4l80e conversion in 1985 suburban. What parts do I need?

[NickTransmissions]

Installed the transmission and drove the first time today. Either this shift tune is bad, or something else is off. This thing feels like a dog now, shift points are too low and worst of all, this thing shudders like a mother when the converter locks up in 4th gear.

Perform a driving line pressure test. Short shifts and TC shudder is likely low LP across the board, which is probably C3-driven. If LP is low, contact the company that man'ed or sold the controller for tech support, if you havent already done so.

 

[txaggie]

Perform a driving line pressure test. Short shifts and TC shudder is likely low LP across the board, which is probably C3-driven. If LP is low, contact the company that man'ed or sold the controller for tech support, if you havent already done so.

Thanks Nick. It’s a Holley sniper trans controller and all the line pressure looks to be pretty similar.

Perform a driving line pressure test. Short shifts and TC shudder is likely low LP across the board, which is probably C3-driven. If LP is low, contact the company that man'ed or sold the controller for tech support, if you havent already done so.

What is “C3 driven?”

 

[NickTransmissions]

Thanks Nick. It’s a Holley sniper trans controller and all the line pressure looks to be pretty similar.

What is “C3 driven?”

C3= communication, command and control.

What exactly are your line pressures for all range positions at idle and at stall?

 

[txaggie]

C3= communication, command and control.

What exactly are your line pressures for all range positions at idle and at stall?

Found the issue. Shudder is most likely a burnt plug wire and dead cylinder:

 

[txaggie]

Perform a driving line pressure test. Short shifts and TC shudder is likely low LP across the board, which is probably C3-driven. If LP is low, contact the company that man'ed or sold the controller for tech support, if you havent already done so.

C3= communication, command and control.

What exactly are your line pressures for all range positions at idle and at stall?

Nick,

After we got the plug wire fixed, it drives pretty good. However the second gear shift is really hard and others are not. Also, after normal highway driving, this thing heats up to 210 ish with nothing being pulled and I have an extra Derale cooler in junction with our radiator cooler. Does this seem a bit high? The turbo 400 without pulling wouldn’t get above 180-190.

Today is hot though, 98 degrees.

 

[txaggie]

Nick,

After we got the plug wire fixed, it drives pretty good. However the second gear shift is really hard and others are not. Also, after normal highway driving, this thing heats up to 210 ish with nothing being pulled and I have an extra Derale cooler in junction with our radiator cooler. Does this seem a bit high? The turbo 400 without pulling wouldn’t get above 180-190.

Today is hot though, 98 degrees.

Just went and drove the crap out of it. Trans temp warmed up to 205 and then cooled back to 198.

I’ll take this to my buddy this next week and get it tuned (engine and trans).

 

[NickTransmissions]

Nick,

After we got the plug wire fixed, it drives pretty good. However the second gear shift is really hard and others are not. Also, after normal highway driving, this thing heats up to 210 ish with nothing being pulled and I have an extra Derale cooler in junction with our radiator cooler. Does this seem a bit high? The turbo 400 without pulling wouldn’t get above 180-190.

Today is hot though, 98 degrees.

Try to keep temps at 175-180 or so for optimum performance if running conventional Dex-Merc. Check for any restrictions in the system, in the lines, and coolers. As far as the harsh 1-2 shift, that could be overly agreessive mechanical calibration such as 1-2 feed orifice drilled too large for the converter stall.

 

[txaggie]

Try to keep temps at 175-180 or so for optimum performance if running conventional Dex-Merc. Check for any restrictions in the system, in the lines, and coolers. As far as the harsh 1-2 shift, that could be overly agreessive mechanical calibration such as 1-2 feed orifice drilled too large for the converter stall.

Thanks. We are running BG full synthetic ATF because we sell it in bulk in our shop. After driving it again today, it appears that it stays at around 170-190 while driving on the highway at lockup. When I get in stop and go traffic (20-40 mph), this is when the temp climbs. Once I stop all the way, it starts to cool back down. Maybe our 1900 stall is hitting the sweet spot at this speed and I’m just slipping?

I’m gonna take this thing to get the Holley Sniper programmer tuned for both engine and trans. Maybe this will help?

 

[NickTransmissions]

I’m gonna take this thing to get the Holley Sniper programmer tuned for both engine and trans. Maybe this will help?

That should definitely help and make the whole powertrain perform better. The TC produces most of the heat that permiates through the transmission so tuning should help bring the heat down a bit. Plus full synthetic is perfectly fine up to about 220 or so, perhaps a bit beyond.