L31/6L80e

[97Centurion]

How did you get TPS and tach to the TCM2650? I also have the 411 PCM but use 24x ignition so tach signal is generated from the PCM.

T-taps right into the 5v wires of the tps and the ignition coil. I connected them a little over an inch away from their plugs for the cleanest signal.

What's your setup?

 

[97Centurion]

This is awsome! Just a couple simple questions if you can answer. 1 bellhousing bolt pattern, i was under the understanding ls motors had a diff belhousing bolt pattern than gen 1 sbc motors. 2. What torque converter and flywheel did you end up using? Im getting confused with how you wrote it. 3. Have you noticed a diff in fuel economy? And thats about it lol seems super simple and the only thing left up to figure out is driveshaft attachment and length which seem its gonna depend on exactly what trans and what it came out of. Thank you for your time!

Thank you!

1. Bellhousing bolt pattern is no issue, as previously mentioned by Grimpala. It bolts right up!
2. I used a stock 6L80 torque converter mated to the stock L31 flexplate. You will have to modify your flexplate and waller out the holes where the torque converter bolts go through. Just match them up together to know where to waller. I had an LM7 flexplate from a previous project that has the same bolt pattern as the 6L torque converter and used it as reference.
3. I haven't driven it a lot to notice any gains or losses. I will happily report back once I get my shifting smoothed out.

Is your truck 2wd or 4wd?

 

[letitsnow]

Last I did the math, to match my 4.10/4L80 in OD the 6L would need a 3.73 in 5th to be comparable.

Are you going to do it?

I've also looked at the TCI 6 speed - I like the gear spread better in that, but its probably over $8,000 all done...

 

[Old 96]

Thank you!

1. Bellhousing bolt pattern is no issue, as previously mentioned by Grimpala. It bolts right up!
2. I used a stock 6L80 torque converter mated to the stock L31 flexplate. You will have to modify your flexplate and waller out the holes where the torque converter bolts go through. Just match them up together to know where to waller. I had an LM7 flexplate from a previous project that has the same bolt pattern as the 6L torque converter and used it as reference.
3. I haven't driven it a lot to notice any gains or losses. I will happily report back once I get my shifting smoothed out.

Is your truck 2wd or 4wd?

Super interested in this swap!! a few Q's. Does the factory speedo work? If so, what VSS are you using? And using the factory column shifter if left in Drive, will it shift thru a 6 gears as a normal new truck/car? I'm thinking I could regear the rear to 3.08 and have better acceleration thru the gears and match the current 3.73/4l60 overdrive up top. Appreciate any info you can share!!

 

[Blad]

Thank you!

1. Bellhousing bolt pattern is no issue, as previously mentioned by Grimpala. It bolts right up!
2. I used a stock 6L80 torque converter mated to the stock L31 flexplate. You will have to modify your flexplate and waller out the holes where the torque converter bolts go through. Just match them up together to know where to waller. I had an LM7 flexplate from a previous project that has the same bolt pattern as the 6L torque converter and used it as reference.
3. I haven't driven it a lot to notice any gains or losses. I will happily report back once I get my shifting smoothed out.

Is your truck 2wd or 4wd?

2wd. Do you see any issues due to that since urs was 4wd?

 

[97Centurion]

Super interested in this swap!! a few Q's. Does the factory speedo work? If so, what VSS are you using? And using the factory column shifter if left in Drive, will it shift thru a 6 gears as a normal new truck/car? I'm thinking I could regear the rear to 3.08 and have better acceleration thru the gears and match the current 3.73/4l60 overdrive up top. Appreciate any info you can share!!

Factory speedo works using the stock sensor and it shifts through all gears in drive. Not like a new vehicle...yet, as I need to tune the upshift from 2nd to 3rd and all the downshifts. Aside from that, it upshifts flawlessly!

 

[letitsnow]

Factory speedo works using the stock sensor and it shifts through all gears in drive. Not like a new vehicle...yet, as I need to tune the upshift from 2nd to 3rd and all the downshifts. Aside from that, it upshifts flawlessly!

Can you adjust the speedometer with that trans controller, say if you added bigger tires?

 

[JeremyNH]

T-taps right into the 5v wires of the tps and the ignition coil. I connected them a little over an inch away from their plugs for the cleanest signal.

What's your setup?

I have a 98 K1500 5.7L. My base tune for the 24x is a 2002 Silverado which uses the BCM for producing signal to the dash tach. Since the 98 doesn't have a BCM the tach is generated from the PCM (can't get it from the ICM any more since I no longer have one). So it looks like you just tee tap the signal wire for the TPS and the tach for input to the TCM. Easy enough just wanted to make sure I had it right.

 

[97Centurion]

2wd. Do you see any issues due to that since urs was 4wd?

I don't think so. You may get away with not having to modify driveshaft length, but will have to adjust the length for the crossmember trans mount such as I did with my 4wd. It almost seems that the 6L90 would more match length from bellhousing to tailshaft.

 

[97Centurion]

Can you adjust the speedometer with that trans controller, say if you added bigger tires?

Yeppers! To include changing the gear ratio if need be.