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T-72 suspension improvement

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  • T-72 suspension improvement

    Out of the box the T-72 is way over sprung so the track and roadwheels don't deflect much over obstacles, The OE adjustment only has 2 positions, medium and high, with medium being the stock position..

    I removed all the swingarms and drilled a 3rd hole in the hull for the tail of the spring, giving the choice of low, medium, and high. After some trial and error, I found the suspension works best with the springs set as follows;

    #1 (front) springs in the stock medium setting.
    #2-3-4-5 springs in the new low setting.
    #6 (rear) springs in the high setting.

    Set up this way I find that it can now go over smaller obstacles such as 1/2" rebar very smoothly without bouncing or rocking over it, and the track will conform to uneven surfaces rather than bridge low spots. On larger hard edge obstacles like a 2X2 it transitions through the balance point in a much smoother rocking motion, rather than an abrupt pivot.

    3rd hole,
    Click image for larger version  Name:	IMG_3333.JPG Views:	0 Size:	123.7 KB ID:	278597

    I also painted all contact surfaces of the swingarms, roadwheels, return rollers, and idler wheels with CRC dry moly lube which is basically a gray-green paint that uses moly instead of pigment. Being a dry lube it doesn't attract and hold dirt like oil.

  • #2
    Originally posted by windmill View Post
    Out of the box the T-72 is way over sprung so the track and roadwheels don't deflect much over obstacles, The OE adjustment only has 2 positions, medium and high, with medium being the stock position..

    I removed all the swingarms and drilled a 3rd hole in the hull for the tail of the spring, giving the choice of low, medium, and high. After some trial and error, I found the suspension works best with the springs set as follows;

    #1 (front) springs in the stock medium setting.
    #2-3-4-5 springs in the new low setting.
    #6 (rear) springs in the high position.

    Set up this way I find that it can now go over smaller obstacles such as 1/2" rebar very smoothly without bouncing or rocking over it, and the track will conform to uneven surfaces rather than bridge low spots. On larger hard edge obstacles like a 2X2 it transitions through the balance point in a much smoother rocking motion, rather than an abrupt pivot.

    3rd hole,
    Click image for larger version Name:	IMG_3333.JPG Views:	0 Size:	123.7 KB ID:	278597

    I also painted all contact surfaces of the swingarms, roadwheels, return rollers, and idler wheels with CRC dry moly lube which is basically a gray-green paint that uses moly instead of pigment. Being a dry lube it doesn't attract and hold dirt like oil.
    Drilling additional wholes to tune suspension spring performance has been being done for a long time. It is just one way to tune the suspension and can be highly effect. It’s good to see you experimenting, and posting your results as so many folks are afraid to try any modifications that are not simple bolt on. 👍👍

    Comment


    • #3
      Originally posted by Rubicon99 View Post

      Drilling additional wholes to tune suspension spring performance has been being done for a long time. It is just one way to tune the suspension and can be highly effect. It’s good to see you experimenting, and posting your results as so many folks are afraid to try any modifications that are not simple bolt on. 👍👍
      I did a bit of searching for suspension improvements with no results, but the solution was obvious once I dug into it. For me, improvements, modifications, and scratch building are half the fun.

      Before I got the T-72, I converted a static 1/16 Tacom FT-17 to RC. The kit comes with fixed suspension, but I modified it by scratch building its double articulating leaf spring suspension, and sprung return roller carrier. Unfortunately the 1/35 Tamiya T-34 RC system I powered it with didn't have sufficient power for the application, and it sits unfinished.
      Click image for larger version

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      The more I dig into the T-72, the more impressed I am with it, and the more I want to do to it. Besides the suspension, I've already upgraded it to steel gearbox, and have metal tracks, sprockets, and return idler wheels on order. I think I will keep the plastic roadwheels, and just add bronze sleeve bushings to them https://www.bronzebushings.com/sae-8...shings/4-mm-id. i might do something with the return rollers too, as they're plastic on plastic. Besides that, I'm open to suggestions.

      Comment


      • #4
        Originally posted by windmill View Post

        I did a bit of searching for suspension improvements with no results, but the solution was obvious once I dug into it. For me, improvements, modifications, and scratch building are half the fun.

