me if the car is goin good put all the good stuff ya can in it :cool:
 
Very tough call. Stock input will handle good power in a Non-Lock application I would say low 10s. Lock-up app. I would say mid to low 11s.

The trans I currently have is lock up.

Is their a difference, when it comes to trans failures, when it comes to L/U vs. N/L trans?

If so, please explain.

I will call the trans builder Monday to inquire about the forward drum.

Great info so far.
 
In the long run

Why chance it? It will cost you the price of the shaft just to pull trans replace, new fluid and so on. At this point and time, why chance it? Better safe than sorry the ole' saying goes.....:wink:

Bruce
WE4
PTS XTREME Transmissions
 
I shattered my stock input shaft while running low 12's with the stock turbo! I had a transmission built MINUS the billet input shaft because I didn't want to spend the extra couple hundred bucks and I didnt think I needed it yet. Then after about 3-400 miles on the new trans I exploded the stock shaft and send metal chips all through the new trans.:( I then paid to have it all redone PLUS a billet shaft. It really would have been cheaper to do it right the first time.

I was running a Vigalante multi disk lock-up and my car broke at 3/4 track after the lock-up, not at the line.
 
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