Rattle/Scratching noise from the Transmission(Updated with video)

[Solo_M_Tech]

Ok fellas, I upgraded some transmission hardware the other day. Dinnan short shifter, cdv delete, and uuc blue street/track transmission mounts. As expected I have more transmission noise in the cabin. However, I've noticed a
Scratching sound. Like bolts in a can when driving at low speeds in any gear. No noise when still. It doesn't do it every time and is amplified when I shift. But then goes away. I understand these transmissions can exhibit gear chatter when using a single mass flywheel, but mine is stock. I've done some research and I believe this noise was there before, but the sound was being absorbed by the stock soft mounts. I'm looking for alternative opinions. I'm gonna have my service tech Flo take a look and listen. Give me your input.

[Pig Farmer]

I suspect it's the DMFW rattle exaggerated by the firmer tranny mounts. When you turn the car off (in neutral) does it rattle for a second or two as the engine shuts down? A lot of people get this rattle after the CDV mod. I sometime get a bit of rattle when driving in first gear while on and off throttle. What is strange is if the rattle persists while driving at a constant speed in a taller gear after the clutch is fully released.

[Solo_M_Tech]

I only notice it in first or second gear on slow driving (less than 30 mph) or third at the same speed on deceleration. It's not consistent, and wasn't noticed for a couple days after the parts were installed.

[Solo_M_Tech]

Ok i wanted to update with the solution. When i installed the mounts, i tightened the mounts down, and then the bracket. Which caused it to twist slightly. I loosened everything up, set the bracket back to it's original position ( I could see the discoloration on the aluminium) then tightened down the trans mounts. Everything is working good, no noises or weird vibrations.

[Solo_M_Tech]

I wanted to re-update this thread.... So after adjusting the mounts, the noise went away for about 2 days. I can definitively say it's transmission related. I get the scratching, rattling noise in all gears, acceleration, deceleration, and in Neutral when coasting to a stop. It's audible to anyone in the car. Some days it's worse than others. My car still has the stock trans fluid, clutch. Car has 27k miles, no clutch slip. I've done everything I can to narrow it down, and I have no idea what it is. Turner Motorsports is telling me it's gear chatter made audible buy the race trans mounts. Didn't notice the noise prior to installing them either, but is it damaging to the transmission? Do I need to do a transmission fluid flush?

[Dackelone]

You could put the old "stock" trans mounts back in and see what happens? IF the noise goes away... its your rear trans mounts.

[Solo_M_Tech]

Dack this is true. I want to make sure this isn't something else before I pay for another half hour of lift time to swap them out again.

[Zesinlijn]

Hello!

Found this topic after searching the internet! My car (e91 n55 335i) started making the same noise without any reason. In All gears with light throttle, clutch in or clutch out and even coasting in neutral. Bmw dealer said transmission needs to be replaced so i have put in a refurbished one in myself with a friend. Noise was gone but now one week later ithe same grinding noise is back. I have no clue what is causing this noise.. transmission mounts are new, clutch and dmfw is new (oem parts). Any idea? Thanks for helping me

[RayE82/135is]

I have the same exact noise on my 2013 135is msport manual transmission. Car is fully stock the noise started to happen a month or so ago. Car has 87k miles it drives and accelerate fine its just noisy. If any of you guys figures it out please give us heads up and same for me if I find anything out I will share it.

[moose09876]

Just bumping this again since it seems many of us have this issue but nobody has posted a complete failure or solution. It's really great when I can just roll with the windows down and music up to override this, but when it's cold out the grinding is just .... alot.

[ShocknAwe]

Have you changed the fluid?

[moose09876]

Twice. First with Redline MTL - no change, ran it for ~7kmi, then with the special sauce - 70w140NS + D4 ATF. No change. No metal in either change but the fluid was darker than I was expecting for 7k mi. I'm assuming the first change was ~80k OEM fluid.

