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LS7 Flywheel Question

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Old 07-24-2013, 04:30 PM   #1
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Default LS7 Flywheel Question

A buddy of mine is having an issue with this below. Does anybody have any constructive input?

One of the three locating dowel pins on the perimeter of the steel flywheel broke in transit. I called a reputable local machine shop I've used and they told me that I should be fine to run without it since there are still two other pins to align the pressure plate, but I'd like to get some opinions to either confirm or deny that.

My main concern is whether the pin which sheared off even with the flywheel would be enough to throw off the balance of the clutch assembly. The assembly is being used with an LS3 mated to an LS T56. The piece of the pin that broke off weighs 2.5 grams (approx 1/8 oz) on my kitchen scale.

If I do have to replace the pin, I've read that the best approach is to drill a 1/16" hole through the back side of the flywheel and then use a punch to knock out the pin. Agree? I assume the hole itself wouldn't weaken the flywheel?
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Old 07-24-2013, 04:40 PM   #2
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I would try and get the pin back in, or get a new flywheel. I don't know if 1/8th oz spinning at 7000rpm will or won't throw it out of balance, but my quess is that it will...

Someone else might have better input...
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Old 07-24-2013, 08:51 PM   #3
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To make installation of the PP and clutch disc easier I went to a local clutch shop who pulled the pins for me. He also balanced the unit while I was there. He gave me three new hardened pins and told me to put them back in as they serve more of a purpose than just locating the PP on the flywheel. Perhaps they fit tighter than the bolts around the PP and give it less of a chance of moving and shearing the bolts? I have all three installed. I put in one pin to rest the PP and clutch on while I installed a couple of screws. Once I rotated the assembly and started two more screws I put the second pin in, then did the same with the third. All are seated well with a punch while still being flush with the face of the PP.

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Old 07-25-2013, 07:37 PM   #4
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I responded to his thread on LS1 tech. The dowel pins only help with installation and don't do anything once the pressure plate is torqued down. My personal car does not run them and you can see the results below. The same pressure plate w/o dowel pins held over 1100rwtq on one of our customers cars with stock GM bolts.
~422rwhp+Monster Level 2/4.10=60'-1.49 1320'-10.99/125.5
Best mph-127.1

~520rwhp 6.0+LT1S/3.42=60'-1.56, 660'-105.9mph, 1320'-132.5 with headwind and 0' DA

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