>As some of you may know, I'm a TR4 vintage racer and I also build both
>competition and streeet engines for other folks. I just sold a used
>aluminum flywheel and ARP fasteners that go with it to a fellow lister. He
>asked me why I was selling it and I wrote the following answer to him. I
>got to thinking that this story might have some interest to the list, so
>I'm sending it out to the general public just for entertainment.
>
>He asked, "BTW, what did you replace it with?"
I replaced it with a steel flywheel that weighs the same. Kind of a long
story that I hope is not too boring. See a picture of what this flywheel
looks like at
http://www.cambridgemotorsport.com/product_templates/product_default.cfm?menu_temp=tr4_cylinder.cfm&dep_id=1&prod_id=514&ass_id=13
Also look at their other pages to see some really exotic stuff. Those Brits
are serious about going fast.
Several years ago I still had a lightened flywheel, and a customer of mine
wanted a really light flywheel but he didn't want an aluminum one, because
when he bought his used race car it came with several aluminum flywheels
and a couple of cranks, all of which were ruined by the flywheel coming
loose. The previous owner had tried so many things on one crankshaft that
the rear flange looked like Swiss Cheese.
Anyway, we found this Cambridge part that is made of steel but weighs the
same as an aluminum one and had it shipped over. As you can see, the cost
is horrific.
i took it to my buddies at Southwick Machine and Design and asked if they
could copy it (has this man no shame?) and we made 12 of them. Those are
all sold and mine was the remaining one. I've had it on the shelf for a
couple of years. I had it on the shelf because in the meantime, Jim Donato,
a Logansport Indiana Jeep dealer and vintage racer, went to Fidanza and
asked if they could make flywheels for our cars. This got Fidanza into a
whole new segment of the market and now they make them for most popular
British cars. The flywheels that Moss sells is from them (at $499, I might
add). I purchased an aluminum flywheel at that time, and have been very
happy with it. I don't know of one failure, and lots of racers have them.
It helped me take a couple seconds a lap off my times at Road America.
I attribute the lack of failures of Fidanza flywheels to two things. First
is the light interference fit between the flywheel and the crank. Second is
that we have all learned that conventional fasteners, even grade 8 bolts,
just plain stretch too much due to the inherent crank vibrations at high
rpm's in both TR4's and TR6's. Therefore we all now use ARP fasteners which
have 175,000 psi tensile and we have no problems. Prior to that, I know of
one guy who had a GT6 vintage racer who had his flywheel come off at least
a dozen times. I helped put it back on a couple of times at the track. Not
fun. We didn't tumble to what was going on, and the owner didn't help
matters much because we finally determined that he had no eye contact with
the tach, and what sounded like 8000 rpm from the pits was really 8000 on
the track as well.
More recently, Kastner related that they had the same problem and couldn't
figure it out, so they put a strobe light on a TR6 flywheel on the engine
dyno, and were astonished to see the flywheel flexing in and out by a half
inch!!!!! That would cause grade 8 bolts to stretch and the flywheels to
come loose just because the grade 8 bolts are too 'stretchy".
Anyway, since I'm rebuilding my engine anyway, and finally bit the bullet
and purchased Moldex billet crank, and since it has eight holes for
flywheel mounting (now isn't that a coincidence -- wonder why they did
that?) I decided to take the steel one off the shelf and use it and sell
the aluminum one.
None of this has much relation to street cars, but i thought it might be
entertaining.
uncle jack
Check out the new British Cars Forum:
http://www.team.net/the-local/tiki-view_forum.php?forumId=8
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