Automatic transmission upgrade

[machmeter62]

Gentlemen;
I purchased new in '78, a Chev Van 30 (one-ton dually). I still have the vehicle, but want to upgrade the three speed auto transmission, or go the "Gear Vendor" method, or other? The existing transmission has had some hard use with towing, and still has less than a total of 20,000 miles on it. This was the last year for that vintage GM engine in that era, with the 400 CID small block, with the siamesed cylinder walls! I had the existing trans rebuilt, after it failed, due to my abuse of over stressing it! I don't know the model of the auto trans in it, but it's the original one. The engine still runs very strong.

The abuse of the engine/trans., was the result of towing a large boat through mountainous terrain for over a couple of decades. The vehicle has less than 20,000 original miles, and has been stored for the last 12 years.

With all the new technology, with these new automatic transmissions, what direction should one pursue for trouble free performance, with less than 9000 GVW. I would like the new multi-speed transmission, for mileage- improved design- gas mileage, etc; the rear-end has a 4:10 to 1 ratio, and cruising at 60 mph yields 3000 RPM too!

Economics could be a factor also, and if one decides on a recent trans from a junk yard, what would be the best option there? Gear Vendor's would be close to $3000 for the mod. (Thanx in advance for all your suggestions.)
LEE

 

[Cami]

I don't know what transmission you need, but I suggest a cooler for whatever one you get.

 

[Raw Dodge]

Im pretty sure Jet Performance used to sell a 4L80E with stand alone controller for under $3000.00.The 4 L80E is plenty strong for what you have there,in fact it will handle a modded 454 pretty easily....I havent checked in a while on them...the 4L80E would give you lockup and OD,which will reduce your rpms quite a bit,from 3000 down to 2250 or so!

 

[machmeter62]

It came standard with a large transmission cooler located behind the front grille; I just exceeded its towing weight limits on the long up-hill mountain grades during those hot summer months.

 

[davo727]

Here is one aftermarket controller from PCS for the 4l80e

PCS - Powertrain Control Solutions - Transmission Control

Heres another one from TCI- $700

TCI Auto 377000 - TCI Transmission Control Unit Systems - Overview - SummitRacing.com

It requires a throttle position sensor to work, you can rig one up yourself with a GM sensor or you can buy there sensor deal for $200.

TCI Auto 377400 - TCI Remote TPS - Overview - SummitRacing.com

 

[davo727]

On my automatic trucks I run 2 large coolers and a transmission temp gage which is how I knew that one trans cooler is not enough when towing heavy.

 

[Diamondpilot]

The issue is cost here. Anything is possible but matching a tranny to the engine is going to be tough due to the difference in the components era. I would not think this could be done for under $3000 and you can buy a lot of gas for that old truck before you would break even. Especially if you are only putting 20,000 miles on a 32 year old truck. Thats only 625 miles per year.

My suggestion is leave it alone. Change the tranny fluid out and install a large cooler.

Chris

 

[Cami]

I forgot....what about rebuilding AND throwing a shift kit in while you're at it?

 

[machmeter62]

Cris,
Thanx for the reply. I know the financial recovery will never pencil-out, but I think in the distant future, we will see fuel in a few years, approach $5.00/ gallon too. China has tied-up recently, all the mayor oil fields that committed to them in Africa, as the car market grows in China. It's that supply and demand factor, that will continue to elevate the price of fuel.

It's that feeling of wasting power when looking at the tachometer turning 3000 RPM, when much less power/RPM is really needed?

I am also going to look at converting a recent late model compatable trans to my van to get more gear ranges, with the transmission seeking the most efficient gear. I could probably have the axle ratio changed for a lot less too, but I am still looking at all the options, since I no longer tow with it. Gear Vendor would be at least $3000 installed?
LEE

 

[machmeter62]

I forgot....what about rebuilding AND throwing a shift kit in while you're at it?

That would rule out my side-kick's driving skills (wife)!

 

[machmeter62]

Thanks, I will check-out that site;those RPM # are favorable.

 

[sld]

Check out the gear vendors unit.

It will make your 3 speed a 6 speed and is probably a cheaper way to go.

 

[machmeter62]

Gentlemen;
Here is what I have discovered for both price and performance. After reviewing 'Gear Vendor's" site, they may offer more speeds, with the over/under gearing, that fine tunes ones performance; but the initial cost and installation costs ($750), is too pricey, well over $3000 total for me,

I think "Raw Dodge" has the answer for my budget, and the installation is less complex, that may not even need the crossmember modified, after taking all the measurements today. I can get the (GM 4L-80E, or 80). for $1537...no sales tax...shipped free to California. This tranny, shipped from AZ, is a re-man with 2 yr/24,000 miles warranty that can handle the RAT-454 engine with > 500hp! I still might get more local opinions from local repair shops for the installation work.

I was also told, it's this GM transmission that is installed in the RollsRoyce?
LEE

 

[machmeter62]

Gentlemen;
Here is what I have discovered for both price and performance. After reviewing 'Gear Vendor's" site, they may offer more speeds, with the over/under gearing, that fine tunes ones performance; but the initial cost and installation costs ($750), is too pricey, well over $3000 total for me,

I think "Raw Dodge" has the answer for my budget, and the installation is less complex, that may not even need the crossmember modified, after taking all the measurements today. I can get the (GM 4L-80E, or 80). for $1537...no sales tax...shipped free to California. This tranny, shipped from AZ, is a re-man with 2 yr/24,000 miles warranty that can handle the RAT-454 engine with > 500hp! I still might get more local opinions from local repair shops for the installation work.

