Re: Overdrive for M1008/1028

From: Michael Howell (doctormv@frontiernet.net)
Date: Mon Nov 21 2005 - 11:06:32 PST


This has been discussed before. You might find it in the archives
listed at the bottom of each post. It is still hard to search though.
Here is a copy of a post I saved that has a lot of info. It also has
some good links at the bottom.

Mike
Tishomingo, MS

-----Forwarded Message-----
From: Erik Lundquist <lundq000@uwp.edu>
Sent: Apr 22, 2005 9:04 PM
To: Military Vehicles Mailing List <mil-veh@mil-veh.org>
Subject: Re: [MV] CUCV - Overdrive? - Now Tranny Questions

Easier yet is a new set of tires..... but he said he didnt want to loose
performance.

----- Original Message -----
From: "Glenn Shaw" <mpmutt@mtaofnj.us>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Friday, April 22, 2005 8:00 PM
Subject: Re: [MV] CUCV - Overdrive? - Now Tranny Questions

> Hi Chris
> The easiest thing to do would be to just swap the ring and pinion sets in
> the axels to a lower numerical (higher) ratio. I would think you can find
> what you need in salvage yards pretty easily.
>
> Glenn
>
> -----Original Message-----
> From: Chris Brunner [mailto:cjbrunner@optonline.net]
> Sent: Friday, April 22, 2005 8:07 PM
> To: Military Vehicles Mailing List
> Subject: Re: [MV] CUCV - Overdrive? - Now Tranny Questions
>
>
> Ok, before I go and drop $3K on a gear-vendor unit or pull out my auto
> to drop in another auto - has anyone ever converted their CUCV to a
> manual? BTW - I don't have any acceleration or speed problems - it's my
> work truck; it's all about low speed bawls and ability to haul around my
> trailers - I'm not looking to go fast, just have some rpm left when I
> hit 55 so I'm not running near red line. Any opinions would be
> appreciated.
>
> Chris
>
> Erik Lundquist wrote:
>
>> 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
>>

>> ----- 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
>>>>

>>>> ----- 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
>>>> >
>

Mike
Tishomingo, Mississippi



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