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Re: [oletrucks] 5 spd behind a 235?

To: "Gordon and Debra Tibbs" <tibbers@earthlink.net>,
Subject: Re: [oletrucks] 5 spd behind a 235?
From: "G. Simmons" <gls@4link.net>
Date: Sun, 7 Nov 1999 14:18:43 -0800
Last week RobXR250 posted this message:

>  [oletrucks] 5 spd behind a 235?

>  From: RobXR250 (view other messages by this author)
>  Date: Tue, 2 Nov 1999 19:44:16

>  Does anyone know of a 5spd that with bolt up to my 56 235 in my 50
>  3100? Im looking for somthing with similar gear ratios to the saginaw
>  show in Patricks.

>  Thanks
>  Rob

I have one of Patrick's Saginaw 4 speed kits on one of my '54s.  It's great
as far as it goes, but it doesn't get you above 55 very comfortably.  That's
probably a good thing on a truck with original brakes.  If you put in a 5
speed or overdrive, you should go to power discs in the front or figure out
some other way to upgrade the brakes.  I am assuming you are going to an
open driveline.  There's no 5 speed option for a closed drive line of which
I'm aware.

There are a number of 5 speeds which are supposed to be able to bolt up in
place of a Saginaw 4 speed, (and by extension the  the original 3 speed or
4 speed in Advance Design or later series).  Unfortunately, none of them is
both suitable and generally available at a reasonable price.

There are racing 5 speeds and 6 speeds like Richmond and Nash, which may
bolt up ok, but sometimes don't give you the overdrive gear and may not have
the shifter in the right place.  These cost way too much and are built for
huge horsepower rather than driving.

Similar comments apply to the Tremec 3550, which was originally a Mustang
tranny, but can now be purchased in a GM version from Fortes and Darkhorse
(both on the Internet).  These are street trannies, but are made for 300-500
horsepower.  They cost close to $2,000 when you get through.  You don't need
one of these monsters for a 235 cruiser.

I'm working on another '54 now, and for it I just had a rebuilt Borg Warner
T-5 assembled by a professional tranny shop.  The trick is that while some
of the T-5s built for cars bolt up OK in the front, the shifter comes out
too far in the rear for a pickup bench seat.  Other T-5s were mounted at a 1
7 degree angle in front, which would make the shifter come out at a funny
angle.  So the one I have has a main housing which bolts to the bellhousing
at the normal angle, and an S10 pickup tail housing, which puts the shifter
in the right place.  The .72 5th gear should make my '55 3.90 rear gears
quite civilized at highway speeds.

T-5s get a lot of criticism from rodders for being too weak to hold up to
abuse.  Even with my dual carbs and Fentons, however, I don't think I'll
overtax this trans.  Lots of people drive them forever.  T-5s have the
advantage of being very common and cheap.

Also take a look at some of the postings from a couple of years ago. I have
attached a couple of selections below, but the discussion went on for a
while.  They note that 3 speed overdrives became available in 1955, although
fully synchro'd versions were not around until the late '60s.  There are
also aftermarket od units. You could look at Advance Adapters' website
wwwadvanceadapters.com for info.  I don't know the price on this, but I
suspect it would be much cheaper just to build a nice 5 speed.

You might want to consider making a nice Saginaw 4 speed overdrive as Jack
Halton discusses below.  I investigated this idea, but I found, as he says
in his posting,  that many of the overdrive parts (solenoids, relays,
switches) are becoming hard to find.  There used to be a company called
OverDrive, Inc., mentioned on p. 93, ff. of Tom Brownell's "How To Restore
Your Chevrolet Pickup" which made manual solenoid replacements.  I tried to
track them down, but one of the principals is deceased and the other is
retired, with no one continuing the business.  Looks like you could do it
yourself if you were inclined, using the diagram on p. 93 of Brownell's

Hope that's helpful / interesting.


Grant S. gls@4link.net

APPENDIX:  from oletrucks archives 12/97:

TRUCK:: 3 spd overdrive

A. Aaron Beck wrote:

 I always hear so much about people installing these overdrive units in
 their trucks and it seems to be an excellent deal for mileage and keeping
 the driveline behavior similar but no one ever says how they obtain one
 of these overdrive units.  I know I should probably already know but
 please forgive my ignorance.  Were these overdrives installed from
 factory in some trucks or were they installed in cars only at the time?
 If any of the above did come with overdrive, what is an easy way to tell
 if they have it?

 thanks for any info

 Aaron Beck

From: Halton, Jack - FIS (view other messages by this author)
Date: Fri, 5 Dec 1997 16:51:24



There were two types of overdrives available from GM - the Borg-Warner OD
(55- 62) and the Saginaw (65 - 70). Some internals will interchange between
the two, as much of the Saginaw was sourced from B/W, but they have
different dimensions and are not interchangeable with each other. To my
knowledge the early units  were offered only on passenger cars, not trucks.

The Saginaw 3 speed OD tailshaft can be adapted readily to the 4-speed
Saginaw transmission; the Borg Warner cannot.  An overdrive tranny can be
spotted at a swap meet by the solenoid on the left side of the tailshaft,
and the governor on the right. There is also a lockout lever on the right,
just behind the solenoid. Most are long gone at wrecking yards, but you may
get lucky.

An overdrive is a nice conversion for an early truck as it overcomes the
gearing problem. The only drawback is that the parts supply is shrinking
rapidly (they are out of production almost 30 years now). I have one in my
truck, but I'm looking for a 5-speed to have ready when the OD gives up.

Jack / Winter Park FL

From: J. Forbes (view other messages by this author)
Date: Sat, 6 Dec 1997 07:28:44


At 07:47 PM 12/5/97 -0500, jhalton@fisnet.com wrote:
>To my knowledge the early units  were offered only on passenger cars, not
> trucks.


Apparently the overdrive was offered on early Task Force trucks....the 55-2
assembly manual shows how to install overdrive as RPO (regular production
option) 315.  But, the 58 truck manual makes no mention of overdrive.  There
is a very original 56 truck in town that has overdrive, it appears to have
been installed at the factory.  Perhaps they dropped overdrive from trucks
in 57 or 58.  It's quite possible that the overdrive couldn't handle the
abuse that was dished out by normal "work truck" operation.

Jim Forbes                                    jforbes@primenet.com


oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959

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