I was also told, it's this GM transmission that is installed in the RollsRoyce?
LEE

Who makes the separate transmission controller for GM's 4L-80E trans?

 

[Stimw]

I have been researching this too because I have a 1989 Southwind motorhome in very good condition and the change over would really help it.
Check 4L80E prices on ebay, there are some good prices and their feedback should help you decide. Check craigslist.org in your area, I have seen them for under $500. locally. The newer 4L80E's are said to be stronger, I think it is 1996 and up. New ones have oil cooler connection lines wider apart on side of trans. 4L80E uses a lot of the same parts as a Turbo 400 so it is a good trans.
You need a controller, google 4L80E controller and you will find suppliers. Some are computer tuneable. You also need a speedo converter from electronic to manual read. There are two kinds of these, tail housing change over (keep mechanical) or elec to manual.
The gear vendors seem like a good product but pricy and you have to shorten driveshaft and make/buy mounting bracket.

 

[Bruce-4310TX]

if you have a turbo 400 now, then a 4L80 will bolt right in i believe its still the same length. I doubt if you have a turbo 350 and 700 r4 did not come out till 1984. shop around for the controllers lots of places carry them even Jegs and Summit. CK out some Hot-Rod forums with a little Googling you should find out all the parts needed to do this swap. If you or someone you know has the savvy to rebuild a automatic go get a good core junk-yard swap meet and get a Kit from Monster Transmission they have every thing you need. They are not hard too rebuild and rebuild manuals are cheap and available on E-bay.I used a few of there kits very complete theyl set you up at a reasonable price. Also if you change the rear Gears to 3.73 that will help and still give a great tow Rating and you could get rid of that 400 s/b and put in 383 S/B OR GM CRATE HT383 more power and better mileage. Recoup some money by selling that 400.

 

[carpenter383]

If you're dead set on spending the money on an overdrive trans, then the 4l80e is a nice heavy duty trans. It's a th400 with overdrive. (your van definately came stock with a th 400) I'm pretty sure a 4l80e is a couple inches longer than a th400, so the driveshaft will need shortened, the cross member will probably need moved too.
It wouldn't be worth changing to 3.73's IMO I wouldn't change gears unless you go a significant ammount (like from 4.10's to 3.55's or higher)
The 400 sb was only made for 10 yrs. ending in 1980 so they're getting scarce and are worth some money, (4-500ish for a decent longblock) yours is a 2 bolt main which is a little less desirable to some people. A 400 sbc has the same 3-3/4 stroke crank as a 383 stroker would (which is where the tourque comes from) but it's a smog motor and prolly don't have much power. A decent 383 with a mild cam (rv) would be more powerfull for sure, but if you're not towing it wouldn't be very justifiable in my oppinoin.
Your biggest bang for the buck (for lower cruising rpm's) would be to keep the th400 and put higher gears in the rear end. It'll take a long time to make up for the cost of a 4l80e swap.

 

[machmeter62]

If you're dead set on spending the money on an overdrive trans, then the 4l80e is a nice heavy duty trans. It's a th400 with overdrive. (your van definately came stock with a th 400) I'm pretty sure a 4l80e is a couple inches longer than a th400, so the driveshaft will need shortened, the cross member will probably need moved too.
It wouldn't be worth changing to 3.73's IMO I wouldn't change gears unless you go a significant ammount (like from 4.10's to 3.55's or higher)
The 400 sb was only made for 10 yrs. ending in 1980 so they're getting scarce and are worth some money, (4-500ish for a decent longblock) yours is a 2 bolt main which is a little less desirable to some people. A 400 sbc has the same 3-3/4 stroke crank as a 383 stroker would (which is where the tourque comes from) but it's a smog motor and prolly don't have much power. A decent 383 with a mild cam (rv) would be more powerfull for sure, but if you're not towing it wouldn't be very justifiable in my oppinoin.
Your biggest bang for the buck (for lower cruising rpm's) would be to keep the th400 and put higher gears in the rear end. It'll take a long time to make up for the cost of a 4l80e swap.

I crawled all over the transmission, and gave up to identify it. I called the Chev Dealer, and he put me in touch with a tranny "guru!" He said, climb under again and tell me the shape of the trans pan, it's either shaped "oval, or squarish" ...the Th-350 is the square one, and the oval pan is for the TH-400. So I have a TH-350 in my '78 van with the squarish one. I purchased it new in the spring of '78.

 

[carpenter383]

I crawled all over the transmission, and gave up to identify it. I called the Chev Dealer, and he put me in touch with a tranny "guru!" He said, climb under again and tell me the shape of the trans pan, it's either shaped "oval, or squarish" ...the Th-350 is the square one, and the oval pan is for the TH-400. So I have a TH-350 in my '78 van with the squarish one. I purchased it new in the spring of '78.

I've never saw a th350 in a 1 ton. Does your trans have a kick down cable, or a wire with a solenoid (at the carb) going from the trans to the carburetor? If it's a cable it's a th350 if it's a wire it's a th400

 

[MossRoad]

Why don't you go with a 700R? You get O.D. and don't need a controller. Just asking.