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Demco SBS Air Force One Supplemental Braking System for Motor Homes with Air Brakes - Proportional

Demco SBS Air Force One Supplemental Braking System for Motor Homes with Air Brakes - Proportional

Item # SM99243
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Tow Bar Braking Systems

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Tow Bar Braking Systems SM99243 - One Time Set-Up - Demco
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Product Expert Mike S

Is this right for you? Product Expert Mike S says:

Yes, if you:

  • Have a motorhome with air brakes
  • Don’t have time to waste setting up a portable system before every trip
  • Tow a nicer or newer car and want the most precise braking possible

No, if you:

  • Upgrade your towed car every few years
  • Are hesitant to make any modifications to your motorhome
This truly proportional braking system uses the air pressure from your RV's brakes to apply the brakes in your towed car in the same manner. Low-profile design installs out of your way and is always at the ready. Lowest Prices for the best tow bar braking systems from Demco. Demco SBS Air Force One Supplemental Braking System for Motor Homes with Air Brakes - Proportional part number SM99243 can be ordered online at etrailer.com or call 800-298-1624 for expert service.
  • All Info
  • Reviews (161)
  • Q & A (606)
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  • Why etrailer?

Demco Tow Bar Braking Systems - SM99243

  • Brake Systems
  • Proportional System
  • Air Brakes
  • Fixed System
  • Demco
  • One Time Set-Up
  • Power Assist Brake Compatible

This truly proportional braking system uses the air pressure from your RV's brakes to apply the brakes in your towed car in the same manner. Low-profile design installs out of your way and is always at the ready.


Features:

  • Supplemental braking system applies towed vehicle's brakes in proportion to braking action of RV
    • Towed car's brakes are activated at the same time and with the same intensity as those in your motor home
  • Truly proportional system uses the air pressure from your RV's brakes to apply the brake pedal in your car
    • Coiled air hose connects air assembly in RV to operating unit in towed car
  • No false braking
    • Coach air brakes must be activated for system to apply towed car's brakes
  • One-time setup - no need to remove or to activate each time you tow
    • Operating unit and actuating cylinder stay hidden so everything is out of your way when you are driving
      • Low-profile design of operating unit allows for more room in the engine compartment of towed car
      • System automatically functions when towed vehicle is connected to RV
  • LED coach notification system illuminates when the towed vehicle's brakes are applied
    • Connects to towed car's brake light switch to ensure proper reading
  • Vacuum-assisted function of towed car is activated with air from the coach brakes
    • Less force is needed to move the brake pedal in the car, resulting in more natural braking and less risk of damage
    • Compatible with vehicles that have continuous-power-assist brakes
  • Breakaway included
  • System meets FMVSS safety guidelines for motor homes that use air brakes
  • Necessary installation components and an instructional CD included
  • Made in the USA


Specs:

  • Application: motor homes with air brakes
    • Can accommodate air-over-hydraulic brakes - additional 1/4" DOT air line (not included) may be required
  • Coiled air hose length when fully stretched: 7'
  • Breakaway cable length when fully stretched: 7'
  • 5-Year warranty


A supplemental braking system is a must when towing a car or truck behind your RV. Without it, the weight of the towed car can create a safety hazard, strain your RV's brakes, or affect your RV's warranty. Most states require a supplemental braking system.


Automatic, Truly Proportional Braking

Air Force One is a proportional braking system. When you apply the brakes in your motor home, the system will engage your towed car's brakes at the same time and with the same pressure as those in your motor home, creating synchronized braking.


To achieve this proportional braking, Air Force One ties into your coach's air brakes. The patent-pending process uses air pressure from your coach's brakes to depress the brake pedal in your towed car. The result is uniform, real-time braking that mirrors the slowing or stopping action of your coach. Whether you lightly tap the brakes in your RV or apply them hard in a panic situation, your towed car's brake pedal will be applied in the same manner.


Many other proportional systems activate the towed car's brakes based solely on inertia. With this kind of setup, any activity that affects the forward momentum of your towed car - from the coach actually braking, to driving over a pothole - can activate the supplemental braking system and apply your towed car's brakes. This potential for false braking, which can occur simply from driving over uneven terrain, can create a rough ride for you in the RV and can also wear out your towed car's brakes over time. Air Force One is different, though. Because it is tied into your coach's brakes and is not dependent on inertia, this system activates only when you apply the brakes in your RV, so there is no false braking.


