4L60E/241C info

[A1971Blazer]

Ready to assemble as soon as bearings and seals arrive........!


Ended up using Rustoleum self-etching primer on the bead blasted, bare metal.

Covered with Rustoleum metallic nickel enamel......we'll see how it holds up on aluminum.

Never had much luck with paint staying on aluminum very long, but it will look nice until it goes under the bottom...!

Ordered all new yellow zinc chromate flange head cap screws.

[First c10]

Looks great. I like the bolts. I just used the originals....just cleaned them up.

What did you do for the VSS and the 4X4 low switch? The ecm needs to see 4low and the 241c just closes a contact at 4wd high and low? I think I am going to have the switch for 4wd goto a light and add a switch to the shifter housing for 4low.

[A1971Blazer]

Originally Posted by First c10

Looks great. I like the bolts. I just used the originals....just cleaned them up.

What did you do for the VSS and the 4X4 low switch? The ecm needs to see 4low and the 241c just closes a contact at 4wd high and low? I think I am going to have the switch for 4wd goto a light and add a switch to the shifter housing for 4low.

It has the VSS already....and I'm like you, I think just an indicator lamp for 4WD and call it good. With the VSS on the output side it will measure actual output speed regardless of TC position. If I'm thinking correctly, I don't think it will matter to the ECM.
Now if it was on the transmission output before the TC...yea, I think it would confuse the ecm...at least the speedometer?

[First c10]

Originally Posted by A1971Blazer

It has the VSS already....and I'm like you, I think just an indicator lamp for 4WD and call it good. With the VSS on the output side it will measure actual output speed regardless of TC position. If I'm thinking correctly, I don't think it will matter to the ECM.
Now if it was on the transmission output before the TC...yea, I think it would confuse the ecm...at least the speedometer?

I agree with you, but somewhere I read that the Ecu needs to know when it is in low range.... I am not sure why. Maybe shift points are different or shift firmness is less???
I changed the harness wire from the 2008 style to the 1991 style and even ordered a new VSS just to make sure I am good.(the one with the TC had a broken connector on one side.)

[A1971Blazer]

Originally Posted by First c10

I agree with you, but somewhere I read that the Ecu needs to know when it is in low range.... I am not sure why. Maybe shift points are different or shift firmness is less???
I changed the harness wire from the 2008 style to the 1991 style and even ordered a new VSS just to make sure I am good.(the one with the TC had a broken connector on one side.)

Well, I hope not....my pcm is from an '02 TransAm........so it may really get confused? So I say......"just put her in Lo and stand on the skinny pedal......

I went ahead and ordered a new VSS too....my tranny is going to the shop this week too to get the output shaft changed and do the upgrades. As soon as it comes back, I will be ready to start fitting the engine and driveline in.

I still have to rebuild and re-gear both axles. I can't make up my mind if I want to run a 2½" lift with 33" tires and 4.10 gears, or 4" lift with 35" tires and 4.56 gears......I am gonna run a truetrac rear for sure.

What tire size/gear are you running?

[First c10]

I am running a 33/12.50-15 dick Cepek with 15x10 Alcoa's with 3.73 axles. 4" lift. It should be fine as I don't think my son will be rock crawling in it. Well you never know.

[First c10]

Tread pattern

[A1971Blazer]

Nice...! never under-estimate what a son will do......
My son and I have been into wheeling for a long time. We built my Jeep then built him one too. If his breaks.....well it's his!

I'm building this one for a driver and probably an heirloom for my grandson who's 7 now, so I don't want to get too aggressive with it but I do want it to be "capable" if the need/itch arises.

[First c10]

This's one place I heard about the 4wd to ecm issue. Vss???

I agree to never under estimate a son. I have 2 that are older. My middle son we built a 70 c10 and he takes care of it pretty good for 16.
Nice to plan to leave a truck for the grandson. That is cool. I am sure I will be there one day. But not yet they are to young to have kids. Lol.

[A1971Blazer]

Originally Posted by First c10

This's one place I heard about the 4wd to ecm issue. Vss???

I agree to never under estimate a son. I have 2 that are older. My middle son we built a 70 c10 and he takes care of it pretty good for 16.
Nice to plan to leave a truck for the grandson. That is cool. I am sure I will be there one day. But not yet they are to young to have kids. Lol.

My oldest son is 36......damn that makes me feel old but I started young with my kids.

I have so far to go that I'm not gonna worry too much about the VSS/4WD issue for now. I guess we'll just cross that bridge when we get there?

One more thing, does your 241 have the companion flange on the front output?
This one does and I have ordered a CV yoke that I think will fit. It measures out the same according to the dimension specs. This one has a stamped metal seal protector pressed on. I may have to make one if it doesn't fit the new yoke....or I may not even need it?

[First c10]

Here is a pic of my front drive line connection. Not sure why my pictures are 90* out all of a sudden.

[A1971Blazer]

Originally Posted by First c10

I agree with you, but somewhere I read that the Ecu needs to know when it is in low range.... I am not sure why. Maybe shift points are different or shift firmness is less???
I changed the harness wire from the 2008 style to the 1991 style and even ordered a new VSS just to make sure I am good.(the one with the TC had a broken connector on one side.)

