Hard Shift 1-2

[MUHSFINK]

Hello all. I'm new to this forum.

I bought a 2008 GMC 1500 Sierra Crew Cab SLT a few months ago and it has always shifted roughly from first to second and then feels lazy from second to third. At first when I bought this truck I just figured that the tranny just needed to "relearn" my driving style. I don't do any stoplight drag races... However after months now it is still shifting with these anomalies. I've checked the fluid and it seems perfect, level and color, temp etc. Since the fluid looks good I'm worried that a simple trans fluid flush wouldn't help anything. Has anybody else had this problem? I really don't want to shell out for a new transmission but I also don't want to get stranded on the side of the road. (It's quite cold up here in Wisco!) Also recently when I'm driving at highway speeds it has felt like I either went over a big bump or like someone hit me in the back, i.e. the whole truck shakes and sort of feels like it slipped out of gear for a fraction of a second. It has only done this 3 or 4 times. This is a new feeling and I'm worried that the hard shifting might be destroying the transmission.

 

Any suggestions guys?

[oldschool327]

How many miles? Tranny is covered until 100K

 

Do you know if the previous owner changed the Servos in the tranny.... Corvette/Billet?

[ChevyTech77]

Aftermarket servo is a possiblity.

 

Have the trans adapts relearned at your dealer, in the tcm, and try it again.

 

My 4L60E has always had a firm 1-2 shift while the rest lacked "stiffness" comparitively. I pulled it down this past week because the torque convertor was howling and found it to look nearly completely brand new on the inside. 195,000 miles and it's never been touched either.

[jro909]

every 60 i've ever driven has the strange 1-2 shift..some bump, some are harsher....mine kind of alternates between bumps and kicks lol

[MUHSFINK]

Thanks guys. I'll make sure to have my mechanic check those things out. I guess I should probably have said that I bought this car rebuilt after an accident. I'm thinking their might even be a crappy rebuilt transmission in there?? Overall the car has 63,000ish miles and because of the accident it wasn't eligible for the warranty. Everybody's said I must have just picked up a lemon/slap-job rebuilt truck. How much would it take to get a rebuilt 4 speed or to rebuild the tranny in it already? Does the new 6 speed "bolt" right in?!

 

Cheers.