The other day I was driving my 120Y (and run one motorkhana course) when I started to hear a hell of a noise and shaking under acceleration and reving. After inspecting the car with some mechanic friends we came to the conclusion that the flywheel bolts have given up the ghost.

Some factors to consider:
- I assembled the motor myself to factory torque specs
- I set up oil clearances and piston ring gaps looser than one might do
- I reused the best flywheel bolts I had because I seem to recall Nissan don't sell them now? (I asked them again and they say the A12 ones are NLA)
- I use a lightened A12 flywheel on an A14 crankshaft
- The motor sees 6000rpm, full revs in top gear, hard launches, missed gears spinning up to 7500rpm and somewhat shakey idle I've been meaning to smooth out( and I just got the synchrometer adaptors too :S)
- I drove the car home 25odd km not going more than 60kph, keeping the clutch firmly engaged the whole way

My question is for those more knowedgeable on this sort of thing than me. Looking at the worst case scenario I'd need to replace the crank, flywheel, my legs, clutch, and possibly some gearbox bits? Could the flywheel mating surfaces be machined? I have not removed the gearbox or motor to inspect the severity yet as money is tight so it's more officialing from me this year.

I don't quite believe Nissan when they say the bolts are no longer available, what would they do for Bakkies?

Normally they are reused, but once come loose I would suspect them and get a different set. Use the ones from an A14, they are the same. Only the pre-B210 bolts were different.

For 7000 rpm use locktite.

Flywheel Bolts

12315-H6200 BOLT-FLYWHEEL (6, 10mm) 1974-

I did use loctite blue. Should have been more patient and dowed the flywheel while it was all apart.

I've never had mine come loose when it was doweled.
I just use 12.9 tesile capscrews on my flywheel. But if you do that, make sure to check the clearance on the center hub of the clutch, against the heads of the capscrews.

The fact is that the bolt PCD is a little on the small side. PLus the bolts aren't a doweling tight fit. Thems the breaks.

My 2cents,

I always use 680 loctite on the threads and under the head of the bolts, and I do the bolts up F.T. (Fucking Tight) Wouldn't have a clue what the factory spec is - didn't know they had one.

I've been using the same modified flywheel bolts for the last 10yrs with out a problem.

If you need any machining done let me know.

I used 7/16 UNF alanhead capscrew’s for mine which required tapping the crank threads bigger using a starter tap and than a bottoming tap but wasn’t to hard as the UNF thread is almost the same number of turns to the inch (check a tapping chart) just 1mm bigger.

I also took the chance to drill out the bottom of the crank holes a little bigger (not deeper) as I noticed the standard threads didn’t go all the way. This gave me better thread inclusion which meant when doing the capscrews up with lots of thread cleaner then lock tight super stud lock I wasn’t scared of pulling the threads out of the crank from over tightening.

Seems to have worked for me and wasn’t expensive just time consuming collecting the right bolts modifying their length both thread and head height to clear clutch, finding someone to borrow taps off.
Now that I think of it very time consuming

Thanks for the input guys, any word on machining the crank providing the surface isn't rounded?

Quote:

Me too, until I went to a class on fasteners..
All threaded studs or bolts must be tightened no more than the "stretch" component allows.

IF you pull the "stretch" out of a fastener, then the assembly is subjected to HEAT, the fastener cannot then stretch any more, failure of the assembly may result..

On flywheel bolts, I suggest Grade 8[
Au = grade 12.9]
US GR-8 will be Gold in color and have SIX marks on the head.

US and Metric Bolt Torque Guide

I suggest Red Loctite, upon removal, simply use a propane torch for a few seconds on the head, and the loctite will let go.

Fastenall Bolt Specs

BigV and A14 both have ideas feasible to me.

Lemonhead's 680 loctite is a Cylindrical Retaining products, not designed for threads.

680 Loctite

Quote:
Is it beat up or what ?

I haven't pulled it apart yet but whichever crank I'm using it's getting the doweling treatment

I had a link to a place that does new engine bolts and studs for Datto's but can't find it, it had flywheel bolt kits for about $12 or something.