How to control speed with a manual trans

The auto tranny with a Tow/Haul mode will control the speed going down hill.
How do you control the speed with a manual tranny with out "killing" the breaks?
Thanks

 

Exhaust brake

 

Downshift.....

It's all the auto does....

 

since a diesel is a big air pump it is VERY easy to gain speed going down hill with no weight, let alone a trailer. downshifting only helps for very small hills alone. this is why Jake Brakes and exhaust brakes work as well as they do...

when i didnt have one i was on the brakes all the time. now i only touch them durring a down shift while going down hill.

 

I say use both methods exhaust brake and downshift.

 

His question has ZERO to do with an exhaust brake. Auto equipped trucks don't come with exhaust brakes....

He simply doesn't understand how to help hold a hill with a manual trans because there is no button to push in a standard rig like his auto does, and doesn't undertand what that button does.

It's simple, the button tries to hold the converter locked and keeps the RPM's up to maximize engine compression to hold it back.

Downshifting a manual does the exact same thing, and in a whole answers what he is asking.

 

Exhaust brakes and holding power is a completely different topic than what the original poster asked.

Diesels do just fine holding weight back, after all they have 16.3:1+ compression....

The tow/haul method with the automatics in all of the big three trucks do nothing more than MAXIMIZE the use of the engine's back pressure, and their systems can do a decent job, and infact the Dmax and Ford guys rave about how well their 5spd auto touch/tap deal works. Nothing changes with a standard, and the engine has the same holding power as it does with an automatic behind, and infact it should be better with the manual.

I can hold back 8K coming down normal grades doing nothing more than downshifting my auto to 2nd gear with an UNlocked converter and just letting it run up to 3K RPM's, hardly even need brakes on most hills. I could likely even hold back more weight if I had a torque converter switch where I could manually keep it locked like the new trucks can.

Granted, exhaust brakes are nice and are great for pulling really heavy or on those really long and/or steep grades and not needing to even touch the brakes at all.

 

True the higher compression will help out more so than with a gas engine.

 

i agree, but no, it isnt near as effective as a gasser because there is nothing to slow the air coming in. my 5k trailer would get my truck going down a hill VERY fast. did he ask about an exhaust brake? no, but will you cook the brakes very easily with a substantial loar and not having one? you could, as with everything else it depends on the driver, the terain and everything else.

does a diesel with a manual slow down on its own while downshifting? not much on a hill. empty i will gain speed as if the automatic trans has been put into neutral.

i drive one every day, and have for the past 3+ years. while living in the hills i found having the brake is very helpful while pulling a trailer, no that wasnt the question.

as for the higher compression helping, yes it will... if something could stop the air entering the engine.... if you ever make it out this way ill let ya drive my truck to see what i mean...

 

oh, and i do admit, i could have gone into more detail on my first post... i was just in a hurry and should not have posted at all.

 

I disagree. A Dodge with a Cummins can hold back more weight than the same truck with a 360 V8, much more IMHO. It's all in the compression, not neccesarely a small butterfly in the intake....


Then we will agree to disagree.

 

Quoted from http://bankspower.com/tech_howexhaustbrakeworks.cfm

[FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]"Diesel engines control engine speed and power output by throttling the amount of fuel injected into the engine. A diesel has no air throttle. Because it has no air throttle, a diesel engine offers virtually no engine braking when the driver lifts off the accelerator pedal. There just isn’t a pumping loss to retard engine speed as the piston descends on the intake stroke. Air is free to enter the cylinder, restricted only by the flow capacity of the air cleaner, turbocharger compressor, intercooler, intake manifold, cylinder head port and intake valve opening. This can be disconcerting to a driver that is used to the engine braking produced by a gasoline engine, and it can be downright unnerving to the driver of a heavily-loaded diesel pickup or motorhome on a downhill grade, especially if the vehicle’s service brakes begin to overheat and fade. That’s why exhaust brakes, such as the Banks Brake, have become so popular for such diesel vehicles."[/SIZE][/FONT]

The high compression levels have nothing to do with slowing down since the engine gulps free flowing air with each stroke. Therefore, diesel engines have very limited capacity to slow heavy loads. Investing in an exhast brake is probably the safest option. And that's MHO.

 

thanks... i needed re-enforcements... lol
Grant

 

Still completely disagree. I will agree that they have no butterfly in the intake, but the compression makes a huge difference.

I've got a half dozen HD pickups, all of which have all pulled identical trailers down identical terrains. Stuff a gas engine into a lower gear and it tries to slow itself down but can't. Our diesels.... different story, barely even need an exhaust brake.

 

Well, stubborn is stubborn. I pull a 10k trailer in the Sierras with my 3500 dually and it's almost scary without an exhaust brake. AND, I've got the training and license to know what I'm doing.

So, to aid in the original question:

If you insist on not getting one then make sure you down shift and lower your speed to the "safe speed" BEFORE entering the downhill. When your speed gets above that speed, apply brakes for no more than 3-4 seconds to bring speed down 5mph under your target.

 

1) to my KNOWLEDGE, diesel motors are not as efficient as gas motors in engine breaking because there is no throttle body that is restricting airflow into the cylinders.

however....

2) according to my EXPERIENCE, even though you would think that diesel motor compression cannot produce effective breaking, i have always been able to keep the trailer at a decent speed going downhill. like RFJ said, you can pop the auto down in 2nd (or even 3rd) and the motor will keep the trailer at a manageable speed while going downhill.

you guys should also consider that diesel motors do have a much higher compression than gas motors along with much more massive engine components... since the components to a typical diesel motor are just bigger and heavier, the motors are limited to how fast they can spin (thus the lower redlines compared to gas motors)... i would think that just the mass and weight of the crank and other components would help to hold back a load more effectively than a gas motor? what do you guys think?

 

Quoted from http://www.everytime.cummins.com/every/applications/ram_braking.jsp

"Unlike gasoline engines, diesel engines produce no vacuum when you release the throttle to help slow the vehicle. The higher compression ratio of the diesel acts like a spring on the pistons, even with no fueling. An exhaust brake restricts the exhaust, making the pistons work harder...slowing the crankshaft and the truck."

Once again, COMPRESSION HAS NOTHING TO DO WITH SLOWING THE RIG DOWN! It actually makes it worse.

I'm done. It's like talking to a wall.

 

all an exhuast brake is on your baby cummins is a butterfly in the exhuast, same theory as a gas throttle plate..................

 

I don't need a lesson on driving, thanks....but no thanks. I'm not the original poster asking the questions.

I have zero problems slowing down with my automatic and no exhaust brake.

 

While one piston is traveling on it's down stroke, another is traveling on it's up stroke. The more compression you have, the harder it is for the air to compress that is in the cylinder (without fuel or with, makes no difference) and thus causes the engine to be tougher to turn over.

If compression didn't make a difference and the "spring" theory pushing back down on the piston overcame the squeeze, then big HP high compression engines wouldn't need a hi performance starter.

You'd be able to take a GM standard starter found on any stock 350 or 454 and put it on a 454 race motor with 13.1:1 compression, or even a Duramax.....but you can't.... because the higher compression makes it harder to turn over because of the higher resistance.....