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I just checked, and the cable swivel end won't even connect to the 6L80 linkage. The "ball" on the 6L80 linkage is way smaller than the one on the 4L80. Sooooo, it looks like I'll have to get a completely new shifter cable.
You can also just put a different "ball" on the 6l80e shift arm
They're usually just a flared end on the bracket. You can grind it then punch it out
Do the same with the 4l80e arm
And then swap the ball and weld the back side.
As for the linkage bracket yes you'll need to make a new one
Alternatively, to make this all easier, I believe all of these cables are 2 piece. You can get a lower half cable from an 07-13 truck/tahoe/suburban etc and swap that lower half out with your current cable.
That way the spacing and ball should all just be correct.
Then just adjust it into spec
Alternatively, to make this all easier, I believe all of these cables are 2 piece. You can get a lower half cable from an 07-13 truck/tahoe/suburban etc and swap that lower half out with your current cable.
That way the spacing and ball should all just be correct.
Then just adjust it into spec
That would be ideal, but I don't think mine is a 2-piece. I don't see the white collar and two springs connection that the trucks have. It's just a slick cable all the way up into the car. I haven't taken the interior apart yet. I did watch one youtube video of a car like mine, and there was no 2-piece connection place. So, it looks like a 1-piece cable assembly...unless I'm missing something.
If yours is the one piece, then just swap the ball end on the shift arm and make a custom bracket
That's the direction I am heading now. So far, I have not been able to find the shift lever with the "big ball" on the end. I already sold the 4L80, and I left the shift lever on it. I didn't think it was such a rare part. If I can't find one, I was thinking about using a bolt/nut to hold the end of the cable to the shift lever. Either way, I have to "shorten" the cable mounting bracket about 2". I'm going to try to do that this weekend. More to come....
I started working on the wire harness. I just have it "temp" routed for now. I'm not sure if I'll leave it where it's at, but this is a start. I still have to figure out how to "tap" into the throttle position sensor and the engine rpm. This wire harness did not come with any installation instructions. It only comes with software download and set-up instructions.
New harness plugged into trans. Old harness zip tied out of the way for now. New and old harness routing. this is just a mess. I'll clean it up later. The new TCM is tucked away down behind the fender. It's still in the ESD plastic bag. I was thinking about attaching the ground wire and hot (12 vdc) here. The OBD-2 can be zip tied down there somewhere.
I also got the new Sonnax slip yoke swapped out and installed on the original (stock) driveshaft.
I made some progress on the shifter cable bracket today. I basically just applied some heat with a propane torch, and bent the bracket with a 24" crescent wrench. I needed to straighten it out before I could slide it forward and re-attach it. I tried to drill the holes a little higher on the bracket so that it would sit slightly lower. I might have to make some slight adjustments on the cable, but it should be pretty close to lining up with the shift lever. I still have to get the old shift lever back from the 4L80 I sold. It has the bigger "ball" on it that the cable fits onto. Here are some updated pics:
Stock configuration After straightening out the long part. The bracket hole was at the wrong angle for the cable so.... I straightened out the bracket hole to about 90 degrees. It was too thick for the cable seat all the way onto, and the hole was too small. I thinned-out the bracket hole area, and enlarged the hole. All done, and painted.
I got some help this past weekend to cut and weld the crossmember. We basically cut a chunk out of the tube, turned it around, and welded it back in. The tube had to be cut about 1/2" for the mounting bolt to clear. Welding the cut out piece back inside was done for support. The flat plate had to be moved to the front side of the tube for the mounting bolt to line up. The flat plate was cut off about 3/8" from the mounting hole, and welded back on the opposite (forward) side of the tube. We used one side piece of the plate to support the plate from underneath. I still need to clean and paint it before installing it. I'm gonna try to do that this weekend.
BMR 4L80 crossmember before mods top view after mods bottom view after mods
Here's a better view of the bottom. It's easier to see the pieces that we welded together. I just painted it. Once it dries, I'll bolt it in the car and take more pics.
1) I got the cross-member fully bolted in. The driveshaft is fully installed. The torque arm is fully installed.
2) I had to make some more mods to the shifter cable bracket. With the cross-member fully bolted on, the bracket was too high. It caused the shift cable to hit the body of the car. So, I cut off the "C" part of the bracket and welded it lower. I was also able to get the original 4L60 shift lever back from the guy I sold the 4L80 to. With the bracket in the lower position, the original shift lever lined up quite nicely. I haven't installed the shifter bracket yet. I just painted it, so I'll try to install it tomorrow.
3) cut and spliced the throttle position sensor wire into the new TCM wire. I was finally able to get the nut loose on the relay box. I used that bolt for the battery-direct power wire on the TCM. I still have to figure out where I'm going to get a "switched" 12v power source for the TCM. I also have to "tap" into the engine speed somehow.
