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Old 03-03-2012, 12:17 PM   #1
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Default Little problem with 05+ LM7 flywheel on LS2 to Muncie conversion

So I'm putting an 06 LS2, carbed, ported 243s, cam and supporting mods mated to a Muncie M22 in a 1970 Nova. I have spent hours reading about the early 4speed conversion. I have found some problems when using the Sachs #1050 05+ LM7 flywheel.

The big one is that when using a standard 11" 10spline clutch kit (in my case, 01735552 - Centerforce DFX, but looked at many brands all with same outcome) the inner radius of the disc is 1" smaller than the inner radius of the flywheel surface. So that's a 1/2" of the disc not coming in contact all the way around with the surface on the flywheel to the inside. When the friction material is only 1 5/8" wide on the disc, that's more than 25% not touching. I feel this might pose a problem when trying to apply 700ish HP on juice and slicks, in a 3000lb car.

Also I'm not to sure I want a flywheel that has "made in china" cast in the back of it spinning around @7000RPM, 6" away from my feet! Being the poor bastard I am, I have had great luck with "china" turbos, radiators, intercoolers, ect. Non of witch could take my foot off. The thing looks like it was cast in river dirt with weld slag! That being said, I cant find an aftermarket cromo flywheel for that app, 05+ 5speed truck.

Lastly, it weights a TON! I'm all for keeping the reciprocating wight up in a standard shift drag app. Having the inertia really helps get the car moving from a dig. I would rather the car go fast then just sound cool because it revs fast. I often use heavy flywheels to make up for weight removed from a knife edged crank. Reduce the parasitic drag, but keep the reciprocating wight up.

So my question is, has anyone tried an Fbody flywheel with a Muncie? Can you get correct clutch fork angle with an adj fork pivot ball? From what I can tell it's the same as the Sachs #1050 just turned down about 1/2" and balanced. This makes the surface wider. It's tapered from the bolt circle up to the surface, so as you turn it down the surface becomes wider to the inside. The pressure plate bolts are in the same location. But in the Sachs #1050 the threads don't start till about 1/2 down the hole. On the Fbody flywheel they start right at the surface. That's another reason I'm sure It's the same part just turned down, and $100 higher because it has the word Camaro attached to it. If an Fbody flywheel will work given you can compensate for the 1/2" more distance from the release bearing. It would open up to the after market availability, and I could save my feet!
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Old 03-03-2012, 02:28 PM   #2
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Well I can tell you from experience, that I had the same issues as you have now with the 1050 flywheel. Was very surprised to find the center cut out as much as it was. I mated a 465 trans to an LS engine, and ended up using a 12" clutch, (More like 11.75), and was concerned with slippage, etc. However, having run it for several miles this way in a 4500lb truck, there has been no slippage what so ever. I am a little concerned with how the disc will wear.

There is a solution though. The same 05 truck's that came with the 1050 flywheel, also came with a clutch made specifically for this. There is more meat/material on the outer edge of the clutch, than on the inside, since it was designed for this purpose. This same clutch is also 10 spline, 1 1/8 shaft. Its also a little over 11" (11.6), and made to work in a 3/4 truck.

The LS flywheels are not as thick, thereby throwing off your fork geometry. However, the 1050 flywheel is still not as thick as a sbc flywheel, so geometry is still not great. It will work, but you'll be pushing limits
See this post
Converting an 86 K10 to an 04 Silverado


You'll need to make up for the correction with an adjustable pivot ball. I think you could get away with a regular LS1 flywheel, if you adjust the pivot ball forward enough. However there are several here that run the 1050 flywheel with only a 10.5 inch clutch and don't have issues. I wouldn't feel comfortable with it, but they claim not to have any issues.
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Old 03-03-2012, 02:54 PM   #3
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Yes you can use an LS1 flywheel/pressure plate. The clutch disk will be 26 spline so you'll need a 10 spline if it's an early muncie. You can get the fork geometry correct with an adjustable stud and longer throwout bearing.
With the LS1 flywheel the disk splines will run off the front of the trans input shaft. So your choice with 700hp, you might burn up a clutch with the 1050, or strip/twist an input shaft with the LS1, or maybe just blow up the trans from the hp alone.
My notes on putting an LS1 flywheel/clutch and 1050 on with a Muncie/Richmond
Mating a SBC/BBC Trans (T10, Muncie, Richmond, TKO) with an LS motor
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Old 03-03-2012, 03:55 PM   #4
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The LS7 (i.e. LS2) flywheel runs the clutch surface into a smaller diameter than the LS1 flywheel. Would something like that work better for you?

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Old 03-05-2012, 10:01 AM   #5
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Thanks a lot for the info guys. I picked up a lakewood bellhousing, that should save my feet. I've decided that I'm going turn the Sach 1050 flywheel down 5/16" just enough that the whole disc will meet the flywheel surface, yet all the splines still make it into the disc. The flywheel will still be alot thicker that an LS1 Fbody flywheel, should help with the clutch fork geometry. The lakewood bellhousing also has a big beefy tab with three taped holes (not just one, like the 621 bell) for the zbar pivot ball. This will make it a lot easier to fab a bracket as it can be made from 3/16" flat steel and not have a 90 bend like the scoggin dickey part that bolts to the bell bolts. I'll post pics soon.

Thanks again.
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Old 03-05-2012, 12:29 PM   #6
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Post some before/after piccs. I'm running a Muncie with the 1050 flywheel, but on a stock 5.3 so I'm not too concerned, but might cut mine.
On the other hand, if you consider how a clutch works, the clamping force is the same regardless of the disk/flywheel contact area. It's only when the the clutch is released and slipping that the decreased contact area will cause accelerated wear. Mine is a daily driver so 6000rpm drops shouldn't be an issue.
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Old 04-05-2012, 02:47 AM   #7
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Quote:
Originally Posted by nopostduece View Post
Thanks a lot for the info guys. I picked up a lakewood bellhousing, that should save my feet. I've decided that I'm going turn the Sach 1050 flywheel down 5/16" just enough that the whole disc will meet the flywheel surface, yet all the splines still make it into the disc. The flywheel will still be alot thicker that an LS1 Fbody flywheel, should help with the clutch fork geometry. The lakewood bellhousing also has a big beefy tab with three taped holes (not just one, like the 621 bell) for the zbar pivot ball. This will make it a lot easier to fab a bracket as it can be made from 3/16" flat steel and not have a 90 bend like the scoggin dickey part that bolts to the bell bolts. I'll post pics soon.

Thanks again.
and?? i plan do the same with my sach 1050.

you have some pics with surface down??

salu2
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Old 04-05-2012, 02:47 AM
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1050, bracket, clutch, conversion, flywheel, fork, lm7, loose, ls1, ls2, muncie, pad, pivot, sachs, starter, t10


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