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Old 01-12-2017, 08:51 PM   #29
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I was basing my statement on my 04 Dodge with the 5.9 Cummins and auto trans with tow haul and no exhaust brake. In this case the engine is not holding back as much as my coach with the ISC and exhaust brake and Allison trans.

But overall thinking about it, you are correct.
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Old 01-12-2017, 10:08 PM   #30
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Quote:
Originally Posted by TonyMac View Post
Well stated plan for brake use and safely transitioning a hill, but the gasser and the diesel are both providing braking by the engine thru the tranny. The tranny itself does nothing to provide braking power, it just transmits that power built up in the engine. A gasser has the throttle plate. Using engine braking, this throttle plate builds vacuum in the engine. There is little air available for the intake stroke because the throttle plate is closed. This vacuum is present in the combustion chamber thru the intake and unpowered power strokes, causing the engine to try to stop rotation.

A diesel has no throttle plate. When you release the throttle, the engine coasts, filling the cylinder with air on the intake stroke (no fuel) building pressure on the compression stroke that 'bounces' the piston down on the unpowered power stroke, and actually exhausts that unburnt air on the exhaust stroke. The braking physics of the throttle plate are performed by the exhaust plate in the exhaust brake, but here, pressure is built up in the exhaust stroke against that closed exhaust plate. The pressure during the exhaust stroke is the engine brake, the downshifting transmission only amplifies the engine forces in both the gas and diesel.
Finally someone who's know what their talking about.

Also if you think the transmission can't handle downhill engine braking, how do you think it handles uphill? The transmission is designed to handle extended durations of these forces so is the engine, your brakes are not.
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Old 01-13-2017, 08:35 AM   #31
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I tried to keep it simple for those not technical. As a Ford Master tech I could go off on a tangent and loose 98% of the readers. Which wouldn't be a help on a forum like this.
The 4R100 and its older brother E4OD only have a few clutches that are engaged on deceleration when the torque converter disengages. With that being said there is not enough to there for longevity like an Allison which is designed to work in conjunction with engine brake systems commonly found on a Diesel Pusher RV, Medium duty diesel truck or Heavy Duty Diesel truck engine. They will do it but it will shorten the life of your transmission, at the end of the day it is your wallet and your coach, do as you see fit. Just trying to help you not create a debate.
Are you monitoring your transmission temperatures via a real gauge or the one that came in the instrument cluster around 2005 ish on the E-Series and 2002 on the F53? If that is all you are utilizing, you are missing the real data. Monitor the output line temperature to the cooler and downshift it, that is where my gauge was plumbed in, not in the pan checking temps after the cooler.
If you have a 4R100 or E4OD (1989-2004) 4 speed automatic transmission and you choose to downshift it manually to slow you down, Thank you for helping to contribute to my mortgage payment for so many years as I have replaced/rebuilt on average 50+ of those a year.
FYI, again to help....the Gale Banks trans programmer will help make it last longer as well as an all aluminum deeper transmission pan. My last gasser coach had a Autometer gauge on the A Pillar and Bully Dog aluminum pan. Another common problem with those is transmission case warp age, the all aluminum trans pan not only gives you more fluid and better air to oil cooling it will also act as a jig and hold the case from flexing, much better than the stamped steel pan.
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Old 01-13-2017, 08:45 AM   #32
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Quote:
Originally Posted by jleamo1 View Post
I tried to keep it simple for those not technical. As a Ford Master tech I could go off on a tangent and loose 98% of the readers. Which wouldn't be a help on a forum like this.
The 4R100 and its older brother E4OD only have a few clutches that are engaged on deceleration when the torque converter disengages. With that being said there is not enough to there for longevity like an Allison which is designed to work in conjunction with engine brake systems commonly found on a Diesel Pusher RV, Medium duty diesel truck or Heavy Duty Diesel truck engine. They will do it but it will shorten the life of your transmission, at the end of the day it is your wallet and your coach, do as you see fit. Just trying to help you not create a debate.
Are you monitoring your transmission temperatures via a real gauge or the one that came in the instrument cluster around 2005 ish on the E-Series and 2002 on the F53? If that is all you are utilizing, you are missing the real data. Monitor the output line temperature to the cooler and downshift it, that is where my gauge was plumbed in, not in the pan checking temps after the cooler.
If you have a 4R100 or E4OD (1989-2004) 4 speed automatic transmission and you choose to downshift it manually to slow you down, Thank you for helping to contribute to my mortgage payment for so many years as I have replaced/rebuilt on average 50+ of those a year.
FYI, again to help....the Gale Banks trans programmer will help make it last longer as well as an all aluminum deeper transmission pan. My last gasser coach had a Autometer gauge on the A Pillar and Bully Dog aluminum pan. Another common problem with those is transmission case warp age, the all aluminum trans pan not only gives you more fluid and better air to oil cooling it will also act as a jig and hold the case from flexing, much better than the stamped steel pan.
But Joe the steel pan is so much cheaper...
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Old 01-13-2017, 08:49 AM   #33
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The 4R100 and its older brother E4OD only have a few clutches that are engaged on deceleration when the torque converter disengages.
I would welcome more detailed information, are you saying those transmissions somehow use less clutches when driven by the wheels downhill than when driven by the engine uphill in the same gear and is therefore worse / harder on the transmission than screaming uphill at 5000 rpm at full HP output?

