Tranny noise at idle in Reverse and 1st gear?

[darnold87]

After the cruiser is warmed up, I get a funny light rubbing / grinding noise in Reverse and 1st gear at idle (~700rpms)... It goes away above 800rpms or so (i.e. hold brake and apply very light throttle). It's very hard to explain the noise. Its not metal to metal grinding, but more like something is rubbing internally (like a bushing has gon bad?). Maybe I'll take a recording of it and post it later.
Thanks for any help!

 

[darnold87]

I'm wondering if 1st gear and reverse share certain 'systems' in the transmission?
Like if they both use a certain fluid psi that causes the noise, it would be aparent in only 1st and R.
Or if certain clutches are used in 1st and R, then it would be aparent in only 1st and R.
I should mention the transmission is fairly fresh... it was rebuilt by AAMCO 15,000 miles ago. Full rebuild plus refurbished torque converter, and some other hard parts. (all done by PO).

 

[BrotherRob]

Without hearing it, it's hard to tell. Sounds to me like some sort of vibration. Since it's happening in and out of gear when not moving, it should be easy the narrow down. Crawl under it when it's running and try to pinpoint the source. The first thing I would check is the motor and tranny mounts and the entire exhaust line.

 

[joinerman]

Your idles to low at 700rpm, should be around 850ish & don't try & rev it with one foot on the brake or you'll be after another torque converter.

 

[BrotherRob]

Your idles to low at 700rpm, should be around 850ish & don't try & rev it with one foot on the brake or you'll be after another torque converter.

Huh, we do this all day long on the trail.

 

[darnold87]

I have some rattles in the exhaust shielding that I'll be dealing with soon. But that is a seperate issue.

The sound I can't determine is a mechanical sound, that sounds internal in the tranny.

The reving with foot on the brake was very temporary and was done only to increase idle from 750rpms to ~900rpms for diagnostic purposes. I noticed the noise goes away upon acceleration and wanted to verify if it did the same while not moving... which it did.

 

[BrotherRob]

I have some rattles in the exhaust shielding that I'll be dealing with soon. But that is a seperate issue.

The sound I can't determine is a mechanical sound, that sounds internal in the tranny.

The reving with foot on the brake was very temporary and was done only to increase idle from 750rpms to ~900rpms for diagnostic purposes. I noticed the noise goes away upon acceleration and wanted to verify if it did the same while not moving... which it did.

I hear ya Davey, my point would be to rule out the easy stuff first. The tranny is a big, ugly problem. You don't want to go diving into it and find out you have a minor problem somewhere else.:whoops:

I've had quite a bit of experience with a bent, mangled exhaust. I can tell you that they can sound like a serious mechanical issue. Ditto the mounts. Thankfully, both are easy to check. You have to crawl under there sooner or later, you have little to lose if you check them out.

 

[darnold87]

I'll be crawling under there as soon as I get home...

I'll try to record the sound so I can offer that to help explain this odd situation...

 

[1000-oaks]

Mine just started doing that a month ago...no idea.

 

[darnold87]

Hmmm... its actually doing it in 1st, 2nd, and R.
Crawled under it and it still sounds internal in the tranny. It was raining so I didn't spend much time under there...

 

[informationjunky]

May not be the case, but, my u-joint was making some strange noises that I wouln't have ever guessed it was causing until I searched on here.