Re: [MV] CUCV - Overdrive?

From: Erik Lundquist (lundq000@uwp.edu)
Date: Fri Apr 22 2005 - 12:07:23 PDT


Bob, good points. The 700r4 benefits from a lower first gear than either the
th400 and the 4l80 along with a slightly lower OD gear .78 to .75. This
gives the 700 a noticeable edge in acceleration, but not as much for
cruising speed. I also believe Bob is understating the parasitic drag of
the th400/4l80, its probably MORE than 20hp. The most of the CUCV's came
with a NP208 transfer case but some of them have the NP205. As far as
rebuilding 700r4; a good rebuild, a new diesel torque converter, biggest
tranny cooler available, and proper TV cable adjustment are the keys to
making it last behind a diesel. There are lots of internal part upgrades as
well. I personally used the 4l80 because I bought all the 4l80 parts for
less than the 700r4 conversion would have cost me.
good discussion.

Cheers, erik

"Our country won't go on forever, if we stay as soft as we are now. There
won't be any America - because some foreign soldiery will invade us and take
our women and breed a hardier race." LtGen Lewis B. "Chesty" Puller USMC
----- Original Message -----
From: "Bob Ternes" <racecadet@yahoo.com>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Friday, April 22, 2005 12:48 PM
Subject: Re: [MV] CUCV - Overdrive?

> Dear List,
>
> Erik has some really good points, but there's
> something that came to mind as I read and re read
> this email. I don't know if it's especially
> salient to the list at large but here's one
> viewpoint on GM tranny swaps.
>
> The TH400 and its newer incarnations, the 4L80
> and 4L80e, are great, strong trannies, but like
> any "slushbox", there are parasitic losses in the
> very nature of the technology, and the TH400
> itself takes somewhere on the order of 20HP just
> to spin. Simply due to size, the 4L80e is going
> to be alot of HP to spin. This is mostly moot
> when the coverter's locked up but until that
> time, you're going to be slinging alot of ATF
> around just to get up to speed. Also, 4L80's are
> spendy trannies because of both supply and
> demand.
>
> Now, a 700r4 can easily be built to take abuse,
> and alot of abuse, and is alot more efficient
> from an energy consumption / parasitic losses
> standpoint. I won't delve into the finer details
> of what generation cases you want to look for and
> what needs to be done, but parts are cheap and a
> good tranny builder can point you to the parts
> you want to use... and this is definitely a
> shadetree job (with video or manual) if you know
> a snapring or two from a hole in the ground.
> 700r4's are also a dime a dozen (comparatively).
>
> Heat is really what kills auto trannies, so make
> sure you run a 700r4 with an external cooler.
> Also, rebuild with the right parts, and you won't
> run into the classic 700r4 problems, which stems
> from the deservedly bad rap from some bad designs
> that didn't get fixed until the 1987-88
> timeframe. As well, go aftermarket with your
> clutches and shells and solenoids and whatnot and
> you can have a tranny that will outlast and
> outgrunt your stock hydramatic 400.
>
> Finally, and what really pushed me over the top
> on posting this, the 6.2 is a dog. There, I said
> it! Anemic oil burner it is, in my opinion. You
> CUCV guys need all the power you can conserve.
> Mating that mill to a big slushbox, and then
> pumping the power out to heavy, friction-bound
> 6000ft-lb-peak axles (save for the M1009) is part
> of the reason those aren't stellar accelerators.
> It's for that reason that I'd be personally
> curious to see what the benefit is to mate up to
> the 700r4, and why I typed this up.
>
> Also, tcases for the 27 spline 700r4 output are a
> dime a dozen, and there is decent enough demand
> for a, say, 32 spline (which is the TH400 and
> 4L80e outputs) NP205 for it to fetch $300 to the
> right person. NP203 is slightly more expensive. I
> honestly don't know what they stuck in the
> CUCV's, but I want to say 205?
>
> Just some ideas. I'm cheap as heck and when I
> needed a tranny to take and transfer the most out
> of my 350ft lbs mill this fall, I went with a
> rebuilt 700r4-type tranny. It made the most
> sense. If you're towing a 25' gooseneck around
> day in and day out, then you should probably
> stick with the 1 ton stuff but for a town and
> parts runner, a slightly built 700r4 wouldn't be
> a bad choice.
>
> Just don't forget to run a TV cable (or you'll
> cook your box within a week!), and check
> www.700r4.com . :)
>
> Just brainstorming. I hope this doesn't waste
> anyone's bandwidth. I got real familiar with the
> 700r4 this fall so hopefully this helps someone.
>
> Some pages I found to explain the lineage and
> differences:
> http://www.chevyhiperformance.com/techarticles/46140/
> http://www.rodandcustommagazine.com/techarticles/82558/
>
> Or just go to a standard gearbox. ;)
>
> Cheers
> Bob Ternes
> Proud owner of a 6'x6' pile of GM trannies and
> transfer cases
>
>
>
> --- Erik Lundquist <Erik_lundquist@hotmail.com>
> wrote:
>> Chris, you have a couple of options. You can
>> get an after market over drive
>> such as a gear vendors unit. Or replace the
>> th400 with another GM over drive
>> tranny such as the 700r4 or 4l80e. the 700r4 is
>> a lighter unit and I
>> personally don't think they are up to the task
>> in anything but a 1/2 2wd
>> truck or car. if you went with one of those you
>> would have to change the
>> transfer case to along with it. The 4l80 is
>> basically a 4 speed
>> electronically controlled th400. you can reuse
>> the transfer case but you
>> need to buy the transmission and tranny
>> controller for it to work. With any
>> of the 3 you will have to have new drive shafts
>> made or your existing ones
>> altered. I personally went with a 4l80, and
>> kept the costs down by buying
>> all the parts I needed on eBay and the local
>> salvage yard. the Gear vendors
>> are neat because you basically can overdrive
>> all your gears making it a 6
>> speed. If you have access to a machine shop or
>> have a buddy that does I have
>> seen Volvo over drive units used you just need
>> to fab up the adaptor. If you
>> have any questions let me know.
>>
>> http://www.gearvendors.com/
>>
>> Cheers,
>> Erik
>>
>> PS. does anyone know the proper way to post,
>> every I try to post something
>> to ask a question I get the following message
>>
>> Failed to deliver to '<mil-veh@mil-veh.org>'
>> LIST module(list mil-veh@mil-veh.org) reports:
>> Your message cannot be posted.
>> It has the content-type:
>> multipart/alternative,
>> and this list accepts text only
>>
>> "Our country won't go on forever, if we stay as
>> soft as we are now. There
>> won't be any America - because some foreign
>> soldiery will invade us and take
>> our women and breed a hardier race." LtGen
>> Lewis B. "Chesty" Puller USMC
>> ----- Original Message -----
>> From: "Chris Brunner" <cjbrunner@optonline.net>
>> To: "Military Vehicles Mailing List"
>> <mil-veh@mil-veh.org>
>> Sent: Thursday, April 21, 2005 8:27 PM
>> Subject: [MV] CUCV - Overdrive?
>>
>>
>> > Anyone know of a company that makes overdrive
>> units for the CUCV? I'd
>> > like to drop my RPM's when on the highway but
>> not sacrifice the gear
>> > ratio's. I'm working with a M1028 but I'm
>> sure others out there might be
>> > interested too.
>> >
>> > Chris
>> >
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