Hard shift in 4wd Lo

[laredo1307]

Last night I was messing around and just checking my 4wd to make sure everything is working properly. When I shift in to 4wheel Hi everything is fine but when I shift into 4wheel Lo my Tahoe jumps really hard from 1st to 2nd. I also have to push harder on the brakes because it feels like it's trying to lurch. When I push the 4wd Lo button I also hear a clunk sound when it engages. About six months ago I had the transmission completely rebuilt and I've put about 5K on my truck with no issues. It's actually my daily driver. Before the rebuild I would hear the same clunk going into 4wd Lo but never had any of the hard shifting. If I take it back to the transmission shop is there something they can adjust that would correct this issue? I assume this is still a transmission issue and not a transfer case issue.

It's a 96 2dr Tahoe with about 191K miles.

 

[SunlitComet]

When going into 4th it will clunk. You will also require more braking because you are fighting more torque in the axles. As for the hard shifting it could be a valve body issue or the pcm is not aware that 4lo has been engaged by means of signal wire from 4wd system. Some harshness is expected tho when in 4lo.

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[kcb37]

So you were messing around, but them just making sure it works?
Which one and what did you do?

Will agree with above.

What were you doing when it shifted hard?

How are you shifting to 4lo, running, in gear, etc...

 

[SunlitComet]

you should not be able to shift into 4lo while in gear. if so then a neutral safety switch is malfunctioning. and doing so will damage your tcase.

 

[laredo1307]

Yeah, I was just making sure everything was still operating. I was on the street outside my house. When shifting to 4Lo I would be at a stop with the transmission in neutral. I understand that's there's going to be more torque but I just didn't remember it being like that before I had the transmission rebuilt. As far as the hard shifting I was just slowly accelerating down my street. You could feel the RPM's build up and then it would just shift hard into 2nd. Unfortunately I have not been able to use the 4wd much since I've owned it so maybe I'm just not used to it, plus it's an automatic. All my other 4x4's were jeeps and samurai's and they all had manual transmissions.

 

[96Taho]

Just another idea of what else to check.....some times that indicates a u-joint thats gone bad.....and if it only happens when using 4-wheel drive.....it's a good chance it's the u-joint on the slip yoke on the front of transfer case connecting to front drive shaft which is covered by the skid plate

 

[2000tahoeZ71]

To be honest, it sounds perfectly normal to me. Mine shifts pretty damn hard going from 1st to 2nd in 4LO. I have not had any problem with mine at all. However, I believe I have read that you are not supposed to engage 4LO on pavement. Don't know if that could cause it or not.

 

[SunlitComet]

engaging 4wd on pavement is fine just don't start riding on it the whole time. as little as possible just in case your tires are unevenly diametered.

 

[laredo1307]

I played around with it again tonight and even got off-road a little bit. I think everything seems to be working OK.

One thing though. When I got home from work I got under my truck and started exploring a few things before I went 4 wheeling. U-joints look good. There's a linkage on the driver side of the transmission with a cable that goes up into the floor board. That linkage was disconnected. I connected it back but I don't know what this was affecting because nothing seemed to change. I know the linkage is working because I put the truck in drive, pushed the e-brake and noticed it had changed positions. I know the previous owner had replaced the 4wd actuator just before I purchased the vehicle because apparently it was not engaging (I think he snagged it on something when he was off-roading).

Still, I talked to the transmission shop where I had the work done and they told me to stop by and they would check it out.

 

[SunlitComet]

Uh, that linkage is the tranny shifting cable to the steering column. Kind of big deal. Imo.

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