Every post in the archives gets high jacked and de railed. Exactly what bolt do I use with a "Spec" aluminum flywheel part #SC94AC. I need a supplier and a part number. Not just " the GM bolt" that doesnt help me. This is frustrating that several people have posted this simple question and no one gives a straight answer. I called Spec and they have no idea.

It depends on what you want. The GM TTY bolts or the ARP cam bolts. This topic is still up in the air because no bolt seems to exist that will offer a promising torque load by design. The GM part is commonly used but is not intended for applications that a number of L67 swap users attempt, when bumping the horsepower. The best compromise I found so far is someone drilling and tapping the holes to accept a larger bolt that can take the abuse. In the end, most just red loctite the GM bolts.

The "GM Bolt" that people are referring to is the bolt for a mid 90s camaro/firebird/transam with a FWD 3800. It is Part # 24505092 and ranges $3-$10 per bolt. It is torque to yield and not reusable.
This is not the 3800 flexplate bolt which is too short for a flywheel.

The other common option is grade 9 bolts and washers from somewhere like mcmaster, I torqued mine to 19 ftlbs. They are 5/16-18 x 1inch.

I'd recommend high temp red loctite for either option. I used the gm bolt the first time I put my 3800 in for maybe 50 miles. When I had to replace the engine I decided on the grade 9 instead.


If you plan on making insane power then re drill for 10mm and use any high grade bolt.
Also make sure to search on here for info about creep issues with aluminum flywheels.

I am using a Spec aluminum flywheel on a 3800 Series 3 SC motor.

I got some Grade 9 1" bolts and washers from McMaster Carr. I think using the 11 ft lbs + 50 degrees method is a good way to go. GM uses this spec to get the proper clamp load on the flywheel to crank joint. At 11 ft lbs there isn't much effect from friction and using the 50 degree additional rotation all the bolts should be very close in tensile load making the flywheel to crank joint pretty close to what GM intended it to be.

I found the manufacturer specs on the bolts and they give a torque spec on their Grade 9 5/16-18 bolts of 36 ft lbs with a thick nut and 14 ft lbs with a waxed locknut. I used a spacer the same thickness as the Spec flywheel with a new bolt, washer and standard Grade 8 nut and tightened it with a bending beam torque wrench. The torque increased to about 44 ft lbs and remained at that point as I kept turning until the bolt broke. I repeated this four times with new bolts and nuts with the same result. Based on a 75% load factor that gives a torque of 33 ft lbs for these bolts with the Grade 8 nuts at the same thickness as the Spec flywheel.

Next I used a new bolt, washer and nut with the flywheel spacer and tightened it to 130 in lbs. I put a torque angle gauge between the torque wrench and the bolt, with the wrench set to 32 ft lbs, and tightened it. The torque wrench clicked over close to 50 degrees every time, sometimes a few degrees short of 50 and sometimes a little over 50. Based on this experiment I think the GM specs with some Loctite would be the best way to install the Spec flywheel with these Grade 9 bolts and washers.

The Spec flywheel bolt holes are slightly oversize. I made some bushings out of steel tube for less slop in the mount holes. I cut the bushings a little shorter than the flywheel thickness and used new Grade 9 bolts and washers with red loctite to install he flywheel.

Probably 5,000 miles on the car since it was installed and so far all is good.

Thanks for the input. Of all the 3800 s/c conversions done I don't recall anybody having all the issues I have had just to get the SPEC flywheel mounted. It would seem to me SPEC would have that info. When I called them they told me to check the Fiero blog pages to see what people use. It would seem to me that SPEC would have tested one of their flywheels in a real world application or learned from customer feedback... Oh yea then there is the pilot hole in the flywheel is 10 thou too small for the crank. When I spend $1000 bucks on a clutch set up I guess I expect more knowledge from the manufacturer.