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3L80 to 4L80E Transmission Swap

Retiredwarhorses

Well-known member
Steel Soldiers Supporter
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Brentwood, Calif
700R4's are worthless....at least in stock configuration, it would need to be built up to even come close to the
durability of a stock TH400.
 

davykeith

Member
50
2
6
Location
Ellisville, MS
Ebay link removed...

Hi all, I'm looking to convert over to a 4L80E from my 3L80. This one looks to be a good price (link removed!). It would be awesome if we have a sticky on sources for other parts needed.

Let me know if I'm going the wrong way here. I want to be able to cruise at 70 mph. That is all.
 
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Dock Rocker

Active member
980
72
28
Location
Jackson ms
Hi all, I'm looking to convert over to a 4L80E from my 3L80. This one looks to be a good price (link removed!). It would be awesome if we have a sticky on sources for other parts needed.

Let me know if I'm going the wrong way here. I want to be able to cruise at 70 mph. That is all.
Take the Link down and post a pic or it will get moderated.

You will need a 242 t case or an adapter to go to the 218 you have. You will need to cut and lengthen the drive shafts if you keep the 218. If you get the 242 you can get a set of factory prop shafts.

You will need a torque converter and a flex plate as well.

You will need an aftermarket controller and a step down unit to give that controller 12v unless you have a dual voltage generator. You will also need to source a throttle position sensor with it. What you use will depend on what controller you pick.

You will need a 4 Speed shifter as well.

If you do all the work you are looking at a cost of $3,000 to $5,000 depending on what parts you use.


Sent from my iPhone using Tapatalk
 
Last edited by a moderator:

hahnmgh63

Member
40
22
8
Location
Roy, WA
Don't do a 700r4, it is a 4spd version of the old Turbo 350 whereas the 4l80e is the 4spd version of the Turbo 400. The 700r4 may be fine if it is a garage queen and only on the highway but if you start putting the torque to it off road it'll die on you quickly. That's a jimmy rig conversion, cost you more in the long run and you'll be regretting it.
 

Sharecropper

Well-known member
Steel Soldiers Supporter
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Location
Paris KY
Don't do a 700r4, it is a 4spd version of the old Turbo 350 whereas the 4l80e is the 4spd version of the Turbo 400. The 700r4 may be fine if it is a garage queen and only on the highway but if you start putting the torque to it off road it'll die on you quickly. That's a jimmy rig conversion, cost you more in the long run and you'll be regretting it.
Hold on a minute hahnmgh63. I can't sit quietly on this one. If a 700R4 is built properly, it will handle any amount of power the 6.5 can dish out. I purchased a Level 2 K-case 700R4 from Bowtie Overdrives rated at 450HP and 450 FPT. Just now getting ready to install it in my M1028 in place of the old tired TH400. It will be coupled behind a brand new P400 coming from GEP. The beauty of the 700R4 is, it is the same length as the TH400 or 3L80 and doesn't require any cross-member relocation or drive shaft modification. Also, it is a "dumb" unit, meaning that it is controlled by a cable to the IP and not some high-dollar electronic device which will fail when AHBL. Another advantage of the 700R4 is, first gear is 3.06, whereas the TH400 and 4L80 is 2.48. So please do your homework before you give advice. Bowtie Overdrives specializes in 700R4 transmissions for the drag race community. They know what they are doing, and in fact, the owner owns a M1008 as a daily driver with a 700R4 unit in there. He knows what is needed for a military application.

Don't mean to offend, just my 2 cents.
 

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davykeith

Member
50
2
6
Location
Ellisville, MS
Hold on a minute hahnmgh63. I can't sit quietly on this one. If a 700R4 is built properly, it will handle any amount of power the 6.5 can dish out. I purchased a Level 2 K-case 700R4 from Bowtie Overdrives rated at 450HP and 450 FPT. Just now getting ready to install it in my M1028 in place of the old tired TH400. It will be coupled behind a brand new P400 coming from GEP. The beauty of the 700R4 is, it is the same length as the TH400 or 3L80 and doesn't require any cross-member relocation or drive shaft modification. Also, it is a "dumb" unit, meaning that it is controlled by a cable to the IP and not some high-dollar electronic device which will fail when AHBL. Another advantage of the 700R4 is, first gear is 3.06, whereas the TH400 and 4L80 is 2.48. So please do your homework before you give advice. Bowtie Overdrives specializes in 700R4 transmissions for the drag race community. They know what they are doing, and in fact, the owner owns a M1008 as a daily driver with a 700R4 unit in there. He knows what is needed for a military application.

Don't mean to offend, just my 2 cents.
I concur with Sharecropper. I've got a rebuilt heavy duty 700r4 that's holding up just fine. This is an ongoing debate. Is it as bullet proof as a 4L80E, IDK but so far I'm having zero issues and mine ain't a garage queen. It's a daily driver. Granted I haven't done anything serious but if I do and blow it up I'll let you know.
 

RichDane

Member
51
8
8
Location
Hatteras, North Carolina
I just pulled out my 3 speed and put in a 4l80e, and a new torque converter, and Oh My God....I love it....runs smoother, quieter, better fuel usage, PCS controller, re welded the cross member to support the trans, 12 volt line, hooked torque convert to brake light, only had to cut rear driveshaft...incredible...the one best thing I ever did for this tank...... that an a $500 4 speed shiftier and off we go !!!!!!!!!!!

4l80e trans.jpgtrans1.jpg
 

RichDane

Member
51
8
8
Location
Hatteras, North Carolina
Drive shaft length

How many inches to take out to shorten the rear drive shaft? 4L80?NP242? thanks
Yes, I had the rear shaft shortened.......by my drive shaft guy who came over measured it, cut it and delivered it ...but I can not tell you how much they cut off....what I can do is go out and measure it and tell you how long it is.......Raining cats and dogs but will let you know....
 
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