emptnest

Most of us agree that deceleration at track speed should be accomplished using the brakes and not by gearing down. The old saying is that brakes are cheaper than transmissions.

I abide by the above when on the track.

But my towing vehicle ( a GMC 2500, 6.0 liter, 6 spd automatic) has an automated engine brake system that kicks the truck into a lower gear, using engine compression to reduce application of the brakes on downgrades. I love it and use it.

Are these opposite practices contradictory, or am I comparing apples and oranges?

How do you operate your towing vehicle?

JeremyGSU

Apples and Oranges. Towing vehicles and transmission setups for towing were designed to do that. It's used to assist with braking to both help slow the vehicle and make sure it's in proper gear.

Slowly a racing car at high speeds by using the transmission is a different scenario.

JerryTX

My Ecoboost in tow mode gears down as well.. its not a jake brake on a turbo diesel but it still aids when I'm towing. The reason I'm ok with using the trans is because on a hard stop my fully loaded F150 could use some assistance so why not add a little wear (maybe) to the engine/trans by downshifting and gain some safety margin.

05dsom

Just towed my ZR1 to the Glen for the first time ever 2 hours ago, (towing not tracking!) and noticed the same thing with my QX56....disconcerting at first, but I quickly figured out that engine braking was set up in "tow mode" on my SUV, especially downhill around Seneca Lake

SouthernSon

Threshold, and especially, trail braking requires a good bias on the track. Downshifts with varying rpm parasitic drag plus braking messes this all up. As was posted above, apples to oranges. On the street you are more concerned with effective straight line braking. If you should find yourself in a panic stop while pulling a trailer, believe me, the trailer will shift plenty of weight to the rear axle of the tow vehicle to make effective brake bias with the added tranny drag. Which brings up a very interesting aspect of loading the trailer properly.

mikeCsix

On top of the excellent comments already made, using the engine/transmission to assist braking will also help keep your brakes cooler.

huskychopper

My perspective is that exhaust brake on the newer trucks are great, for CONTROLING the load for long periods of time where the brakes would heat and fade. You said it, on down grades...

An open car trailer with electric brakes shouldn't stress a good trucks brakes. A 20Klb load could save some brake wear by running the exhaust brake all the time. Either way I don't think you are going to hurt that Allison towing, as long as you're not adding too much extra power to the engine...

I'm in Colorado. When my trailer is hitched on my exhaust brake is on and I'm in tow/haul mode. I run the exhaust brake in the mountains when I have heavy loads in the bed as well, but not in tow/haul.