Transmission whine

[SERE Guy]

Just a question does the stock transmission whine when in fourth gear? Mine for some reason whines in fourth gear but not in any other gear, at least as far a I can tell. Oh by the way this is the first road test ive ever taken it on.

[O.D. Fever]

Don't realy know, have not had mine up to speed. I think you have a small block Chevy in it , if I remeber rite. You might just be speeding over 55mph.

[SERE Guy]

Nope a stock 230 and i was going about 35ish

[randyscycle]

Its probably not the transmission, but the transfer case. They sing at anything over 30 MPH.

[SERE Guy]

So do I need to worry about it?

[O.D. Fever]

I too hope do 35 miles a hour someday....someday....not today

[SERE Guy]

Lol

[randyscycle]

Not unless you decide to drive over 50 MPH for any long periods. The noise doesn't hurt anything, but the inherent heat issue of the NP200 does.

The NP200 will whine loudly at slower speeds, but ramp it up to 45 or higher and it sounds like you have a jet engine in the cab with you with the outlet pointing at your ear.

You can eliminate most if not all the noise by moving the rear driveshaft from the right hand output to the center with the park brake, but it requires some machining. It won't take care of the heat issue though.

Do a quick search for "NP200 noise" or "NP200 heat." You can read all you like from there.

[Don Cavey]

One thing that I always look forward to hearing is that whine from the transfer case. All of the trucks that I drove in the army, 1969-1970 did that and I actually used ear protection on long drives in Germany. To me, that is a 5/4!

[brute4c]

If it is transfer case whine, it is normal for the NP200 case used in the stock M715. Go in 3rd gear until you run 35 or so and see if you can hear the whine starting when you let off the gas...then you will know if it is speed related, transfer case, or 4th gear related, transmission.

If it is the tcase, you can move the rear drive shaft from the stock location on the right side of the case to the other rear output location...this means either taking off the parking brake or using a modified setup to adapt the driveshaft and paring brake to the same location. It is possible to take the ebrake off and, instead of having it on the tcase, put it in the drums with GM Corporate 14bolt backing plates.

We have threads on both things...though I am pretty sure we dont have all the details for the parking brake cable to run to the rear wheels and the pedal, or other actuating mechanism, for the front.