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Convert rear suspension from leaf-springs to trackion bars

Discussion in 'Suspension' started by Nova1967, May 22, 2024.

  1. May 22, 2024 at 7:38 PM
    #1
    Nova1967

    Nova1967 [OP] New Member

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    Rear Sway bar, TRD dual exhaust, HR Light front hood light bar, front grille and bumper chrome deleted. Replaced all parts with smoked mesquite
    I currently have a 2021 tundra crew-max with leaf-springs. I installed a new rear sway-bar but the over ride is still bounce. Has anyone converted from leaf-springs to the new 2022-2024 rear configuration? The long bar which replaced the leaf-springs. I call them torsion or traction bars. The 2022 and above models does have a smoother ride.
     
  2. May 22, 2024 at 9:14 PM
    #2
    Chad D.

    Chad D. New Member

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    Can you convert from a leaf-sprung rear suspension to a trailing arm system? Off course. It’s going to cost a pile of money and take a good amount of work. Much of it custom.


    Much more common would be to invest in a high quality pair of leaf springs and great shocks. I also have a CrewMax, and went with Deaver U748 springs. This is a very common swap and bolts right in. For max shock adjustability and tuning, look at some high end bypass shocks.

    You’ll need to upgrade the front to keep up….
     
    redrdr67, snivilous and blenton like this.
  3. Jun 3, 2024 at 6:51 PM
    #3
    iamsmokey

    iamsmokey Smokey the Tundra

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    What shackles are you running with the U748s? Also, how much overall lift height did you get? Thank you in advance!
     
  4. Jun 3, 2024 at 7:23 PM
    #4
    Chad D.

    Chad D. New Member

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    I have Total Chaos shackles. Believe they’re about 1.75” longer than stock, and total rear lift is in the 2” range.

    If you go this route, it will take a while for the springs to settle in. Mine started at about 4” it felt like! Once settled, they’re perfect.
     
  5. Jun 3, 2024 at 7:33 PM
    #5
    iamsmokey

    iamsmokey Smokey the Tundra

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    Holy smack! Touching clouds with the rear at 4" haha! thank you for the info. Getting close to that time of touching my suspension again and am leaning towards the U748s. Hoping for 1.5"-2" of actual lift height after settling. Carrying any weight in the rear?
     
  6. Jun 3, 2024 at 9:30 PM
    #6
    Chad D.

    Chad D. New Member

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    Yes, I carry a lot of weight.

    Canopy that’s not a cheap light weight model. Also have 200W in flexible solar panels on top of it between the roof rack rails.
    Bedslide with a tote full of basic tools and crap.
    My turnout bag is typically in the bed.
    50L Dometic fridge.
    285/75-18 matching spare tire and wheel.
    Sub box behind seat.


    That’s most of my weight in the back half of the truck. Maybe 450-500 pounds more than stock? The U748s handle it very well.

    A K37 pack is another option that is softer, but lots of folks find that they can’t support the weight of a CrewMax for long term.
     
  7. Jun 4, 2024 at 12:12 AM
    #7
    blenton

    blenton New Member

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    I haven't seen anybody do it here on the forums, but that doesn't mean it can't be done. As @Chad D. said, it would take a pile of time and money. You would have a few options, all of which requiring rear frame reinforcement and fabrication. The newer coil sprung trucks are designed to absorb all of the suspension spring force over a small region of the frame, so it the area around the coil spring is reinforced. It's also more rigid which allows the multiple links and bushings to flex a move a little without feeling squirley. A C channel frame could feel looser, depending on your suspension design.

    Your first option is a trailing arm design that uses a heim joint or bushing where the arm attaches to the frame, and fixed mount at the axle to keep it from rotating. These two parallel arms locates the axles front to back and up and down, but you still need to locate it side to side with a pan hard bar attached at the fame on one side of the axle, and the axle housing on the other side. Technically, you could use a sleeved bushing at the front of the trailing arms to locate the axle side, but you would have very little axle articulation.

    Second option is an asymmetrical four link. Use two bottom link running from the bottom of the frame rails to the center of the axle, attached with helms, johnny joints, bushings, etc. Build two more links tied up high on the frame close to the carrier bearing and run them to the outsides of the axle close to where the leaf springs were. This gives you two sets of non parallel bars that will allow the axle to move up and down and articulate, but limit front to back and side to side movement as the bars travel in different arcs. This is a great rock crawler setup but can feel loose on the street.

    Third option is a parallel four link with pan hard bar. Run two sets of links - an upper set attached high on the frame to high on the axle, and a lower set below the frame attached below the axle - with each set being different lengths. These will keep the axles located front to back and keep it from rotating, but you still need to keep it from moving side to side with a pan hard bar. Even though this uses five links instead of four, it is simpler to locate the links and clear everything else under chassis.

    You have other fun options like weird 3 links, semi-elipictal springs, watts links, etc, but we'll ignore them.

