Last weekend I went searching for Flywheel Bolts for an Ecotec. Everyone locally told me to go to the dealer. When I did, they said $12 per bolt and it would be a week before I could have them.

So, I decided to look for another alternative. ARP makes good bolts, so I checked with them first. They did not have anything specific for J's, however they did have a 10mm x 1.25 x 1.050 in. Chromemoly flywheel bolt for Toyota's that looked promising. My only concerns were:

1. Length of the bolt (Stock Flywheel bolts are 25mm, with translates to 0.98 of an inch. .07 didn't seem like a big deal to me), and
2. Size of the head. (Stock Flywheel have a head about 1/8 of an inch. These appeared much larger.)


I gambled with my luck, and ordered the bolts (part number: ARP-203-2802) from Summit Racing ($40 for 8, shipped). They came through for me with the parts in 2 days, despite having them shipped via UPS ground.


The first thing I wanted to do was make sure they weren't too long. I inserted one into the crank with the flywheel attached. It tightened down with no problem (btw, they use a 12 Point 1/2" SAE socket to attach). So, I'm batting 1 for 1 thus far.

Next, I compared them to the stock bolts.


As you can see, the head is significantly larger. This is now my main concern, as you'll see from the rest of this post. So, now the question is whether the head of these are large enough to hit the clutch at all.

I removed the flywheel, placed it on a flat surface with a hole in the center (aka the pressure plate), and inserted a stock bolt and one of the ARP bolts. Then I placed a level over top to see if the bolt protruded past the flywheel mating surface. (See pics)



It just BARELY clears the flywheel surface. Now I'm batting 2 for 2.

So, time to see if it would hit anything on the clutch. I took the clutch, placed it on a flat surface, and used the level to see if anything protruded past the clutch disc's contact surface. I immediately noticed the rivets that hold the spring assembly hit the level. The other potential for problems would be the springs and raised surface around them (I didn't think to take more detailed pics of this area ).



Swing and a miss... batting 2 for 3 now.

So, now the question is, how far from the center point are these, and will they potentially hit the ARP flywheel bolts? I took a handy piece of paper and taped it to the flywheel. I attempted to center the clutch as perfectly as possible, and then traced where the rivet and the springs protruded from the clutch disc.




Next step was comparing them to the Flywheel with the ARP bolts "in place."



According to this, the rivets will clear the bolts with no problem. These were my main concern, as they are the only thing that protruded past the clutch disc contact surface. Additionally, the highest points of the area where springs come through are also on the outside of the bolts.

Here are some closer pics of this.


So now, the only question is will the clutch surface wear away enough so that the bolts eventually come in contact with the areas around the spring.

This is where I'm seeking your help. You have the pictures here. What do you think about this?

Thinking about this some more...

What I can do next is measure the actual clutch contact surface as well as the distance from the springs to the bottom of the level.

If:

the contact surface thickness < (the distance from the level to the spring + the level to the ARP bolt)

... I should be fine in using them and not have to worry about the clutch wearing down enough to hit the bolts. If this is true, the rivets in the clutch contact surface should actually give way before the surface is ever worn enough to allow the area around the spring to hit the flywheel bolt.

That thread sounds like the same the 2.3/2.4's use. The ones I used were from a Ford modular V8 and the head was the same height as stock and the bolt itself is a hair longer than stock




Jason
99 Z24
157hp/171tq
wheres my boost??

I found these by searching 10mm x 1.25 on summit... those are the only flywheel bolts within these dimensions.

When searching ARP's catalog, the v8 modular came up as 10mm x 1.0.

I'm not sure if the 2.3/2.4's use a different thread than the Eco or not (I know the 2.2OHV did, I have a spare set of those too), but I wanted to stick with the OEM thread size and pitch.

did you end up using th ARP?If so any problems?
thanks,james

so what was ever the final verdict for this?

I used the stock bolts out of necessity (as in, I had to get the car moved), though I kept the ARP's in case I wanted to try later on.

At the time, I didn't have a digital caliper to measure precisely. And now that I do... well it's all been installed on the car so it's hard to get measurements without tearing @!#$ apart.



The idea is to re-evaluate this when I've killed the current stage 3 clutch. Considering it's still not even broken in, that may take a while!