[Fot] TR Racing cranks- and another question?

[fubog1 at aol.com]

OK I guess that is my question. If the spacers on the pin are locating 
the rod fore & aft (vs the cheeks), then obviously there are loads 
going into the piston...?
Thanks,
Glen

-----Original Message-----
From: Bill Babcock <Billb at bnj.com>
To: fubog1 at aol.com
Cc: fot at autox.team.net
Sent: Fri, 12 Sep 2008 11:51 am
Subject: Re: [Fot] TR Racing cranks- and another question?

It doesn't have to, the spacers just need to keep the rods from moving 
too far. They can be pretty loose, certainly looser than thrust bearing 
clearance. Still, I think it would work a lot better to put spacers in 
the pistons where the movement is relatively slow rocking rather than 
spinning. That's what we came up with for racing two stokes--no reason 
why it couldn't work here as well. I discussed that with Uncle Jack, 
but nothing came of it. 
On Sep 12, 2008, at 8:06 AM, fubog1 at aol.com wrote:Two questions 
actually...
1) the spacers on the pin... does this not induce side thrust loads on
the piston? This is not good.
2) if the BE is narrower, there is excessive cheek clearance. Again, a
bad thing.
I'm curious as to how this works in service...?
Glen


-----Original Message-----
From: Larry Young <cartravel at pobox.com>
To: Greg Solow <gregmogdoc at surfnetusa.com>
Cc: FOT <fot at autox.team.net>
Sent: Fri, 12 Sep 2008 9:47 am
Subject: Re: [Fot] TR Racing cranks





Greg,

To get a larger radius on the20crankpins, do you weld the edges and then
regrind? On my current engine, I welded the edges of the crankpins to
reduce their width so they would accommodate chevy rods. I them
reground with a larger radius to reduce the stress riser.  This is a
cheap approach that addresses both weaknesses, rods and cranks.  Others
on the list have used chevy or other commodity rods, but have used
spacers at the wrist pin to center the rod. The only problem is that
welding puts a lot of stresses in the crank and proper nitriding
requires stress relieving.  The grinder had a hard time getting it
straight.  He said it was out 0.022 the first time it came out of the
oven.

Larry Young



Greg Solow wrote:





  A good used crank properly race
prepared, deep case nitrided and ground with the proper radii on the
journals, is very reliable at power outputs of up to 16
5 hp as long as
the revs are kept below 6800 rpm. The weak link in bottom end is the
connecting rod. For use over 6,000 rpm they need to be replaced with
steel billet rods.
                                     
                                                        0   Greg Solow
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  Bill BabcockBabcock & 
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