On Wed, 5 Mar 2003, David Friedlander wrote:
> When re-installing the flywheel, is it OK to re-use the same bolts?
You can re-use _provided_ that the bolts are undamaged and have never been
overtorqued. Try threading a nut all the way up the threads by hand. If
there's any resistance, toss the bolts and replace with new.
> If not, what size and grade bolt is best for this task?
These are more or less "specialty fasteners". The thread is 7/16-20, but
you _need_ a bolt with a proper shoulder for the "in the hole" part, and
you _must_ use a bolt that is better than grade 8. Harder is better. The
other "trick" is that the heads are pretty big (presumably to spread the
load) - you want the widest clamping area that you can get. Don't use
washers unless they are better than grade 8 (so they won't crush under
severe loading).
There are two tricks to finding the right replacement bolt. The first is
finding one, the second is coming up with the appropriate torque setting
for the bolts that you use.
That said, if you absolutely _must_ use non-stock parts, it is suggested
by Kastner, et al, to use tool-steel bolts.
If you don't mind dishing out $20 or so, the ARP replacement bolts
(NAS-type 12pt heads) are really, really nice. You have to buy 4 bolts and
4 special "chamfered" washers, and you get a special moly lube for
the install. Call www.aptfast.com for a listing. But these bolts are
"trick".
Frankly, the stock bolts are quite adequate if installed correctly. I
happen to use stock bolts with red high-strength loctite, but my
applications are pretty "severe" and the loctite is suggested by racers.
Bottom line - if you keep the motor under 6000, stock is okay.
> Dave Friedlander
> CF25194UO
regards,
rml
p.s. if you do buy new bolts, check the heads carefully for any "burrs". I
bought some from one of the "big three" that had some burrs on the
back-side of the head that were pretty "stout" and I had to file them down
to remove the potential stress riser... but this is rare.
------------------------------------------------------------------------------
Bob Lang Room N42-140Q | This space for rent
Consultant MIT unix-vms-help |
Voice:617-253-7438 FAX: 617-258-9535 |
------------------------------------------------------------------------------
|