Manual shifting your auto for engine braking

[GrimsterGMC]

I was just thinking, how many of you manually downshift your autos to make better use of the engine braking. I have a 1988 GMC K1500 with the 350TBI and 4L60 that has been changed to a B&M Hammer shifter in the centre console. This is a ratchet shifter that selects one shift at a time. It is excellent when you are bouncing around on a rough dirt road etc. I have noticed in the pictures you all post that most of your trucks are still column change so that got me thinking is it common practice to downshift going into corners, coasting down steep grades etc or do you just let the auto do it's own thing and also whether being a column shifter is a factor in that? I would love to hear some feedback and also whether you have changed to floor shift for this reason.

 

[df2x4]

Very rarely. When my dad had a house at Lake of the Ozarks there was a very steeply graded gravel road leading down to it. Every time I went down there I'd put the trucks in manual first and just coast down at about 5MPH. Don't think I've done that since he got rid of that place.

 

[Schurkey]

On ancient, manual-transmission cars, engine braking was a big deal. Some of them didn't have brakes on the front wheels.

Buicks tended to have the biggest/best brakes of the GM Sisters, because the Dynaflow transmission had really-crappy engine braking.

With the end of the Dynaflow (and the functionally-similar but fragile Chevy "Turboglide") family of transmissions at the end of '63 model year, virtually all auto-trans vehicles had automatics with at least some amount of drag in "Drive", and strong engine braking in the lower gear(s) via transmission brake bands.

That said...use your brakes for braking. Let the trans stay in "D" or "OD" unless you've got a LONG down-hill stretch where the wheel brakes could overheat. It's crazy to make the transmission do the job the brakes were intended to do as a routine procedure. Brake pads 'n' shoes (and even rotors and drums) are cheaper to replace than transmissions.

 

[618 Syndicate]

Engine braking is fine. It's a feature on transmissions with a tow/haul setting which holds gears longer on both accel and decel.

 

[Supercharged111]

I'll do it with a load, but not for every red light or stop sign. More in the instances Schurkey pointed out, a prolonged grade that could cook the brakes.

 

[0xDEADBEEF]

It will work better if you can lock the torque converter. Because of the fluid connection you are working the trans fluid more than normal which heats it and shears it over time. Trans cooler recommended, more frequent fluid changes, etc.

 

[GrimsterGMC]

Thanks for the replies, sometimes I get thinking about random stuff and wonder what other perple do in the same situation. The 4L60 will over run in O/D but will brake in 3rd. As my truck only has the JB3 brakes I have been in the habit of pulling it back into 3rd when slowing for a give way or slow bend. Also, when I coast into low speed a left turn in O/D (right turn for you guys in the US) the trans will downshift itself, but as soon as I touch the gas it jumps up into O/D and quickly back to 3rd again as I roll on the gas, so it avoids this happening.

 

[Schurkey]

As my truck only has the JB3 brakes

Upgrade the brakes, give the trans a break.

Also, when I coast into low speed a left turn in O/D (right turn for you guys in the US) the trans will downshift itself, but as soon as I touch the gas it jumps up into O/D and quickly back to 3rd again as I roll on the gas, so it avoids this happening.

Is the trans SHIFTING, or are you feeling the torque converter clutch?

First Guess: The TCC is disengaging/engaging with throttle. The vehicle is set up to disengage the TCC at low throttle opening, and then reingage the TCC when the throttle is opened again. GM specifically does not want the TCC engaged when slowing.

 

[L31MaxExpress]

I do it all the time in my Express, it is heavy and the 4L85E has no issue with engine braking. Even bumping it down to 3rd engages the over run clutch to provide additional engine braking.

No sense burning up the brakes and burning the fuel that would otherwise be used idling the engine while slowing down from highway speeds on an off ramp. Engine braking will actually slow you down more quickly as well. With my 4L85E, I can pull the shifter into 1st at 80 mph if I want and the trans will downshift at points that do not over rev the engine yet allow for strong engine braking.

In tow/haul I have my 0% TPS shift points higher than the next cell in the table by a considerable amount to allow for coasting downshifts. To get much engine braking with a 700r4, 4L60E or 4L80E requires the shifter be in 3rd or lower though. I mostly use 3rd in town though and have for years.

 

[PWC Repair]

I've used downshifting when towing forEVER. Have never had a trans go out on me, including my old Jeep with 4.0 and 42RE, and my S10 Blazer with 700R4.....both of those transmissions people are always whining about NEVER gave me any issues. I do it now towing with our Nissan Xterra. Now, when NOT towing and I need to stop quicker I pop it in Neutral.