        Before I got the T-72, I converted a static 1/16 Tacom FT-17 to RC. The kit comes with fixed suspension, but I modified it by scratch building its double articulating leaf spring suspension, and sprung return roller carrier. Unfortunately the 1/35 Tamiya T-34 RC system I powered it with didn't have sufficient power for the application, and it sits unfinished.
        Click image for larger version  Name:	IMG_3334.JPG Views:	2 Size:	180.0 KB ID:	278609



        The more I dig into the T-72, the more impressed I am with it, and the more I want to do to it. Besides the suspension, I've already upgraded it to steel gearbox, and have metal tracks, sprockets, and return idler wheels on order. I think I will keep the plastic roadwheels, and just add bronze sleeve bushings to them https://www.bronzebushings.com/sae-8...shings/4-mm-id. i might do something with the return rollers too, as they're plastic on plastic. Besides that, I'm open to suggestions.
        I am big believer in upgrading to metal road wheels with bearings and have them on two of my three T72s. That said one of my T72s has been running plastic wheels on the stock metal shafts for some time now and I have seen little wear to the inner wheel or axle shaft surfaces that would require either to be replaced anytime soon. Not long ago this would not have been the case, but HL upgraded most of their designs with better road wheel to axle fit and this has done a lot to keep dirt/dust from getting between the road wheels and their axles. The dirt/dust has the effect of sand paper and would wear down the axles and causing the road wheels to become extremely loose and even fall off after just as short time of outdoor running.

        So unless you want to sleeve the axles just because go for it, but they don’t really need it.

        The T72/90 both have a design flaw that tends to show up after a short time of outdoor running. The lower forward hull on both sides in the area just in front of the idler wheels tend to crack. This causes the idler wheels to pull outward and become misaligned and can even come in contact with the #1 road wheels. I noticed on my last T72 bought not long ago that HL had added reinforcing braces to the lower forward inner hull to help with the cracking issues. Check to see if yours has these small braces and if not you should look at adding some reinforcements in the area. Even with them on mine I went ahead and added some metal reinforcements.

        Comment


        • #5
          Originally posted by Rubicon99 View Post

          I am big believer in upgrading to metal road wheels with bearings and have them on two of my three T72s. That said one of my T72s has been running plastic wheels on the stock metal shafts for some time now and I have seen little wear to the inner wheel or axle shaft surfaces that would require either to be replaced anytime soon. Not long ago this would not have been the case, but HL upgraded most of their designs with better road wheel to axle fix and this has done a lot to keep dirt/dust form getting between the road wheels and their axles. The dirt/dust has the effect of sand paper and would wear down the axles and causing the road wheels to become extremely loose and even fall off after just as short time of outdoor running.

          So unless you want to sleeve the axles just because go for it, but they don’t really need it.

          The T72/90 both have a design flaw that tends to show up after a short time of outdoor running. The lower forward hull on both sides in the area just in front of the idler wheels tend to crack. This causes the idler wheels to pull outward and become misaligned and can even come in contact with the #1 road wheels. I noticed on my last T72 bought not long ago that HL had added reinforcing braces to the lower forward inner hull to help with the cracking issues. Check to see if yours has these small braces and if not you should look at adding some reinforcements in the area. Even with them on mine I went ahead and added some metal reinforcements.
          Great info on the roadwheels, I'll just keep an eye on them. I can always do it at a later time if need be.

          So the big question is, what version do I have? The hull has some braces in the vicinity of the Idlers, but not having any point of reference I'm not sure they are what you alluded to.
          Click image for larger version

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          Comment


          • #6
            Originally posted by windmill View Post

            Great info on the roadwheels, I'll just keep an eye on them. I can always do it at a later time if need be.

            So the big question is, what version do I have? The hull has some braces in the vicinity of the Idlers, but not having any point of reference I'm not sure they are what you alluded to.
            Click image for larger version

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            You have the new version👍👍

            The old ones did not have the forward bracing.

            Comment


            • #7
              Originally posted by Rubicon99 View Post

              You have the new version👍👍

              The old ones did not have the forward bracing.
              That's good news.

              Apparently its a potential issue in 1/1 scale too.
              Click image for larger version

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              Comment


              • #8
                Originally posted by windmill View Post

                That's good news.

                Apparently its a potential issue in 1/1 scale too.
                Click image for larger version

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                What a lot of us that have been in the hobby a while have learned is these 1/16 tanks tend to have some of the same design flaws/weaknesses show up as in the real ones.


                Comment


                • #9
                  Installing Mato metal tracks called for some adjustment.

                  #1 (front) spring medium
                  #2, 3, 4, spring low
                  #5 spring medium
                  #6 (rear) spring high

                  The metal track needing higher tension, combined with the extra weight was causing the rear end to squat. With the metal track and 4 .69 cal musket balls in the front of the hull, the tanks balance point is now the center of the turret which improves its obstacle climbing abilities.

                  Comment

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