AutoFlex Pickup Truck air ride Revisited

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Auto Flex or Kelderman ?


Complete rear truck suspension replacement with air bags for improved handling, braking and load carrying. Self levels adjusting to your load. I’m sure you’ve noticed semi trucks and trailers have air bag suspensions. With AutoFlex pickup truck air ride, your truck can to!

The semi-tractors have had air bag axles, air ride cabs and air seat for decades. Our pickup trucks are rated for larger trailers and payloads each model year. Why aren’t we copying how semi trucks are made? Larger trailers and payloads also means more rear axle squat and more axle travel between empty and loaded. That difference between a loaded and empty truck, changes the pinion angle effecting the drive shaft alignment with the end of the transmission. When the angle from transmission to rear differential isn’t at the proper angle, your truck will buck, shake and pitch. If too straight, you’ll have vibration.

This is a growing problem in the last 10 years with truck manufactures trying to split the difference in pinion angle from loaded to empty by shimming the differential angle with blocks between the springs and axle. This is not a good fix for the problem, but a band aid. The right way to solve the pinion angle problem is a total air bag suspension that self levels to keep pinion angle the same all the time automatically. Whether you are hauling 1 horse or 4 horses, the truck will be level.

We keep our trucks longer, Auto Flex air suspension can make it handle better than new. Fixing up your truck instead spending $60,000 on a new truck makes sense now more than ever. Gas engines can last 200,000 miles and diesels 300,000. We’ve been talked into trading trucks often. Save money keep your truck longer.

Auto Flex can dramatically improve your trucks ride and handling. Keeping your truck level automatically, with better braking, and handling curves flatter. Headlights won’t be star searching and oncoming traffic won’t be flashing you. Have you ever had your truck full of feed or a slide in camper and the truck squatted and wandered, making driving work? The suspension your truck came with is a compromise.

I tow trailers across the country, mostly on Interstates. While we seem to be always driving in road construction during the summer, even the normal asphalt is rough with potholes, washboards and patches. I’ve broke battery cases, headlights and blown tires on Interstates. You’d think you were on forgotten county roads instead of federally funded super highways. Auto Flex on my F250 is the cats meow. I might even take some shortcuts cross country on the next trip. We also added Auto Flex to my Safety Hitch giving me air ride on my auxiliary axle. This summer we’ll add Trailer Flex to my gooseneck. Then I’ll be floating on air on these off-road Interstates. Everything should last longer including me. I’ll miss seeing my belly bounce. Why do you think semi-trucks went air ride on trucks, trailers, seats and cab? Truckers knew the Interstates were getting worse each year with less road tax being used to keep the roads maintained. If we can’t elect officials that will invest in infrastructure, we better get air ride.



We installed two Auto Flex Systems and tested on different trucks, both diesels both 3/4 ton’s that tow trailers as part of their job description, both had aftermarket air assist. One was a 2006 Ford F250 diesel, 129,000 miles new front brakes. Second was a 2006 GMC 2500 diesel, 104,000 miles new front brakes.

Easy install as bow replaces the factory leaf springs, eye to eye replacement. No welding or drilling, just chain the axle each side to the frame, put a jack stand under the pinion and take the leaf springs off. You’ll reuse the rear hanger on the new bow arm to fit where the spring was. Then you attach the lower swing arm to the axle and the front of the bow, add the air bags, compressor and tank. The tracking bar goes from the drivers side bow to the passenger side lower swing arm. All that’s left is the leveling valve from cross member to the differential, air lines and juice. AutoFlex comes with a dump valve to lower the truck to ease hooking to a trailer. Each air bag comes with a valve to lock air in or out. This allows you to level a slide in camper on uneven ground or hold air in the bags if you have a line leak.

Comes with all brass fittings, no 45 or 90 degree fittings in line from tank to air bags. This makes the air flow faster for the automatic leveling system. Steel braided line from compressor to tank for faster flow and pressure using a high performance air compressor with a check valve. The compressor has 20 amp fuse, fills a 3 gallon air tank. I went with the optional 5 gallon air tank. With the performance compressor putting out 120 psi, I can run an impact wrench to change tires. The system comes with a female coupler for attaching air hoses for airing up truck and trailer tires.


AutoFlex Pickup Truck air ride Revisited

Also comes with new hydraulic shock absorbers. The factory gas shocks come off, air bags only push up, need hydraulic shocks to dampen the suspension.

Locking nuts on the bows, 3/4 in grade 8 bolts. The air lines are 3/8″ just like the semi-trucks. That keeps them from freezing as well as the compressor tank and brass drain petcock. My old system aftermarket air bag helper springs would freeze the 1/4 air line each winter. Then they stopped working until they thawed out, and you couldn’t do anything to speed that up. AutoFlex was developed in the cold part of Canada, if they don’t freeze there, I should be in good shape in Colorado.

Auto Flex and Trailer Flex are manufactured by LBC Trailers. They’ve been making logging trailers with lift-able axles since 1998. Fourteen years building semi trailers with air suspension, I’d call that well tested.

Bow framework on top fits F250-550 and 2500-5500, just different air bags, lower trailing arm attaches to truck axle. Lower arm pivots at axle. Bushings in trailing arm are greaseable. Rubber bushing in tracking bar for quiet and rubber bushing with steel sleeve for trailing arm keep the suspension tight. The lower arm oscillates for uneven roads.

Auto Flex single stage air bags self center, are a rolling bag to give on corners. Double bellows used in after market air assist products, just support weight, aren’t a real suspension. Auto Flex is not an add on, but leaf spring replacement. No drilling, welding or cutting your truck means is doesn’t’ affect you warranty. On-board air compressor adjust the pressure inside the air bags to match a truck’s load.