I have never heard of this behavior. I have heard of plenty of transmissions overheating and failing towing uphill, never heard of one failing from downhill engine braking.

Maybe Mark K. who was a Ford transmission engineer will chime in and give some insight into this as well.
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Old 01-13-2017, 09:26 AM   #34
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I will have to support the transmission shop of the future, rather than ride my brakes until the fluid boils and they disappear.

I can monitor the trans temp thru the OBDII. Is that sender in the correct spot ?
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Old 01-13-2017, 09:45 AM   #35
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I live in Mid Michigan so not many steep hills, but we do have some. My rig is on a 2004 F53 chassis, should I be dropping to a lower gear on steep downhill sections, also is true I can fade the brakes if used too much?

I don't have a tow/haul mode, but do have Overdrive.
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Old 01-13-2017, 10:01 AM   #36
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Originally Posted by jharrell View Post
Finally someone who's know what their talking about.

Also if you think the transmission can't handle downhill engine braking, how do you think it handles uphill? The transmission is designed to handle extended durations of these forces so is the engine, your brakes are not.
and to TonyMac.
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Old 01-13-2017, 11:32 AM   #37
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I don't know if this story has any meaning to this conversation. It is however one of the reasons for my asking the original question.

I was in Asheville, NC (very mountainous area) where I drove a new 2016 Newmar Ventana LE 4002 and Thor Palazzo 36.1 both diesel pushers. They were the first diesel coaches I ever drove and is where I was first acquainted with the exhaust brake.

I then drove the Newmar Canyon Star 3925 gas coach where I was also acquainted with Tow/Hold brake.

All three test drives were over with same roads with the same stop signs, stop lights and same interstate highway. To my knowledge I drove all three coaches the same way. With the gas coach I came off the off ramp and stopped at the stop sign not far away. And there was a pronounced burning smell and the salesman said it was the brakes!

My first question to the salesman was "was it me, did I drive this coach any different than the other two"? And he said no! I had already decided the diesel was for me so I didn't persue the brake conversation.

In my SUV I always downshift coming down the mountains so it's not a new concept to me. I don't ride the brakes, I don't do it in an SUV and wouldn't in a motorhome. I'm not telling you this for any other reason than "that's what happened"!
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Old 01-13-2017, 12:06 PM   #38
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I understand the OP is about a Class A, I drive a RAM 3500 diesel, six speed and tow a 5th. I've spent 50 years driving in the Rockies and some experience with hills. My goal in a decent is to never or seldom touch the service brake. I slow down on the top prior to starting the downgrade and drop the tranny into one gear lower than I would use to come up that grade. I also leave the tow/haul engaged and engage the exhaust brake. With those actions I can drive down any grade with comfort and control of my rig. NEVER allow the speed to start getting beyond your comfort handling zone. Different drivers will have different zones with their rigs. Understand your own zone for your equipment.

The Class As can't do this, but in an extreme case I can drop into 4 wheel drive low range and have to press the accelerator to even go down hill.

Oh yea, about those drivers behind you. You are responsible for the safety of your rig and passengers first and foremost. If I get a line of traffic behind me, I'll find a safe place to pull over and let them pass, but in the mean time my attention is on what's in front of me.

Always be safe first and understand your equipment.
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