usra bmod set up

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  • cgs
    Member
    • Jan 2009
    • 91

    #1

    usra bmod set up

    what are the shock and spring placements on a usra bmod?
    ie shock and spring on front or do you guys separate them? also when the track goes slick how much lr bar angle will you use?
  • hpontap
    Senior Member
    • May 2008
    • 574

    #2
    A friend of mine runs LR spring in front on a slider with shock behind. RR spring on top of housing with shock in front.
    Raise the LL bar up on chassis to add drive. Around 42 - 45 degrees LL bar angle at full drop.

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    • cgs
      Member
      • Jan 2009
      • 91

      #3
      thank you. what I'm also curious is how much is everyone using for drop? I have 4 in of drop at ride height which puts my bar angle at 38. is 4 in the ballpark and add angle or do I need to extend my drop to 6 in to get 45 degrees?

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      • hpontap
        Senior Member
        • May 2008
        • 574

        #4
        I want to say you need 5" - 5-1/2" of drop should get you pretty close. Let out on your limiter chain until you get to around 43 degrees and see how much drop you have. Make sure that you dont over extend your shock in case you need a shock extension on it. And check that you dont over-index the birdcage and get it hung up.

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        • powerslide
          Senior Member
          • May 2007
          • 2696

          #5
          Originally posted by hpontap View Post
          I want to say you need 5" - 5-1/2" of drop should get you pretty close. Let out on your limiter chain until you get to around 43 degrees and see how much drop you have. Make sure that you dont over extend your shock in case you need a shock extension on it. And check that you dont over-index the birdcage and get it hung up.
          He is on a 2link.

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          • hpontap
            Senior Member
            • May 2008
            • 574

            #6
            Forgot to add that your LL bar will probably already be in one of the upper chassis holes when using that much angle.

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            • cgs
              Member
              • Jan 2009
              • 91

              #7
              thanks. ya I'm almost to the top. I had it limited with a chain from my four link. I'm not actually a usra car. imca and two linked it cause it fits my driving style better. is there an advantage to putting the shock up front on the left side when it slicks off? right now I'm dominating heat races when its heavy and or rough. just need some help when it slicks off.

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              • hpontap
                Senior Member
                • May 2008
                • 574

                #8
                One of the worst mistakes I ever made was to make too many changes at one time. If you increased you LR bar angle, I would try that and see what it does before changing anything else. One change at a time so you can see how the car reacts.

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                • cgs
                  Member
                  • Jan 2009
                  • 91

                  #9
                  winner winner!! track was heavy rough. went right thru the ruts like they weren't there while all the 4bar cars jarred there teeth out. yes one change at a time. the car is close so I don't need to throw the kitchen sink at it.

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                  • hpontap
                    Senior Member
                    • May 2008
                    • 574

                    #10
                    Glad to hear you are getting better and thanks for the feedback also. Give 'em Hell.

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                    • cgs
                      Member
                      • Jan 2009
                      • 91

                      #11
                      you're welcome. what I need help with is slick conditions with this two link. has anyone ran a really soft lr spring on a two link. to help it get on the bar and to also keep some kind of preload on the spring at full hike? like a 125?

                      Comment

                      • hpontap
                        Senior Member
                        • May 2008
                        • 574

                        #12
                        I have ran the soft spring/lot of pre-load deal in a few different class cars. What I found was after the spring is past a certain point , the effects start going the other way from how you intend. I had good luck with a Shaw Modified with a 150 spring on the LR with a LOT of pre-load in it. Some guys used to run soft ( 125-150 ) spring but 20" on the LR also.

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                        • powerslide
                          Senior Member
                          • May 2007
                          • 2696

                          #13
                          I would try a clamped swingarm LR if you want to get better traction in the slick.

                          Comment

                          • cgs
                            Member
                            • Jan 2009
                            • 91

                            #14
                            Originally posted by hpontap View Post
                            I have ran the soft spring/lot of pre-load deal in a few different class cars. What I found was after the spring is past a certain point , the effects start going the other way from how you intend. I had good luck with a Shaw Modified with a 150 spring on the LR with a LOT of pre-load in it. Some guys used to run soft ( 125-150 ) spring but 20" on the LR also.
                            right now I have a 200 and with it jacked up i have an 1in between the spring and saddle. I was thinking a softer spring with more preload might help keep a little more pressure on the left rear when it's at the top of hike. I'll be at a slick track in a couple weeks and will give it a try. thank you

                            Comment

                            • cgs
                              Member
                              • Jan 2009
                              • 91

                              #15
                              Originally posted by powerslide View Post
                              I would try a clamped swingarm LR if you want to get better traction in the slick.
                              spring on the arm and the shock on a clamp?

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