Is it bad to use the transmission to decelerate

[jmd4100]

I have a 2007 1500 5.7 545-rfe I was wondering if its bad to downshift to 1st or 2nd when going down a hill or is that bad for the trans?

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[crash68]

This debate is almost as bad as asking which is the correct oil to use..
If your towing heavy you definitely don't want to rely on just your brakes and don't try force too much downshifting where the revs skyrocket. Once you've overheated the brakes going down a hill, hopefully you find a run off lane as a transmission is cheaper than crashing.

 

[BWL]

No

 

[392DevilDog]

I am going to assume you never drove a manual transmission.

The automatic in the RAM trucks can be downshift manually both for going down or up a hill.

I would suggest going in order as you go down the hill. 5 4 3 2. I believe 1st will be too low unless you are really going slow.

If you are going down a known steep hill you are best to select a lower gear at the top and allow the truck to engine brake the entire time.

So for instance at the top select 3 and then just coast down the hill.

I see you said 2007. I have a 2003 and have now drawn a blank if you can pick each individual gear or just D 2 1.

Still you could select 2nd...just not 1st unless going real slow.

 

[jmd4100]

I am going to assume you never drove a manual transmission.

The automatic in the RAM trucks can be downshift manually both for going down or up a hill.

I would suggest going in order as you go down the hill. 5 4 3 2. I believe 1st will be to low unless you are really going slow.

If you are going down a know steep hill you are best to select a lower gear at the top and allow the truck to enginee brake the entire time.

So for instance at the top select 3 and then just coast down the hill.

I see you said 2007. I have a 2003 and have now drawn a blank if you can pick each individual gear or just D 2 1.

Still you could select 2nd...just not 1st unless going real slow.

Yes I know you can engine brake by downshifting a manual. Ive done it. But I wasnt aure if it was bad for the clutch bands on the automatic. I have D-2-1. TOW/HAUL will kill 5th, O/D OFF will bring me down to 3rd and then i can use 2 and 1 to slow down even more. I just wasn't sure if it was bad for an automatic tranny to do it frequently

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[392DevilDog]

Ok. You driving a manual makes it better. If you are in the proper RPM range then there would be no adverse affects.

What 2 and 1 are intended for...if speed and RPM apply properly.

Use when needed

 

[Snake15eyes1998]

I use 3rd and 2nd to help with braking all the time while towing.( you can do it even when your not towing). I also use 2nd to climb steep grades. 1st if I'm down around 40MPH. That's the whole reason why you have the ability to manually shift to 2nd or 1st. You can see a steep grade, your truck can't. So doing it right before you hit that grade, helps immensel. Like what crash68 said, it's better to use your transmission, then you're brakes. If your brakes go. Then you're in a Sh#$$ creek. Definitely use your brakes when needed. But it should be sparingly to some degree.

 

[Sherman Bird]

I have a 2007 1500 5.7 545-rfe I was wondering if its bad to downshift to 1st or 2nd when going down a hill or is that bad for the trans?

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The answer is: It depends. Using manual engine braking on any vehicle adds stress to both the engine and transmission. If you are towing a heavy trailer and are using the transmission manual low function and are at minimum throttle, line pressure is low as well. The added strain of providing braking through the trans friction surfaces (clutches and bands) at minimum throttle and low line pressure will stress these friction surfaces beyond their limit to hold and force slippage which will burn them up with a heavy load pushing against them.

I've seen this many times before when guys didn't have properly working trailer brakes, and/or if going downhill to aid braking.

If you are using engine braking in conjunction with the service brakes, and the truck isn't loaded down, you should be alright.

 

[Smokeybear01]

Shoot, by the heading I thought he was referring to throwing his trans out with a chain tied to it like an anchor. With that said, I agree with what Mr. Bird stated. They used to put trans brakes in gasser motor homes, not sure if they do anymore. But when you came down a super long grade the trans would get really hot and lots of people couldn't understand why their trans were going out with less than 50K miles on them. Low pressure and high friction not good. Period.

 

[Snake15eyes1998]

The answer is: It depends. Using manual engine braking on any vehicle adds stress to both the engine and transmission. If you are towing a heavy trailer and are using the transmission manual low function and are at minimum throttle, line pressure is low as well. The added strain of providing braking through the trans friction surfaces (clutches and bands) at minimum throttle and low line pressure will stress these friction surfaces beyond their limit to hold and force slippage which will burn them up with a heavy load pushing against them.

