Diagnosing mysterious sound from Tran/Tcase

[bucket]

I think you might have two separate issues. In the first video, was the t-case in 2wd, 4x4 or neutral? That squeak is the most abnormal thing going on there, to me anyway. In the second video, that does sure seem like a driveline vibration. Doesn't seem like tires to me though, otherwise the whole truck would have the vibration too.

 

[saltdog]

I had a similar noise years back and was sure it was the transfer case. It wasn't. Check the rear pinon.

 

[chief_shotts]

I think you might have two separate issues. In the first video, was the t-case in 2wd, 4x4 or neutral? That squeak is the most abnormal thing going on there, to me anyway. In the second video, that does sure seem like a driveline vibration. Doesn't seem like tires to me though, otherwise the whole truck would have the vibration too.

The first video was trans in nuetral. T case in 4 hi and I was rotating the drive flange in reverse motion. The reason I posted that video is because that rattling noise is very similar to the rattle you can hear at highway speeds in the second video.the squeel noise is a whole other can of worms I'm sure but the trans operates correctly. Shifts well.

 

[chief_shotts]

I had a similar noise years back and was sure it was the transfer case. It wasn't. Check the rear pinon.

so you experience that rattle noise present in that second video aswell? What exactly did you end up doing? Whhat adjustments were needed for your rear pinion angle.
I've been hard pressed to find straight forward answer as to exactly how two piece driveline angles should be set up.

 

[bucket]

The first video was trans in nuetral. T case in 4 hi and I was rotating the drive flange in reverse motion. The reason I posted that video is because that rattling noise is very similar to the rattle you can hear at highway speeds in the second video.the squeel noise is a whole other can of worms I'm sure but the trans operates correctly. Shifts well.

The rattle could be an effect of the vibration, rather than the vibration being an effect of the rattle. 205's aren't exactly quiet.

 

[chief_shotts]

The rattle could be an effect of the vibration, rather than the vibration being an effect of the rattle. 205's aren't exactly quiet.

ya I kind of figured the vibration whether it's in the transfer case or driveline is causing a bearing to rattle in the t case. If I can stop the vibes I suspect the rattle will stop as well.

 

[chief_shotts]

I just found some useful information on two piece driveline geometry.

Driveline/Propshaft 101

I guess there's more than one way to set it up correctly. Im gonna focus on adjusting these angles for now and if nothing changes from that I'll start looking at tearing down the t case.

 

[SquareRoot]

Is your 205 output shaft fixed or a slip yoke?

 

[chief_shotts]

Is your 205 output shaft fixed or a slip yoke?

Fixed

 

[SquareRoot]

Fixed

Ok I had a similar issue when I rebuilt my 205. Drove me nuts cause I had new driveshaft as well. Make sure there is Zero lateral play in the yoke. I had like a 1/16" and dismissed it. Turned out that was the problem. There's an internal bearing on the output shaft that needs to be completely seated. I got frustrated and eventually took an impact to it and just like that, solved my issue.

 

[chief_shotts]

Ok I had a similar issue when I rebuilt my 205. Drove me nuts cause I had new driveshaft as well. Make sure there is Zero lateral play in the yoke. I had like a 1/16" and dismissed it. Turned out that was the problem. There's an internal bearing on the output shaft that needs to be completely seated. I got frustrated and eventually took an impact to it and just like that, solved my issue.

Interesting I'll disconnect the driveline tonight and take a close look at the rear output yoke.

 

[SquareRoot]

Interesting I'll disconnect the driveline tonight and take a close look at the rear output yoke.

So on mine, it wasn't that the yoke was loose, it was tight on the output shaft. It was the output shaft that was moving with the Yoke. Cranking down that big nut is what allowed the internal shoulder on the shaft to seat that inner bearing.

Seriously bummed with this drivetrain setup right now :(

Many of you know that I recently made some serious progress on my truck. A complete rebuild of the NV4500 and 205 T-case. Only the best parts available, meticulous attention to detail following the manual and everything visually inspected and measured with a micrometer. Brand new driveshafts...

www.gmsquarebody.com

 

[chief_shotts]

update:
I adjusted the 2piece driveshaft so as to straighten the 1st shaft and put all angles onto the second shaft going to the differential. This did not stop the noise or vibration but it appears to have changed the noise to a constant rattle as opposed to a pulsing rattle. Vibrations seams more or less unchanged at high speeds(hard to tell). While road testing I also tried putting the truck in neutral at speed. I've been told this should not be done with a turbo 400... so I hit the transfer case into nuetral instead... With a clean swift wack to the rear axle shifter I popped it into neutral and the rattle instantly stops. Thought that was interesting.. not sure exactly what that tells me but maybe someone else has an idea.

I have not yet looked into the rear output of the transfer case as suggested by square root. Hoping to do that later today.

 

[chief_shotts]

So today I popped off the rear output of the transfer case and inspected on the work bench. I took some time to aquaint myself with the parts and this is what I found.

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I'm not an expert on these transfer cases but in my experience play between splines is no good... would I be correct in my assumption?

 

[chief_shotts]

^ thoughts ?