Just joined? Please introduce yourself.
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 21

Thread: '59 Corvette chassis mods

  1. #11
    Registered Member
    Join Date
    Dec 2018

    Member #:4017
    Posts
    176
    Quote Originally Posted by 55 Rescue Dog View Post
    What is the big benefit of a narrow axel over a wide axel, especially on an IRS? Seems backwards to me. Something to consider, with your single shear dog-bone mounts, it would be a great application in which to use spherical bearings on., which would eliminate the twisting forces. A little noise is just part of the mechanical symphony.

    This is exactly what I was inquiring about but c-nut discounts that. You (55 Rescue Dog) seems to understand my concern. “More directions” as in arc travel not linear straight line. The smaller the arc radius the more inward and outward displacement. I just see a lot more than 2” spindle movement up and down suspension travel on an arc path centered on the inner u joints. Spirited driving will see a lot more. So I don’t buy 2” travel. Pot holes are more not to say inclines and bumps.

    The purpose of a 4 link is to control the up down movement so it is more linear rather than arc. True this is more of a concern with a sprung differential. Thus the position of the pivot and link length will have optimum functional positions and lengths. This is what is implied by “tuning” regardless if a fixed or sprung differential.

  2. #12
    Registered Member chevynut's Avatar
    Join Date
    Nov 2011

    Member #:115
    Location
    Fort Collins, CO
    Posts
    10,835
    Like clockwork, every time narrowing a C4 IRS is mentioned on any thread RD has to jump in with his incessant "I don't see how/why blah, blah..." BS. I've explained all of this extensively, at least two or three times if not more, so go dig up the info or grab a pencil and paper and figure it out for yourselves with real numbers like I did. I'm tired of having to do your homework for you and you just don't learn.

    There are no significant twisting forces on the dogbones as I've proven in the past. As for travel, go and look at the travel of a typical coilover shock and maybe you'll start to understand what's going on in the real world. My upper axle bumpers sit 2" above the pads on the knuckles. Yeah, I think that's pretty close to 2" of upward travel. Even if it was slightly more, the geometry changes aren't significant.

    Then when you can explain in detail how narrowing a C4 IRS 3-4" negatively affects anything, and by how much, please post your results. I've calculated and posted the differences in camber gain between a stock width C4 rear and a 3" narrowed one over the range of travel and I showed that it isn't significant. Changing the pivot points affects geometry more than narrowing it. GM did that in 1988.

    When you study and understand what a C4 IRS does maybe it will start to make some sense. You talk in generalities and don't understand the details. I still want to know how you "tune" a C4 suspension with the fixed dogbone end locations. Adding adjustable rod ends doesn't change those pivot locations.

    Now I wonder how AME narrows a C5/6 front end 5-6" without causing something to break and the car to wreck. And how can their 55.5" wide IRS possibly work being that narrow? Can either or you explain that?
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  3. #13
    Registered Member chevynut's Avatar
    Join Date
    Nov 2011

    Member #:115
    Location
    Fort Collins, CO
    Posts
    10,835
    Narrowing a C4 IRS allows you to run a wider tire under the car with a deeper (less positive offset) wheel and it makes changing the tires easier. It's that simple, and there are minimal if any negative effects. How many times have I explained this now?

    The wheelwell lips on a C1 are 68" wide inside, which is over 3" narrower than a tri5.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  4. #14
    Registered Member NickP's Avatar
    Join Date
    Mar 2012

    Member #:1653
    Location
    De Queen, AR
    Posts
    4,157
    So, I guess AME doesn't know what they are doing either by offering 4 different widths on their IRS.

