Scraping Noise under MH

[spat61]

I'm hearing a scraping noise underneath what appears to be about midway. It's a sound like there is a tool held against the drivesahft. I went away for sometime and today when I put the MH in reverse, it started with the scraping noise again. Any thoughts would be greatly appreciated. This is a 2003 Land Yatch 30' Motorhome Gas. Thanks.
Steve

[overlander63]

Is it an Allison transmission, or a regular(4L80E) transmission?

[spat61]

This is standard GM transmission.

[Robfike]

Parking brake problem?

[overlander63]

That was my thought. Allison transmission has a parking brake that mounts on the rear of the transmission, and a loose piece of friction material, or a pump that won't hold pressure, could cause a scraping noise.

[spat61]

Originally Posted by overlander63

That was my thought. Allison transmission has a parking brake that mounts on the rear of the transmission, and a loose piece of friction material, or a pump that won't hold pressure, could cause a scraping noise.

I pumped grease into the four Zerks on the drive shaft and the noise seems to have gone away. If it returns, I will check the park brake. I don't have the Allison Transmission but there is a brake drum behind the transmission. Is this what you are referring to? Thanks for the response.
Steve

[zamboni]

You might want to have your u-joints checked sometime soon...better to check them while in town than have one break under load outside of town or on way to that "get-away"

[myfirstrv]

On my LY
I heard a noise , by the time I could find out wwhere it came from ,
I lost my rear differential
Seems a bolt worked its way out and killed it. Cost me half my 401K to fix while on Vacation
Maybe service the diff just in case
Just my opinion
Rob

[Poprivet]

Wheel bearing?

[Robfike]

Steve,
Yes, the unit that looks like a brake drum at the back of the transmission is the parking brake. There could be something between the shoes and the drum. The other guys also have good ideas as well. U-joints, center carrier bearing, differential oil, wheel bearing, etc.
Also have you checked for something that may have come loose under the coach and could be rubbing the shaft?
Good luck, Rob

[Steve & Susan]

Have you been underneath to look?
I had a similar occurence with my TV and it turned out to be a piece of metal strapping from road construction that wrapped around my drive-shaft.

[GlenCoombe]

I would most definetly check below. Sounds like parking brake or center hanger bearing.

Are all family members accounted for.... cats? Dogs?? You don't want to be dragging somebody rather than something..around.

Let us know what you find...if you find anything.

Time to check the rear diff. too.

[spat61]

Thanks to everyone for all suggestions. I'm starting at the transmission and working back. I'll post my results. Thanks.

Steve

[SgtMunger]

Since it went away but came back after having gone in reverse, the first thing I'd do is pull apart your parking brake drum and clean it out real good. Inspect for loose or foriegn parts, or scoring of the drum and shoes (an indication that something was loose and possibly wedged between the drum and shoe).
If that turns up clear, set your parking brake on level ground with the trans in nuetral and check the play in your ujoints (note the rear diff will have some play, this is normal). Or if you have 2 people you can have 1 person in the driver seat with the brakes applied and have them switch from forward to reverse a couple time while you observe the shaft from a safe area (often times a bad joint will cause the whole shaft to "PING" from the play).
If those check out, I'd look tward your rear brakes. Mine has a rear brake noise that sounded for all the world like it was coming from the mid section. If it makes noise at low speed you can have someone drive it while you walk along both sides to narrow it down.
I highly doubt its your rear end, you should have a Corporate 14 bolt. When a diff starts to go it usually sounds more like its chewing a fist full of gravel rather than a squeak. But if you dont know how long its been since its had a fluid change its not a bad idea. If you've done the fluid recently, you can take a small sample through your fill plug with a piece of clear tube. The fluid should be a dark amber color at the most and should not smell burned. If its black or smells like any thing but gear oil, change the fluid and inspect the diff while you have the cover off.
Hope this helps and its a quick simple problem.

[spat61]

SgtMunger,
Thanks for the great response. I have never got into the parking brake drum behind the transmission but I will now. Are there any precautions or tips you can suggest while I get into it. I don't want to make things worse and I'm about to take a 1500 mile trip. Thanks again.

Steve