spridgets
[Top] [All Lists]

Non LBC brain teaser - Kinda Long

To: "'spridgets@autox.team.net'" <spridgets@autox.team.net>
Subject: Non LBC brain teaser - Kinda Long
Date: Thu, 12 May 2005 01:30:50 -0700
User-agent: Mozilla Thunderbird 1.0.2 (Windows/20050317)
O.K. this is not an LBC, but the technology is just as old.  I have a 
2002 Harley Davidson Heritage Springer.  The Heritage Springer has the 
1450cc (now 1550 on mine) Twin Cam counterbalanced motor.  For the old 
school hard tail look that us old farts want, but our backs can't take 
anymore, HD bolted the motor directly to the frame on Softail models 
just like the old days, thus requiring a counterbalance system to offset 
the two piston long stroke mass.  There are two steel rollers about 3.5 
inches in diameter that are chain driven off the drive shaft that are 
timed to offset the pistons.  There is a slice taken lengthwise off the 
cylindrical stock which is calculated to offset the weight of the 
rotational mass above them.  A great system that makes the bike almost 
as smooth as (dare I say it) a Japanese bike such as the Gold Wing.  The 
problem is that this system does not like high RPM and the manual states 
not to exceed 5600 RPM.  Well, sometime during one of the dyno runs I 
have made to fine tune the bike, one of the technicians set the rev 
limiter in the crane ignition module to 6200 RPM!  It had the undesired 
effect of shelling out the counterbalance shaft end bearings and the 
motor had to be opened up to replace them.  My mechanic had an inspired 
idea to remove the counterbalance shafts completely and replace the 
counterbalance system with a product called "Active Balance"  It 
consists of a groove machined into the outer edge of the flywheels and a 
continuous Teflon tube epoxied into it.  The Teflon tube is partially 
filled with Mercury.  This is supposed to act as a counter balance,  
They used something similar in WWII by filling copper tubes with oil and 
some ball bearings to counterbalance aircraft engines.  Not a new 
technology.  Well, it did not work as we had hoped.  At 60 MPH on the 
freeway, the bike was fairly smooth.  As soon as I rolled on the 
throttle it started to vibrate.  At 70 MPH my hands and feet were numb 
within 5 minutes.  So this "Active Balance" system is not the panacea we 
had hoped for.  The counterbalancers are going back in.  If you have 
stuck with me this far, I am coming to the brain teaser part of this.  
If I put the counterbalancers back in and leave the "Active Balance" 
system in the flywheels, will the two systems fight each other at 
certain RPM?  Will one system cancel out the other at certain RPM?  My 
idea is to take the "active Balance system out put the counterbalancers 
back in and limit the RPM to 5600 and hope for the best with the 
bearings.  It is a lot of work to remove the epoxy from the flywheel, 
but we will do it if we have to.
Mike MacLean
60 Sprite
56 BN2


-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.308 / Virus Database: 266.11.8 - Release Date: 5/10/2005





<Prev in Thread] Current Thread [Next in Thread>