Page 1 of 2 12 LastLast
Results 1 to 10 of 20

Thread: Clutches: Re-use flywheel vs. Replacing vs. Step height vs. Performance vs. MFR

  1. #1
    Banned Feedback Score 11 (100%) J. Fast's Avatar
    Join Date
    Sep 2010
    Owner Since
    - O - SIX -

    Location
    Colorado, USA
    Posts
    2,755
    Thanks
    412
    Thanked 203 Times in 143 Posts

    Clutches: Re-use flywheel vs. Replacing vs. Step height vs. Performance vs. MFR

    I went to Havana Machine to have three OEM TT flywheels balance checked. One was brand new in the box from Mitsu, the other two were used but in good enough shape to salvage. Everything balanced out just fine but when it came to having the two used ones resurfaced I thought I'd share something interesting, the spec isn't in any of the manuals at Team 3/S, Stealth316, 3si, or here. The machine step height spec for our flywheel (according to whatever manual the machine shop was referencing) is apparently .827? I couldn't find it in the 1991 Technical Information Manual, The 3S Transmission Rebuild Guide, or the paper or disc manual so what's the spec? I didn't have internet on my phone to check the spec when I was there so I called Erron S to verify the cut and he couldn't find it either. Apparently the book the machine shop is using is called the Automotix Flywheel Spec Book. This is the spec info they gave me for mitsu was incorrect as this is what it says verbatum:

    MITSUBISHI F FLAT 1.5 G15B CARB MIRAGE PRECIS
    C .600-.605 2.0 4G63 DOHC MFI ECLIPSE
    F FLAT 2.4 4G64 MFI SOHC
    C .605-.608 3.0 MIF DOHC
    SEG/PED

    DIAMANTE
    C .603-.608 3.0 MFI DOHC TURBO 3000GT
    C .620 3.0 MPFI SOHC 60^ DIMANTE
    C .820 3.0 DOHC 60^V6 DIMANTE
    C .600-.605 3.0 DOHC TURBO 3000GT


    Well, I called a Master Elite Tech buddy of mine for the spec and he gave me a measurement of .827. So here's the kicker, the OEM flywheel I purchased from Cherry Hill was cut to .834 and the two used ones were .838 and .832. Erron and I both found it strange that the spec isn't referenced in the manual. What I ended up having to do is taking the pressure plate and clutch pack (I luckily had with me at the time) and measuring from the seat on the pressure plate to the backside of the clutch disc laying on it. I came up with .822 for the total space requirement loose laid. From there I realized there book was way wrong. Looks like it's reversed in there manual so I had to phone a friend. If the step height is supposed to be .827 is .005 of clearance between the pressure plate, disc, and flywheel enough? That seemed really tight so I just wanted to double check.

    Anyway, the last time I changed my clutch and resurfaced the flywheel I just had them take a measurement on the flywheel surface before they cut it and then take a measurement afterward. Whatever was taken out... I had them cut that off the step. I never checked the spec before and never had an issue. So was I just lucky then?

    This is pretty much the first time I really checked on it and I wouldn't have caught it if the machinist didn't call me and ask me if I wanted to cut all the flywheels to the same spec since they were all different. I said show me and returned to the shop and sure as shit he measured all three flywheels right in front of me and all three flywheels were a different spec. None of them were cut to the OEM spec either. How important is that? I went ahead and cut two of the flywheels to .827 and one to .832. It seemed strange that all the flywheels were out of spec, especially the OEM unused one.

    How much does this effect chatter and engagement and what not? Maybe we could start a database of various styles of pressure plates and clutch discs ant write down the measurements to see if the are all the same spec and if not how that effects engagement and long term performance.

    I will say the last ACT disc and HD Pressure plate I had in there was on a flywheel cut to .838 according to my old reciept I dug up to check. The engagement on that was awesome and it had like zero chatter on it. Was that because of the extra tenth? Had it been cut to OEM spec of .827 instead of .838 would it have chattered more or changed the engagement? Lets discuss...


