The mythical CUCV 4L80E swap

[richingalveston]

pretty sure it is driver side goes to front battery.

I am going to do the same as far as the cooler. My tranny is running to hot.
The radiator keeps it at about 210 and can climb to 230 (that is the highest mine as ever gone)
under heavy load.

I am going not use the radiator cooler portion and install a stand alone. I am in texas and heat is a bigger problem than cold. I do not plan to run the two in a series.

what is your tire size, and what are your rpms at 55,65 and 75?
I have 39 and I am at 55=1500, 65=1800 and 75=2200. Approx. RPMS. I am reading a dial not digital read out and my Dakota digital does need to be dialed in, But it is not far off if any.
rich

 

[richingalveston]

I did confirm last weekend I am getting 16 MPG on the high way. I drove I-45 from Texas city to Madisonville. (bucees to bucees for those that are familiar with the route.) Verified with garmin. I ran 70 to 75 the entire way and got almost exactly 16mpg which is the same as my 2014 duramax

 

[brazengoat06]

i believe you are correct on the alternator, seems like ive heard that that is the one that always goes out.

Im not sure on my rpms yet. my dakota digital isnt sending a very good signal to the TCI. I was gonna try and use the high output side of the DSL and see if the TCI would pick it up better. Was hoping the OP would chime in and let me know how he wired his up.

 

[richingalveston]

if you are having alt. problems, fix that first. It may resolve the Dakota digital signal. My DS1 drives a large tach in the dash and the US shift module. I get an intermittent blip on the tach, it has a little bounce every 20 to 30 seconds but it does not seem to bother the trans computer. I just need a way to calibrate the DS1. I am considering a tiny tach just to set the timing and then put it on the shelf. I have it close but I cannot verify it.

 

[Kaiserjeeps]

Interesting on the heat issue. So do trucks that have 4l80E's from the factory have aux coolers? I suppose I had better get ready to get one since it looks like both you guys are having the same problem.

So this is a 4l80E thread. And like me I am sure there are a fair amount of people wanting to put a NP205 behind their new trans. I have found a nice discovery. I am rebuilding my NP205 and putting in a SLE kit. So when rebuilding the 205 the intermediate gear requires shims for the proper preload of .000 to .002 end play. I have searched for ever to find these shims. One company previously mentioned sells them. But with shipping they are just under 50 bucks. For a small shim pack.
I found a 19 different size shim kit at Mc Master Carr for only 16.95. The ID is perfect. The OD is a shade bigger and does not interfere with anything. The part number is
3088A939, Steel Shim, Round, 19 piece assortment, 19 different sizes, 1 3/8ths ID.
I got them in and they fit great! Don't assume your old shims will provide correct end play. This gives economical choices.

Stock shims on the left, Carrs shims on the right with one installed on the intermediate shaft behind it.




The current state of my 205. It's getting a fixed rear yoke, 4 new gears, new sliders, and lots of other stuff like bearings, seals..



I am in need of at least one thrust washer anti rotation pin. Does anyone have a scrap 205 and have one or two of these I can finagle off you?



My one hundred million dollar 4l80E with shift kit, rear adapter and used and shortened rear fully splined shaft.




Cutting the shaft with a cut off wheel in a 4.5 inch peanut grinder.




Here is where the input gear splines in the 205 rest. The o-ring is where the splines start, the forward mark is not spot on. The next silver mark back is the end of the splines,
Take away the 9/16th thick adapter and it all moves forward leaving not very good spline contact.



I am still waiting on the US Shift controller. I'll have the 205 back together as soon as my parts show up. And I guess I had better find a transmission cooler eh?

EDIT: trying to change these to visible pics. The link looks correct on the edit page. I used the IMG copy and paste on PB. Not sure what is up.

 

[rustystud]

Great find on the shims Kaiserjeeps ! The only parts you can buy for the NP205 are either NOS which they want a fortune for. Used which can be a crap-shoot or parts made in China which are usually garbage. It's nice to find some parts that are new and still reasonably priced !

 

[True Knight]

i believe you are correct on the alternator, seems like ive heard that that is the one that always goes out.

Im not sure on my rpms yet. my dakota digital isnt sending a very good signal to the TCI. I was gonna try and use the high output side of the DSL and see if the TCI would pick it up better. Was hoping the OP would chime in and let me know how he wired his up.