Permanent Installation with Concealed Components

Once you install the Air Force One system, it stays concealed and out of your way - both in the RV and in the towed car. Unlike systems that require you to keep the actuating box under the seat or in the trunk of your towed car, Air Force One does not take up valuable storage space inside of your car. And the components that install on your RV all remain hidden beneath the vehicle so that no room is taken up in its interior either. Because the entire system installs permanently, there is no need to constantly set up and remove this system. You never have to worry about where to store a bulky actuator box when you're not towing. And while most of the components do remain on your vehicle and RV at all times, none of them will interfere with normal driving or braking.


Coach Air Connection Assembly

Because Air Force One uses air to activate, it is a natural choice for diesel motor homes that have air brakes. The coach air connection assembly taps into your RV's air brakes and delivers the air necessary to activate the towed car's brakes through the included coiled air hose. The valves on the coach air connection assembly ensure precise airflow.


Pressure Protection Valve

A 1-way check valve collects air from your RV's brake lines so that it can power your towed car's brakes. This pressure protection valve also ensures that your RV's air lines maintain the same amount of pressure so that the braking in your RV is not affected.


Relay Valves

Metered air from the coach's brakes connects to a service relay valve. This relay valve collects air from your RV's brake lines so that it can power your towed car's brakes. When you activate the brakes in your RV, the delivery relay valve releases the appropriate amount of air to the operating unit in your towed car.


The coach air connection assembly is best mounted in a location on the RV where the air lines will not be near direct heat sources or moving parts, such as in front of the rear axle.


Note: Air Force One is designed for motor homes that have air brakes, but it will also work with RVs that have air-over-hydraulic brakes. Additional parts (not included) may be required for installation on RVs with air-over-hydraulic brakes.


Operating Unit

The operating unit, which mounts in your towed car, receives air from the coach air connection assembly. The unit then diverts a matching amount of air through a hose to the actuating cylinder that mounts on your towed car's brake pedal. That air activates the cylinder so that it applies proportionate braking pressure.


The unit goes under the hood of your towed car, so it is out of your way and always ready. Because this system is a universal fit, you can remove it from your towed car and reinstall it in a different car or truck if needed.


Actuating Cylinder

Small Cylinder

The actuating cylinder depresses your towed car's brake pedal upon receiving the air that is delivered from the operating unit. This small cylinder stays mounted on the arm of your towed car's brake pedal at all times and will not interfere with braking while driving.


Actuator on Pedal

Mount this cylinder so that it is perpendicular to the firewall when you depress the brake pedal. A clamp anchors the actuator to the firewall.


To connect the actuating cylinder to the operating unit, you will need to run the included air hose through your towed car's firewall. You can usually create the necessary, small opening without drilling. In most instances, you can cut a slit in the hood release cable grommet. Simply cut the end of the air line at an angle to poke it through the slit.


Coiled Air Hose Connection

Coiled Air Jumper

The coiled air hose, also called a jumper, connects your towed car to your RV by connecting the operating unit to the coach air assembly. When you are ready to hitch up your car and tow it, simply hook up the coiled air hose at the same time as you hook up your tow bar.


Vacuum Pressure Creates Smooth Braking

Normally, when you activate the brakes in your vehicle, a vacuum multiplies the pressure you apply to your brake pedal, creating the force necessary to stop the full weight of the moving car. On most cars and trucks, this vacuum-assist function does not work when the engine is off. As a result, many supplemental braking systems on the market have to use an excessive amount of pressure to effectively depress the towed car's brake pedal.


Air Force One reactivates the vacuum-assist function of your car's brakes when it's being towed, even though the towed car's engine is not running. As a result, the actuating cylinder does not need to apply extreme force to the brake pedal to achieve proper braking. The operating unit ties into your towed car's vacuum line with a tee so that it can use the air pressure from your RV to create the vacuum your car needs to brake gently. As a result, no additional vacuum pump is required to create the vacuum-assist function for your towed car's brake pedal. Air Force One will replenish your towed car's vacuum after each braking event so that you will get smooth, even braking every time.


