7.3L Power Stroke Engine and DrivetrainDiscussion of the 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.
I've read post after post on using the stock auto trans for braking on steep declines. It appears 1st gear is out of the question. I've been using 2nd gear at slow speeds, 30-35 mph, along with braking to slow down my 5th wheel. I've read where guys say they would rather pay for brake shoes instead of a new trans. Can someone say for sure whether this is ok or what proceedure is best. What mph is ok. Thanks, T
What year is your truck, miles, & what rear axle ratio do you have? Until you upgrade your trans, you will be burning or heating stock clutches downshifting manually, especially with a load behind the truck. Any trans builder from the mountain regions can show you if the truck has been downshifted, because the stock clutch packs will show heat & wear quite consistently.
Yes, you can downshift your trans, a 55mph downshift to 2nd is acceptable (3.73 gears) 45mph with 4.10's IMO. And it shouldn't fail the first time you do it, but every time it's taking away a little bit of tranny life. Stock transmissions fail all across the board with no sign or reason. Some have 200k some get 20k.
The stock trans is the weak link, so until you get a rebuild (Brian's Truck Shop or another high end trans rebuilder) you are on borrowed time in my book, regardless. Plan to upgrade the trans or buy a different truck that you'll need to upgrade as well.
The 4R100 can be essentially bulletproofed, and for the most part eliminate worry's. It's a big trans, & has nice capabilities.
I have no interest in driving down a grade without downshifting, totally relying on vehicle brakes. All it takes is one time & need more than brakes, I don't want to fear downshifting the trans. When my family is in tow, that truck will be used in any means necessary to keep them safe. A built trans is good insurance.
If a built trans isn't in your budget, get a trans temp gauge, synthetic fluid, bigger trans cooler, transgo tugger kit & a Torque Converter Lock up switch, keep you temps in reason & the trans will last the longest it can in stock form.
My opinion is, the trans will eventually fail, that's just the way it is. Brian's Truck Shop has transmissions out there with 500,000, 600,000 miles on them. Just get a BTS and be done with it, the sooner you get one, the longer you get to actually benefit from the investment. They completely change the truck!
__________________ My Photos----- BTS BUBBA "Life Member"
2002 7.3L Excursion 4x4, FTVB, MBRP 4" SS Exhaust, Rancho 9000X shocks, "V" code Front Springs & "B" Code Rear Springs, Ride Rite AirBags, Rear Hellwig Swaybar, Cut Front BumpStops, DieselSite Ext Trans Filter Kit - Coolant Filter Kit & 203 stat, "Scotpart" mod, "Hutched & Pooned", "LandYot" Radius Rods US Gear Overdrive 75mph @ 1750rpm's
2001 7.3L F350 CC LB 4x4 5" Exhaust, pillar guages, BTS Trans, US Gear Underdrive, DP 6 pos chip, V10 Trans Cooler, DieselSite - Coolant Filter Kit, Evans Coolant, 203 stat, DI reg Fuel Return, GT38R BB Turbo, AFE 2 Intake, Banks Intercooler, Air Rite Bags,
2000 Excursion Limited V10 4x4 7" Lift
I'm sorry, my truck is an 02 with 60,000 miles, 373 rear end. I've upgraded the cooling and have a temp gauge added. I always watch the temps. I feel there is no way to control the speed without using the trans. Thanks T
Get you a good exhaust brake. SPDiesel makes a good electronic one and there are the Pac brake, De-celerator and others. The ele. will be cheaper than the mechanical ones. I have the ele. and it works for me.
