Time for a new clutch for my e36 m3, a flywheel question...

So the clutch on my e36 track day car is on its way out.

I am looking at several different kits and am leaning towards one manufactured bt Sachs.

The question is should I go with a 10.5 lb aluminum flywheel or the 14.5 steel one.  Both are significantly lighter than the stock 23lb dual mass that is in the car.

I have heard a lighter flywheel will cause transmission noise from gear lash on these cars?  Does anyone have any experience with this?  Tell me about your setup.

Car is used for track days, autocross and is occasionally driven on the weekends.

UUC E34 M5 clutch and lightweight flywheel.  Been on the car for years, I've used this setup in two different cars.  Works well, flywheel does make noise but not obnoxiously so.

The UUC flywheel doesn't have the greatest reputation on the forums, but I've never had an issue with it?

In reply to docwyte :

How much does the uuc flywheel weigh?  Why a e34 m5 clutch vs a e36 m3 one?  Is the flywheel an e36 m3 application or an e34 m5?

DMFs are hamonic dampers at the other end of the crank.   Given that the M3 engines were known for eating themselves if you eliminated the damper at the front, I'd be leery of eliminating the one at the back.

And yes, transmissions seem to get more unhappy when you replace a DMF with a solid flywheel.  More of the engine harmonics get transmitted right through to the gears, which may have only been sufficiently engineered if they were protected by the DMF...

DMFs are fiddly and expensive but they do serve a purpose.

Don't worry about the gear rattle.  It won't make an ounce of difference to the transmission.  As to the choice of flywheel, buy quality.  I put a cheesy aftermarket one in my Neon IT car and it had cracks in the bolt circle within a year.

I've put tens of thousands of miles with lightened, single mass flywheels on my E36 M3 without a single issue.  Don't worry about it....

I switched from a dual mass to an aluminum flywheel on a c4 vette (zf transmission also used in the 8 series) and couldn't have been happier (the rattle at idle sounded bad but was harmless)

Don't forget however the move may bump you in a class at autocross.

What about 14.5 lb vs 10.5 lbs?

If others haven't had issues, go to it then.  I've noticed that CTS-V transmissions get really unhappy when you remove the DMF, and that's with a V8.  I've noticed a similar effect on VWAG 1.8ts.

Personally, when talking SMFs, I don't think one can ever go too light.  But driver technique plays a role, too.  If you expect to be able to engage the clutch without meeting it with throttle, you're going to have a bad time.

So does anyone know the reason for running e34 m5 clutch on the uuc flywheel? Is it just for the added weight? I've got an e36 m3 clutch sitting here and need this thing together asap. 

The e34 clutch has a sprung hub, when eliminating the dual mass flywheel using the sprung hub clutch can help with noise.  Light weight flywheels do seem to increase the chances of the oil pump nut backing out, every car that I have seen with a loose oil pump nut has had a lightweight flywheel, but it may be that cars with those  modifications are driven harder as well.

I have the standard setup with an m5 clutch and 13lb fidanza single mass flywheel on my 318ti.  It isn't exactly apples to apples with a 6 cylinder but I think it is close.

Transmission secondary shaft play sounds like a rod knock at idle.  It is worse when the AC compressor kicks on it.  The sound goes away completely when you put the clutch in.  This is pretty standard for 6 cylinder cars too.

My car has a loud vibration around 3k rpms when engine braking.  It isn't a big deal on track.  Slowing from 75 to 65 on the highway is annoying 

The transition from power to engine braking is much quicker.  On a dedicated track car, the single mass flywheel is worth it for this alone.  The car feels much more responsive to your inputs.

Personally, I went with the Chomoly steel flywheel and a 6 pack race clutch. Back when ebay f1racing kits were around. Worked good. Was happy. 

I wouldn't worry at all about gear noise/rattle on a car that's primarily driven in anger. It would more so be an annoyance for a daily.

I think I'm right in saying that the lighter the flywheel, the touchier it'll be taking off gently from a start but, again, with a car that is primarily track/auto-X focused, that doesn't matter. In my mind, for a track car, the lighter the rotating assembly, the better.

ojannen said:

It isn't exactly apples to apples with a 6 cylinder but I think it is close.

Transmission secondary shaft play sounds like a rod knock at idle.  It is worse when the AC compressor kicks on it.  The sound goes away completely when you put the clutch in.  

Same on my e36 M3.

As the above poster noted, the e34 clutch disc is sprung.

I have had mixed experiences...

On our '05  Subaru Legacy GT, eliminating the factory dual mass flywheel completely transformed the car for the better.  The factory setup was awful.  Street car.

On my NA Miata, a light flywheel setup has been fantastic.  Track only car.

On our NC Miata, the light flywheel causes significant transmission noise, and I'm seriously considering swapping back to the factory flywheel.  Mostly street car.

Most of the chatter on the BMW forums is that eliminating the dual mass flywheel is not an improvement... I don't have any personal experience, but my plan when I replace the clutch in my E36 Touring is to go dual mass....  Street car.

YMMV...

TIL that Subaru ever used dual mass flywheels.  Must be a Legacy thing, as I've only worked on manual trans Imprezas and Crosstreks.

I've put lightweight flywheels in my last 4 or 5 cars.  As was said, it does change the personality of the car.  It becomes much more responsive and actually easier to shift.  All of them had that tranny rattle which didn't bother me at all.  The 135i now has 183k on it, most of which with the light flywheel.  No ill effects on the tranny at all.  

Before the 135i I had a Mini Cooper S R53.  That trans was really loud at idle with the light fw.  My kids were younger and my son borrowed the Mini to go to a friend's house.  Another friend at that house needed to run an errand and the Mini was the last car in the driveway.  My son let her borrow the Mini.  She quickly returned terrified that she had destroyed the transmission!  "But, but it sounds like a metal bucket full of gravel!"  No worries, it's normal!  

When researching the clutch for my Mini, the tech support at Sachs Performance was helpful answering questions and making a recommendation based on application and usage. 

I'd contact them to see what feedback they have. 

In reply to GopherBrokeRacing :

"Normal" doesn't mean "right" though, all that clatter is gear rattle that hammers on things.  I'd change the fluid more often to keep things happy inside.

Pre DMF Mazda transmissions had a spring loaded two piece input gear to cut down on gear rattle.  It worked well but at the expense of gear width 

Sure wish I have hive knowledge back when I had an E30 M3, I pulled the trans and put in a new throw out bearing to cure the input bearing noise.  Surprise, it didn't work.  My vote is go with the steel 14.5 for your use, a little extra fly isn't bad for launching.  Strictly a track car then I say go with the lightest.