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Bump Steer Kit for Evo I/II/III

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  • Bump Steer Kit for Evo I/II/III

    Hi guys!

    See bottom of post for a description of "Bump Steer" and how it affects the Early Evo.

    As some of you may know, I have come up with a solution to the Early Evo's bump steer tendencies. I have decided it is time to make them available for everyone. I have made two kits: one that is used with an un-corrected roll center (standard ball joints) and one that is used with a corrected roll center (extended ball joints). The kits include:


    - (2) New inner tie rods
    - (2) 6061 T6511 Tie Rod Tubes
    - (2) Fk 5/8"-18 4340, PTFE lined Rod Ends
    - (2) Rod End Boots
    - (2) Mitsubishi Tapered Adjustable Heim Adapters (Standard OR Raised Roll Center)
    - All necessary hardware for install





    Both kits (adjusted roll center and non adjusted roll center):




    This kit can be used on the street, but it was designed for the track. The rod ends are fully sealed and teflon lined so they should last for quite some time in any environment. The steering systems on the Evo I/II/III are nearly identical physically and geometry wise to the 1g DSM so I installed this kit on my daily driver '90 Eagle Talon 3.5 months ago. The kit has been heavily abused and has shown NO signs of wear or grittiness during my weekly checks. It is the middle of winter here in New England where they use some real nasty stuff on the roads so I am very happy with the rod ends' durability and performance; I can only assume due to the awesome Seals-It rod end boots used.

    Bump steer has been eliminated from my lowered Talon and the steering has become extremely predictable. Before the install of this kit the car would jolt from a mid corner bump and a steering correction would be needed. This upsets the chassis and unbalances the car enough to be a nuisance. Limiting bump steer inspires confidence and provides the driver with a more informed feeling of what the tire is actually doing.




    - Year, Make, Model of your Evo
    - Stock ball joints or aftermarket? (If you don't know then 99% sure they're stock :) )
    - Name
    - Address
    - Any special instructions for delivery, etc.





    Although exaggerated, this short video demonstrates how bump steer (sometimes referred to as "self steer") affects tire direction when the suspension compresses and rebounds.



    Bump Steer is when your wheels steer themselves, either toeing in or toeing out, without input from the steering wheel. This self steering affect is happening at the wheel before the steering linkage so it is generally not felt by the driver through the steering wheel. The undesirable steering is caused by bumps in the road or track interacting with improper length or angled suspension and steering linkages.



    Bump steer generally gets worse when you start changing the stock suspension geometry, including lowering. When you lower a MacPherson strut vehicle like the Evo I/II/III (or any Evo for that matter), you end up changing both the lower control arm angle and the tie rod angle. The problem is that the tie rods and lower control arms are different lengths so they end up at different angles. To eliminate bump steer the lower control arm and the tie rod angle need to be parallel or very close to it.

    For more info on bump steer see the links below:

    Wiki Bump Steer Definition

    Longacre Bump Steer Article

    BUMP-STEERING: WHAT IS IT, SHOULD I CARE, AND WHAT CAN I DO ABOUT IT ANYWAY?
    Last edited by xloki77x; 07-04-2015, 03:47 PM.

  • #2
    Brilliant Pete, as always.

    Good to see you're bringing this to the forum. :good:

    Comment


    • #3
      Awesome stuff. Thanks so much for bringing this product to the Evo 123 world. Top-notch stuff!

      Comment


      • #4
        very nice

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        • #5
          So if we want this kit and using stock lower arm ball joint i cant use the corrected roll center one?

          Lets say i want this and will buy the one u have for stock .but in the future if i get lower arms with corrected roll center ball join i cant use the one i got?

          Comment


          • #6
            Thanks for the kind words guys. I have a couple other things that will be posted soon so keep your eyes peeled. Camber and toe arms that eliminate all rubber bushings (including the awful "dog bone" design) in favor of spherical rod ends (same that are used in the bump steer kit) and adjustability ^_^.


            For you Nik?! Yeah we can do that :). Actually, that sounds like something i should list in the ad as an option for everyone. The only difference between the kits are the spindle/heim adapters so I can include both sets for an additional $25 so total amount of $450 usd.

