[DeTomaso] I *hate* it when that happens....
Ken Green
kenn_green at yahoo.com
Fri Mar 23 00:53:10 EDT 2012
With all the drilling going on, maybe get the flywheel/pressure plate re-balanced (with input from the engine builder) when you're done?
From: Forest Goodhart <forestg at att.net>
To: MikeLDrew at aol.com; detomaso at realbig.com
Sent: Thursday, March 22, 2012 9:33 PM
Subject: Re: [DeTomaso] I *hate* it when that happens....
Mike,
Be sure to check the bolts to see if they have a shoulder under the head. If so
then the holes will need to be counterbored enough to clear the shoulder. The
pressure plate holes may also need to be bored out.
Forest
________________________________
From: "MikeLDrew at aol.com" <MikeLDrew at aol.com>
To: detomaso at realbig.com
Sent: Thu, March 22, 2012 9:16:29 PM
Subject: [DeTomaso] I *hate* it when that happens....
So, my engine has been sitting on a stand for months now, after the
distributor gear ate the cam gear at the POCA Fun Rally last year. The cam has
been replaced and the motor is all back together, so today I thought I'd take
care of some last details to get it ready to go back into the car.
When I put the engine back together, I noted that one of the six pressure
plate bolts was not a genuine Ford pressure plate bolt, but rather a Grade
Zilch hardware store special. I decided to buy some whippy dippy ARP Ford
pressure plate bolts, and swap them out before mating the engine to the
gearbox.
Today, out with the old, in with the new. Surprisingly, there is no
published torque spec for the pressure plate bolts anywhere in the shop manual
(at least, none that I could find), but a search of the internet showed
multiple sources consistently saying that the magic number was 35 ft/lbs,
lubricated.
So I got out my handy dandy torque wrench and started installing them. I
figured I'd step the torque up gradually and started with 25 ft/lbs. The
first few started tightening up normally, but then one of them started
getting tight and then...didn't. :<(
I had a good hard look, and discovered that the ARP bolts were marginally
shorter than the Ford bolts. What's worse, the thickness of the flange on
the clutch coupled with the hardened washers left precious little thread
engagement in the soft aluminum flywheel. When I removed the not-tightening
bolt, it came out looking like this:
http://www.poca.com/index.php/gallery/?g2_itemId=35807
Only three threads engaged the flywheel, not nearly enough to do the job.
To be fair, this flywheel came to me used, and clearly clutches had been
installed and removed numerous times during its life. It's entirely possible
that somebody before me had just about completely trashed the threads, and
I just finished them off. All of the holes bore indications of prior
damage at the hands of another. I just consider myself lucky that I found the
problem now, rather than at 6000 rpm on a track.
So what to do?
Fortunately, I had an idea. Ford pressure plate bolts are traditionally
rather puny, 5/16-24 affairs, but Chevys use much meatier 3/8-16 bolts. I
phoned ARP's tech department and described my problem; they confirmed that
the Chevy bolts are about .200" longer too. The larger diameter coupled with
greater length should solve all my problems.
So a new set of Chevy bolts and some ARP bolt lube are both on their way.
Since I don't have access to a drill press, I'm going to take the flywheel
to a machine shop tomorrow to have them drill out the holes and tap them for
the 3/8 bolts, which should arrive by tomorrow afternoon. I figure that
by the end of the day, I should be in business. :>)
Mike
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