If compressor or air line failure, each bag has a valve for filling or shutting off bags. Rubber stops inside air bags are in case of air loss you can still drive to get repaired. Automatic leveling valve You don’t have to think about it. Just enjoy it.


Popup Gooseneck Cushion Coupler

AutoFlex Pickup Truck air ride Revisited – Results: 

Both trucks nosed dived braking from 60-0 mph with stock leaf springs. With Auto Flex there was less body roll, most trucks don’t have anti-sway bars anymore. Handling improved, ride improved with more wheel travel. In our brake test stopping from 60 mph, factory leaf springs stopped 133.9 ft verses 120.7 ft with Auto Flex, 13.2 ft. shorter with the Ford F250. More controllable handling under braking.

During acceleration, the air bag pushes up on the truck body pushing down on the axle for more traction and better fuel mileage.

If your trucks loaded and squatting, your drive shaft angle to transmission and differential is in a bind and will cause vibration, bucking and wear. Wheel hop and pinion angle deflection are hard on U-joints. Imagine always being level in your truck, no sagging, being level with different trailers and heavy loads. you don’t always haul the same load with your trailer, so sometimes, the trailer is level and sometimes it goes down hill. Brakes on your trailer work best when equal load is on both axles. The dump valve will lower your truck 5 inches to get under your gooseneck without as much cranking on the trailer jack.

The steering problems are not just from the front, with a loose rear suspension, the truck can wander. Auto Flex takes the slack out of the rear suspension. The two test trucks we used had over 100,000 miles on them and dramatically improved handling and steering after Auto Flex was installed.

If you race your truck or just accelerate when passing or the on ramp to the freeway, you’ve experienced axle rap from flexing both sides of the axle on leaf springs. This air suspension eliminates axle rap. when the rear of the truck squats, this changes the frame angle which changes the drive shaft angle to the pinion.

Adjustable tracking bar makes for tighter suspension. Your rear end won’t be doing the Elvis pelvis action. Auto Flex air bag is behind the axle for leveraging the trailing arm and is as wide side to side as leafs for stability and less teeter toter action than you get with after market air assist bags that are inside the leaf springs. Aftermarket air assist bags puts pressure on one spot on the axle and frame. With Auto Flex, the air bag pushes on the replacement bow not the frame.

We used an accelerometer to test movement. Auto Flex had a rounding impact smaller range verses a sharper spike with leaf springs. This could be a big improvement in the RV market especially Class C motor homes.

Video below; with the extra wheel travel you can see when the truck accelerates shifting gears, the air bags push down on the axle for more traction. During braking you can see how level the trucks stays. Big improvement in handling and braking while automatically load sensing to self level your truck. Sport camera left, stayed steady with the Auto Flex Suspension.

See it work, SEMA Video

Dodge Ram 1500 with rear coils 2009 + have a big problem with squatting at their max capacity rated by the factory. Auto Flex replaces the coil with an air bag to dramatically level the Ram and improve handling.

And the truck will stay level loaded or empty

We’re going to test Auto Flex on a new truck next, to see the difference. 1-807-623-0590

Auto Flex:

Trailer Flex:

Kelderman Air Ride Suspension

For your truck and trailer

Kelderman’s Dodge is on the cover of  Truck Trend Magazine (November/December) as well as having 4 trucks at SEMA. Their Ford Harley truck was one of the highlights of this years SEMA show. You will be seeing Jeff Kelderman’s lifted air suspension trucks on many more magazine covers in the following months. Here are the 2004 SEMA trucks.

Kelderman 12″ air lifts, the bed lifts & rolls flat on the ground to unload the Harley


Your Truck can ride on air. Why get a air hitch when you can have air ride all the time. Modern pickup trucks are more powerful and haul heavier trailers. So it’s natural that they follow the technology used in modern over-the-road semi trucks.

If you like a raised truck like the one above at 10 inches or just the comfort of a level air ride, Kelderman has a model for you.

This is the truck I drove, a 03 Dodge 2500 Quad Cab short bed 4×4. It was lifted with the complete Kelderman air suspension. The factory Dodge rear leaf springs where completely replaced along with the front drag links and shock-in-coil springs. It adjustable with the onboard compressor, tanks and gauge. Frame matching black parts and Rancho shocks.

The model I drove was self contained with the optional 3 air tanks and a compressor. The gauges and operating button are in the cab. Automatic Ride Height is another option were a leveling valve on the Air Ride Suspension System senses the position of the Air Ride and makes adjustments automatically. If the load on the truck increases, air is added to the system, if load is reduced, air is bled from the system – all automatically.

Front stamped factory drag links are replaced with Heavy Duty bars.

Here is the Kelderman add on rear air suspension. The Kelderman Air Ride Suspension comes with a hitch receiver rated to pull over 10,000#’s

Click on the pictures below to see the details of the ten inch lift.

Here is the complete factory replacement Kelderman air suspension on a 03 one ton dually which pulls heavy trailers at normal height. I did say heavy trailers, like this 48 foot trailer pulling the high mountain passes in Colorado.

Pickup Truck manufactures leave room for improvement. With today’s more powerful diesels pulling larger trailers, get the suspension that will hold up to your trucks maximum weight capacity. There is a reason air-suspensions are so popular in modern semi-trucks and trailers. If your truck is a serious hauler, get a serious suspension. Looking to lift your truck, Kelderman manufacturing makes the one built like a tank with a 1/2 ton ride.  I drove a 2003 Dodge 2500 short bed with a lifted air suspension, it was great and looked custom with a self contained air system. AutoFlex pickup truck air ride!

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