1995 K3500, Fresh 4L80E...1-2 shift is too harsh

[454/4X4]

I just got this truck, its a 95 K3500, Reg cab, TBI 454, and it had a bad trans in it. I took it to a shop for a rebuild, I asked for a stock rebuild. What I got was a trans that will chirp 33" tires on the 1-2 shift every time...regardless of throttle.

If i roll into the gas, gently accelerating, right at 12mph it slams into 2nd gear. With so much force that I can feel the springs shuddering in the back.

2-3 shift is good, 3-4 is good, Lock up is good...downshifts fine, no slippage....only problem is the 1-2.




He said the only way he can soften it up is to replace some kind of module that is now "new" with my old one...? To me it sounds like he did the HD2 shift kit and went for the aggressive setting!

But...any ideas on what can cause it to be like this? He said he put a gauge on it and the line pressure is right at reccommended settings...and he used all new parts, solenoids, harness, etc..


Thanks

 

[RED90]

how long have you had this transmission in your truck? how many miles have you put on the new one

 

[454/4X4]

Ive had it in about a week now, Ive put about 50 miles on it, but im afraid to drive it at this point because of the 1-2 shift. My Z71 has a 4L60E with a shift kit, 2100 convertor, Corvette servo, etc etc...and with a strong crate 350, and the same tires as this 3500...it hits 2nd much more softly, I nfact it is just as I would expect, the more pedal I give it, the firmer it gets. Id expect this 4l80E to be the same...soft id low power conditions, and firm at Wide open...but no, it thinks im balls out all the time.

 

[RED90]

my best guess would be that it needs more break in time. it should already be starting to calm down or shift normal by now though. I know that when I just rebuilt my transmission it shifted hard at first but once I put a few miles on it it calmed down. kindof a memory thing of how one drives really. during the big blizzards this winter when I was out driving around in 4x4 I had to really mash it to get out of some drifts on the road and once it all melted and I was able to put in back in 2wd and take it easy it shifted really hard and held gears way longer than normal. just kept driving it and it went back to normal. that's my best guess...

 

[rhino]

I would swing it by somewhere and get the codes checked. Even if the check engine light isn't on, I would get them checked. It shouldn't need a break in time.