Transmission Upgrade/change

[randydupree]

the early pts would run 70 mph,wfo..with stock gearing..they were built during
the 55mph days too. the fc's with a turbo will run that fast too..no matter
what,you don't want to run your engine with the pedal on the floor.
randydupree93wb
----- Original Message -----
From: freewill2008
To: WanderlodgeForum@yahoogroups.com
Sent: Thursday, June 02, 2005 6:28 PM
Subject: [WanderlodgeForum] Re: Transmission Upgrade/change


I've not heard any complaints about the many Birds that have been
changed to taller gearing. Apparently a 4.11 or 4.44 will still pull
steep grades in the Rockies. Does anyone have a guess as to why BB
chose such low (high numeric) ratios for the FC buses?

It has occured to me that these rigs were built during the 55 MPH
national speed limit, but that didn't stop BB from buiding PTs that
would run 75 MPH all day.

Bob Griesel '84 FC31 WLII MT643/4.88 11R22.5

--- In WanderlodgeForum@yahoogroups.com, "Jeff Miller"
wrote:
> Adapting an MD-3060 to the 3208 will be an expensive conversion
after
> the electronics etc.
>
> Although the MT643 is not a high-tech transmission, there are other
> (read: cheaper) ways to skin that cat. If the MT-643 is still
> servicable, you might start with a good checkup including fluid and
> filter change, might improve your shifting, might need work on the
> modulator?
>
> As far as the addition of an overdrive and lower diff gears, it
> sounds like you'd be spending a lot of $$ and expecting more than
> you'll get. You would be saving money to add an overdrive.
>
> I've changed gearing, run the 3208/FC from 210hp (Na) to 300hp
> (ATAAC) with 5.29:1 gears to 4.11:1 gears, MT-643 and HP-500
w/ .83:1
> overdrive. The simple things I've learned are that 1) gearing
doesn't
> add power, 2) even with 4:11 diff gears you don't run out of low-
end,
> 3) there is a sweet-spot, depending on many factors such as
intended
> cruise speed / intended load / expected terrain, and 4)
Experimenting
> is very expensive.
>
> As far as your goal of a reliable transmission (1 below), a reman
MT-
> 643 with a warranty will cost you less than the electronics for the
> MD-3060 (probably).
>
> Goal 2, faster top-end, an overdrive will help but so would 4.44:1
> gears which should cost less than $2k. If the gearing spreadsheet
is
> no longer in the files, I can try to submit it again, or I could
> email it to you.
>
> Goal 3, pulling better on hills. This is a matter of gearing, you
> have lower gears in the transmission. If you run below 1st gear,
then
> you're in trouble, I didn't have that problem pulling 14% at
10,000ft
> with my 210/Na so I doubt you will with a turbo. I found that
taller
> diff gearing can actually help somewhat on hills, I was able to
> downshift into 3rd at a higher speed and hold a higher speed.
> Climbing is largely a product of your power to weight ratio, and
> gearing doesn't help that (unless you can't stay in the high end of
> the power curve, which on the 3208 is at max. RPM).
>
> I don't mean to discourage your project, I'd rather have a MD-3060
> than an MT-643, but unless you can do it really cheap I just don't
> see the return on investment either in coach value or performance.
>
> - Jeff Miller
> http://www.wanderlodge.net
>
>
> --- In WanderlodgeForum@yahoogroups.com, "hsaddock"
> wrote:
> > Folks:
> > I am giving serious thought to changing the transmission in my
> > 83FC35 from the Allison MT641 to an Allison MD3000. The reasons
> > are: 1) current transmission with 112K miles on it shifts a
little
> > slowly from 1st to 2nd at full throttle - it shifts just fine if
I
> > back off the throttle slightly and in all other gears. (perhaps
> this
> > is the beginning of a bigger future problem?) 2) I want to travel
a
> > little faster at top-end, and the MD3000's 5/6 speeds gives the
> > overdrive(s). 3) I want to pull a little better going up steep
> > hills so if I lower the differential ratio while doing this
> > conversion, I can pull better in the lower gears and still tool
> down
> > the road faster on the flats with the overdrives.
> >
> > Has anyone tried this conversion? Comments on anticipated
issues?
> > The MD3000 appears to be an inch shorter in length than the MT641
> > and a similar bolt up pattern so I don't expect to see any major
> > issues with mounting. The MD3000 is computer controlled - can it
> be
> > fooled into working with an older 3208?
> >
> > Harry Saddock
> > 83FC35
> > South Windsor, CT




------------------------------------------------------------------------------
Yahoo! Groups Links

a.. To visit your group on the web, go to:
http://groups.yahoo.com/group/WanderlodgeForum/

b.. To unsubscribe from this group, send an email to:
WanderlodgeForum-unsubscribe@yahoogroups.com

c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



[Non-text portions of this message have been removed]