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I've read post after post on using the stock auto trans for braking on steep declines. It appears 1st gear is out of the question. I've been using 2nd gear at slow speeds, 30-35 mph, along with braking to slow down my 5th wheel. I've read where guys say they would rather pay for brake shoes instead of a new trans. Can someone say for sure whether this is ok or what proceedure is best. What mph is ok. Thanks, T
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First cancel o/d that applies braking all by itself. If your transmission is in good condition, speed becames limited by the engine rpm @ 1 to 1 ratio plus braking. Then a shift to 2M will provide a gear 2 hold for more braking. M2 range is correct for down hill braking and designed for it. With od canceled you have 2 extra holding components using M2 range. This is how you make transmissions last, and why some don't. M1 also has an extra component for hold back braking. The owners manual has the proper tranny use in it, anytime a refresher is needed.
Adding some exhaust braking is a good idea, and the conversion type using the EBPV such as SP sells work. A disabled veteran also sells the same type for a little less. You must throw a toggle switch on these type. Actually the cheapest brakes to use up are on the trailer. Set trailer brake controller to highest setting thats comfortable. Knowing the hill and when to begin backing her down is a big plus in caring for your truck.
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__________________ TheRacer XBuilt E4OD THAT CAN Video. 1997 F-350 7.3 Twin Turboed Power Stroke Diesel. Fueled with 473 + cc's of Dieseland nitrous!
Family owned & sponsored by : FloridaNorth
I have not read it suggested (or maybe I just missed it) but is there any reason to not put it in 4 wheel drive to slow things down?
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Two ideas when combined together will always make a third better idea!
I don't have to be wrong for you to be right.
Kent
@235K miles @ 071127
>202K miles @ 070828
2001 F350 7.3 PSD SD CC DRW Lariat, 4R100 (replaced at 41k w/rebuilt by dealer), 3.73, FX4 ESOF, Long Box - 3rd CPS. CPS in Glove Box MOD. K&N Filter. 6.0 OTA Cooler. Green to Red Coolant. Water filter. 203º T-stat. Fumoto Valve. Monroe Gasmatic Shocks.
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Yes, you can downshift your trans, a 55mph downshift to 2nd is acceptable (3.73 gears) 45mph with 4.10's
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Is this a need to be 'going at least 55' before shifting or is it more like 'going no more than 55'??
__________________
Two ideas when combined together will always make a third better idea!
I don't have to be wrong for you to be right.
Kent
@235K miles @ 071127
>202K miles @ 070828
2001 F350 7.3 PSD SD CC DRW Lariat, 4R100 (replaced at 41k w/rebuilt by dealer), 3.73, FX4 ESOF, Long Box - 3rd CPS. CPS in Glove Box MOD. K&N Filter. 6.0 OTA Cooler. Green to Red Coolant. Water filter. 203º T-stat. Fumoto Valve. Monroe Gasmatic Shocks.
You can shift to ANY gear at ANY speed! Now for those who don't believe me, here's why.
The computer is smart enough to prevent a downshift if the speed is too high for the engine. You can move the shifter all the way down to 1 at ANY speed, but it won't make the shift until the speed is safe. If you are in overdrive it will downshift to third, then to second when it slows enough, then to first when it slows enough.
I don't use M1 on my 4R100 because I believe that clutch was under designed. If it sees high pressures like happen at high RPM in M1 it tends to come apart. You can use M2 for braking all day long. While it's true that every time you downshift you wear the clutch, it's also true that every time you upshift the trans you wear a clutch. Likewise, everytime you press the brake pedal you wear the brakes. Every time the tires turn they wear, too. The only way to completely avoid wear is to never move the truck. I bought mine to use it.
As for using 4x4 for braking, there will be a bit more braking in 4x4 because there is more drag from the system. If you are on pavement there will be A LOT more drag in the turns because the 4x4 system will be binding and trying to tear itself apart. I would not use 4x4 just for braking. Use it for low traction.