I'm having trouble with my iphone not sharing pics right now. I'll try to get that sorted out and post them.
It doesn't look like your driveshaft is slid into the transmission far enough. Most transmissions you can get 2 fingers between the end if the trans and the base of the yoke.
It doesn't look like your driveshaft is slid into the transmission far enough. Most transmissions you can get 2 fingers between the end if the trans and the base of the yoke.
It's in further than it looks. This is not a factory slip yoke. It was meant for a 4x4 6L80, so it's much longer. I measured the slip yoke before and after install. It has about 3" of spline engagement with the trans. The 4L80 slip yoke barely had 3" of splines.
I got the exhaust all tightened back up. I installed the shifter bracket and cable. I had to adjust the cable a little bit. My measurements for the weld were off about 1/4". No big deal. The cable fits and looks pretty straight now.
Great thread. Thanks for documenting this. Answers a lot of questions, but I have a couple.
What shifter will you use with this?
What type fitting is in the trans that you have to use the ICT adapter plate?
Do you know the weight difference between 4L60, 80 and this?
Is that TCM2650 really a grand!? lol
Last edited by 95wannabe; Jan 30, 2024 at 09:05 AM.
Great thread. Thanks for documenting this. Answers a lot of questions, but I have a couple.
What shifter will you use with this?
What type fitting is in the trans that you have to use the ICT adapter plate?
Do you know the weight difference between 4L60, 80 and this?
Is that TCM2650 really a grand!? lol
1) I am still using the stock shifter, cable, and lever. Luckily, I was able to get the original 4L60 shift lever back from the guy I sold the 4L80 to. He wasn't too far away.
2) I don't know what it's called, but it looks like the 6L80 uses a "push-in" type hard line. This pic below is the best I have that shows the opening. It looks like it has a metal-rubber seal around the opening. You can't stock use gen-4 lines with this transmission. You might be able to fabricate your own, if you're that good, but ICT Billet makes it easy.
junkyard 6L80
3) I have no idea what the weight difference is, but I'm sure it's huge. The 4L80 makes the 4L60 look small. The 6L80 looks like a 4L80 with a pot-belly. Going from a 4L60 to a 6L80 would be a huge weight difference, but sometimes necessary.
4) Yes. $975 plus shipping. I'm not an electronic engineer, so I have to pay the price.
This is the most expensive mod I have done to my car so far. I wish I could have done this instead of the 4L80 though. If you still have a 4L60, this is the swap to do. I wouldn't bother with the 4L80 if you have the budget for a 6L80. The 6L80 gives you the strength you need, and the gear ratios you really want.
[QUOTE=Utinator;20539954]1) I am still using the stock shifter, cable, and lever. Luckily, I was able to get the original 4L60 shift lever back from the guy I sold the 4L80 to. He wasn't too far away.
2) I don't know what it's called, but it looks like the 6L80 uses a "push-in" type hard line. This pic below is the best I have that shows the opening. It looks like it has a metal-rubber seal around the opening. You can't stock use gen-4 lines with this transmission. You might be able to fabricate your own, if you're that good, but ICT Billet makes it easy.
3) I have no idea what the weight difference is, but I'm sure it's huge. The 4L80 makes the 4L60 look small. The 6L80 looks like a 4L80 with a pot-belly. Going from a 4L60 to a 6L80 would be a huge weight difference, but sometimes necessary.
[/QUOTE
I understand you're using the stock cable, but what about the shifter itself? I don't understand how the 6L works...are you able to "shift" a 6 speed with a 4 speed shifter?
Do you know if paddle shifters are an option for this trans?
Understand original line won't reach around to drivers side, but does it use the same hard-line push-in type connection the 4L uses?
yeah was just curious if you had any idea the difference. I've been looking at this swap for a while and trying to decide the expense, weight difference, etc would be a good idea for me or not. I Autocross my car. Rebuilt 4L60E that I can manually shift when & were I want. I normally only use 1 & 2 gear. 98% of people use a manual trans, but that swap is approaching $5K by the time you buy a good trans, shifter, clutch PP & flywheel, pedal swap etc..
I understand you're using the stock cable, but what about the shifter itself? I don't understand how the 6L works...are you able to "shift" a 6 speed with a 4 speed shifter?
Do you know if paddle shifters are an option for this trans?
Understand original line won't reach around to drivers side, but does it use the same hard-line push-in type connection the 4L uses?
I haven’t tried shifting it yet. It was my understanding that the 6L80 vehicles still had the same 4 detents for the forward gears and same P,N,R detents. It should shift the same mechanically.
Yes, paddle shifters are an option. There is a wire in the TCM harness for that. I’m not using it though.
The hard lines are a different size. The adapter is really the only option.
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