Built-In Safety Features

AFO Light in Towed Car

Most supplemental braking systems have methods of letting you know you when the system itself is activated, regardless of whether the towed car's brake pedal is depressed. Such setups leave opportunities for false notification. Air Force One's system is different. This system's LED monitor connects to your towed car's brake light switch. When your car's brake light goes on or off, so does the notification light. So you can tell whether your car's brake pedal is depressed.


Air Force One Monitor Install

You can install the monitor light on your RV's dash, or you can save time by attaching the monitor light to the back of the rearview mirror of the towed vehicle . This way you can see the light from your RV's backup camera or rearview mirror. The system includes the necessary parts for either installation method.



AFO Breakaway

The breakaway system ensures that your car will come safely to a stop if it accidentally detaches from the RV while you are towing. A switch mounts to the front of the towed vehicle . This switch - which is wired into the operating unit - includes a pin that connects to your RV's hitch receiver with a breakaway cable. If the car separates, the cable pulls the pin from the switch, causing a signal to be sent to the operating unit. A reserve air supply will then apply your towed car's brakes. This system also has "total coach protection" built in. If there is separation, the RV's air supply is sealed off, so its brakes will continue to function as normal.


Air Force One meets Federal Motor Vehicle Safety Standard (FMVSS) guidelines requiring that supplemental braking systems use a separate air supply and activation relay valve.



9599007 AFO115 Demco SBS - (Formerly SMI) Air Force One Supplemental Proportional Braking System

Replaces Demco SBS SM99202 and SM99243

Installation Details SM99243 Installation instructions

This Product Fits The Following Vehicles





Customer Reviews

Demco SBS Air Force One Supplemental Braking System for Motor Homes with Air Brakes - Proportional - SM99243

Average Customer Rating:  4.9 out of 5 stars   (161 Customer Reviews)

This truly proportional braking system uses the air pressure from your RV's brakes to apply the brakes in your towed car in the same manner. Low-profile design installs out of your way and is always at the ready.

- SM99243
by:
2014 Honda CR-V

AF1 is amazing so far. I did the installation by myself. I have a 2014 Honda CR-V and bought it for towing. Watching the video helped me through it. The car installation portion was pretty straight forward. The video is better than the instructions overall, but I read through the entire instructions before beginning. I was able to install the RV tank without putting the rig on a lift. Depending on how big you are and flexibility, it can be done with the RV on the ground...it just takes longer. Also, I would recommend knowing where you are going to mount your RV tank. I mounted the tank near the rear and didn’t have enough brake tube after doing the car. Picked up an extra 20 ft at Autozone or order the tube with etrailer. The customer service center is very helpful too. Many thanks to Mariah for the outstanding assistance. Finally, I would say that if you order the brackets to mount the emergency brake away for your car, you may have to cut them down with a grinder. It is so much nicer not putting the brake buddy in the car now. Looking forward to enjoying it on trips. I drove the rig about 20 miles yesterday, and the light came on and I honestly couldn’t tell the car was back there other than looking in the video and seeing the light on the car during braking. Highly recommend this unit.


Comments
5.0 Product is working great! No issues. Minor adjustment to brake cable after a year. It took 5 mins.
Darryl W - 07/28/2021


- SM99243
by:
Allegro

I ordered an Air Force One breaking system one year ago, for my 2019 Allegro Bus 45OPP, and my 2012 Honda CR-V. I paid $1080.00 with free shipping from E-Trailer. The unit arrived in perfect condition. I installed the system myself, in about three hours on the Motorhome. I had previously ordered a special hose/ tube cutter. The only part of the installation that was a little intimidating was cutting the correct air lines on the coach, however after viewing the installation video everything was made clear. The install on the Honda took about two hours, I did have to call the people at E-Trailer , but they cleared up my questions.



- SM99243
by:

I believe the AFO is the best supplemental braking system for air brakes on the market today. Probably the most expensive also. A lot of work to install but a good system that is truly proportional and safe to use with an air brake system.



