Want overdrive, don't want to spend a fortune

[scottveazie]

Currently running a sm420 with 4.56 rear end gears, probably going to go to 4.10s. Don't want a 700R4, want something that looks stock and is fairly easy to do. I did read about either a A-833 or T-85N. The 85 would require me going to three speed column shift. Not totally opposed to it but would rather find something that's easier to do while retaining my stock setup or at least the look. The new overdrive units you can buy are too expensive. Any ideas?

[66Chevrolet]

I have the A833 behind my 350/305 heads and 3.73s out back. The gear ratios are very similar to a 700R4, it is really easy to rebuild and it handles every bit of power my motor puts out. If you can find the cast iron case version, you'll be set for a long time.

There is a transmission shop out of New York that has tons of these transmissions in stock. I purchased a complete shifter and linkages from them for a reasonable price.

[vin63]

I found a used 4L80E for $200 on Craigslist a few years ago to replace the TH400, and have found a few others for friends and customers at local wrecking yards for between $500-$800. I would keep an eye out for one. These days, you can either run the TCM electronics, which have come down in price, or go manual with no electronics. A couple of my friends run the manual version behind their big blocks and have a lot of fun with them (floor shifter recommended, though).

[luvbowties]

Originally Posted by vin63

I found a used 4L80E for $200 on Craigslist a few years ago to replace the TH400, and have found a few others for friends and customers at local wrecking yards for between $500-$800. I would keep an eye out for one. These days, you can either run the TCM electronics, which have come down in price, or go manual with no electronics. A couple of my friends run the manual version behind their big blocks and have a lot of fun with them (floor shifter recommended, though).

When u say manual, are u referring to using a manual valve body? And does it require ALL manual shifting with ALL automatic shifting disabled? If I have assumed correctly, what is the cost to convert say a 4L80E to meet those specs? What parts would I need to buy for my tranny-friend to install? And how much $ would the parts alone cost?

I have a known good '80E--an '04(or close) from behind a 6.0--which I drove around for a couple of months before removing it. I'd like to put it in a '66 project st-sd/sh-bed.
Thanks,
Sam

[cortcomp]

I have an A-833 (2 actually) but remember it's a side loader, so will be hard to get the shifter to come up where a factory 4 speed would. T5 really is the way to go there.

[66Submarine]

I'll just throw in I'd be VERY leery of any junkyard auto's in anything. I don't have firsthand experience with the 4l80, but the 4l60 is garbage, just a later 700r4. 100,000 miles is about what people get out of them, and lot's of people seem to botch rebuilds. T-5's seem to work pretty well. The A-833's are real interesting, but kind of rare/hard to come across. An NV4500 is kind of the modern SM420, pretty much the same gear spread + a .73 OD. I'd probably look for one of those, personally.

66Chevrolet, Welcome to the forum!

[cortcomp]

I don't consider 100,000 miles out of a stock tranny bad at all behind modern power, and for the prices as they've been coming down (or just a good used one for 300 or so bucks) i figure almost any overdrive is worth it in lower wear and tear and saved gas, and just less noise while driving. However, i had good luck with 200K in a 4L60 in an astro van, and there's one in my wife's trailblazer i believe and it has about 160 on the clock. Both have done light to moderate towing, small boats and such.

A local guy builds 700's here for about 1K, and we have one behind a mild but upgraded 454, with the corvette servos/shift kit amongst other upgrades, shifts nice and firm and has been reliable, does bring the RPMs down on the 454 so you can talk in the cab now, but no issues yet. Haven't put 100K on it yet, but my '66 has 80K original miles in 50 years...might take me a while to get 100K in it to see how the A833 holds up.

I don't want to ruffle any feathers, but any stock motor in our trucks is about as powerful as a v6 now on a good day...i can't imagine any popular tranny that i wouldn't run stock behind our motors (motors running basically stock or mild cams, not like some crazy 600HP small block) that'd i'd really worry about. A lot of us like to buy over-upgraded parts, but i've found more often than not, if you're not racing or beating on stock parts HARD, they hold up pretty well.

What i DO worry about and see, is botched TV cable jobs, or no TV cables on 700-R4 and 200-4R trannies (and even some others like the packard ultramatic with the TV linkage) where maladjustment, incorrect linkage, etc ends up in burned up tranny's and people cussing that it was a bad rebuild, when i think the installer doesn't take the time to double check things like the cable adjustment, and most people just don't know any better when something isn't right.

[66Chevrolet]

Originally Posted by 66Submarine

I'll just throw in I'd be VERY leery of any junkyard auto's in anything. I don't have firsthand experience with the 4l80, but the 4l60 is garbage, just a later 700r4. 100,000 miles is about what people get out of them, and lot's of people seem to botch rebuilds. T-5's seem to work pretty well. The A-833's are real interesting, but kind of rare/hard to come across. An NV4500 is kind of the modern SM420, pretty much the same gear spread + a .73 OD. I'd probably look for one of those, personally.

66Chevrolet, Welcome to the forum!

Thanks for the shout out, long time lurker of the site. Here is a picture of the old girl.

[66Submarine]

Nice truck, 66', looks really solid.


-As for the whole 4l60 thing, "modern power" was in this case the mighty 4.3 V6. In a drag race I think I'd put my money on the lame ol' 454BBC with a mild cam, maybe even a GM factory solid lifter 327, but that's just me.

I know people are using them in hotrod stuff now, but the general consensus seems to be that there just isn't enough friction material for them to last a long time. Just about every time you see something with one for sale it has something wrong with the trans. It would be a giant gamble used, and I personally would never buy one that way; much less put one in something. Just too many of them blown up. For the price of a rebuild you can buy most any good manual OD tranny you want, or you could get a brand new Advance Adaptors OD that goes in front of whatever trans you want. SM420 = OD 8 speed!

For me, my trucks are still trucks. It is both my primary means of travel, and something to pull logs out of the woods with. My SM420 has taken that for 48 years and hundreds of thousands of miles, along with being abused by idiots. I can't see replacing that with something that I know won't hold up in the best case. My father has clocked about 100K on his '66 C-10 in seven years or so of driving. If you are only driving a couple thousand miles a year, why bother with an OD auto anyway? It'll take years to pay for itself with something that rarely gets driven. 3,000RPM won't hurt a decent engine, if it bothers you just put a quieter muffler on. Passing gear all the time FTW.

[Clyde65]

Originally Posted by scottveazie

Currently running a sm420 with 4.56 rear end gears, probably going to go to 4.10s. Don't want a 700R4, want something that looks stock and is fairly easy to do. I did read about either a A-833 or T-85N. The 85 would require me going to three speed column shift. Not totally opposed to it but would rather find something that's easier to do while retaining my stock setup or at least the look. The new overdrive units you can buy are too expensive. Any ideas?

I think if your running a 6 cyl or a very mild SBC, you could go with an nv3500 behind it. I would also look at a t5, they were in the fbodies and s10's, you would want the s10 shifter though.

[par4tom]

I just went through this whole situation a few months back...look up some of my earlier posts and you can see the challenges I dealt with. It will save you a lot of time.

In the end, I got a great NP-440 / MY6 (GM Code) 4 speed manual with overdrive. .73 on the overdrive.

I got a little bit lucky as well.

T

[theastronaut]

A T56 six speed would be plenty strong enough and the .50 sixth gear would work with your current 4.56 gears- no need to change rear end gears. MalibuKasey just swapped one in his C10 behind a small block and used an original 4 speed shift lever so it looks stock. You would need to buy/install a shifter relocation kit so it clears the bench seat (if you have a bench seat).