What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[gooffeyguy]

went and picked up the yukon from the dealer after having the rear u joints and fuel pump done and mf'r is vibrating like a sob.
called them and they said they do not balance the shafts and would have to send it out, so 1st thing Monday i'm going to run it down to the driveline shop
and tell them I need a rush on it already paid for a bunch of stuff for the vacay no time to screw around.
apparently they do not have a QC guy on Saturdays and it was closing time so limped it home even though I didn't want to vibrations f-up the ring & pinion .

Try clocking the driveshaft 180*

 

[Doubeleive]

Try clocking the driveshaft 180*

i'm going to mark it when i take it off but still going to have it balanced, I don't think flipping it alone will do anything but I guess I could try it in the morning it's scorching hot here today not even going outside unless I have to

 

[gooffeyguy]

Not sure on our vehicles, but others I've had, there would be match marks on the drive shaft and on the pinion housing or flange and usually when removing the driveshaft you would re-install matching up the marks.

 

[Doubeleive]

Not sure on our vehicles, but others I've had, there would be match marks on the drive shaft and on the pinion housing or flange and usually when removing the driveshaft you would re-install matching up the marks.

I took the drive shaft on the wifes 05 to be done at the driveline shop I didn't notice any factory marks but there could be

 

[swathdiver]

@swathdiver do you have the torque spec's for the rear u-joint bolts so when I slap this thing back together I can do it right

18 ft lbs. While I've never done it previously, the manual says to use new retainers and bolts. 89029380.

 

[swathdiver]

I took the drive shaft on the wifes 05 to be done at the driveline shop I didn't notice any factory marks but there could be

Tom is mentioning that it's best to install it the same position that it came out to minimize the chance of vibration. So we put scribe or chalk marks on each end and match them up when re-installing.

 

[Doubeleive]

Tom is mentioning that it's best to install it the same position that it came out to minimize the chance of vibration. So we put scribe or chalk marks on each end and match them up when re-installing.

makes sense but had the dealer do it so no telling I will try and flip it in the morning while it is cool out, 108 deg right now or more

 

[j91z28d1]

definitely flip it 180 and make sure the cups are seated correctly in the pinion flange. tighten even.. I'm sure the dealer did non of that.

try not to drive your trip with it vibrating. I've killed tranny tail housing bushings and it messes up the crush bushing and the whole thing loosens, wears badly and eventually takes out the pinion seal.

I hate drive shafts

 

[j91z28d1]

I use the data from the Torque Pro app on my phone or the Tech-2 for the fuel pressure. I have had my Tech-2 connected to two GMT900 hybrids and they also ran at 43.5 psi like mine.

Haven't changed a u-joint in decades as we'd been driving FWD minivans until I bought the truck. Never had a problem back then.

A common problem is that folks will buy a Spicer 1350 and jam the retainers into place which causes binding issues. We run AAM 1355 joints which Spicer also carries but too many get the wrong parts and have issues.

I'll try to remember to photograph or video us changing them and what to look out for when we do it.

I did have a working pid in tq for fuel pressure. of course it's wacky hybrid stuff haha. before it cranks the engine it's 60psi, the longer it stays in auto stop creeps up to 63-65. once it starts it drops down to 43, fluctuates a bit down to 41.9 sometimes randomly, doesn't seem like throttle effects it.. long time off throttle decel it creeps back up towards 50 haha.


so yeah, without seeing the target psi, which maybe the tech 2 has. I have no idea if any of that is right.

I think I'll put a pump on the list to change over the next few months. can't hurt. I didn't think about it, but with a constant 60psi off and stopping starting a 100 times a day, leaking injectors would reek havoc in this thing haha. probably wash rings out.

 

[Doubeleive]

definitely flip it 180 and make sure the cups are seated correctly in the pinion flange. tighten even.. I'm sure the dealer did non of that.

try not to drive your trip with it vibrating. I've killed tranny tail housing bushings and it messes up the crush bushing and the whole thing loosens, wears badly and eventually takes out the pinion seal.

I hate drive shafts

no if it can't be address before I absolutely have to leave then w'ell just take the Silverado, or I will grab a rental
I didn't even want to drive it home