experience with gear vendors over/underdrive anyone?

[Frankenchevy]

anyone have any experience with a gear vendors setup?

i like the thought of keeping my th400 but have overdrive. at $3100 it wont be happening till later this year if at all. nothing needs modifying except rear drive line length. is there a way to justify this over 4l80 swap? it'd be nice to hear from the knowledge base here on the matter, maybe i can start scouring CL for a rebuilt/rebuildable 4l80 if that makes sense.

While i'm on the matter, is a manual swap possible without moving a bunch of crap around and cutting everything up (besides the hump). i'll likely never put much power through it, but i like everything as stout and possible. so any suggestions put forth, i'd like along the lines of a th400 strength wise. and yes, i'm aware people can build a 700r4 to handle xxxHP, just not looking that direction. i want close to stock internals...thoughts?

http://www.gearvendors.com/buy-now.html?MANUFACTURER=GM&VEHICLE_TYPE=TRUCK&YEAR=80-87&TYPE=TOWING & RECREATION&FUEL_TYPE=GAS&WHEEL_DRIVE=4-WHEEL DRIVE&TRANSMISSION_TYPE=AUTOMATIC&remove=true&TRANSMISSION_MODEL=3-SPEED NP-208 T-350/400&submit_x=23&submit_y=19&submit=GO&MODEL=3500

 

[CSFJ]

If, you're considering the possibility of going manual, look up the A833 trans. There are a couple of good threads about them on this site. It's a 4 speed, with 4th being an overdrive. Ratios are very similar to the 700r4. They were factory offered in these trucks during the '80s. They also came attached to a 208 transfer case, with the same 32 spline output shaft that your 400 has.

 

[74 Shortbed]

Had a GV in my dually, gotta love having 6 speeds, should have kept it..

 

[Jrgunn5150]

No, there is no way to justify it over a 4L80E, unless you get it for free or something.

For that matter, there's no way to justify a 4L80E.

 

[Craig 85]

At $3100, you may look for an old GM motorhome for sale that has one in it. If you have the room to part it out, you could recoupe part of the cost by selling the 454/TH400 out of the motorhome.

 

[74 Shortbed]

If you can find an old core you can trade it in for a new modernized one for about half the price, thet's what I did..

 

[Frankenchevy]

would they all bolt onto the back of the t case? i think thats a selling point on the new tcase specific ones.

i thought for some reason and i don't know why...that the rv ones are on the diff side?

 

[SDJunkMan]

you may look for an old GM motorhome for sale that has one in it.

Damm, I never thought of that, passed up many cheap motorhomes but didn't have a need for a big block. I'll probably never see one for sale again now that I have something to look for.

 

[Frankenchevy]

No, there is no way to justify it over a 4L80E, unless you get it for free or something.

For that matter, there's no way to justify a 4L80E.

what you're saying is there's no way to justify the 4l80e swap over th400? i wasn't sure what you meant.

why is this not a viable swap over current th400? i'm a newb and need 'splainin to.

it does quite a bit of 40-55mph cruising, but i do use the freeway for trips too. last time i drove to hollister ohv it took forever. i dont like going over 60 with the current setup. i'm trying to drop the rpm for the longer trips. i know i could re gear stuff but i'd rather pick up a fourth gear if it made sense.

 

[Frankenchevy]

At $3100, you may look for an old GM motorhome for sale that has one in it. If you have the room to part it out, you could recoupe part of the cost by selling the 454/TH400 out of the motorhome.

trust me if i had it my way i'd make a little clearing somewhere on my property for a junk lot. i need to broker deals one at a time with my wife, haha! my buddy has a two post lift he'll sell me for cheap, that's the current scheme i'm working on. she usually comes around. i'm a lucky guy

 

[Jrgunn5150]

what you're saying is there's no way to justify the 4l80e swap over th400? i wasn't sure what you meant.

why is this not a viable swap over current th400? i'm a newb and need 'splainin to.

it does quite a bit of 40-55mph cruising, but i do use the freeway for trips too. last time i drove to hollister ohv it took forever. i dont like going over 60 with the current setup. i'm trying to drop the rpm for the longer trips. i know i could re gear stuff but i'd rather pick up a fourth gear if it made sense.

It's viable, it's just by the time you buy a 4l80E for 500-800 used, get a way to control it for 400 or more, for a 3-4 mpg increase, you'd have to put alot of mileage on it to get your money back really. And with you having a 4x4, you'll need two new driveshafts now too.

 

[CSFJ]

what you're saying is there's no way to justify the 4l80e swap over th400? i wasn't sure what you meant.

why is this not a viable swap over current th400? i'm a newb and need 'splainin to.

it does quite a bit of 40-55mph cruising, but i do use the freeway for trips too. last time i drove to hollister ohv it took forever. i dont like going over 60 with the current setup. i'm trying to drop the rpm for the longer trips. i know i could re gear stuff but i'd rather pick up a fourth gear if it made sense.

That's why I mentioned that manual trans that I did. It can be done using factory parts, and would bolt right up to the front of your t-case. I have everything to do it to mine except for the flywheel I still need to order. Not sure if it would require changing either of the driveshaft lengths or not yet. I'm hoping that the front will be able to use the factory one, but won't know for sure until I get it behind the engine. I figure after I'm done, it should net me a 65-70mph top speed.

 

[Frankenchevy]

That's why I mentioned that manual trans that I did. It can be done using factory parts, and would bolt right up to the front of your t-case. I have everything to do it to mine except for the flywheel I still need to order. Not sure if it would require changing either of the driveshaft lengths or not yet. I'm hoping that the front will be able to use the factory one, but won't know for sure until I get it behind the engine. I figure after I'm done, it should net me a 65-70mph top speed.

Let me know when you get it together. I’d be interested to see how it turns out. I’m in no need to change it right away, but I’d like to.


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[CSFJ]

Let me know when you get it together. I’d be interested to see how it turns out. I’m in no need to change it right away, but I’d like to.


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Hopefully I'll be at that point in a month or two, taking my time disassembling it right now. I want to try to get everything set and ready to paint once the weather breaks and warms up again.

 

[Affende]

I am in a different boat, but considering the same options. I have an '84 K3500 crew cab 454 w sm465 (bombproof, but super wide ratios and no overdrive).

I considered the gearvendors O/Udrive ..... but $3.1k plus another $500 for a new driveshaft is a lot. $3600 is a lot...

I want to to keep the manual but i am looking at some 6 speed options.

The only reason i like the O/Udrive is the fact that i will essentially have 7 gears (possibly 8, but they dont list low over, i assume the torque may be too much for the unit)

BUUUT ... overdrive at 0.78:1

IF i go with a NV5600 (adapters were once made, possibly have to source a custom one now), i can get a slightly better OD at 0.73:1 and i still get a good low ratio and better gear splits. but $3600 for a rebuild with a $2000 core charge is a too stiff ... $5600 is a bucket of money.

WAHT I REALLY WANT THOUGH .....

is to go with a ZF S6-650 from a GM ... hard to find, but it should bolt up to a BBC with gearing nearly identical to the NV5600 ... but the overdrive is a few percent taller at 0.72:1. $3200 plus a $1500 core charge is still a lot at $4700 bucks

Now with all that said ... i think a 5 speed would be a great improvement, and easy to source, but a 6 speed would be amazing to me. and if you really want to get a move on ... do the 6 speed swap and the GV O\Udrive ... double OD would barely sip the gas out of the tank!