GVR-4 Help Finding Correct OEM Flywheel number/Replacement Flywheel

[S_39]

Hey all, I'm going to be changing the clutch in my '91 Galant VR4 (6 bolt) because the previous owner had installed a twin-disk Competition clutch and it's honestly undriveable in a DD setting. I already had the car de-tuned way below where it was at before and it's sitting well below the torque safety threshold for the ACT 2600 — I am currently leaning heavily towards getting the sprung street disk in combination with the 2600 pressure plate.

In addition to changing the clutch, I'm going to need to change the flywheel and I wanted to get the weight as close to stock as possible, as the car is missing all the electronics necessary to keep the car idling and it dies at red lights if I don't press the clutch pedal in. Doing A LOT of research, I found the following MD part numbers for flywheels:

MD173425
MD119309
MD119308
MD168697
MD168696

Needless to say, I am extremely confused as to which one I actually have to order and whether or not it comes with the ring gear pre-installed or if I have to acquire that separately (ordering from Amayama). An alternative option for me would be to find a flywheel that is compatible with the ACT 2600 clutch kit that also has a weight similar to the stock one so the car stops stalling every minute.

Also, I just remembered that the previous owner made a change to the clutch pedal so that it doesn't have to be pressed in when starting the car? I am unsure of how this will affect any alignment procedures after installing the new clutch or if this is something that I absolutely need to reverse/fix as soon as possible.

 

[We're on Boost]

Also, I just remembered that the previous owner made a change to the clutch pedal so that it doesn't have to be pressed in when starting the car? I am unsure of how this will affect any alignment procedures after installing the new clutch or if this is something that I absolutely need to reverse/fix as soon as possible.

No don't reverse this. This is a good thing. When you step on the clutch pedal to start the car, all that thrust load that you put on the clutch is taken by the crankshaft thrust bearing, which then has to start rotating before the oil pressure is up. Then if you have a heavy clutch in the car, that makes it worse (more thrust load). So being able to start the car without stepping on the clutch is a good thing. This is usually done just electrically, by disabling a little switch that is up near the clutch pedal pivot point under the dashboard.
So it's one of the things we do to try to prevent "crankwalk" which is something you could read about all day if you wanted to.

 

[S_39]

No don't reverse this. This is a good thing. When you step on the clutch pedal to start the car, all that thrust load that you put on the clutch is taken by the crankshaft thrust bearing, which then has to start rotating before the oil pressure is up. Then if you have a heavy clutch in the car, that makes it worse (more thrust load). So being able to start the car without stepping on the clutch is a good thing. This is usually done just electrically, by disabling a little switch that is up near the clutch pedal pivot point under the dashboard.
So it's one of the things we do to try to prevent "crankwalk" which is something you could read about all day if you wanted to.

Ok that makes a lot of sense, thank you for clarifying for me! Now to see about getting a replacement flywheel...

 

[We're on Boost]

the car is missing all the electronics necessary to keep the car idling and it dies at red lights if I don't press the clutch pedal in.

This is a little strange, I don't understand it. A heavier flywheel won't help that though.

I am currently leaning heavily towards getting the sprung street disk in combination with the 2600 pressure plate.

An alternative option for me would be to find a flywheel that is compatible with the ACT 2600 clutch kit that also has a weight similar to the stock one so the car stops stalling every minute.

Hmm, well opinions are all over the map about clutches for the 1g cars in here. But I liked my ACT clutch with ACT flywheel. I might still have it but I needed a different disk with a bigger splined hub in it and that sent me down the whole rabbit hole with clutches, and now I have a clutch you would hate.

Probably you should say what you figure your torque is going to be, since you have downward revised the engine tune for less torque. Maybe you could use something smaller than a 2600?

That's another point. ACT hasn't called it the 2600 for almost 10 years now. Even when I bought mine in 2016 they didn't call it the 2600. Now, for your car and for DSMs it is the:
MB1-XTSS - XT/Perf Street Sprung (Pressure plate and organic street disk kit)
https://www.advancedclutch.com/products/transmission/mb1-xtss-xt-perf-street-sprung

And if they did still use the old naming convention for it, they would call it the "2700" according to ACT tech support.

