I ran the same 4-speed overdrive, that Jack has, behind my Inline 261. I
loved it for all the same reasons. I could drive around town in 3rd or 4th
gear with out shifting down and yet when I hit the highways and byways, I
could flip the switch and watch the RPM's drop by 30%. When I put in the new
261, I put a 700R4 behind it and I get the same benefit except I don't have
to flip anything, this tranny automatically goes into overdrive at 37 miles
per hour and with a 3.90 rear end the engine is turning 2250 at 65 MPH. Love
it when I am cruising down the freeway at 70 to 75 and have all these people
give me the 2nd look.
Ralph Linnell
Membership Chairman Inliners International
ChevySix@seatac.net
Http://www.seatac.net/chevysix/
-----Original Message-----
From: owner-oletrucks@autox.team.net
[mailto:owner-oletrucks@autox.team.net]On Behalf Of Grant Galbraith
Sent: Tuesday, May 09, 2000 2:15 PM
To: Jack Halton
Cc: Steve Parham; oletrucks@autox.team.net
Subject: Re: [oletrucks] the need for speed
I share Jack's enthusiasm for OD tranny's. I like the low rear ratio for
torque and feel that going to a higher ratio' can be a compromise- trading
low end driveability for top end and not getting the best of either. This
can be more noticeable with a six than if you're running a 300 plus HP
eight.
Since you're running a TH 350 now another option is a 700-R4 or similar
OD auto if auto's are your preference.
Grant
50 Chevy 3100
52 GMC 150
Jack Halton wrote:
> I have been using overdrive transmissions for years and they have a big
advantage in that you can keep the 3.90 for torque but drop to 2.73 on the
highway when cruising with no load.
>
> The 5 and 6 speed trannies common today have up to .50 top gear for which
we can probably thank EPA/CAFE/OPEC so the net result is the same or better,
but these trannies are rather costly in most cases and present some problems
in adapting to old trucks..
>
> The Borg-Warner and Saginaw overdrives from the 50's and 60's are
relatively inexpensive, adapt pretty easily to the truck drivetrains, and
are what I call a "true" overdrive in that they use a solenoid-engaged
planetary gearset, a free wheeling clutch, speed governor to prevent damage
from engaging at too low a speed, and a kickdown for passing. The nice
little extras with these units are clutchless shifting and free wheeling.
>
> Downside to this type of OD is that they are pretty much swap meet items
these days and parts can be tough to find.
>
> www.Chevytrucks.org has a HRM '75 reprint discussing the Saginaw OD
4-speed conversion. This is what I use in my old truck and I highly
recommend it.
>
> ------Original Message------
> From: Steve Parham <thebttmline@yahoo.com>
> To: oletrucks@autox.team.net
> Sent: May 9, 2000 5:09:10 PM GMT
> Subject: [oletrucks] the need for speed
>
> Hi all!
>
> I've been browsing the archives and it appears
> that most folks obtain higher highway speeds by
> replacing the rear end - replacing the standard
> 3.90 gears. This is what I've been planning to
> do also, but before I do I was also wanting to
> consider keeping the 3.90 gears and adding
> overdrive. My transmission was replaced with an
> automatic (350) by a previous owner.
>
> To say I'm an amateur mechanic is probably an
> overstatement. This truck is an education for
> me - (one which I'm thoroughly enjoying). I was
> hoping someone could give me some of the pros and
> cons of a new rear end vs. overdrive to help me
> with this decision.
>
> This truck will become my daily driver. The highway
> speed limit here is 70 mph. I just want to be able
> to cruise comfortably at 80 so I can go with the flow.
>
> Thanks for your help,
> Steve
>
> __
> _____|L\___ Steve Parham
> (_,._____,._) 55 3100 1st
> ---`'-----`'-- Knoxville, TN
>
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
> Jack Halton
> 51 GMC 1/2 ton
> Winter Park FL
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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