What pickup are you using for the Dakota Digital? I originally had and issue with the magnetic flywheel tooth style pickup, but it was my fault. I didn't have it installed close enough to the flywheel teeth for it to create a reliable signal. Once I reinstalled it with the correct distance from the flywheel it worked perfectly.

 

[brazengoat06]

What pickup are you using for the Dakota Digital? I originally had and issue with the magnetic flywheel tooth style pickup, but it was my fault. I didn't have it installed close enough to the flywheel teeth for it to create a reliable signal. Once I reinstalled it with the correct distance from the flywheel it worked perfectly.

I'm using the same method. Alternator is fixed. Still don't have a good rpm signal. Also I did install an auxiliary cooler and trans temp still likes to creep up to 210. I've noticed that since the transmission likes to cruise in overdrive out of tcc lock up (because it's hilly here and m1010 is heavy with non turbo 6.2) so I'm thinking this is where I'm getting all my heat from. In town driving is slightly better but the controller tends to short shift a bit so I'm gonna try and fine tune a bit and correct this issue. Transmission works great but was wondering what everyone else's experiences were. Thanks

 

[True Knight]

I would make sure you get the pickup as close to the flywheel teeth as possible without touching.

If I remember correctly, you can tune the settings for when the converter locks and unlocks too. Just takes some playing with to get it the way you like.

 

[Kaiser67M715]

I would make sure you get the pickup as close to the flywheel teeth as possible without touching.

If I remember correctly, you can tune the settings for when the converter locks and unlocks too. Just takes some playing with to get it the way you like.

My trick for mounting up flywheel sensors(or any other magnetic pickup) is to tape a piece of credit card to the teeth, then rotate it till you can see the card through the mount. You can then mount the sensor tight to the card and that gives almost the perfect distance, you could also use cardboard from a cereal box if you want it even closer

 

[brazengoat06]

Thanks for the tips. I thought I had it close enough but turns out you really do have to get it right on the teeth for a good signal. Makes a big difference in the shifting.

 

[aleopard]

Awesome write up, and I want the same setup. Could you email me a list and how to on a 4L80E swap in my CUCV 6.2 allowing me to keep the NP205? What years 4L80E would work best? My email is aleopard@gmail.com. Thanks

 

[Glockfan]

I did not intend to resurrect an old thread but there is a wealth on knowledge in this single thread. Hopefully I will avoid making costly mistakes and get the right stuff in the first place for my 4L80E swap. Thanks to all who contributed!

 

[aztrekker]

I did not intend to resurrect an old thread but there is a wealth on knowledge in this single thread. Hopefully I will avoid making costly mistakes and get the right stuff in the first place for my 4L80E swap. Thanks to all who contributed!

I am glad you did! It brought this thread out to my attention I have been trying to figure out what to do to bring down my RPMs and raise my mileage at highway speeds. I was looking at an overdrive kit, but seems like this is a better solution. I have a 1986 M1008. 6.2/TH400 It is in mint condition, 80k miles, and pretty much stock. It works perfectly so I am a bit leery of fixing something that isn't broken. I also am a bit concerned about using the 4L80e because of the electronics on it. I have a bit of a hang up with EMP scenarios and the like and thus prefer an all mechanical solution. (Yes I know I am one of those weird guys who thinks about that sort of stuff. I can't imagine I am the only one on this forum with those type of ideas but please be kind when you make fun of me ).

So to my point: Would/Could/Should one use the 4L80 (note the missing e) ... My understanding is it is the same tranny without the electronics. Please correct me if I am wrong about that or anything else I have said so far. I understand it to have been in 86-93 6.2 and 6.5 configurations for 3/4 ton trucks. If you think it is a good idea, do you have any idea where to get one? I have been poking around on the net and I have yet to find one I can actually buy. Lots of 4L80e options but nothing without electronics.

Any input, guidance, or criticism would be greatly appreciated!

 

[Kaiser67M715]

I am glad you did! It brought this thread out to my attention I have been trying to figure out what to do to bring down my RPMs and raise my mileage at highway speeds. I was looking at an overdrive kit, but seems like this is a better solution. I have a 1986 M1008. 6.2/TH400 It is in mint condition, 80k miles, and pretty much stock. It works perfectly so I am a bit leery of fixing something that isn't broken. I also am a bit concerned about using the 4L80e because of the electronics on it. I have a bit of a hang up with EMP scenarios and the like and thus prefer an all mechanical solution. (Yes I know I am one of those weird guys who thinks about that sort of stuff. I can't imagine I am the only one on this forum with those type of ideas but please be kind when you make fun of me ).

