View Single Post
Old 03-04-2014, 11:08 PM   #7
MyblackS13
Leaky Injector
 
MyblackS13's Avatar
 
Join Date: Oct 2002
Location: Indiana
Age: 42
Posts: 128
Trader Rating: (4)
MyblackS13 is an unknown quantity at this point
Clutch

The clutch decision was a big one for me and one that I didn't take lightly. The clutch can have a huge effect on how the car drives. My final decision was to go light to lessen the hit on the tires and let the engine rev faster for the approximately 2600lb car. First I bought a 7.25" racing clutch.



The plan was to use this with a button flywheel on an automatic flexplate for an extremely light set-up, but after seeing a lot of you tube videos with extremely jumpy, light switch like clutches and reading manufacturers recommendations to not even drive cars onto the trailer with them I got the idea that it was a little more aggressive than I want to deal with. Dru Nichols (SicBastard) compiled some great information on moment of inertia of clutch assemblies. For those of you not familiar with the term or the concept, moment of inertia in context of a clutch is the idea that the same weight at the same rpm has more energy the further it is placed from its axis of rotation. A good example is a baseball on a string, a baseball on a 2 foot string rotating at 100rpm is only going about 7mph, but the same baseball on a 17 foot string at the same 100rpm is going about 60mph. Enough about the physics and back to the clutches.

Tilton Clutch Assemblies MOI (lb-in^2)
Includes: Clutch cover with diaphragm spring, pressure plates and floater plate(s)
(add 66 MOI and 2.5# to include the button
(add 87 MOI and 3.4# to include a Sonic ultra-lightweight flexplate)

13 4.4” Tilton carbon carbon 4 disc
21.4 5.5” Tilton 1 disc cerametallic
29.4 5.5” Tilton 2 disc sintered metallic (6#)
32.2 5.5” Tilton 2 disc cerametallic
52.4 7.25” Tilton 1 disc cerametallic
76.3 7.25” Tilton 2 disc cerametallic
89.6 7.25” Tilton 3 disc sintered metallic (10.2#)
99 8.5” Tilton 1 disc cerametallic
100.2 7.25” Tilton 3 disc cerametallic
158 8.5” Tilton 2 disc cerametallic
337 9.0” Mantic street dual sprung clutch (33.8#) cool set up!
>3200 11.5"? Stock LS2 flywheel and clutch (52#)

(MOI list thanks to Dru Nichols - SicBastard)

I also put together the following list of weights without MOI with a lot of google searches for light weight clutch assemblies for the LS series engines.

McLeod RST 9-11/16 dia. w/Aluminum Flywheel 560530 (36#)-w/13.5# flywheel
McLeod Mag Force 8" dia twin Assembly (25#)
Spec Lightweight flywheel w/Al PP Option 11-1/2 dia. (33.4#) (McLeod also offers a similar set-up if you call them)
RPS Street Twin 1/2 Carbon (40#)
RPS Street Twin Full Carbon (36#)
RPS Billet Carbon Street Twin w/Steel Flywheel (32#)
RPS Billet Carbon Street Twin w/Al Flywheel (25#)

After talking with Lee at McLeod clutch and Scott at SPD Metalworks I went with the Mag Force twin. They put together a custom assembly based on the pin drive Mag Force, with a strap drive pressure plate, and ceramic discs.








The McLeod Mag Force Twin is a seriously beautiful piece, its really sad that it has to be buried behind a bellhousing. I bought it to run it though so it has to go in. This being a twin its a little different from other clutch installations I have experienced.




First you pop off the pressure plate to see the ceramic pucked solid hub disc that's backed up by a floating pin drive center disc. I chose the floating center disc based on recommendations that it would drag less as the clutch begins to wear, allowing me a slightly longer interval for re-shimming the clutch.



On top of the drive pins there are shim stacks calibrated from the factory for proper finger height on the clutch diaphragm. As the clutch wears, shims will be removed until either one of the plates are out of spec or the clutch is worn or damaged to the point where it needs to go back to McLeod for a full rebuild.





I have the strapped pressure plate to keep some of the noise down.



I'm using ARP pro series 12pt flywheel bolts to protect the investment p/n 330-2802



Using the standard clutch alignment tool this is all the further the transmission would engage, I thought I could get away with it, but I no matter what I tried I couldn't get it any closer than the last inch. Finally I broke down and bought the Quarter Master 1-5/32" x 26 spline alignment tool. Its under $50 and well worth it to just go ahead and get it if you're going to install a multi-plate clutch.





Here's a video for an example of about how I expect it to rev.

<iframe width="480" height="360" src="//www.youtube.com/embed/VXcMR-ejxsU" frameborder="0" allowfullscreen></iframe>
__________________
Dustin - S13 Build
LS1 Inside
MyblackS13 is offline   Reply With Quote