I've seen this many times before when guys didn't have properly working trailer brakes, and/or if going downhill to aid braking.

If you are using engine braking in conjunction with the service brakes, and the truck isn't loaded down, you should be alright.

The answer is: It depends. Using manual engine braking on any vehicle adds stress to both the engine and transmission. If you are towing a heavy trailer and are using the transmission manual low function and are at minimum throttle, line pressure is low as well. The added strain of providing braking through the trans friction surfaces (clutches and bands) at minimum throttle and low line pressure will stress these friction surfaces beyond their limit to hold and force slippage which will burn them up with a heavy load pushing against them.

I've seen this many times before when guys didn't have properly working trailer brakes, and/or if going downhill to aid braking.

If you are using engine braking in conjunction with the service brakes, and the truck isn't loaded down, you should be alright.

Well, I won't be dropping it into 2nd anymore while towing. I don't do it often and when I do. It's for short intervals. But I'm curious because. I have a 2017 F250 work truck, when I'm pulling heavy loads with that. It will downshift into 3rd and sometimes 2nd by itself. If you start slowing down on steep grades. But of course, it's a complete different transmission. But yeah, now I learned that's not good to do, while towing or loaded down. Ok, what about going up hill ? Dropping it into 2nd gear? Will that eventually kill a transmission? I have to favor 2nd gear a alot up hills with my 35x12.5x20 rims, and 3.55 gearing. Thats my reasoning to why I need to favor 2nd. What are the consequences of constantly doing this?

 

[Wesley2103]

the newer trucks by design downshift automatically going down a grade so I don't believe that hurts the truck except under extreme conditions as was stated by another here on the forum.

 

[Snake15eyes1998]

the newer trucks by design downshift automatically going down a grade so I don't believe that hurts the truck except under extreme conditions as was stated by another here on the forum.

How About constantly manually shifting into 2nd gear Uphill? What does that do long term? What's your opinion on that ?

 

[RoadRamblerNJ]

I had an '09 SLT 1500 QC 4X4 5.7 and the same 5 spd you have. Also had CAI, MF Cat back, Predator tuner and I drove that truck like I stole it every day for 5 years. Driving at 9/10ths was common. 10/10ths sometimes. 90 miles a day to work & back. I shifted that thing like it had paddle shifters and it didn't hurt the trans until I hit 96k miles. FCA fixed it under warranty a gave me a 12k warranty on it. I beat the crap out of it for 5k miles and it started feeling like it wasn't right. I traded it in for a more appropriate 3 digit speed car.

Bottom line, use the gears, you'll be fine. Somebody said earlier a blown trans is cheaper than crashing. I always heard it as brakes were cheaper than a trans job. On steep hills or when towing heavy, definitely use the trans. If you "need" to go down into 1st gear, you already screwed up.

Life was simple when our rides had a 2-speed Powerglide.

 

[hoe...]

You should select the appropriate gear at the top or bottom of the grade to avoid changes whilst under extreme loading.

You should use engine braking only, ideally you should not need to touch your service brakes.

Engine/exhaust brakes work best at high rpm.

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[Sherman Bird]

Well, I won't be dropping it into 2nd anymore while towing. I don't do it often and when I do. It's for short intervals. But I'm curious because. I have a 2017 F250 work truck, when I'm pulling heavy loads with that. It will downshift into 3rd and sometimes 2nd by itself. If you start slowing down on steep grades. But of course, it's a complete different transmission. But yeah, now I learned that's not good to do, while towing or loaded down. Ok, what about going up hill ? Dropping it into 2nd gear? Will that eventually kill a transmission? I have to favor 2nd gear a alot up hills with my 35x12.5x20 rims, and 3.55 gearing. Thats my reasoning to why I need to favor 2nd. What are the consequences of constantly doing this?

