T-400 to 700r4 in '84 C20 sub,454,4.11s

[Darth Vader]

Hi Guys
I stumbled across this website and it seemed to contain a lot of info geared towards my newly aquired C20 Sub. I'm new to the sight and I'd like to swap out my T-400 for a 700R4. I recently acquired a beautiful black 1984 C20 92wd) suburban. It has a 454 and 4.11 gears. I'll use it for towing my '66 GTO. Car and trailer weigh 6500# combined. Anyone done this conversion and can tell me what I'll need to swap? Any specific cross member I'll need or a driveshaft that I caqn use that won't need to be shortened? Carb brackets from a newer year that will bolt onto the quadra-jet and aleviate and TV cable alignment woes?
I have what I believe to be an '89 700r4core and I also have access to a reasonably fresh '84 700R4 for $200.
Thanks in Advance,
Brad

 

[crazy4offroad]

Welcome to the forum!

I hate to burst your bubble the 700R4 is not the best choice for a towing trans. Maybe with a little lower gear ratio, 4.56 or 5.13 but you would be ahead of the game looking into the 4L80e computerless swap.

 

[bucket]

Howdy!

Unfortunately, the 700r4 will likely die an untimely death even if properly built. I mean, you might get several years and 50K out of it, but the current th400 will probably last that long as it is. Having overdrive will save on engine wear and tear, but if you are primarily towing, you won't really gain much mileage.

 

[Jims86]

Howdy!

Unfortunately, the 700r4 will likely die an untimely death even if properly built. I mean, you might get several years and 50K out of it, but the current th400 will probably last that long as it is. Having overdrive will save on engine wear and tear, but if you are primarily towing, you won't really gain much mileage.

Agreed, 700r4's barely live in harmony with 1/2 tons unless they are built right.
The 400 is your best bet, and maybe a rear gear swap, or larger diameter tires if you want better highway mpg.
The only other option, is to get a 4L80, and a TBI computer from a 94-95 Tahoe/Sub/silvarado, and fab up some sort of Throttle position sensor bracket for the carburetor, like dis:

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You can also go the expensive route and buy a trans controller.

 

[HotRodPC]

X however what number I am. Avoid the 700r4 for your purpose. To many things wrong here. Towing #1, going behind torquey 454 #2. You can get around the 454 with a good build and light non towing ride, but the towing, pretty much kills it for you. I'd run 3.73's and a Th400 behind a 454 before I'd do a 700r4/4.10's. But, you have the 4.10's and that is good for towing. I'd keep the 4.10's. As said, look into the 4L80-E is your best bet.

 

[89Suburban]

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[Darth Vader]

Thanks for the warm welcome and the good advice. I'll avoid the 700R4.....may just use the Suburban as it is. The T-400 is fresh w/ a shift kit....thought about a gear vendors overdrive, a might pricey though. Anyone got a used one they wanna part with??

 

[HotRodPC]

Gear Vendors are awesome, but they're so expensive, unless you're driving 100 miles day, they'd take forever to pay off. Seen a truck on CL one time, in fast the ad was posted here. The truck looked rough as hell and didn't turn and someone made the comment his $1000 price was a joke. And it was too. BUT, this truck had a Gear Vendor in it. The gear vendor alone made it worth over $1000. I'da took the gear vendor vendor, parted out the cores, sold a few parts, the rest over the scale and had me a gear vendor with the cut driveshafts, crossmember and all for about $300. WIN !!!

Also, keep an eye on old Motorhomes that are being sold for dirt cheap for not running or burnt, flooded etc. Sometimes, some motorhomes came from their manufactuer with a Gear Vendor installed.

 

[Darth Vader]

Just ran across a few pics I snapped of the newly acquired Sub.
I've done a few upgrades since these were taken....so I'll update when I get a chance to snap a few more.
I

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[Kapdin]

dayum... sick burb. props.

 

[woodsrider250]

NICE! What size tires are those by chance?

 

[bucket]

Nice nice nice!! Is it lowered a little in front? It looks a little lower than mine.

NICE! What size tires are those by chance?

Looks like 235/85/16

 

[Darth Vader]

It is lowered all the way around.....I'll hafta check the tire size. Thanks for the kudo's, Guys.

 

[Darth Vader]

Few more improvements.....
New Michelins (235/85/16) , New Grille and Bezels and a new front spoiler.

 

[bucket]

Where did you get the front spoiler? I wasn't sure they made them anymore.