Metal in Trans Fluid

[bigjae46]

I'm anecdotally convinced that redline eats synchros, have stopped using anything but CV-2 from them.

I never liked the D4ATF. I run MT90 in my ZF320 which is a little higher in viscosity 75w-90.

[eacmen]

I never liked the D4ATF. I run MT90 in my ZF320 which is a little higher in viscosity 75w-90.

I'm actually thinking the lighter weight oil won't develop thick film on the synchro friction surface. I have some 90 weight to try as well but the issues have don't seem to matter whether the fluid is cold or hot.

[eacmen]

I had really good success with Ravenol MTF-2, ran that for a while and flushed every 2-3 events I believe. The old six speed would grind on fast shifts in 3 and 4 when cold but when it warmed up it was fine. I'm testing out Motul Gear Power 75w-80, the GL-4 one because there's also a GL-5 one, on the ZF320 I just put in.

Curious did you actually run MTF-2 or theBMW specific MTF-LT-2 from Ravenol?

[CrookedCommie]

This is what I was ordering :
Ravenol Gear Oil MTF-2 75W-80 GL-4 1L

[oceansize]

I use Ravenol as well. This is what I buy.

https://www.amazon.com/dp/B00FGXB15O

[eacmen]

Update:

Just did a weekend at VIR and there were no issues with the trans grinding. This is what I did before the event:

- flywheel and clutch (both OEM)
- replaced GPS
- replaced clutch slave
- replaced all detents and springs
- replaced gear shift actuator with rebuilt unit
- replaced input shaft speed sensor (?) in the trans. It was leaking oil through the connector
- drained and refilled with RL D4 ATF. Slightly underfilled. Fluid wasnt coming out the drain hole, it was maybe 2mm below the fill hole lip.

hard to tell what made a difference. Time will tell if it is truly fixed. It was a much cooler ambient temp than last event and also a different track.

[sapote]

Their contention is that the 3/4 gearset sits in the sump of the transmission in the oil and causes the slipping.

Those people just BS as all gear synchros are on the same main shaft -- the one connected to the output flange -- and so 3/4 is no different than others. Regardless the oil is whipped into a mist and it so it's on everything inside the box, submerged or not.

[sapote]

I filled with D4 ATF but not all the way. I *slightly* underfilled to where i could feel the oil coming up to the fill plug but not pouring out. The hope there is maybe the 3/4 gearset will spend less of its life sitting in the sump of the trans and building up oil film on the syncros.

I don't think under fill is helping here. Now you have the box freshed up and working, I would add oil to the factory level and its performance will be the same. The idea that 3/4 sync is lower is wrong.

[sapote]

- flywheel and clutch (both OEM)
- replaced GPS
- replaced clutch slave
- replaced all detents and springs
- replaced gear shift actuator with rebuilt unit
- replaced input shaft speed sensor (?) in the trans. It was leaking oil through the connector
- drained and refilled with RL D4 ATF. Slightly underfilled. Fluid wasnt coming out the drain hole, it was maybe 2mm below the fill hole lip.
hard to tell what made a difference. Time will tell if it is truly fixed. It was a much cooler ambient temp than last event and also a different track.

GPS: only the sensor replaced or the roller pin also replaced?
all detents and springs: you found no broken springs, but I think the new balls or pins play a big part in this.

I don't think the new input shaft speed sensor, slave, actuator have a role in this, as if they are bad then for sure there were error codes for the parts.

[eacmen]

GPS: only the sensor replaced or the roller pin also replaced?
all detents and springs: you found no broken springs, but I think the new balls or pins play a big part in this.

I don't think the new input shaft speed sensor, slave, actuator have a role in this, as if they are bad then for sure there were error codes for the parts.

GPS: just the sensor, but the actuator was rebuilt and the GPS bolts up to the SMG actuator.

Correct I found no broken springs.

[sapote]

GPS: just the sensor, but the actuator was rebuilt and the GPS bolts up to the SMG actuator.

Correct I found no broken springs.

Sorry I was mixed up the SMG GPS with the manual box GPS. The actuator has the linear and angular position encoders to feedback the shift shaft position between the odd and even gears, and the gates, and it's not the same as the GPS on the manual which is much simpler sensor to detect neutral or not.
Did you replace the roller pin under the plug on the left side of the box?

[eacmen]

Sorry I was mixed up the SMG GPS with the manual box SMG. The actuator has the linear and angular position encoders to feedback the shift shaft position between the odd and even gears, and the gates, and it's not the same as the GPS on the manual which is much simpler sensor to detect neutral or not.
Did you replace the roller pin under the plug on the left side of the box?

Yea I replaced the roller pin and the spring.

[sapote]

I think the new roller pin and the other detent balls/pins fixed the box.

[eacmen]

I think the new roller pin and the other detent balls/pins fixed the box.

I hope you're right! Time will tell. I will probably drain the fluid from the event and look for more non magnetic sparkles.

[eacmen]

Those people just BS as all gear synchros are on the same main shaft -- the one connected to the output flange -- and so 3/4 is no different than others. Regardless the oil is whipped into a mist and it so it's on everything inside the box, submerged or not.

I have zero experience rebuilding a trans but isn't the circled part from this screengrab a pair of syncros?

src: https://youtu.be/vyPDjyXBkDI