The opposite of engine braking in a manual mode is what you ask about.... going uphill in manual 2nd. Since you are ACCELERATING, going uphill, you are sending the computer a load increase message in the form of MAP sensor in some cases, (Ford used MAP on the 7.3 Power Stroke/4R100 transmission), increased accelerator pedal position, and maybe Mass Air Flow (MAF). Computer responds to these higher load inputs (higher APP signal, etc.) with a command to increases line pressure, so the clutches and bands are under higher pressure so as to reduce the tendency to slip. You can get a more accurate idea by reading up on towing strategy on Dodge (RAM) in the owner's manual. Perhaps RAM's strategy (computer algorithm) allows for minimum throttle engine braking under high loads. I'd opine that it would still shorten the life of the transmission and wouldn't recommend it.

Remember that the computer on any electronic controlled transmission (All of them these days) controls line pressure in response to load inputs from several components like I mention above. It's why the transmission shifts earlier and softer when you are light throttle cruising, yet holds the shift until much later and increases it's firmness at WOT on a sliding scale from minimum to max throttle!
Cheers!

 

[Sherman Bird]

Life was simple when our rides had a 2-speed Powerglide.

The Power glide. like the 4R70/75W's in Fords were Ravigneaux designs. These were extremely strong and durable units, yet heavy. In 1955, a fellow named Simpson was granted a patent on a more compact and lighter design unit which has become the norm in manufacturing these days.

Power glides were used in dragsters due to their durability.

 

[Snake15eyes1998]

Hahaha crash68 was right. This debate is just as bad as, what oil I should use, what's the best tire, what's the best air filter. Lots of opinions and real life experiences. I like it!! Alot of good comments and advice. In the end, you do what you have to do in that moment, while towing or just cruising. Whatever makes you feel comfortable.

 

[ramffml]

The answer is: It depends. Using manual engine braking on any vehicle adds stress to both the engine and transmission. If you are towing a heavy trailer and are using the transmission manual low function and are at minimum throttle, line pressure is low as well. The added strain of providing braking through the trans friction surfaces (clutches and bands) at minimum throttle and low line pressure will stress these friction surfaces beyond their limit to hold and force slippage which will burn them up with a heavy load pushing against them.

I've seen this many times before when guys didn't have properly working trailer brakes, and/or if going downhill to aid braking.

If you are using engine braking in conjunction with the service brakes, and the truck isn't loaded down, you should be alright.

I am really confused by this. My truck has tow haul mode and when enabled, going downhill it makes an effort to really hold the gears. The idea being, keep your foot off the gas, drive down the hill, let the truck "engine brake" as much as possible, and apply brakes as needed.

That's how the truck was designed to operate. Are you suggesting even though it's designed to work this way, that it's very hard on the transmission?

 

[392DevilDog]

I guess I do not understand the inner workings of the transmission

But I am pretty sure if you read the owners manual it will describe that 2 and 1 are to be used for going downhill and for increased power uphill

Even the manual in my 1987 dodge Aries Station Wagon says to use 2 and 1 this way.

The RFE transmission definitely will downshift to hold speed. And with tow haul mode on the transmission actually can read if you are going uphill or downhill.

I would use the transmission to engine brake and to go up the hill in the power.

But I am not a mechanic or an engineer. So take my thoughts with a grain of salt.

It is proper instruction to select a gear one gear lower than you would use to go up to go down a grade.

And you should do this at the top.

If your RPMs are in range...exactly like you would decide with a manual...i would downshift.

And going up the hill, it will keep the transmission from upshifting when you release the gas for a turn etc. And keep the transmission from hunting.

My opinion

 

[Sherman Bird]

I am really confused by this. My truck has tow haul mode and when enabled, going downhill it makes an effort to really hold the gears. The idea being, keep your foot off the gas, drive down the hill, let the truck "engine brake" as much as possible, and apply brakes as needed.

That's how the truck was designed to operate. Are you suggesting even though it's designed to work this way, that it's very hard on the transmission?

I'd really suggest you read the OWNER'S manual! Re-read what I wrote . I said that using the transmission manual range is likely OK when the truck is unloaded, but when the manual braking is used with a heavy load, maybe not such a good idea and I stated why.
BUT, These NEW models may have been upgraded where the use of the transmission to provide a surrogate braking would be OK. I would not do that. I'd use the brakes and IF I HAD to use the transmission, I'd certainly try my best to let the brakes handle the lion's share of the load and be very cautious about using the trans.

BTW.... the old school trans controls said "OVERDRIVE OFF" when that button was pushed. Since so few people really read the owner's manual, which said to select that in the event of towing, manufacturers had to make it more plain and simple!