Random hard shifting

[rolfsent]

My 1997 Yukon 4wd has started randomly shifting hard between 1st and second and it only happens every so often. It seems to only happen after driving the truck for more than 45 minutes. Could this be something electronic? Because I really don't think my trans is starting to go.

 

[SunlitComet]

Wasnt that a leaky valve body or something issue? I believe there is a pan down fix for that. Scan for a code that does not light up the cel.

 

[BattelWagun]

Wasnt that a leaky valve body or something issue? I believe there is a pan down fix for that. Scan for a code that does not light up the cel.

I believe you're correct. Once the valve body starts to get a little leaky, the transmission develops that trademark 1-2 bump. I drove mine like that for 35k before i had it rebuilt for an unrelated issue. I'm not sure what the fix is though....

 

[04SS99Denali]

my 99 denali did this. put 20k on it and traded it in lol it never failed. best fix IMO would be to drive it till it fails and just rebuild it. once you start fixing little things in the trans it usually opens up a can of worms

 

[rolfsent]

I believe you're correct. Once the valve body starts to get a little leaky, the transmission develops that trademark 1-2 bump. I drove mine like that for 35k before i had it rebuilt for an unrelated issue. I'm not sure what the fix is though....

Did yours only do it occasionally or all the time? Because I was driving all over today and it started doing it after about 30-40 minutes of driving (mostly highway). After that I stopped at my brothers for about 20 minutes and when I got back to driving home it wasn't doing it anymore.

 

[SunlitComet]

it was a 1-2 accumulator that was not softening the shift i think.

 

[rolfsent]

it was a 1-2 accumulator that was not softening the shift i think.

How exactly do I fix that? or am I gonna need to take it to a shop?

---------- Post added at 01:05 AM ---------- Previous post was at 12:42 AM ----------

it was a 1-2 accumulator that was not softening the shift i think.

You are talking about this correct? http://parts.nalleygmc.com/products...sion-Servo--Accumulator/2991178/24204496.html

 

[SunlitComet]

i believe so and can be worked by dropping the pan.

---------- Post added at 12:34 AM ---------- Previous post was at 12:33 AM ----------

but i still think you should scan for non-cel codes first when it is going on first.

 

[rolfsent]

i believe so and can be worked by dropping the pan.

---------- Post added at 12:34 AM ---------- Previous post was at 12:33 AM ----------

but i still think you should scan for non-cel codes first when it is going on first.

I'll check for those.

 

[Donnie Yukonie]

sounds like a bad torque converter to me , mine did this exact same thing and the TC was slipping ended up destorying the clutches in my trans , found this out when i rebuilt the trans and ran into the same issue right after rebuild took it to the dealership guy drove it for about an hour and called me and said TC was bad replaced it and wala fixed
same thing as you described doesnt do it at all at first then after 30 or so minutes of driving come to a stop and have harsh shift shock from 1st to second even when i baby the accelarator

 

[rolfsent]

sounds like a bad torque converter to me , mine did this exact same thing and the TC was slipping ended up destorying the clutches in my trans , found this out when i rebuilt the trans and ran into the same issue right after rebuild took it to the dealership guy drove it for about an hour and called me and said TC was bad replaced it and wala fixed
same thing as you described doesnt do it at all at first then after 30 or so minutes of driving come to a stop and have harsh shift shock from 1st to second even when i baby the accelarator

So just an update on this situation I figured out when this hard shifting happens if I turn the Yukon on and off it goes away? And now also my trans is starting get reluctant of shifting from 1st to 2nd. I really hope this trans doesn't take a shit on me now, it's the original trans with 193,000 miles do I'm planning on the worst.

 

[psfr311]

Mine has shifted hard out of 1st since I bought it. 50k miles ago. Never gotten better never gotten worse. Hasn't caused any other problems either

 

[rolfsent]

Mine has shifted hard out of 1st since I bought it. 50k miles ago. Never gotten better never gotten worse. Hasn't caused any other problems either

I'm not really worried about the hard shifting anymore that comes and goes every so often. I'm now more concerned on why it takes forever to shift out of first and what's weird is the shift is as smooth as can be, it just takes way longer than it should to shift to second. Any ideas?

 

[BattelWagun]

Improper line pressures possibly? Or maybe a bad servo in the valve body? Hopefully somebody else will chime in here...

 

[Gzes]

On my explorer the shift solenoid pack was bad so when changin gears it would kick. Dont know what gm uses but i got kine done at a trans shop and it was expensive... $500 for the pack

 

[rolfsent]

On my explorer the shift solenoid pack was bad so when changin gears it would kick. Dont know what gm uses but i got kine done at a trans shop and it was expensive... $500 for the pack

I don't have any kicking when it decides to come out of first, just takes a awhile to shift 1-2.

 

[Gzes]

Maybe ur trans is taking a shit. When my trans in the 2dr started going it took forever to shift....

 

[rolfsent]

Just got a check engine light, not sure if what's wrong with the trans would set that off. I'll scan for codes tonight.

---------- Post added at 11:41 AM ---------- Previous post was at 10:15 AM ----------

Alright so I'm coming to the conclusion my trans mission is taking a shit. The 1-2 lag has gotten worse and now 2-3 lags, shifts hard and even is starting to slip. Also overdrive seems to just come in and out on the highway. Since I'll most likely need a rebuild or new one which should I go with?

 

[Donnie Yukonie]

pretty sure sounds like a bad TQ

 

[rolfsent]

pretty sure sounds like a bad TQ

I'm gonna take it somewhere tomorrow and have it checked out. I'll update when I find out more.