    Jeremy

  2. #2
    you know you like it Not Verified Feedback Score 0 Chris GTO TT's Avatar
    Join Date
    Sep 2010
    Owner Since
    2003

    Location
    Sacramento CA
    Posts
    308
    Thanks
    18
    Thanked 7 Times in 7 Posts
    Iirc the reason there is no reference is because Mitsubishi says you are supposed to REPLACE the flywheel it is not supposed to be resurfaced.

  3. #3
    Banned Feedback Score 11 (100%) J. Fast's Avatar
    Join Date
    Sep 2010
    Owner Since
    - O - SIX -

    Location
    Colorado, USA
    Posts
    2,755
    Thanks
    412
    Thanked 203 Times in 143 Posts
    I'm not getting it, is resurfacing bad? My new in box OEM flywheel was out of spec and had to be recut. None of them were warped and all were still balanced so what gives?

  4. #4
    I AM IMPORT POWER Feedback Score 1 (100%)
    Join Date
    Sep 2010
    Owner Since
    2001

    Location
    Driving Vicki Crazy
    Posts
    1,457
    Thanks
    58
    Thanked 281 Times in 134 Posts
    .827" +/-.002" is what I have always used for the TT. The NA is different and I can't remember off hand as I only have done a few.
    I measured a new OEM and it was .827" +/-.002"

    -Chris

  5. #5
    Wrench Monkey Not Verified Feedback Score 1 (100%) TwIzTeD_3kGt's Avatar
    Join Date
    Sep 2010
    Owner Since
    2005

    Location
    Rochester, NY
    Posts
    714
    Thanks
    41
    Thanked 26 Times in 19 Posts
    Quote Originally Posted by Ninja Performance View Post
    .827" +/-.002" is what I have always used for the TT. The NA is different and I can't remember off hand as I only have done a few.
    I measured a new OEM and it was .827" +/-.002"

    -Chris
    This is what I've always gone by. I want to say NA is .613 +/-.002". I've done both resurface and brand new, doesn't make a difference so long as it has the correct step height.

    I would say you got lucky, and perhaps a tenth over isn't 'too far'. I do know I've completely worn out a clutch in 1200 miles thanks to too much clearance. Didn't have the flywheel resurfaced and learned my lesson. How much past spec it was, I don't know. But if you were a tenth past and it was fine, it would be interesting to know the real limit and pros/cons.
    1997 3000GT VR4 - Solano Black Pearl - E85 - E316G-BIG - All the boost
    1993 3000GT VR4 - Maroon/Blacktop - Back to stock/Restoration
    1994 Stealth R/T - Primer - Parts store

  6. #6
    I AM IMPORT POWER Feedback Score 1 (100%)
    Join Date
    Sep 2010
    Owner Since
    2001

    Location
    Driving Vicki Crazy
    Posts
    1,457
    Thanks
    58
    Thanked 281 Times in 134 Posts
    Quote Originally Posted by Chris GTO TT View Post
    Iirc the reason there is no reference is because Mitsubishi says you are supposed to REPLACE the flywheel it is not supposed to be resurfaced.
    I have replaced umpteen clutch and flywheel combos reusing the OEM flywheel that came out and having it step cut to .827" and have never had an issue. My own car included. Clutch grabs and releases, wear is fine.

    Of course they want you to replace it, they are proud of that part, ever price one?

    -Chris

  7. #7
    you know you like it Not Verified Feedback Score 0 Chris GTO TT's Avatar
    Join Date
    Sep 2010
    Owner Since
    2003

    Location
    Sacramento CA
    Posts
    308
    Thanks
    18
    Thanked 7 Times in 7 Posts
    Quote Originally Posted by Ninja Performance View Post
    I have replaced umpteen clutch and flywheel combos reusing the OEM flywheel that came out and having it step cut to .827" and have never had an issue. My own car included. Clutch grabs and releases, wear is fine.

    Of course they want you to replace it, they are proud of that part, ever price one?

    -Chris
    Hey I'm not saying you can't resurface it, I'm just saying that its not recommended by the mfg. I'd rather do it right once than cut corners and have to do it twice.

