L83 6L80 Chevy Chevette swap (Help needed)

[AlanDC]

Hi all, I have a 1987 Chevy Chevette (Stock car is below the 2200lbs dry weight) LT swapped with a L83 and 6L80 combo, out of a 2017+ Silverado. The transmission has a shift kit partially installed (just the pump valving, not the valve body components). I?m running to an issue when the transmission is shiffting up/down the rear tires slips a little making the ride very unconfortable, specially when downshifting (Specially 4-3 3-2). I?ve tried to lower the up/downshifting pressures and had little improvement, but the tires still spinning. Can anybody please help me out on what parameters should I check to address this part? Also the downshifting pressure tables has a lot of "???" on it (please see img).

TCC is only aplying on 5th and 6th.

Also, how can I lower the gas pedal sensibility, in order to get the car more driveable at low speed? i.e. when parking it?

hpt file attached. Thanks!

[edcmat-l1]

Yeah, uh, we're gonna need pics of said 87 Chevette with L83 crammed in it LOLOL

I don't have an answer for you, but I will say I am not a fan of increasing trans pressure mechanically only to then have to try and back it down via tuning. To me it doesn't make sense.

[AlanDC]

Yeah, uh, we're gonna need pics of said 87 Chevette with L83 crammed in it LOLOL

I don't have an answer for you, but I will say I am not a fan of increasing trans pressure mechanically only to then have to try and back it down via tuning. To me it doesn't make sense.

Hey! for sure. You can check it on my social media accounts IG: dsr_garage tiktok: dsr_adc

[edcmat-l1]

Hey! for sure. You can check it on my social media accounts IG: dsr_garage tiktok: dsr_adc

I'm allergic to social media. This is as social as I get LOL

[AlanDC]

but I will say I am not a fan of increasing trans pressure mechanically only to then have to try and back it down via tuning. To me it doesn't make sense.

Totally agreed. The thing is, I did the shift kit to prevent premature wear of the valving (didn?t know the cons of it).

I?ll share 2 links you can check it without logging on social media hehe
https://www.instagram.com/p/CwSt73Sgf_N/
https://www.instagram.com/p/CxTSc7pA2m7/

[GHuggins]

I'm going to go ahead and tell you pedal sensitivity isn't necessarily something easy to address. It might wind up requiring you to alter the pedal progression and throttle rate/area tables that are in the background on top of the DD and torque model tables. Since the engine is unaltered VE dial in won't help any in this case. You can start by changing the airmass tables counter to how you modified the MAF scaling. In other words if you added 10% then take that much out.

[AlanDC]

I'm going to go ahead and tell you pedal sensitivity isn't necessarily something easy to address. It might wind up requiring you to alter the pedal progression and throttle rate/area tables that are in the background on top of the DD and torque model tables. Since the engine is unaltered VE dial in won't help any in this case. You can start by changing the airmass tables counter to how you modified the MAF scaling. In other words if you added 10% then take that much out.

That's exactly what I thought, being a Gen V. Thanks for the input.

[easttxss]

I bet that's a blast to drive (when you get it right). I had a Chevette with a small block and TH400 with a 325hp nitrous plate that would wheelie 150'. Ran 6.399 in the 1/8 mile.

[AlanDC]

I bet that's a blast to drive (when you get it right). I had a Chevette with a small block and TH400 with a 325hp nitrous plate that would wheelie 150'. Ran 6.399 in the 1/8 mile.

Absolute blast man. With the only issue being the trans behavior. I have a 98 C1500 (L33+4L80e) that now feels like a "ship" to drive

[easttxss]

Switch it over to a TR6060, problem solved.

I had a friend in Houston back in the early 90's that built a '78 Chevette with a 350, Muncie 4-speed on the stock rear end. Would fry the tire at freeway speed. Made one pass down the drag strip, smoking the tire the whole way. Second pass snapped the pinion extension. Then went in the 4 link and 9". That car inspired me to build my own.

[AlanDC]

Switch it over to a TR6060, problem solved.

I had a friend in Houston back in the early 90's that built a '78 Chevette with a 350, Muncie 4-speed on the stock rear end. Would fry the tire at freeway speed. Made one pass down the drag strip, smoking the tire the whole way. Second pass snapped the pinion extension. Then went in the 4 link and 9". That car inspired me to build my own.

That's one of the options for sure. Rear end is one concern too. There's some upgrade levels depending on power output.

Now I'm running on stock rear end. Waiting for a lower gearing. From 4.11 to 3.45

Level 2 is stock axle housing (dana 26) with billet axles and spool (sourced from Brazil).

Level 3 is a built dana 44, but there's some fabrication involved on it.

[[email protected]]

Yeah, uh, we're gonna need pics of said 87 Chevette with L83 crammed in it LOLOL

I don't have an answer for you, but I will say I am not a fan of increasing trans pressure mechanically only to then have to try and back it down via tuning. To me it doesn't make sense.

I'm just here for the pics...

[snives]

I had a look at your tune. Your transmission torque management is maxed out, all your trans output, axle, propshaft torque figures are maxed out. The ECM has no visibility to manage torque during a transient. Not withstanding mechanical aspects of your shift kit contributing to the issue, but, that's the first thing I would change.

The gas pedal sensitivity can be addressed with the driver demand table.

In general though, my approach to isolating the problem would be to flash back to stock and see if you can recreate it, if not, then you know somewhere along the line you made tuning edits which cause that behavior.

[AlanDC]

I had a look at your tune. Your transmission torque management is maxed out, all your trans output, axle, propshaft torque figures are maxed out. The ECM has no visibility to manage torque during a transient. Not withstanding mechanical aspects of your shift kit contributing to the issue, but, that's the first thing I would change.

The gas pedal sensitivity can be addressed with the driver demand table.

In general though, my approach to isolating the problem would be to flash back to stock and see if you can recreate it, if not, then you know somewhere along the line you made tuning edits which cause that behavior.

Thanks for the input. It resulted on a Cyl #6 missfire that was getting the AFM, VVT off and the trans was acting weird (also temps were on the high side). I fixed it and now it works perfect!!!