Dual Mass or Single Mass Flywheel

[eacmen]

My 0.02 Unless you’re adding a ton of torque or full track car stick with stock.

[jet_dogg]

Sorry I can't be of much help since mine isn't installed yet brosef.

[Hotchkess]

+1 or 2 or whatever on going stock. I'm doing a manual conversion on my M3 right now and after doing a whole bunch of research, it seems like stock really is the best way to go for a mainly street/occasional autocross or track car. Plus it's cheaper by about ~50% or so for the LUK kit. That's what I bit the bullet on going for at least.

[Casa de Mesa]

For what it's worth and to circle back on this, I ended up going all stock. RockAuto had amazing pricing on the Luk stuff.

[WestBankM4]

I too wanted to upgrade during the time of my 6-speed conversion. Even with my limited knowledge at the time on the S54, I steered way clear of aftermarket after a few hours of reading.

Ended up reusing my OEM clutch/flywheel as they were recently replaced, put the money towards the Turner SSK. Talk about lack of knowledge at the time. 😂

Sent from my Pixel 7 Pro using Tapatalk

[sapote]

It seems to me the single flywheel causing gears lashing noise is due to the light weight oil and not the transmission, as there is no significant changes from the older tranny design to the G420 box, but the oil. For those who had tried with the single flywheel, did you tried with the W90 gear oil to cut down the rattling noise?

[BigDave]

My DMF was not replaced with a new one by my (former) idiot mechanics on my last Sachs clutch renewal. Now, many miles later, my clutch is fine but my DMF is toast.
I plan on a new one. I can get a LUK DMF for less than $400. Good as a Sachs? Better? No difference?

[Ramps]

It seems to me the single flywheel causing gears lashing noise is due to the light weight oil and not the transmission, as there is no significant changes from the older tranny design to the G420 box, but the oil. For those who had tried with the single flywheel, did you tried with the W90 gear oil to cut down the rattling noise?

This is an interesting question, I wonder if a change in fluid could make it livable to use the LWF on a street driven car. I love the way cars rev with a LWF but it seems the noise makes it so unrefined it’s not worth it.

[Anri]

]s there is no significant changes from the older tranny design to the G420 box, but the oil. For those who had tried with the single flywheel, did you tried with the W90 gear oil to cut down the rattling noise?

Sapote,

There is little change. The Older say G280 E28/E34M5 both
they come from the factory with Single mass fly. E28M5 weight is
16.5lb on 3.6 is 12.5lb(forgot exactly but it right there)

Inside the gear box in the guide sleeve internally BMW installed
if memory serve me well 4 small springs. This way when the engine is
at idle the chatter is taken by those springs to certain extend.
Without Vanos S38 idle is very lumpy and they do chatter ones the
box is driven 50k+ miles the lash increases so do the chatter.

On G420 BMW canceled those internal springs because the spring
that helps to dampen the chatter is the actual Dual Mass flywheel.

So installing single on S54 with G420 at idle the chatter is steady
and consistent without any damping springs.

I mix 70% MT90+30%MTL but in very cold weather I would chose ATF
because the 3 piece G420 synchronizer design is veeeeery moody
In cold weather in Cali at 50F crisp morning after start and drive out
going into to 2nd gear forget it.......up until the engine put little heat in
the gear box.


Regards,
Anri

[sapote]

Inside the gear box in the guide sleeve internally BMW installed
if memory serve me well 4 small springs. This way when the engine is
at idle the chatter is taken by those springs to certain extend.

Anri,
Could you post a pic of the part where the springs located? I don’t know anyone had a design that had the springs associated with the TOB guide tube.

[EthanolTurbo]

Sapote,

There is little change. The Older say G280 E28/E34M5 both
they come from the factory with Single mass fly. E28M5 weight is
16.5lb on 3.6 is 12.5lb(forgot exactly but it right there)

Inside the gear box in the guide sleeve internally BMW installed
if memory serve me well 4 small springs. This way when the engine is
at idle the chatter is taken by those springs to certain extend.
Without Vanos S38 idle is very lumpy and they do chatter ones the
box is driven 50k+ miles the lash increases so do the chatter.

On G420 BMW canceled those internal springs because the spring
that helps to dampen the chatter is the actual Dual Mass flywheel.

So installing single on S54 with G420 at idle the chatter is steady
and consistent without any damping springs.

I mix 70% MT90+30%MTL but in very cold weather I would chose ATF
because the 3 piece G420 synchronizer design is veeeeery moody
In cold weather in Cali at 50F crisp morning after start and drive out
going into to 2nd gear forget it.......up until the engine put little heat in
the gear box.


Regards,
Anri

Sounds right to me. My E34 M5 has a lighter flywheel and you can't even hear it really. Also revs incredibly fast.

However I believe the E34 M5 S38B36 has a dual mass stock, not a single.

[Anri]

Anri,
Could you post a pic of the part where the springs located? I don’t know anyone had a design that had the springs associated with the TOB guide tube.

Sapote,

I will sent you picture, ones I have the box apart.

TOB means (Throw-out-Bearing)? Sorry to ask I am
not so good with those.

Regards
Anri

[Mayan-Viking]

I loved everything about the SMF. Everything...except the noise. My best mate told me the car sounded like a diesel at idle. Once I realized he was right I couldn't bear to live with it another day. I'd consider going back if I knew a different oil could fix that chatter issue.

[sapote]

Inside the gear box in the guide sleeve internally BMW installed
if memory serve me well 4 small springs.

TOB means (Throw-out-Bearing)?

Yes, as you said about the guide sleeve and so I believe the guide sleeve for the throw out bearing. I just can't see how do the 4 springs around this location can dampen the input shaft and the gears inside from rattling.

[sapote]

My Citroen SM with the Maserati 90* V6 odd-fire engine with the ignition timing having different period, and so it runs so uneven at idle like a Harley Davidson. But why no tranny gear rattling? Heavy gear oil I think. 90* V8 is smooth because the ignition firing is even, not the V6.