The noise is:
Only present while moving
Independent of input or output speed / engine rpm or wheel speed. It does not change pitch.
Present in or out of gear, clutch in or out - makes no difference.
Coming from the case of the transmission. Ran it on the lift in 4th gear idling and it was coming from right in the middle.

New clutch, flywheel, throw out bearing, rear differential.

I get that it's probably the transmission, but what I can't wrap my head around is how it's so loud and there's zero metal debris.

Edit: I just found an interesting fact. The 2020+ M3 6spd also uses a Gs6-53BZ.... Much more likely to find a low mileage one of those than something 10+ years old.

[moose09876]

Spent a bunch of time today troubleshooting. Ran for probably 6 mins with no driveshaft connected idling in gear, completely silent - https://youtube.com/shorts/Gvn3MLL8P_w?feature=share

Reattached the driveshaft and just let it idle in 4th. No noise. Revved up / down, changed gear, clutch in / out. No noise. I was under the car for 5 mins and nothing. Finally caught the transition on video.

[iminhell1]

Its a bearing noise.
Just looking at another video of what the guts look like and what's where,
I'd say the location of the noise would be around where the Countershaft Bearing is.

Being manuals are splash oiled, I'd say just try overfilling the trans some and see if that helps.

[moose09876]

Originally Posted by iminhell1

Its a bearing noise.
Just looking at another video of what the guts look like and what's where,
I'd say the location of the noise would be around where the Countershaft Bearing is.

Being manuals are splash oiled, I'd say just try overfilling the trans some and see if that helps.

That's literally what I tried to do. I think I should try and fill it more... somehow. "fill it till it drips out and that's when it's full" is one of my least favorite methods. I've been assuming countershaft bearing, but I'm betting it's probably the rear....

[iminhell1]

I don't know what side the fill plug is on, but don't fill level. Get the fill side higher, drive one tire up on a ramp or something.

Anything splash oiled is pretty imprecise. LOL

[moose09876]

Originally Posted by iminhell1

I don't know what side the fill plug is on, but don't fill level. Get the fill side higher, drive one tire up on a ramp or something.

Anything splash oiled is pretty imprecise. LOL

That's what I did. Got about another half quart in. Just have to wait for the plastic coolant hose I broke to come in. Such fun having semi-rare older cars!

Edit: That made no change. Following up with a guy on the 18th for a 53bz swap. Sigh. - This wasn't the correct transmission. I'm now contemplating pulling it and trying to replace the bearings.

"On the GS6-53:

The countershaft spins whenever the output shaft spins

It is always engaged, regardless of selected gear

It carries load even in neutral while rolling

When it fails, it produces a steady grinding / gravel noise instead of a whine"

[moose09876]

Originally Posted by iminhell1

Its a bearing noise.
Just looking at another video of what the guts look like and what's where,
I'd say the location of the noise would be around where the Countershaft Bearing is.

Being manuals are splash oiled, I'd say just try overfilling the trans some and see if that helps.

Confirmed, not splash oiled. Has pump and filter. Replacement filter? HAHAAHAH no, GFY. "lifetime"

I'm not seeing anything TOO crazy so far, but I need a deep 36mm 12pt to continue disassembly. The front countershaft bearing doesn't seem to be the issue from what I see. The shaft has some hazyness, but from the noise it was mking I'd expect more damage.

Just starting an album since I can find 0 pics of this except in a short from a transmission shop in the UK. https://photos.app.goo.gl/3RNtk6dUfW2jYEmP6

[moose09876]

We've reached 0% chance of this transmission going back together and being fixed, I'm now looking for a replacement. Nothing is so obviously wrong that it's worth sourcing a replacement. The bearing rollers look fine, the most damage I could find is on the shaft.

Edit: 96k mi GS6-53BZ purchased. Sigh.

[GoRomeo]

This is why I chose to rebuilt mine a couple of years ago. I would never mess with a tranny issue. Buying a replacement is too risky in my opinion.

[moose09876]

Installed replacement yesterday, working fine. Let's hope this synchro holds up.