sr20det flywheel UHL

[drb5721]

When installing my flywheel, 7 of the 8 bolts torqued beautifully. 1 bolt will act like it is going to tighten then gets loose. I ran a tap down the hole and cleaned up any threads the tap would get to, seeing as it is a taper tap. Also ran a die on the bolt and made absolutely sure everything looked as clean as possible and tired again. Still nothing. Looking at the bolt, it looks like the VERY end threads are slightly rolling. I have ordered a bottom tap and awaiting the arrival.

My question is how deep is the hole in the crankshaft for the bolt? I see there are some bolts measuring 1in of UHL and some available at 1.15 of UHL. I am concerned with using a slightly longer bolt for balancing concerns even if minute. Also, wary of helicoils or tapping to a larger diameter bolt, say a 7/16-20. Having done some research on helicoil, timesert, etc, helicoil actually passed more tests in regards to torque stress than the timesert. Granted these tests were in aluminum...not a crankshaft.

Either way I have to figure out which route to go and if the bottom tap does repair any threads deeper in the hole, perhaps I may need a slightly longer than stock bolt to engage and torque properly.


Sorry for the long post. Wanted to get all my current thoughts in this one so I don't forget any.

[drb5721]

Was able to get my hands on a caliper tool.

The bolt hole for the sr20 flywheel bolt in the crank has a depth of 28.5mm from the surface of the flywheel in.

The factory bolt has an UHL of 24mm and is 30mm in total length.

Taking into account the flywheel thickness, which LOOKS to be roughly 6-8 mm, with a FACTORY bolt you have 16-18mm of threaded bolt in the hole.
With a 1" UHL bolt you could have 17.4-19.4 mm of threaded bolt in the hole.

Perhaps if something like a m10-1.0x1.1 could be found, it would allow for almost 19.94-21.94 mm of threaded bolt extending into the hole which is almost complete reach of the depth.

Hopefully ill have my tap by thursday at the latest. Gonna order a factory bolt for testing. May order 1 factory and one with 1in UHL like the ARP bolts. All this to hopefully avoid a helicoil/different size and pitch bolt.