I have now broke my second 300m billet shaft in my 4l80. The setup Is a 427 TT, circle d 5 discs lockup converter,4l80 with Tci manual valve-body with trans brake. The first shaft broke on a 3 to 4 shift blowing the tires off on the street. The next shaft broke in front of my house on the trans brake @4000rpm's.... I have been buying the shafts from patc transmission and at $400 bucks it's getting kinda expensive...... Any thoughts ?

 

maybe get them cryo'ed too? not sure if it will be any better

 

Pic of where its broken?

May want to try a different manufacture's input, as at least 1 4L80Es have seen 7's.

 

 

send it back to them and ask for a warranty?

 

PATC is getting that shaft from CKPerformance.
If they won't warranty it call Chris, he may.

Jake

 

I hate to say this but that shaft looks like a factory shaft. Can you take a picture of the front of the shaft that goes into the converter? I want to see the area where the hole is on the end of the shaft. Also do you have your TCC applied when you are shifting? I have seen this break shafts in the past. Just a thought. Vince

Edit.....Also take a pic of the end that broke where either there is a set screw or check ball installed. This will be the end that is installed in the forward drum.

 

Vince,
You are probably correct,
all the billet shafts I've seen have a set screw in the rear hole.
The ones I use look totally polished, CKs look similar to stock and PATC uses/sells CK parts.

Did you ever get a chance to test the transbrake?

I've got new 4L80E seperator plates made as well.

 

Good point Jake. I did edit my above post to get pic's of both ends!

As for the brake no I have not had a chance yet. Just need to get caught up so I can spend some time to test it against the "other". The one issue IMO is the low starting position that we discussed a while back. I did see the plates on the bullet!

 

You might try TCI's new 300M input shaft. It sounds like you have a pretty nasty hot rod!