alex226

Just finished up my 4L80e swap in my 4x4 NNBS Suburban. I replaced the input shaft on the transfer case to allow them to mate up. All gears work except reverse. When selected a loud grinding sound that makes me cringe occurs (like trying to put a manual trans into gear without using the clutch). It also sounds as though it maybe coming from the t-case. Anyone have this happen before?

alex226

I should note, the t-case worked fine prior to the 4L80e install, but it was torn completley down to put in the new input shaft.

The 4L80e is a factory reman that's been sitting in an old mans garage for years. Should have 0 miles on it.

tgui

How long was the trans sitting?

03regcab sierra

iTrader: (7)

I had an issue one time with the converter bolts backing off and it would make a grinding sound in reverse. Might want to double check them

alex226

Probably since early 2000's and full of fluid. I had to change the fluids though when I dropped the pan to change out the shift shaft to the longer one for my electronic neutral safety switch.

Hmmm. I loctite'd those and torqued them down to spec. Should be easy enough to pull the inspection plate and check though. It really sounds like gears mashing together. Like it's not fully getting into reverse. I had to keep filling the trans. When I initially started it all up and tried to move the truck it wouldnt move at all in any gear. Checked the fluids and ended up having to add a few quarts. Then it pulled in all forward gears, but started making the grinding noise in reverse.

What is also making me think transfer case is the fact that the speedo jumps around when it makes the grinding noise in reverse. So the trans is moving, to make things inside the t-case move, which is being picked up by the VSS in the t case correct??

tgui

Oh ****! I had a grinding noise from my transfer case after I rebuilt it. I over tightened the vss and they were grinding on the toothed gears that provide vss the signal. The had to back em out a tad. I bet $100 this is your issue!!!!

From my build thread.
http://www.tahoeyukonforum.com/forum...3&postcount=77

alex226

I wish it were that easy!! I would have to suspect I would hear it all the time though like you did. I jacked it up yesterday and ran it through the forward gears. No weird noises from anything. Mine is failing to fully shifting into reverse. Or possibly commanding a drive and reverse at the same time?

Last night it went into reverse once. I had the back tires jacked up and went from D, to R and it actually clicked in!

When I log it with hptuners, and I go to select reverse, the "current gear" bounces between 1 and 2. Now, I'm almost positive it never showed reverse, even with the old trans, i'm pretty sure it would just say 1 when I was in reverse. But why is it now flashing second?

I'm using the frost wire harness, and havent disabled any of the codes yet. I didnt drive the vehicle at all though, was just trying to select different gears while filling the fluid.

alex226

Ok, I read somewhere that Reverse is shown in Hptuners as 2. So why would it be flashing 1 and 2 when I go to select reverse?

alex226

Got it in reverse again. With the wheels jacked up, letting it roll ever so slightly in 1 then going straight to R seemed to work a few times. It held reverse great, up an incline and out of the driveway. I drove it around the block and do not have engine braking in any gear (D, 3, 2, 1). When it tries to engine brake it seems to kick out and start making that same awful grinding noise.

Aside from that, the trans seemed to shift smoothly and go from 1-3 nicely. I tried to force 4th with hptuners, it seemed like that only fully locked the converter in 3? I saw a slight drop in rpm and a felt a little thud, so I'm assuming that's what that was.

Could someone have forgot a checkball during the reman?

*and i'm working on getting a video of the noise.

alex226

http://vid37.photobucket.com/albums/...6/IMG_1902.mp4