Manual shifting your auto for engine braking

[L31MaxExpress]

These were the average temps.

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These were the minimum temps

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I like that the temps stay within a ~20°F range once it is up to temp regardless of speed, load or ambient temp. I have a 160F thermal bypass which could lead to problems but it has been rock solid thus far. Running at 156F it seems that in some cruising conditions the 4L85E does not even need external cooling other than what it recieves from airflow over the pan and unit. I see guys installing the Trucool 40K on these without a bypass and know that their trans is overcooling in cool weather.

 

[99xcss4]

454 TBI that I put a 4L60E behind.

why would you put a 4l60e behind a big block that seems like a bad idea to me

 

[L31MaxExpress]

why would you put a 5l60e behind a big block that seems like a bad idea to me

It was a fresh and built up transmission in a 1995 2 door 4x4 Tahoe. My friend blew up the 350 and had a 454 TBI from a wrecked 2wd truck. It is still running today with the same 4L60E. Using the 4L60E was a time/budget move since the 4L80E and transfer case would have needed to come apart and both driveshafts modified. The 454 was esentially stock save for a mild roller cam upgrade and tuning. It has 4.10s and 33s. The thing that has probably saved that 4L60E from demise is relatively weak TBI 454s output, low maximum upshift rpms, and the rudimentary shift torque management GM used in the TBI computers. It cuts the ignition timing to -5° during all upshifts killing off most of the torque output. The PWM valve was also modified and I tuned PWM out of the lockup. I also re-shaped the line pressure mapping to give the 4L60E full line pressure by 33% throttle given the larger 454 throttle body and peak torque under 2,000 rpm. Against common wisdom it has held together though.

 

[GrimsterGMC]

You're correct...Pressures below are a good generalization of what to expect from the 700R4:

PND,D3: 60-75 PSI at idle
R: 90-110 PSI at idle
2/L: 165-190 PSI at idle

Depends on what boost valve and pr spring are used and assumes TV cable geometry and adjustment are optimal.

That would explain the harsh shifting I experienced when downshifting manually, despite a closed throttle, but smooth when trans downshifted automatically.

 

[Scooterwrench]

Hey Nick,
I bet you know the answer to this. My throttle gets heavy when I fire up and even heavier when I put it in gear. Feels like line pressure is pulling against the TV. Makes feathering the throttle a little tough. TV is adjusted to full extension at WOT.
I'm running a 700R4.

 

[Scooterwrench]

You're correct...Pressures below are a good generalization of what to expect from the 700R4:

PND,D3: 60-75 PSI at idle
R: 90-110 PSI at idle
2/L: 165-190 PSI at idle

Depends on what boost valve and pr spring are used and assumes TV cable geometry and adjustment are optimal.

I knew this was the get smart place!!!

 

[NickTransmissions]

Hey Nick,
I bet you know the answer to this. My throttle gets heavy when I fire up and even heavier when I put it in gear. Feels like line pressure is pulling against the TV. Makes feathering the throttle a little tough. TV is adjusted to full extension at WOT.
I'm running a 700R4.

What are your line pressures at idle and stall?

 

[Scooterwrench]

What are your line pressures at idle and stall?

I'll have to get back with you on that,having to do a little recovery.

 

[Pinger]

the rudimentary shift torque management GM used in the TBI computers. It cuts the ignition timing to -5° during all upshifts killing off most of the torque output.

On a Vortec, is it the same (ignition timing retard) or is the fuelling interrupted?

 

[Scooterwrench]

I wouldn't think they would lean out the fuel for a shift. Seems that could create a stumble and spike in combustion temps.