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I want Overdrive! Options?
- Thread starter Jeremy_C
- Start date
1BEATK5
1/2 ton status
4l80e, but if you arent towing, or putting a butt load of power to it, 700 is the way to go.
4l80e needs a controller too, which upps the $
4l80e needs a controller too, which upps the $
Running a 350, nothing fancy and never will be. Its purpose in life is to get me from point A to point B and look good doing it. 
Right now, about 55mph is as fast as it really wants to go. 3.73 gears as well.
Right now, about 55mph is as fast as it really wants to go. 3.73 gears as well.
dfl701
1/2 ton status
You can go manual I suppose but the 700 would be your best bet for overdrive. 4l60 and 4l80 could get pricey
gotblazers
1/2 ton status
maybe look up a gear splitter?
700R4 would be the easiest and least expensive conversion. You will also need the adapter to go between the trans and transfer case for the 700 as the 350 adapter will be too long.
Stomis
Professional Amateur
Given said duties of your truck 700r4 is definitely the way to go.
DrkZide
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Don't they make under/overdrive units?
i have an oddball question.. how big are your tires? what rpm are you at doing 55mph?
i only ask as i had a turbo 400 with 3.73's and 33" tires... it was just fine.. 14mpg.... i think with overdrive i would have chugged the motor if it actually went into OD and i didnt go much faster.....
maybe some peeps with said 2 choices... can go out on their way to work or shopping.. and check their RPM @55mph in OD.. and drop it down a gear and check their RPM again.... hopefully they have something close to 3.73....
i only ask as i had a turbo 400 with 3.73's and 33" tires... it was just fine.. 14mpg.... i think with overdrive i would have chugged the motor if it actually went into OD and i didnt go much faster.....
maybe some peeps with said 2 choices... can go out on their way to work or shopping.. and check their RPM @55mph in OD.. and drop it down a gear and check their RPM again.... hopefully they have something close to 3.73....
CGT80
1/2 ton status
a gear vendors over/under drive is an awesome unit, but very expensive and overkill for the OP. I run one on my truck but it hauls a heavy trailer (16k pounds total weight for truck and trailer) and had a 383. I am in the process of having a 406 built to push 525 foot pounds of tq and the GV will easily handle it. The GV can be shifted at any time to run 1st over and 2nd over as well as 3rd over, where an OD trans only gives you the 3rd over.
A 700 r4 can be built pretty well and is less expensive than some of the other OD trannies. My uncle, who owns and runs a trans shop, recommended a 700r4 to me over the GV before I bought my trailer, but he did admit I may wear it out quicker than a stock engine and average weight truck. That was for a C20 pickup as a daily driver/ work truck.
A 700 r4 can be built pretty well and is less expensive than some of the other OD trannies. My uncle, who owns and runs a trans shop, recommended a 700r4 to me over the GV before I bought my trailer, but he did admit I may wear it out quicker than a stock engine and average weight truck. That was for a C20 pickup as a daily driver/ work truck.
700R4 is what I'll be looking for. What year range/type trucks normally had this transmission?
As far as RPM, i dont have a Tach but it sure sounds like its wound out tight at 55mph plus. The faster i go, the more the speedo is off.
As far as RPM, i dont have a Tach but it sure sounds like its wound out tight at 55mph plus. The faster i go, the more the speedo is off.
DrkZide
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I didn't know it could do that. So you could go 1st 1stOD 2nd 2ndOD 3rd 3rdOD, or do I have the pattern screwed up?
I was just asking because I have the SM465 and I hate having to wind the motor up so high just to go 75. I'm not geared either so having an overdrive would be awesome.
Look for any 700R4 from 1987 through 1992 in a 4 wheel drive V-8, 1/2 or light 3/4 ton application. Of course, if you go used expect it to have high miles, but if you get lucky maybe you can sniff one out that has been rebuilt. If buying used, inspect fluid color, if it is bright clear red or pink, chances are it will be in good working order, if the fuid is brown and opaque then keep looking. It is hard to judge by smell anymore as even new fluid has a little funk to it, but a dark brown fluid will usually have a noticeable burnt and acrid odor about it.If you know your gear ratio and tire diameter I can figure out your rpm for you at any given speed: MPH x Gear Ratio x 336. divided by Tire Diameter will give you the rpm.
Example: 70MPH x 3.73 x 336 = 87729.60 divided by 33 = 2658 rpm
55mph is as fast as I need to go around town. Its hard to judge RPM with dual flowmaster 40 series. At 55mph and above it is pushing RPMs, It needs another gear.
It will go faster, but I dont want that strain on the motor. I dont think its a mechanical issue.
It will go faster, but I dont want that strain on the motor. I dont think its a mechanical issue.
shovelbill80
1/2 ton status
at 55 you're turning less rpms than stock....bet those mufflers make it sound like high revs 
. if i remember right i changed the gear in my '85 700 to set the speedo very close to stock with 35's, thats why your speedo keeps getting worse. aren't the '90+ trannys electric speedo?
. if i remember right i changed the gear in my '85 700 to set the speedo very close to stock with 35's, thats why your speedo keeps getting worse. aren't the '90+ trannys electric speedo?
Not trying to be a jerk, but at 55 your truck your truck souldn`t be working to hard.My pos has got 373s a 305 and a turbo 400 with 31s and it sounds ok. Also your truck sould have come with a 700 in it .
CGT80
1/2 ton status
You have it exactly right. I now have 6 different forward gears with one overdrive gear. I have a very stout Th400 in front of the GV. The drawbacks are that I have to shift the GV manually to split the lower gears. I start in first and then tap the foot switch for the GV to hit 1st over, then shift the trans to 2nd and tap the GV out of overdrive for 2nd direct. Also the GV will not work as an engine brake in overdrive without damage. Going down grades with a trailer, I use direct 1, 2, or 3rd.
The GV is the next best thing to an allison 6sp auto for me. My th400 has a torque converter that is as close to what the allison is, as can be put into a th400. The internals of the 400 were beefed up to address all of the weak areas of a 400.
Check out Gear Vendors web site. I have been very happy with mine, but I know its limitations and I drove another truck with a GV unit before I bought one for my truck. I spent around $2500 for the GV and to have the drive shaft shortened. My brother and I installed the GV ourselves in less than a day.
WOW!!! did you do that because you didnt want to put an allison 6 speed in?
or you didnt want to go stick?
id love to go NV4500.. but more NV5600.... and i believe in the stick world you can do either for about that if not cheaper....
im only curious...not bashing your choice.. as i was thinking of getting an OD for my beater... but beater may just get trailered...
