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Mercedes CLK GTR Replica from Scratch

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  • #46
    It sounds like you're talking about adding 2" per side or 4" overall to the front track width. As to doing this while still using the C4 rack & pinion, do the pivot points in the R&P line up with the inner pivot points on the lower A arm prior to this change? They most likely do. If the extenders are outboard of the R&P pivot points and you move the lower A arms pivot points outboard, then these pivot points will no longer be aligned with each other. That might cause a bump steer issue (or might not) but I'd sure test it to make sure. The end goal is to have no changes to toe settings as the front suspension moves through the entire range of up and down movement.

    Will having a wider track width allow you to use a wider windshield? I think the visual mockup with the RX8 windshield looked pretty good, but you might be able to do even better if a wider piece of glass enables you to look at a bunch more car models to choose from.
    Last edited by C5GTO; 01-26-2020, 12:25 PM.
    Joel Heinke
    Be original; don't be afraid of being bold!

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    • #47
      Originally posted by C5GTO View Post
      It sounds like you're talking about adding 2" per side or 4" overall to the front track width.... That might cause a bump steer issue.
      Joel is right. When you view your suspension drawings from the front (or rear) view, draw a hypothetical line from the inboard upper control arm pivot point to the inboard lower control arm pivot point. Your steering rack inner tie rod must fall along that line to avoid unwanted toe changes in compression and rebound.

      In your case, if you move the left and right hand suspensions 4" further apart, and keep the same steering rack, your inner tie rod pivot points will be too far inboard. As the control arms pivot through their arc, they will scribe a smaller radius than your longer tie rods. The effect will be that as the wheel rises in jounce, or falls in rebound, the effective length of the tie rod will "shorten" slower than the control arms, and will push the front of the knuckle outward. That will cause the car to understeer. By how much is anybody's guess unless you work out the geometry with some stick drawings or with some animation software, but from my experience, 4" could be significant. If I were you, I'd find a wider rack, or new wheels.
      Last edited by Bloozberry; 01-26-2020, 10:20 PM.

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      • #48
        I think MK posted this link a long time ago, & it comes in very handy for setting up.
        Go by the numbers it spits out & your setup should be spot on.
        Click on the blue icon on the left top of the page, The rest is quit self explanatory.

        I use to use a very expensive Lotus program , but find this one much easier & free:-)
        http://vsusp.com/?help=2d#what_is_vsusp
        [I][URL="http://www.osicustomcars.com"]www.osicustomcars.com[/URL]

        [/I][URL]https://za.pinterest.com/cd9984/pins/[/URL]

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        • #49
          I don't see a problem with machining up some extensions if need be that go between the rack and the tie rods. I have Performance Trends suspension analyzer and can crunch some numbers if you want.

          Chip

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          • #50
            Thanks to everybody here lending a hand, I greatly appreciate it. Here are the 2" extensions I mentioned a few posts ago. The illustration shows how they move the inner rod's pivot point outward.
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            Using a pair of these and widening the cradle looks like the best option right now.
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            Also, along with this is swapping in a late model rack, the 97-2004 Mustang is on the top of the list right now. Finding a front-steer rack is not easy these days. It has the correct thread on the inner rods to fit the extensions, it will also will thread onto the Corvette outer tie rods which need to be re-used. GM came up with a oddball taper at the knuckle that only Vettes use on the outer end. Gheeze I hate GM sometimes.
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            My local Wrecking Yard has a Mustang rack I can play with.
            -Vinny
            Last edited by TRcrazy; 01-27-2020, 10:27 PM.
            Remember, there is always next year.

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            • #51
              That's a nifty part. I wrongly assumed from your earlier post that you were installing the extensions between the inner and outer pivot points. What you're proposing will work just fine.
              Last edited by Bloozberry; 01-28-2020, 05:58 PM.