The matching ACT street flywheel for the 6-bolt is very nice, has the starter teeth already on it:
600150 - XACT Flywheel Streetlite
https://www.advancedclutch.com/600150-xact-flywheel-streetlite

So, I had those 2 things on my car for 3 years and it was easy to drive on the street. Easy engagements from stopped. You could slip it all you want in normal driving, like for maneuvering around in gas stations or in the driveway. No accidental stalls and I don't remember any chatter to speak of.
The tribal knowledge shortcoming of it is a heavy pedal (high effort) which also means you'll get some deflection in your pedal assembly so your slave cylinder travel won't be enough to allow shifts at 9,000 rpm or maybe even lower, I don't know. I've only ever shifted my car below 8000 rpm and I could shift just fine with it.
Also due to the heavy effort, the end of the rotating rod in the pedal assembly can wear down (round off) where it drives the master lever that attaches to the clutch master cylinder. And those parts are no longer available new so people sometimes weld them together! I haven't had to weld mine (yet).

So for those reasons you might also consider a less heavy duty clutch. The ACT one would be in the "HD" series, rather than the "XT" series:
MB1-HDSS - HD/Perf Street Sprung
https://www.advancedclutch.com/products/transmission/mb1-hdss-hd-perf-street-sprung

For any of these ACT parts, look at the "Vehicle Fitment" tab, and for their clutches also look at the "What's included" tab. You'll see that the HD and XT clutches use the same disk. They also include a throwout bearing but most people say the Mitsu OEM throwout bearing is probably better.
It does seem to me that ACT street clutches can take quite a bit more torque than what ACT rates them for. Mine did.

I don't know anything about the stock flywheels. I'm sure some people prefer them.
With the ACT organic street disk, I don't think you need the extra weight for nice engagement. But it's cast iron (OEM) vs steel (ACT) for the materials. So for the friction surface of it to stay in proper shape for a long time there might be an advantage to cast iron. I don't know, maybe I've just never used a steel flywheel long enough for any problems to show up with it.

 

[S_39]

Thank you so much for the detailed explanation. I did actually manage to find a seller that was offering resurfaced 1g AWD DSM flywheels for really cheap, so I think I'll stick with the OEM flywheel for now. Unfortunately, I don't have the dyno graphs on-hand though I'm sure if I contacted the shop they'd most likely have them saved somewhere (hopefully).

As for the clutch decision, I'm currently torn between the MB1-HDSS and the MB1-XTSS because I don't know where my torque is at. I'm going to try and contact the shop that tuned the car and see, the only thing I remember is that they gave me a HP number ~270 at the wheels. In the case that they don't, I'm leaning towards being more safe than sorry because I do enjoy driving the car pretty aggressively out here on the back roads and I'd rather not encounter issues with my drivetrain.

 

[We're on Boost]

You should for sure contact the shop and get whatever record they have of your final dyno run.
Anyway, if it was 270 hp, you can be pretty sure that the torque is not over 300 ft-lbs.
That is what I would call just right for the "HD" clutch, the MB1-HDSS.

What turbo is on the car? You should start a Specs and Mods page for your car and list that type of stuff in there. That way people have a clue at least about what is reasonable to expect for your car.

Back on the dyno thing again, if your shop has the actual dyno file from your final power run, you should ask them to email it to you. Also if they have a log of the run, like from DSMlink or whatever, see I don't even know what engine management you have. Anyway the log would be good to have.

The dyno file, what would you do with it if you had it? Well, if the graphing software for it is freely available to the public without needing any user license, you could download that software and make a nice graph with it. You can do that with DynoJet files. I did. You can see the result in my Specs and Photos. Pick the tile with the English Racing truck on it, the dyno is in there as a photo. It's better than some crappy cell phone shot of a screen on the wall, or some crumpled up sheet of paper. One of my peeves sorry haha! If you don't know what the hell I'm talking about with graphing software I could help you figure out how to do it if the shop won't help you. In my case my shop did help me (English Racing). On the other hand if you had to use the graphing software with a cell phone, it might be just too painful to even bother. (Another peeve ). Then you'd be better off with a good photo file of the dyno result properly plotted out.