  8. #8
    Banned Feedback Score 11 (100%) J. Fast's Avatar
    Join Date
    Sep 2010
    Owner Since
    - O - SIX -

    Location
    Colorado, USA
    Posts
    2,755
    Thanks
    412
    Thanked 203 Times in 143 Posts
    Quote Originally Posted by Ninja Performance View Post
    I have replaced umpteen clutch and flywheel combos reusing the OEM flywheel that came out and having it step cut to .827" and have never had an issue. My own car included. Clutch grabs and releases, wear is fine.

    Of course they want you to replace it, they are proud of that part, ever price one?

    -Chris
    That's exactly why I took the used ones in. I was surprised to find the one I just took out that had the CM HD pressure plate and ACT 6 puck unsprung fuzed together on it was still balanced. You could just tell that thing was used and got very hot. Cut back to .827 and it looks brand new.

    You think you can keep resurfacing them as long as they will balance and the surface is still raised above the main casting or do you thin you can keep resurfacing well below the casting?

    For future reference you or anyone else have a good pressure plate or unused clutch disc laying around to pull some measurements from? What's the height and end gap on the Spec clutches, same as Clutchmaster and ACT, .0025 on each side of the disc or .005 between the pressure plate, disc, and flywheel? My new clutch setup has a height of .822 so that leaves .005. What's your opinion on the endplay? Should that number stay the same with stage 4 clutches and above? This one goin in is really aggressive. It's another multi disc unsprung with a clamp rating of 700ftlb.

  9. #9
    I AM IMPORT POWER Feedback Score 1 (100%)
    Join Date
    Sep 2010
    Owner Since
    2001

    Location
    Driving Vicki Crazy
    Posts
    1,457
    Thanks
    58
    Thanked 281 Times in 134 Posts
    Quote Originally Posted by Chris GTO TT View Post
    Hey I'm not saying you can't resurface it, I'm just saying that its not recommended by the mfg. I'd rather do it right once than cut corners and have to do it twice.
    Just for the record, having it correctly 2 step turned at a good machine shop is not cutting corners. I have run a whole drag season on turned flywheels, and have customers with many 10's of thousands of miles without a complaint. If done right there is not an issue and it's not cutting any corners, just the flywheel.

    That would be like saying don't bore out a block, just get a new one. It's just machining. When done right.

    -Chris

  10. #10
    you know you like it Not Verified Feedback Score 0 Chris GTO TT's Avatar
    Join Date
    Sep 2010
    Owner Since
    2003

    Location
    Sacramento CA
    Posts
    308
    Thanks
    18
    Thanked 7 Times in 7 Posts
    Quote Originally Posted by Ninja Performance View Post
    Just for the record, having it correctly 2 step turned at a good machine shop is not cutting corners. I have run a whole drag season on turned flywheels, and have customers with many 10's of thousands of miles without a complaint. If done right there is not an issue and it's not cutting any corners, just the flywheel.

    That would be like saying don't bore out a block, just get a new one. It's just machining. When done right.

    -Chris
    I know it can be done and many have success with it, but I won't be turning mine.

    Also a more apt analogy is; its like turning brake rotors down to their min thickness. Most will have no problems, but I still won't recommend it.

    I really don't think there is anything wrong either way, I just like following directions. As such if the fsm says replace I usually will.

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
The 3000GT/Stealth/GTO Web History Project
3000gt.com
3000GT / Stealth International WWWboard Archive
Jim's (RED3KGT) Reststop
3000GT/Stealth/GTO Information and Resources
Team 3S
3000GT / Stealth / GTO Information
daveblack.net
3000GT/Stealth/GTO Clubs and Groups
Michigan 3S
MInnesota 3S
Wisconsin 3S
Iowa, Nebraska, Kansas 3S
North California 3000GT/Stealth
United Society of 3S Owners
3000GT/Stealth/GTO Forums
3000GT/Stealth International
3000GT/Stealth/GTO Event Pages
3S National Gathering
East Coast Gathering
Upper Mid-West Gathering
Blue Ridge Gathering