First...............you got me losing sleep over this now....
I've got a real good 700R4 laying around........that would solve the 4lo PCM issue.......also got the adapter that came with the TC.......and the 4WD output shaft I have is the same as the 4L60........since my motor is DBC it won't make much difference. A few less wiring issues too......talk me into it or out of it........????

[First c10]

Never was my plan to have you loose sleep unless it staying up late working on the truck.
I vote to keep the package together. I would just ask your harness builder (I think psi) about it. I am building my own harness from the stock one. I have added a few pins to my harness for a few things so even if your harness guy didn't add anything for 4x4 can't be too hard to do. I am thinking a micro switch for 4low on the shifter should be good.

[A1971Blazer]

Originally Posted by First c10

Here is a pic of my front drive line connection. Not sure why my pictures are 90* out all of a sudden.

I'm gonna switch to this....I pressed the stamped flange off the square flange, and it will fit perfectly on this CV yoke.

[First c10]

Isn't the stock cv joint a bolt on flange that bolts to the square flange? This is something I haven't worked on yet. So I am not sure.

[A1971Blazer]

Originally Posted by First c10

Isn't the stock cv joint a bolt on flange that bolts to the square flange? This is something I haven't worked on yet. So I am not sure.

Probably is, I wasn't sure......this old blazer had a CV front yoke on the 205 transfer case and the CV and drive shaft slip joint is shot........I had to get a yoke either way....and I have a good CV unit I can use to build the front drive shaft. I just never used the flange type before......it looks plenty healthy though.

[clinebarger]

Originally Posted by A1971Blazer

First...............you got me losing sleep over this now....
I've got a real good 700R4 laying around........that would solve the 4lo PCM issue.......also got the adapter that came with the TC.......and the 4WD output shaft I have is the same as the 4L60........since my motor is DBC it won't make much difference. A few less wiring issues too......talk me into it or out of it........????

The worst thing that will happen is....You may hit the rev limiter before the transmission can shift at WOT in 4/lo, And may set wrong ratio codes if you were to hit 4th/Lock-up for a good bit while in 4/Lo.

Hitting the rev limiter is also possible on a 700R4....In high range, Because the Governor is on the trans output shaft. Tune the Governor for 4/lo or high range? GM tuned for high range. It will be opposite from a ''E", Shift normal in High range then shift way early in 4/lo. It would also AT LEAST need to be a "K" case 700R4.


Use the 4L60E, If for nothing else.....The stiffness of a modular trans case, And the bellhousing is structural member of aluminum block LS engines, Though "YOU" could make a good strong dust cover

Your 0411 PCM is easily tuned for 4/lo shift tables! Don't sweat this stuff.

[First c10]

All I can say is damn I need to get out and get working on this truck. Great information guys.

[A1971Blazer]

Originally Posted by first c10

all i can say is damn i need to get out and get working on this truck. Great information guys.

x2.................

[First c10]

I picked this up yesterday with the 91 suburban frame I got. Can or have you measured the length needed for the front driveline??? If so do you mind sharing?

[A1971Blazer]

Originally Posted by First c10

I picked this up yesterday with the 91 suburban frame I got. Can or have you measured the length needed for the front driveline??? If so do you mind sharing?

................I'm a long way away from measuring for drive shafts(s)...

I just yesterday brought my frame back into the garage. I did get the TC all re-assembled and I'm waiting on the transmission.

I still have to get my lift kit installed, re-build and re-gear both axles, and fabricate my motor mounts and cross members.

THEN I can get drive shaft lenghts....

[First c10]

What your not done with that truck yet???

I was just wondering the length if you had figured it out yet. No worries I can wait!!!

[A1971Blazer]

Originally Posted by First c10

What your not done with that truck yet???

I was just wondering the length if you had figured it out yet. No worries I can wait!!!

My progress is really SLOW!.......

I originally intended to use the NP205 TC and mount everything using it's original location. When I disassembled the TC, it had some major issues and adapting it to the 4L60 was gonna be more costly and time consuming. That when I started looking for a 241. Using it will change the entire scenario....

[A1971Blazer]

OK..............slowly but surely......

Got the tranny back with all the upgrades and 4wd output shaft installed.....
new core support from GMC Paul's leaned up behind it too....


Got the correct adapter.....4-7/16" long.....clocking looks like it may need some massage..?....
PFab swap mount is on the way.
I could make it but time is more expensive right now....

Mock up with bare tranny case....wish I had a bare block too.....!


It ain't a lot.......but it's a start.......
plan is to get the motor and all the drive line in, all the fab work and all necessary holes drilled.....
then pull apart, sand blast, and re-furbish from the ground up.

You can see where I hit the frame and top of the front chunk while I was blasting some other stuff......then just rattled canned it.
Amazing how even cheap paint will stick to blasted bare metal.
Just had to make a teaser to keep me going......

[A1971Blazer]

This has taken some time too........but I gotta make it easier....

Body jig/rotisserie