__________________ Mark
Former Automatic Transmission Engineer 1988-2007
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2000 4x4 PSD Limited Excursion The Beast
DPTuner 40Tow, 60Tow, 80Econo, BTS Valve Body, AIS Intake, AIH Delete, MBRP Stainless 3.5" DP and 4" Exhaust, 5" All spring Edge lift, Rize Traction Bars, CV joint driveshaft, 315 BFG ATs on Alcoa wheels, Warn Transformer with multi mount winch power front and back, 1000 watt power inverter, VCR, 4.10 gears and ARB Lockers Front and Back
If I am descending a steep hill with my 11,500 lb toy hauler behind me, I set the cruise control for the speed that I want to go, with the transmission set in overdrive, and the truck maintains the speed that I set on the cruise control, and I never have to touch the brakes. Is this normal? I can't figure out how it does it.
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2001 F350 XLT 4X4, shift on the fly, 38 gal fuel tank, running boards, sliding rear window, black, crew cab, long bed, 4.10, automatic transmission, 11,500 gvwr, 20,000 gcwr, 7500 gvw, dual rear wheels, 7.3l turbo diesel, completely stock, 114,00 miles when purchased, now has 125,000 miles, repairs so far: starter, batteries, cps.
2005 Nomad Rampage toyhauler made by Skyline. 11,500lb gvwr.
You can shift to ANY gear at ANY speed! Now for those who don't believe me, here's why.
The computer is smart enough to prevent a downshift if the speed is too high for the engine. You can move the shifter all the way down to 1 at ANY speed, but it won't make the shift until the speed is safe. If you are in overdrive it will downshift to third, then to second when it slows enough, then to first when it slows enough.
How easy is it to screw up this programming? You think this will still be true on chipped trucks?
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2000 F250 Lariat CC SB 4x4 PSD Auto
If I am descending a steep hill with my 11,500 lb toy hauler behind me, I set the cruise control for the speed that I want to go, with the transmission set in overdrive, and the truck maintains the speed that I set on the cruise control, and I never have to touch the brakes. Is this normal?
Mark dug up this thread from last August. I wonder why?
I never descend the mountain pass without killing the overdrive, and my 5er weighs only 8,000 pounds, so I'm not sure about your exact scenario. But I know that when in direct drive if I set the cruise on the minimum speed I want to come down the pass, the truck seems to do a good job of holding close to that speed without me having to use the brakes. On interstate mountain passes, if I set it on my normal flatland cruising speed of 62 MPH, the speed will vary between 62 and about 70 without using the brakes.
At 65 MPH the torque converter stays locked, the coast clutch in the tranny is working hard, and I'm not sure what having the cruise control active does. Maybe it activates the coast clutch? Apparently Mark's 4R100 tranny calibrating buddies made it work pretty good. But they didn't document it anywhere I have found so that Joe Average could learn about it. So using the cruise control to help add engine braking when a heavy trailer is pushing you down the mountain will remain a secret between you and me and Mark, plus a couple of others who might read this thread.
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My Sierra Blanca is a '99.5 PSD CrewCab hot-rod Towing Machine! BTS tranny; TurboRamAir intake and 4" stainless turbo-back exhaust; DP-Tuner tunes flashed into an Edge Evolution tuner; ISSPRO EV gauges and TTM; AIC; SP-Diesel exhaust brake and torque converter controller. I special-ordered it new and plan to drive it until it quits.
I just traded up to 2002 and this is what I found out with my 97.
When you start your descent and you first tap the brake the Torque Converter unlocks and puts you on fluid flow which is not good for braking. Switching to 2 helps but if your TC is unlocked you will still have poor engine braking. I connected a voltmeter to the TC clutch solnoid line so I could tell visually when the TC clutch was locked.
Later I decided that I would install a switch so I could lock the clutch when starting a descent to override the computer. Now when using 2 and the TC lock you get some real braking.
Also installed the DIY exhaust brake. So I can usually go down mountain grades at 50 without truck or trailer brakes applied. This saves the linings for an emergency.
Maybe Mark can add something about the TC clutch and how it works.
I am going to do the same thing for my 2002.
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2002 F250 Stock PSD Crew Cab SRW pulling Same Montana as old truck
E4OD THAT CAN Video.
nitrous! 
Linear Mode
