ok it looks like I will dowel it now should I or should I not use locktite and where should I use it, I've tried it on everything before but last time I did't use any as I realised that I could get more load on the bolts if I used the oil supplied by ARP (Molly). Would it be better to use studs and nuts instead of bolts.
olboy

Ahhh, the 'weak link' of the A series. I too had this problem with the big missed gear over-rev and I agree that it is an harmonic problem as mine threw off the flywheel AND damaged the front pulley. Having said that, I feel the Datsun flywheel bolts are a joke - they locate in the flywheel like a 'dick in a bucket' so to speak. Therefore you are relying on clamping force only and once you get some BIG inertia and some vibration you have to expect some movement. I have had my crank machined to accept 7/16 UNF aircraft bolts - two of which act as dowels(my flywheel is machined to finite tolerance for these two) and clearence for the others. Hardened and ground washers complete the picture. My theory is that if it comes off again I want half a crank attached to it Doesn't mean cant happen, just trying to eliminate some of the shortcomings.
Cheers

My racecar spun the alloy flywheel of recently and destroyed the flywheel,gearbox. Luckily I still have my legs.

Problem was I used factory Nissan bolts that weren't long enough for the extra flange thickness of the alloy wheel.
My fault... I didn't check

I now have a cast iron flywheel back inplace with longer 12.9 grade caphead screws.
I didn't really think there was enough space to dowel the flywheel/crank between the 6 bolts myself. Unless you used 4 bolts and setup the crank for 2 dowels.
I was thinking of using studs mounted into the crank thru the flywheel and then just a nut on the flywheel side. Using a stud with a non threaded shank so the flywheel can sit on them kinda like a dowel...... but ran out of time to have a play and needed to get the car running again.

Will possibly change it all again for next season and go back to another alloy flywheel. Or change to an SR :)

My A14 runs 8000rpm with out any problems. I run a standard clutch lightend flywheel doweled to the crank with ARP bolts & have not had any problems.
Put some dowels in & i think that will solve your problem.
Mark

I don't like saying this as it will probably come back to bite me but. . .

I have never had a flywheel come loose.

Make sure you lube the threads of the bolts (not the head) and got 5 lb's up on the factory spec. Make sure that the crank snout is flat as with the inner face of the flywheel.

Have not had a problem with light or heavy (with 8inch clutch) flywheels in high rev engines regularly seeing 8000+ rpm.

Have never used locktite either. . . lucky?

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THIS is the prototype one that was made from a Falcon harmonic balancer. Note that the pulley is machined right into the rim of the balancer itself, which is how these ones were made originally.
There were problems with this design, like too large a pulley & the outer ring sliped without being noticed, This threw the timing mark off causing problems with setting the ignition timing

Olboy flywheels to stay on at those revs need to be lightened $100 and also loctite to be put on the threads but especially the face of the 6 bolts as well (im talking A series). Then tighten to 60ftlbs (factory spec)...no probs with it then.

Is this Chrises harmonic balancer you are talking about, It was made out of a falcon one wasn't it. How was it made ?? I used to split the front pully through the keyway and I fixed it by making up a sleeve to fit over the outside making the pully much stronger in that area. I had to use a different size seal. That fixed the pully but I know what you mean about the harmonics
Olboy

This doesn't fix a 'pulley problem' this addresses the flywheel problem. The smaller pulley is a bonus.
The cause of the problem seems to be crankshaft harmonics.

what is a tilton clutch like and how would it fix the problem??. I have already solved the front pully problem so I tend to think it would be easier to dowl the flywheel if that works rather than making a harmonic balancer. Do you think that by dowling the cranksharft I would weaken it at all and risk creating another problem.
olboy