- SM99243
by:

Product works good. No longer have to put the old box between the seat and the brake pedal and hook up to brake petal. So easy to hook up. Be sure your air hose connections are are secure. Unit does not work when one end of air hose is on the ground. I know from experience. Would suggest ordering an additional air hose just in case you need it



- SM99243
by:

Seems to be working well. Wife and I did our own installation and it was challenging. Standing on my head under the dashboard mounting the breaking air cylinder at the brake was tough but doable. Tapping into the air brake system on our motorhome also challenging but it all appears to do the job. Glad that job is behind us.



- SM99243
by:
2012 Saturn Relay

"Out of sight, out of mind" would be the best description I could offer for the Air Force One supplemental braking system! When properly installed, it's effective as well as quick and easy to hook up. Connect the tow bar, safety cables, safety switch cable, tow plug and air line, you're done! Five minutes at most. I did add a couple of features to my towing system: 1. Using a relay and the extra wire in the connector to the coach, I installed the LED indicator strip on the dash of the coach; no need to rely on the back-up camera to verify operation of the brake cylinder. Coaches that have a tow connector are usually equipped with a power wire to the cab for electric brakes - this wire is a good way to get the indicator signal to the front of the motorhome. 2. I used the 12 V power connection from the coach to connect a charging wire to the car battery to ensure it would not discharge; I used an auto-resetting breaker with a rating below the glass fuse in the 12 V circuit to prevent a fuse from blowing if the charge current gets to high. In all, a great investment! I have an article I wrote on the install if anyone is interested.



- SM99243
by:

We've had a good experience using the Air Force One braking system. Installation was easy and all you do is hook up an air line to the tow vehicle and off you go. No other adjustments needed so I like this unit.



- SM99243
by:
2016 GMC Canyon

Vehicle 2016 GMC Canyon Diesel. Installation of the SMI Air Force One supplementary braking system was not too difficult. The instructions from SMI were good as was the video from etrailer. The only reason that I didn't give it a 5 star is because the air cylinder installation on the brake pedal was complicated by an unusual shape of the brake pedal arm. I eventually found a solution. Tapping into the truck's vacuum line was a little difficult but the kit included everything I needed to T into the vacuum line and install the check valves. All in all not a bad installation, this summer we'll see how it holds up.



- SM99243
by:

I’ve fitted it to my Jeep Wrangler then taken of and fitted to our new Jeep Grand Cherokee. Works perfectly . I had used our 53ft coach without it and in an emergency stop, was a problem stopping in the rain. Now we have had a couple of fast stops and it works great, would be without it.



- SM99243
by:

I installed it myself, followed the eTrailer installation video. I have used it a year, works great, have put over 3000 miles on it. No issues. Struggled with using a portable brake system and decided to do it right. It was the right choice.



- SM99243
by:
Jeep Wrangler

We tow the Wrangler behind our 36' Monaco. Easy setup, confident towing, and easy disconnect. Highly recommend.



- SM99243
by:
Jeep

Have had the Demco Air Force One on my towed Jeep for a year now, with many trips. Works perfectly, very glad I bought this. Simple to hook up, just hook up the one end of the air hose, since while traveling I leave the tow bar on and the hose hooked to the coach. Glad I didn't get one of those boxes that goes on the floor that has to be taken in and out each time.



- SM99243
by:

My Air Force One braking system arrived quickly and I installed it using the vidio on there site. It works great and I thank etrailer for there partnin my success.



- SM99243
by:

I purchased an Air Force One brake system from etrailer. The gentleman that helped me was extremely knowledgeable and helpful. The product arrived on time and has been working well for over a year.



- SM99243
by:
Ford Ranger

This system has worked great for my flat towing of my Ford Ranger. Had my local dealer install the system for me and have had not one single issue with the operation.



- SM99243
by:

We love our Air Force One braking system. The confidence it was done right by etrailer allows us to tow our 4x4 van without worrying about it!



- SM99243
by:
2004 Chevrolet Avalanche

Pulled entire length of route 66 and then some. We had absolutely no issues with all of our etrailer equipment. Thanks for all of your help.



