okay i just had another 4l60e break, it was just rebuilt. i took it on 3 passes and on the third pass it broke. i called the guy that did the rebuild (which has been in racing for 26 years, very reputable around this area). anyway he said that with as much hp as i have and the low gears that i have in the stock rear end that it is causing to much stress on the transmission, which is causing it to break. could this happen. any help would be appreciated. he said that if i change the gears to 3.55 or 3.73 it would help. i know that would give me better track times but what affect would that have on the transmission.

 

When did the trans fail? Also what are your rwhp #'s? Where are you located?

 

it failed on the shift into 3rd both times. it is blowing the clutches out of the drum. i'm running close to 470 rwhp with a 4000 stall i'm near raleigh nc

 

Let me get this right so I understand what you are saying. Are you breaking the drum or burning up the clutches?

 

its breaking the tangs out of the drum and clutches are fine, no burn marks or anything

 

A couple of things come to mind. These are a couple of questions that you might want to ask your builder. How large of a feed hole is being used for 3rd? How much pressure is the unit seeing on WOT? How loose is he setting the 3-4 clutch clearance? Are you locking the converter up before the 2-3 shift? These are things I have addressed before working at FLT. I have seen this happen in cars that don't even make the power that you do. I honestly think that one of the above things mentioned might be an issue. We have built many unit's with your power level or more and do not see this issue.