Got tired of burning through 4L60's so I did an M6 conversion.
For the first month the tranny was quiet but then the drivetrain started making a shush shush noise like metal rubbing on sheetmetal.
I thought it was wheel bearings but the car checked out and my mechanic said M6s are or can become noisy.
I had the trans checked out by a transmission place before instal and they said everything looked good inside.
How noisy are other cars that have an M6?
Is this something that can be fixed or short of putting in another M6
will I just have to live with this shush shush noise.

 

mine is rather noisy, but I also did a swap from a4. It was built by 6speedinc years ago and I was told the stronger parts were louder. I dont know if that was bs, but it works just fine.

 

My M6 was stock bought from a boneyard on ebay.
It started out quiet then became noisy.
The noise starts at about 10 mph.
Any idea why it would start out quiet then get noisy?
I had a saginaw or muncie 4spd in a 68 firebird 400 when I was 20 and it never made any noise like this M6.

 

The t56 has what most people call "can of marbles". I know that the corvette with the t56 has this same noise. It has something to do with the way that the synchro mesh works. My t56 is incredibly noisy in 2nd gear.

 

What the hell are you doing that you burned up more than one 4L60?????

 

I'm a natural born leadfoot putting 100k on the original 350 1/4 mile at a time. 20k with the supercharger. LOL!
I've had the car since 2000, it had 28k on it when I bought it.
Used the firm setting on the HPP3 at first.
Tranny lost 3rd gear.
Had the A4 rebuilt by a local shop.
Wasn't as good shifting as the firm setting but when I upped the line pressure it shifted so hard it broke the tranny mount then failed soon after.
Then got a CPT rebuild which lasted longer but also failed when the
front pump died after I put in the 383.
Local shop redid it again reusing the good CPT parts and softened up the shift which was too hard then a band failed and it needed another 500.00.
I didn't like the way the trans felt and thought it was only a matter of time before it failed again.
Since it's no longer a daily driver I tired of the A4 shortcomings and decided to go with the M6.
With 3.73 gears the car reved 2800 rpm at 80 in OD with the auto.
Now it's more like 2000 rpm in 6th gear.
That 4L60 belongs behind a 6 cylinder.
Typical GM fragile for the use bs.
Even frank's CPT rebuild only lasted so long.

 

I also did the a4 to m6 conversion. I lost OD and 3rd 3 times on a year and a half. I drive a LOT between VA and ME so i get a ton of highway miles. It 'was more cost effective to do the conversion than to keep rebuilding 4l60e

 

I also did the a4 to m6 conversion. I lost OD and 3rd 3 times on a year and a half. I drive a LOT between VA and ME so i get a ton of highway miles. It 'was more cost effective to do the conversion than to keep rebuilding 4l60e

 

IMO the T56 noises are primarily caused by loose preload on the mainshaft bearings as a result of normal wear. I recently rebuilt my own and noticed the input shaft was sloppy so I decided to reset the preload to Tremac spec. Once I did this, the input shaft had no more slop up and down and all of the can of marbles sounds at low RPM were gone as well as most of the other undesirable sounds.

 

I dont have any noise (that I can hear) coming out of mine, got 200km (or 125mi) on it, fluid is clean and running GM synchromesh fluid

It is still EXTREMELY TIGHT, and the whole car is EXTREMELY tight

however, my extremely noisy exhaust may overshadow any tranny sounds

 

I'm going to have mine pulled and inspected for wear and get the mainshaft bearing preload checked before I drive it this season.