- SM99243
by:
2014 Jeep Wrangler

Just finished a 10,000 mile trip trailering a 2014 Jeep Wrangler with Air Force One braking system and we are very satisfied with the product. No issues or failures and once installed, it is very easy to use. We can connect and disconnect from the Air Force One and our Blue Ox towing system in 2-3 minutes.


Comments
After a year, we are still happy with the AF One. We had one issue where it didn’t work and it turned out we let a little grime get into the air fitting. Took some time to figure it out but we cleaned with compressed air and the problem went away. Lessen learned it to keep rubber covers on the air fittings when not in use.
Joe T - 05/17/2020


- SM99243
by:

One year and over 10K miles, it's great. Hook up & go! Did the install myself, instructions are excellent, I contacted Demco support for some clarification of air line connections on the coach, very helpful. Trouble free operation, toad gear is unobtrusive, simple to connect & works flawlessly. Highly recommend!



- SM99243
by:

Should have bought this system sooner. I love that it's fully proportional and truly "plug and play." So much easier to use than my old supplemental braking system that sat on the floor of the car and had to be installed/removed at every overnight stop. I installed it myself, which requires an intermediate level of mechanical aptitude. The instructions that came with the kit and DEMCO's tech support were extremely good.



- SM99243
by:

product shipped quickly, installed with video instructions and one phone call, 13000 miles behind motor home and everything works as it should. Great resource for DIY and saved thousands over professional installation, just follow the instructions and double check everything.



- SM99243
by:

This is really slick and works very well with the MH’s source system.



- SM99243
by:

Only problem was I had to replace vacuum check valve about two months ago. Called tech service told them my problem diagnosed instantly. Braking is excellent even one panic stop .



- SM99243
by:

Overall I am very pleased with this product. It operates well and is easy to hook and unhook the towed vehicle. I gave this 5 stars because of its operation, but do-it yourselfers be cautious, installation is a bit complicated and would be a challenge for most. I have been a truck technician for 30+ years and understand air brake systems well, so it was not a big deal for me, but I could see some struggle. It is really geared for professional installation. There are modifications necessary to both the tow and towed vehicles, and an incorrect line selection or wire could affect the operation of either unit. The kit is very complete, I only had to buy one fitting and a couple wire ends to adapt to my units. This was installed on a 2017 Entegra Insignia and 2013 Jeep Wrangler Unlimited.



- SM99243
by:
2016 Jeep Wrangler

SMI Air Force One was the choice I made when we outfitted our 2016 Jeep Wrangler Unlimited last year. I can honestly say, without any hesitation,...this was the best choice ever. The installation was very straight forward. I was reluctant to cut my coaches brake lines...but the technicians at SMI were very helpful. I emailed them a picture of the brake lines that I had identified per the instructions, and wrapped a piece of colored electrical tape around the lines to identify them. The SMI techs wrote back within 20 minutes and confirmed that I had correctly chosen the correct air lines for splicing into. The fittings where a breeze to install. The system has performed flawlessly...and it works so well ---- if it weren't for a video camera view on my dash...I wouldn't even know the Jeep was back there. When I go to hook and unhook the Jeep. I keep my components in a canvas bag. It contains my Safety cables for the tow bar, lighting umbilical, and the two SMI parts...a coiled quick connect air line, and a safety breakaway cable. The other components of the system stay in place...no lugging them around. They are totally out of sight. If you have a coach with Air Brakes...this, in my opinion, is the best thing going. Proportional braking...directly metered by your coaches signal line. The system is robust...and includes it's own ping tank, and D.O.T. approved metering valve. I feel it's the safest...and best performing braking system built for a towed vehicle PERIOD.


