Transmission whine

Kelpiesgmc

Kelpiesgmc

Active member
Aug 19, 2023
153
100
43
Tucson Az
Just had a great little trip in the coach with the newly broken in S&J engine. It had been a long time since I had the coach on the highway. I remember the transmission being kinda loud, but I think it's gotten louder. At around 45mph and above it almost whistles or hums whenever gas is applied. Sound instantly stops when coasting. Should I be concerned?

I checked the fluid and it looked to be correct. It shifts through all the gears like a dream.
 

Attachments

  • IMG_1337.webp
    IMG_1337.webp
    1.8 MB · Views: 6
I dropped the tanks and did some other work on it so it has been a while since I last drove it. Anyway finally got around to looking into this and driving it around again.

The final drive oil was quite low. I put about 1 1/4 bottles in it and that topped it off. It still whines quite a bit starting around 40 MPH. It's screaming by 60 MPH. Sound disappears the moment I take my foot off the gas.

Maybe I should pop the cover off and have a look.
 
  • Wow
  • Like
Reactions: dsmithy and tmsnyder
Kelpiesgmc said:
I dropped the tanks and did some other work on it so it has been a while since I last drove it. Anyway finally got around to looking into this and driving it around again.

The final drive oil was quite low. I put about 1 1/4 bottles in it and that topped it off. It still whines quite a bit starting around 40 MPH. It's screaming by 60 MPH. Sound disappears the moment I take my foot off the gas.

Maybe I should pop the cover off and have a look.
Click to expand...
My bet would be final drive noise.

Ia it original gearing? You can find used final drives with the original 3.07 pretty easy. Getting one from a car is a good bet.

But a new ratio is always a big upgrade.

Taking the cover off. May or may not indicate a problem. It has to be drastic.

But a failure in a final drive can be catastrophic. I have seen where a final drive bearing goes out and rips off the front of the tranny on a could of coach’s.
 
  • Like
Reactions: Carl Stouffer, Kelpiesgmc and tmsnyder
Kelpiesgmc said:
I dropped the tanks and did some other work on it so it has been a while since I last drove it. Anyway finally got around to looking into this and driving it around again.

The final drive oil was quite low. I put about 1 1/4 bottles in it and that topped it off. It still whines quite a bit starting around 40 MPH. It's screaming by 60 MPH. Sound disappears the moment I take my foot off the gas.

Maybe I should pop the cover off and have a look.
Click to expand...

It doesn't take much more oil than that. Sounds like you ran it dry for a while, the damage may be done.

Let me know if you need a 3.07 final drive, I have several planned to drop off with Jeff I in Atlanta to build into 3.70s and LSD but he won't miss it.
 
  • Like
Reactions: Carl Stouffer, pvfjr and dsmithy
tmsnyder said:
It doesn't take much more oil than that. Sounds like you ran it dry for a while, the damage may be done.

Let me know if you need a 3.07 final drive, I have several planned to drop off with Jeff I in Atlanta to build into 3.70s and LSD but he won't miss it.
Click to expand...
Looks like you're in the north east, it would probably cost a pretty penny to ship one down to southern Arizona?
 
pvfjr said:
I shipped a final drive from Oregon to Georgia for $160 using Pirate Ship, with an extra gearset included.
Click to expand...

I'll check that out b/c best I could find on freightquote.com was $280 through FedEx. When I tried FedEx myself with no account, it was almost $1000.

Wow, PirateShip has a quote for UPS, Buffalo to Tucson, for $135!
 
Last edited:
  • Like
Reactions: pvfjr and Kelpiesgmc
Sounds like it was run low on lubricant and the bearings, and maybe the gears are worn out. This would be a good opportunity to upgrade to a lower geared final drive. I recommend a 3.70 for Western states driving. upgrade to a limited slip if you ever drive in dirt. Pricey, but well worth the cost overall.
 
Carl Stouffer said:
Sounds like it was run low on lubricant and the bearings, and maybe the gears are worn out. This would be a good opportunity to upgrade to a lower geared final drive. I recommend a 3.70 for Western states driving. upgrade to a limited slip if you ever drive in dirt. Pricey, but well worth the cost overall.
Click to expand...
That's why mine went to Georgia and back. I sent them to Jeff Ianitello for his LSD and installation of a set of 3.70 gears.
 
  • Like
Reactions: tmsnyder and Carl Stouffer
Carl Stouffer said:
Sounds like it was run low on lubricant and the bearings, and maybe the gears are worn out. This would be a good opportunity to upgrade to a lower geared final drive. I recommend a 3.70 for Western states driving. upgrade to a limited slip if you ever drive in dirt. Pricey, but well worth the cost overall.
Click to expand...
Would love to— and under normal circumstances I would. But I just got laid off from my job and funds are very tight. I have a really important trip in the middle of June that I need the coach ready for. It's all very unfortunate timing.
Plan now is to use the donor tmsnyder is shipping me. I'm very grateful to have the donor given my circumstances.
 
  • Like
Reactions: dsmithy and Carl Stouffer
Get your shine on at www.cruzingear.co
GMCMI Fall 2026 Rally

Share this page

Share this page
Top Bottom
Back