Done with 700R4

86suburbanNJ609 · Aug 14, 2018

Well transmission went again this morning on my way into work. It still has warranty just rebuilt 3 months ago. My question is has anyone on here done the 4l80 swap on a 350 208 transfer case before? If so what vehicles have the trans I need and what year? I'm going to start aggressively looking now because I don't want to put money into something that's junk. Thanks in advance for any input guys I'd appreciate it.

Blue Ox · Aug 14, 2018

I'm pretty sure your 208 isn't going to work with the larger output shaft from a 400/4L80.

Crispy · Aug 14, 2018

86suburbanNJ609 said:
Well transmission went again this morning on my way into work. It still has warranty just rebuilt 3 months ago. My question is has anyone on here done the 4l80 swap on a 350 208 transfer case before? If so what vehicles have the trans I need and what year? I'm going to start aggressively looking now because I don't want to put money into something that's junk. Thanks in advance for any input guys I'd appreciate it.

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Check this thread out:
https://www.gmsquarebody.com/threads/383-to-4l80e-to-np208.16889/

I think after its all said an done there would be a lot of money into this swap. Maybe take the 700R4 to a high performance shop? Then theres the LS swap. If you're gonna do the wiring and electronics might as well go all out.

86suburbanNJ609 · Aug 14, 2018

The trans is under warranty so it's going back today I just want the truck to be reliable and this trans is not it. So I am definitely going to be looking for a newer truck with a decent motor and making the swap just gotta keep a lookout for the right deal... In the meantime I just gotta baby this POS 700 it looks like.

crazy4offroad · Aug 14, 2018

NP205 would be easier to adapt to 96-06 4L60/80e

PBALLARD · Aug 14, 2018

I put a 4L80E in my 1986 behind the 6.2 with a NP205 bring up the rear. very easy swap from the TH400 that was original. the only thing I had to do was to machine the adapter front housing of the NP205 to fix the 4L80E - $50 at the machine shop

TravisB · Aug 15, 2018

My Grandfather and Father both had 84 model k10s. I have posted a few pics of my Grandfathers we still have. It had a 350 trans it has never gave us an ounce of trouble. Dad's had the 700r4 and it was changed at least 4 times before it found a new home. I feel you on the unreliable side. Maybe look at a 350 transmission and an overdrive? You could have that for low cost of another truck for a spare. haha http://www.gearvendors.com/4x4gm3s.html

Super-Dave · Aug 21, 2018

Are you sure it's not the shop that's the issue? I had mine rebuilt from a core with all the good parts where they needed to be. Runs like a swiss watch. If I get on it, it kicks gears nice and hard with my 3:73's. A soft shoe on the go peddle and it cruises through the gears smooth but firm. I have heard horror stories from all over the country and most can be traced back to a DIY botched mess or a shop that wasn't turning out quality work.

Good luck with whatever you decide to do!

glockholiday · Aug 21, 2018

While you might be done with your 700R4 there's no reason it can't be a reliable transmission for you, it just needs to be built right. And by right I mean right parts installed by the right person.

Cuba · Aug 21, 2018

100% agree with Glock & Super Dave... it's all about WHO does the rebuild. Rebuilders, mechanics, shops, etc are NOT rated equally. You have butchers and crooks, then there's the aces and quality control, great workers.

Since your in NJ, maybe NY is not too far from you? I know for a fact Gary Ferraro at AAA1 Transmissions, is the top in his field and 100% guarantees his work. It can be a hike, but he's beyond reasonable and well worth it for RELIABILITY.

He's near JFK airport..... address is 66 Hempstead Tpke
West Hempstead, NY 11552

I've done my own trans work on the 700R4 and it's always been reliable as well. I have 3 trucks, all 700R4. I favor these trannys in fact. Instead of trying to convert to fit a different trans and modify other things... which takes time and unknown amount of $$, stick it through and just get it fixed right. Should last 100k miles easily

4WDKC · Aug 21, 2018

700s can be reliable if built correctly but most shops dont know how to do that. FRom what I have read about the 4l80 swap you need to get the adapter plate with it from the donor truck then find a 208 from a truck with a turbo 400. After that you will move the cross member backwards, shorten rear shaft, lengthen front shaft and have to make something to get the 4x4 selector to function correctly. All this on top of getting the ecm, wiring it up, install a tps on existing setup or just going to a ls swap.

Camar068 · Aug 21, 2018

size tires and gear? My k10 had 350/700r4/np208 w/31" tires and 3.08 gears. It didn't have much get go going up big moutains at higher speeds, but it worked decent through 3rd gear everywhere else. Towing was a different story though.

Edit: This was after a trans rebuild by a builder I trust. Before the rebuild was the same as after.

May be the combo you have or the trans builder you have. I've read that you can beef the 700r4 up pretty good with aftermarket parts. The first question will help us help you a lot.

86suburbanNJ609 · Aug 22, 2018

Super-Dave said:
Are you sure it's not the shop that's the issue? I had mine rebuilt from a core with all the good parts where they needed to be. Runs like a swiss watch. If I get on it, it kicks gears nice and hard with my 3:73's. A soft shoe on the go peddle and it cruises through the gears smooth but firm. I have heard horror stories from all over the country and most can be traced back to a DIY botched mess or a shop that wasn't turning out quality work.

Good luck with whatever you decide to do!

I got it back tonight and shifted fine in drive but overdrive was different she definitely didn't like it. I to have 373 gears but I'm running 33s on a 6 inch lift and I really think that I shouldn't be driving this thing in overdrive only shift it in when over 55. It doesn't try to find gears but it will shift prematurely if I'm not on the throttle. My question is do you drive yours in drive or overdrive?

Cuba · Aug 22, 2018

Me, I drive in drive when doing local, lower speeds up to 45ish, especially with a lot of stop and go or if the area is hilly with steep inclines & declines.
I also use drive in inclement weather or any towing.

OD for most driving, like 45 and above speeds, long stretches of road, highways.

Generally, you should be able to use OD at all times for normal driving, period.
Although the 33s changes things.

Did you say you have 373 rear? I didn't quite understand that part in last post

glockholiday · Aug 23, 2018

I have 3.42 gears and 33's and while it definitely wouldn't tow anything in 4th I leave it in OD all the time anything over 45mph and it cruises and pulls it just fine. Sounds like your TV cable needs adjusted, which is a pain in the ass in my opinion but I got mine set pretty good. If it's off it'll shift too early like you said or if it's off the other way it'll smoke your transmission.

Done with 700R4

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