    No matter which option you choose, you still need to suspend the weight of the vehicle. Coil springs would work but you don't have much room for a coil spring between the axle and frame. You would need to relocate the spring inside the frame, fab up another beefy crossmember to support the entire load of the rear of the vehicle, cargo, and trailer, and make clearance around those new links, the exhaust, brake lines, etc to clear the springs.

    Air bags would fit between the frame and axle, but for you to have even stock levels of down travel, you would need to use a cradle on the bag which disconnect it on downtravel, then possibly limit that down travel with a strap unless you want to use the shock as a limiting strap. You would need to properly size the bag or you would run in to up travel issues as well, possibly making the ride worse.

    You could use cantilever arms to run the springs parallel to the frame. This, again would require some beefy crossmembers and more linkagage, plus clearance issues with the exhaust, gas tank, EVAP system, spare tire, etc.

    Another option is just a good ol' fashioned coilover. This would most likely require cutting through the bed and running aggressive offset wheels to clear the coilover bodies.

    So, ya, you could make it happen. :D
     
    redrdr67 likes this.
  8. Jun 4, 2024 at 12:24 PM
    #8
    iamsmokey

    iamsmokey Smokey the Tundra

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    This is stupidly helpful info. I've got a Yakima rack with sidebars, 2 rotopax for water (planning on getting more), and full size spare. So this is starting to sound right down my alley. Now just trying to figure out what shocks will pair with it...
     
  9. Jun 4, 2024 at 1:25 PM
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    Chad D.

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    Lots of options for shocks, just make sure they’re long enough for the Deavers.

    I have ADS shocks, and they offer a longer option for aftermarket spring packs like Deaver for Tundras.
     
  10. Jun 4, 2024 at 1:32 PM
    #10
    iamsmokey

    iamsmokey Smokey the Tundra

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    Been contemplating ADS as well. I'm trying to be practical (lord knows I'd drop $$ if I got what I "wanted" haha).

    The ADS ones I've been looking at:
    https://www.adsshocks.com/products/direct_fit/direct_fit_race/parts/250-TN07R-000

    Now compare it to 5160's: Their compressed and extended lengths are very similar yet ADS claims 0-3" while Bilstein claims 0-1.5". Here is where I get confused.
     
  11. Jun 4, 2024 at 1:32 PM
    #11
    NatesNightMare

    NatesNightMare Is what it is

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    Pro comp 7", 35" tires, method wheels, brush guard, light bar, roof rack, pedal commander, magnuson 2650 supercharger
    Lol I dont have a spring lift but im lifted about 8" on 35s
     
  12. Jun 4, 2024 at 3:04 PM
    #12
    Chad D.

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    That ADS you linked appears to be for stock spring packs. They offer another option that is the same travel, but about 3/4” longer to accommodate for the thick spring packs.

    https://www.adsshocks.com/products/direct_fit/direct_fit_race/parts/250-TNK37-000
     
  13. Jun 4, 2024 at 3:30 PM
    #13
    redrdr67

    redrdr67 New Member

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    What blenton suggested is spot on. Keep in mind when going with any of those options, you'll need to catalog the wear parts, bushings, heims, etc. for down the road replacing.
     
    blenton likes this.
  14. Jun 5, 2024 at 11:19 AM
    #14
    iamsmokey

    iamsmokey Smokey the Tundra

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    Good catch, I posted the wrong link haha. Here is where we are at...

    Fronts:
    https://www.adsshocks.com/products/direct_fit/direct_fit_race/parts/250-TN07L-000
    Rears:
    https://www.adsshocks.com/products/direct_fit/direct_fit_race/parts/250-TNK37-000

    Paired with Deaver U748s and TC Shackles.
     
  15. Jun 5, 2024 at 1:07 PM
    #15
    Chad D.

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    Worth checking with Matt at MCM for this package. His pricing was a little better than MSRP last time I checked. He makes shackles that are essentially identical to TC.

    Don’t forget the UCAs and Duro Bumps for the front.
     
  16. Jun 5, 2024 at 1:40 PM
    #16
    iamsmokey

    iamsmokey Smokey the Tundra

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    Just reached out to MCM! Currently have Camburg balljoint arms, working well with the 5100s at max setting. Also have wheeler superbumps in the front and have a pair for the rear when the leaf packs get swapped
     
  17. Jun 5, 2024 at 8:17 PM
    #17
    Chad D.

    Chad D. New Member

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    You’re set.
     
    iamsmokey likes this.
  18. Jun 10, 2024 at 11:51 PM
    #18
    Nova1967

    Nova1967 [OP] New Member

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    Rear Sway bar, TRD dual exhaust, HR Light front hood light bar, front grille and bumper chrome deleted. Replaced all parts with smoked mesquite
    Thank you for the many options on leaf-springs conversion traction bars. I ran out of money while reading the entire solutions. The Gen-2 tundra's stand above the Gen-3's, any day of the week. They are faster with the twin turbo's until I install the Magnuson Supercharger. Their technology upgrades have been tremendous with competing against the other truck dealerships. The Gen-2 crew-max is much more spacious with room to spare.
     

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