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            • #7
              awesome . Waiting on a sale for my current tie rods . As soon as i sell them ill shoot you a pm .
              also i didnt quite got the difference from one and the other any chance u could detail it out?
              are those washers on the one of the kits?
              also do you know how much do these babies weigh? they look kinda chunky

              Comment


              • #8
                Pete, this is probably unrelated but will ask it here anyway. When I'm driving on roads (the surfaces aren't perfect in this part of Japan), bumps in the road can cause steering wheel movement needing a little correction all the time. Alignment is dead on and I know part of it is probably because of the coilovers I've got giving me a stiffer ride. But does that sound like some of the bushings are on their way out? If so, which ones do you think I should take a look at first.

                Excellent looking kit, BTW :)

                Comment


                • #9
                  Originally posted by soldave View Post
                  Pete, this is probably unrelated but will ask it here anyway. When I'm driving on roads (the surfaces aren't perfect in this part of Japan), bumps in the road can cause steering wheel movement needing a little correction all the time. Alignment is dead on and I know part of it is probably because of the coilovers I've got giving me a stiffer ride. But does that sound like some of the bushings are on their way out? If so, which ones do you think I should take a look at first.

                  Excellent looking kit, BTW :)
                  That sounds like exactly what i suffer from also. All my bushings are in excellent shape, i'm thinking it could be the coilover dampers getting weak... they have been on for about 3 years now. What you guys think ... bump steer or weak damper ?

                  Comment


                  • #10
                    Dave/Dupstone -

                    Generally, the steering wheel does not move with bump steer, but it can. But this could also point to a few other things. Could be over damping of your front shocks, too high a spring rate, weak/loose/old tie rods, ball joints, or bushings, or a combination of the lot. Try lowering the damping of your shocks all the way (if they are adjustable) and see if the symptoms remain. Next, try jacking up the car and shake the wheel with your hands at 12 and 6 o'clock. This is a quick check for ball joint play. Then shake at 9 and 3 to check tie rod play.



                    Originally posted by nikolas4g63 View Post
                    also i didn't quite got the difference from one and the other any chance u could detail it out?
                    For Evo's with standard ball joints, the tie rods need to moved to the top of the knuckle to correct bump steer.
                    For Evo's with aftermarket ball joints, the tie rods need to be moved below the knuckle to correct bump steer.
                    It gets way more confusing because Mitsubishi changed the tie rod/knuckle configuration on the Evo II/III so that's why I need to know which Evo you have.

                    Originally posted by nikolas4g63 View Post
                    are those washers on the one of the kits?
                    Yes they are washers. You can move them above or below the rod end to adjust its height on the bolt. These allow you height adjustments of 2.5mm increments.

                    Originally posted by nikolas4g63 View Post
                    also do you know how much do these babies weigh? they look kinda chunky
                    Weights are as follows:

                    Stock Inner and Outer Tie Rods - 34.0oz
                    Bump Steer Kit One (5/8" Heim Adapter) - 34.3oz
                    Bump Steer Kit Two (1/2" Heim Adapter) - 33.3oz

                    They're not really chunky but there are certainly ways to lighten them up. However, inner and outer tie rods are an EXTREMELY important piece of vehicle safety. Safety was my number one concern building these because I won't be the only one using them. Plus I wanted them to be able to withstand the extreme stresses of track abuse and also minimize the chance of failure on the street so I overbuilt them. To be within an ounce of the stock tie rods, more than twice as strong radially and axially, and have bump steer adjustability, I am extremely happy with how they came out.
                    Last edited by xloki77x; 15-02-2013, 09:03 PM.

                    Comment


                    • #11
                      Originally posted by xloki77x View Post
                      Dave/Dupstone -

                      Generally, the steering wheel does not move with bump steer, but it can. But this could also point to a few other things. Could be over damping of your front shocks, too high a spring rate, weak/loose/old tie rods, ball joints, or bushings, or a combination of the lot. Try lowering the damping of your shocks all the way (if they are adjustable) and see if the symptoms remain. Next, try jacking up the car and shake the wheel with your hands at 12 and 6 o'clock. This is a quick check for ball joint play. Then shake at 9 and 3 to check tie rod play.
                      Thanks for the advice. There is no up and down play but there is a tiny bit of 9 and 3 o'clock play.

                      Comment


                      • #12
                        Dave, I was thinking about this and it could also be your steering rack mount bushings letting Ho. They are two thin rubber bushings that could easily loose their form and cause something like this. Just a thought

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                        • #13
                          You talking about this? It's the only bushing type thing for the rack i could find, but there's only one of these.

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                          • #14
                            Yes, he is.

                            Comment


                            • #15
                              Thanks. That looks like it's gonna be fun to get to!

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