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              • #52
                Thanks Blooz, I am glad there are other eyes following this because in the mix of trying to think of everything, I can miss something along the way, so when you guys post its a great help. The mustang rack measures out to +2 (pivot to pivot ) over what I have now, adding 2 extensions makes it too long (+6). The 99-2004 Camaro rack looks to be 3.25 wider (pivot to pivot) than my current set up. Its close to the 4 Im after and no extensions needed. My local Wrecker shows both racks in stock. I may go there with a tape measure . Thanks for following , -Vin
                Remember, there is always next year.

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                • #53
                  Went to the wrecking yard Thursday afternoon for look at a 99 camaro rack, I'm chasing a front steering rack that measures 30" across to where the inner tie rods pivot. The Camaro rack was 29". Funny thing is I came up with a measuring formula on the computer that uses photos of racks and their inner tie rod lengths. I had the camaro rack at 29" before I actually measured one. When I mentioned I wouldn't be taking the camaro rack home because its the wrong size, the Yard Manager invited me to come back when I had more time and measure the assortment of racks they have on hand. I plan on going there tomorrow with a helpful printout of a "Rack Spotters Guide" I found online, it identifies the several common racks and what vehicle manufacturers' used them: TRW, Saginaw, Ford etc.
                  Last edited by TRcrazy; 02-02-2020, 11:33 AM.
                  Remember, there is always next year.

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                  • #54
                    Vinny;

                    You can always end up with a 1/2" spacer as well if you can't find anything just right. Do the same as the pic above and just drill until you measure 1/2" from end of inside hole and end of outside thread and you should be OK? Need a lathe to do it but it could work as a plan B?

                    Good luck with the search.
                    Don
                    308 Ferrari replica
                    Prova Countach 5000S

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                    • #55
                      True Don, and that was the outcome after sorting through a mountain of steering racks today. The majority of the racks were the rear steer variety common on FWD cars and trucks . I took home the camaro rack I had previously measured , it was still on the table where I had left it . There is no need for the inner extensions pictured above with this rack, it will accept the corvette outer tie rods . I just need to add 1/2 wheel spacers behind each front wheel. This should put the width where its needed, along with widening the cradle 3.
                      Last edited by TRcrazy; 02-03-2020, 10:10 PM.
                      Remember, there is always next year.

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                      • #56
                        Working on widening the front suspension cradle the necessary 3.125" (79.37mm) to line up with the 99 Camaro steering rack geometry. The green section is the added width I'll be welding in place on the 3 cross beams on the cradle.
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                        The cut lines are marked in silver paint pen in the image below, which also shows the 99 Camaro rack above and the 85 Corvette Rack below. I needed the steering coupler section along with the pressure and return line fittings for the Camaro rack, fortunately these all swapped over from the Corvette unit even with a 15 year difference between the two. I'll also re-use the Corvette outer tie rods end as they have a taper unique to that car and will fit the Covette knuckles I'm using. And both Camaro and Corvette share the common 14mm x 1.5 threaded ends. Good thing I wrote all this down !.
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                        The SketchUp image with the blue vertical line represents the plane that the 3 points are aligned in: the upper and lower suspension pivot points and the inner tie rod's pivot point (pink). When these 3 are in line with each other, Bumpsteer should be eliminated
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                        Thanks for following, Vin
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                        Last edited by TRcrazy; 02-09-2020, 06:34 PM.
                        Remember, there is always next year.

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                        • #57

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                          Remember, there is always next year.

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                          • #58
                            Getting the Camaro Steering Rack located in the front cradle tonight. The assortment of chassis tabs I had purchased are being put to use here, they provided a perfect standoff for the rack mounting. Highlighted in Red are the gussets I will add to connect the cross bar to the cradle sides.
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                            Remember, there is always next year.

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                            • #59
                              Working on how to create body buck stations in SketchUp. This is tonight's effort.
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                              Last edited by TRcrazy; 04-25-2020, 12:57 AM.
                              Remember, there is always next year.

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                              • #60
                                Click image for larger version

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                                I posted video #3 on Youtube today.
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                                Here's the Link:
                                https://www.youtube.com/watch?v=0x6L3ombNdg
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                                Remember, there is always next year.

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