So to my point: Would/Could/Should one use the 4L80 (note the missing e) ... My understanding is it is the same tranny without the electronics. Please correct me if I am wrong about that or anything else I have said so far. I understand it to have been in 86-93 6.2 and 6.5 configurations for 3/4 ton trucks. If you think it is a good idea, do you have any idea where to get one? I have been poking around on the net and I have yet to find one I can actually buy. Lots of 4L80e options but nothing without electronics.

Any input, guidance, or criticism would be greatly appreciated!

You're probably thinking 700r4, which IMO is a rather weak transmission, plus you need to find the elusive T.V. cable bracket.

You can convert a 4l80e to a manual valve box, but that requires you to manually shift through each gear.

The best bang for your dollar (my opinion only) is the 4l80e with a standalone controller. It's very heavy duty, and there are millions out there.

If you had the blazer, a 700r4 might have been a better fit, but the pick up definitely needs a beefier transmission.

Sent from my SM-S920L using Tapatalk

 

[Sharecropper]

You're probably thinking 700r4, which IMO is a rather weak transmission, plus you need to find the elusive T.V. cable bracket.

You can convert a 4l80e to a manual valve box, but that requires you to manually shift through each gear.

The best bang for your dollar (my opinion only) is the 4l80e with a standalone controller. It's very heavy duty, and there are millions out there.

If you had the blazer, a 700r4 might have been a better fit, but the pick up definitely needs a beefier transmission.

Sent from my SM-S920L using Tapatalk

Hold on there Kaiser. Before you go bashing the 700R4, you probably should do a little more research. I have a rebuilt Bowtie 700R4 I'm installing behind my P400 6.5 which is rated for 450 HP and 450 FPT. In its stock form, yes a 700R4 is not as strong as a 4L80E. But the drag racers have preferred the 700R4 for years due to its ability to be built even stronger than a 4L80E. Plus, the 4L80E first gear is 2.48, while the first gear of a 700R4 is 3.06. The 4L80E indeed requires electronics which is an additional cost, while the 700R4 is dumb and is operated by the TV cable. Which means when TSHTF the 4L80E will be sitting on the side of the road. The 700R4 TV bracket is available regularly on Ebay, and in fact I have an extra laying right here. Also, the 700R4 is the exact same length as the OEM Th400 which means no modification to crossmember or driveshafts. C'mon man.

 

[Kaiser67M715]

@Sharecropper

I have never liked the 700, yes you are right it can be beefed up, the TV cable can sometimes pose an issue if not correctly set. Otherwise it's not an overall bad trans, I just don't think it has a place in trucks over 1/2 ton rating.

I'm also very biased against automatics....I'd much prefer to use manual whenever possible.

It's not my intention to start a debate on what is a better option, just wanted to voice my opinion on the matter.

Sent from my SM-S920L using Tapatalk

 

[Sharecropper]

@Sharecropper

I have never liked the 700, yes you are right it can be beefed up, the TV cable can sometimes pose an issue if not correctly set. Otherwise it's not an overall bad trans, I just don't think it has a place in trucks over 1/2 ton rating.

I'm also very biased against automatics....I'd much prefer to use manual whenever possible.

It's not my intention to start a debate on what is a better option, just wanted to voice my opinion on the matter.

Sent from my SM-S920L using Tapatalk

Well then, since you admit that you are biased, I don't believe you should be giving advice to aztrekker, a new member with only 2 posts, who is obviously asking for help. I have never liked manual transmissions, but I don't come on here and bash them. If you can't provide meaningful, non-biased advice to a newer member, then I think you should keep your opinions to yourself.

 

[True Knight]

Well, coming from someone who did the 4L80E swap, it was definitely worth it. The 4L80E is easy to tune the shift points, shift firmness, torque converter lock up... And the stock 4L80E is far stronger than the 700R4. Plus you don’t have to worry about the TV cable that is a pain to adjust, and can come out of adjustment.

You don’t have to spend any money modifying the transmission to handle the heavy duty CUCV. The electronic control is waterproof and mine is mounted in the engine compartment. Now if you’re really concerned about EMP then I would think the easiest solution would be to surround the control box with a faraday cage to protect it from EMP. I don’t know exactly how that would work, I don’t have experience with faraday cages, just hear people talking about them.

In the end it’s up to you, but I really love the 4L80E.

 

[Keith_J]

You don't need a computer.. https://www.youtube.com/watch?v=ozbWf_QsPrw