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Ask the Experts about this Demco Tow Bar Braking Systems

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  • Can Demco Air Force One Fit 2021 GMC Sierra 1500 Diesel
    I checked with Demco and they do not have the versions of your 2021 GMC Sierra 1500 with the diesel engines excluded with the Air Force One # SM99243 so this would fit and work great. There would be enough room for the canister to fit. This uses vacuum to build a vacuum in the air tank that this kit installs on your vehicle and then that same vacuum activates your brake system so that the line that pulls the pedal can do so relatively easily.
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  • Recommended Equipment to Flat Tow a 2017 Ram 3500 with a Motorhome with Air Brakes
    Thank you for all of the information! To flat tow your 2017 Ram 3500 you will need a base plate kit, tow bar, safety cables, vehicle tow bar wiring, a supplemental braking system, and possibly a high-low adapter. Since your motorhome has air brakes I recommend using the SMI Air Force One Supplemental Braking System # SM99243 because it installs permanently on your 2017 Ram 3500 and is easy to set up after the initial installation. Aside from it being the best option for air brakes it...
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  • Does LED Indicator Light of SMI Air Force One Light Up When Vehicle isn't Connected
    The LED notification strip that typically attaches to the rearview mirror of the vehicle being flat towed will not always light up when the vehicle brakes are applied. It would have to be connected to the tow vehicle. I attached a diagram for how it wires up as well.
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  • Second Vehicle Kit Recommendation for Flat Towing with SMI Air Force One Braking Kit
    It does appear you have an air nozzle from a SMI Air Force One Supplemental Braking System # SM99243 which would mean that all you'd need further is the second vehicle kit part # SM99209 to install on the vehicle you plan to flat tow and you'd be set. You should trace the air line socket to make sure it looks like it goes to what I attached a picture of. In the picture is the portion of the Air Force One that mounts on the motorhome.
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  • How to Make the Airline Connections on the SMI Supplemental Braking System Part # SM99243
    There are two airlines that must be spliced into on the coach which will then run to the air tank assembly included with the SMI Air Force One Supplemental Braking System part # SM99243. One of these lines is for supply-air and the other is for metered-air. The supply-air line is a 5/8" diameter hose (usually green but not always) which goes from the service relay valve to the braking air tank (see first photo). Once you find this line you will need to cut it in half and install the...
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  • Does the Reed Switch Eliminate the Brake Light Switch on an SMI Braking System
    According to the installation instructions for the SMI Air Force One Supplemental Braking System for Motor Homes with Air Brakes part # SM99243, the reed switch attached to the actuator will power the LED. The brake switch will no longer be providing the signal for the monitor light. Exercise caution when installing the reed switch. If the reed switch arcs to ground, it will either no longer work or cause the LED to stay illuminated at all times. You can reference the installation of...
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  • Monitor Light In Motorhome and Vehicle Brake Lights On With SMI Air Force One
    I spoke to my contact at Demco about the issue you are having with the SMI Air Force One Supplemental Braking System part # SM99243. They informed that if both the monitor light and toad's brake lights are on while driving without the motorhome's brakes depressed then the cylinder is most likely engaged just enough for you not to notice that the brakes are being applied but enough for the system to detect it. The cause for this is due to not having the proper slack on the cable in between...
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  • Can SMI Air Force One Brake Indicator Light Mount in Motorhome?
    I reached out to the manufacturer in regard to your questions about installing the SMI Air Force One Supplemental Braking System # SM99243 and was told that in regards to the indicator light, you can run 14 gauge wire the length of the coach though you will have to wire in a 4 post relay because the reed switch can only handle 100mA of current and will not be able to send the signal that distance; and that the 4 terminals on the relay will be 12v power-Ground-Signal from the reed switch...
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  • Availability of Replacement Parts for SMI Air Force One Supplemental Braking System SM99243
    We do offer replacement parts for the SMI Air Force One Supplemental Braking System # SM99243. These items include a replacement Installation Kit for the motorhome, part # SM99627, a Replacement Towed Vehicle Installation Kit # SM99226 as well as other smaller individual parts such as a replacement Air Jumper # SM99666. You can see all replacement parts by clicking on the linked page for the Air Force One and scrolling down to the heading Replacement Parts.
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  • Can the SMI Air Force One Braking System be Installed if Vehicle Has Adjustable Pedals
    That is a great question! Demco/SMI has actually already thought about vehicles with adjustable pedals, like your 2019 Ram 1500, when installing the Air Force One # SM99243. Basically you just need to adjust the pedal so that it sits closest to your seat when installing the Air Force One and then move it to this position when flat towing your pickup. Their official statement (found in the attached installation instructions) says: Special attention must be given to vehicles with adjustable...
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