Brian,
Sorry to take so long to answer this post. Been too busy to spend much time
on the computer.
The rear end ratio in your truck is something like 6.7 in high range and 8.3
in low range. Don't remember exactly. I was looking for a different ratio
and nothing could be found in the old dealer parts book, so I suspect all
were the same. It isn't as bad as it sounds because of the tire size. My
calculator shows that with 9.00 x 20 tires you should tach 3750 RPM at 60
MPH. Not sure how accurate that is since the calculator uses modern tire
dimensions (section width and aspect ratio) and I'm not sure if I guessed
them right for a 9.00 x 20. It shows a tire height of 35 inches, but mine
measure closer to 39 inches tall IIRC.
The 'Brownie' auxiliary transmission was made by the Brown-Watson (or
Watson-Brown) division of Spicer. There were several versions. The one I
have is a two speed - either direct or underdrive/overdrive. The top of the
case is flat with four large tapped bolt holes. It should bolt directly to a
frame crossmember or a custom crossmember. Also you'll need at least one,
probably two new/modified driveshafts. There is a shifter rail that sticks
through the case. You can adapt a shift rod or heavy duty flex cable to do
the shifting. Also the model I have has a neutral position (necessary to
allow shifting I guess) and PTO covers on the sides.
The brownie can be used as underdrive or overdrive. One end of the case is
marked "This side forward for underdrive" or some such. I haven't checked it
but the overdrive ratio is supposed to be about 20%. That would reduce
cruise RPM (for example) from 4000 to 3200 or from 3500 to 2800.
Since I just got this unit and haven't installed it or taken a cover off I
don't know if it is synchronized or not. I suspect not. Shifting will take
good RPM matching. I expect to use it in overdrive all the time except when
I have a heavy load on. I'll use the 2 speed rear end for shifting while in
motion.
They are a noisy gearbox, and I suspect straight cut gears instead of bevel
to allow it to be installed with either end as the input end. I think the
whine will be cool on a big truck. Guy I bought this one from had it in a
pickup and couldn't stand the noise.
Gwyn Reedy
Brandon, Florida
mailto:mgr@mgrcorp.com
-----Original Message-----
From: Brian _ [mailto:pkupman57@hotmail.com]
Sent: Thursday, September 21, 2000 12:15 AM
To: mgr@mgrcorp.com; NTemple46@aol.com
Cc: oletrucks@autox.team.net
Subject: Brownie Box
list,
i may soon be getting a 1955 two ton flat bed with a 235, 4 speed (syncro or
not, im not sure yet) and a 2 speed rear end. what i want to know, is what
kind of speeds and RPMS am i looking at with that combo? and what about this
brownin box, could i get one of these to get higher freeway speeds at lower
RPMS? if so, where does one mount this thing, how to i control it? how
difficult would it be to put one in, and what kinds of costs am i looking
at?
i dont know a lot about the big trucks, 3200s i know, but this is a 3800,
and im not sure about it, all i know is that its all original except the bed
has been shortend to 10 feet, and its been raised slightly (done really well
i might add, nice welds) to clear modern big rig tires on stock 20" rims.
thanks for your help
Brian M
'57 Chevy 3200
soon to be owner of; 1955 Chevy 3800 (two ton)
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