    2014-Page5-8.jpg

  5. #15
    Registered Member chevynut's Avatar
    Join Date
    Nov 2011

    Member #:115
    Location
    Fort Collins, CO
    Posts
    10,835
    Quote Originally Posted by NickP View Post
    So, I guess AME doesn't know what they are doing either by offering 4 different widths on their IRS.
    My point exactly. I'm still waiting for either of these guys to post their detailed analysis of what happens to a C4 rear when you narrow it. I'm guessing I might be waiting for a long time.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  6. #16
    Registered Member NickP's Avatar
    Join Date
    Mar 2012

    Member #:1653
    Location
    De Queen, AR
    Posts
    4,157
    I recall that I worked up the actual movement in all directions for this very same discussion b4. As memory serves me the distance in actual motion difference was less than .04" from stock width versus your Nomad unit. search might reveal those AutoCAD drawings.

  7. #17
    Registered Member chevynut's Avatar
    Join Date
    Nov 2011

    Member #:115
    Location
    Fort Collins, CO
    Posts
    10,835
    Quote Originally Posted by NickP View Post
    I recall that I worked up the actual movement in all directions for this very same discussion b4. As memory serves me the distance in actual motion difference was less than .04" from stock width versus your Nomad unit. search might reveal those AutoCAD drawings.
    I used CAD to lay it all out and calculated the change in camber in 2" of travel for an early C4. late C4, and my narrowed late C4 I'm not going to re-post my results until the peanut gallery posts their results, or admits they have no clue which is probably the case.

    I predicted before I started this thread that RD would spew more of his BS about the narrowed rearend. True to form, he didn't let me down.

    noun: peanut gallery;

    • the top gallery in a theater where the cheaper seats are located.
      • a group of people who criticize someone, often by focusing on insignificant details.


    Last edited by chevynut; 10-02-2019 at 03:13 PM.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  8. #18
    Registered Member WagonCrazy's Avatar
    Join Date
    Mar 2012

    Member #:530
    Location
    Santa Clarita, CA
    Posts
    1,793
    Narrowing a C4 IRS allows you to run a wider tire under the car with a deeper (less positive offset) wheel and it makes changing the tires easier. It's that simple.
    Yup. My stock C4 width rear means a not-very-deep dish wheel and I have to drop the bottom shock mount to drop the rear halfshaft low enough to get the wheel to clear the fender. 57 rear fenders are not that "high" to start with.

    That's a nice C1 AME frame mod there Laszlo. Good work. That corvette will drive like a slotcar when it's done. Woot!
    1957 Nomad- LS1/T56 on C4 chassis
    1959 Fleetside Apache 1/2 ton, shortbed, big window, 327ci.

  9. #19
    Registered Member chevynut's Avatar
    Join Date
    Nov 2011

    Member #:115
    Location
    Fort Collins, CO
    Posts
    10,835
    Quote Originally Posted by WagonCrazy View Post
    Yup. My stock C4 width rear means a not-very-deep dish wheel and I have to drop the bottom shock mount to drop the rear halfshaft low enough to get the wheel to clear the fender. 57 rear fenders are not that "high" to start with.

    That's a nice C1 AME frame mod there Laszlo. Good work. That corvette will drive like a slotcar when it's done. Woot!
    Thanks Paul. The limiter for tire width is the distance between the dogbones and the fenderwell lip on these C4 chassis. The only way to increase that is to move the dogbones inboard, which requires narrowing the frame. The distance from the wheel mounting surface to the dogbones stays the same, but you gain room from the wheel mounting surface to the fenderwell lip. That means a deeper (less positive offset) wheel is needed. Some people seem to have a hard time grasping that concept.

    This chassis was a real challenge to design due to all the constraints imposed by the body, suspension, frame, etc. We ended up using the same Strange coilover shocks on the rear as AME uses in the front and they worked out perfect. I wanted to use slightly longer ones, but we had no room. Pretty much every bracket is a custom design and was cut by hand. The shock mount tube is 1.75" x .188" Chromoly that Larry wanted for that purpose. I set up the lower coilover mounts to achieve the correct ride height shock length.

    As I may have mentioned before, Larry and I are trading labor for my interior. He wasn't sure if the time I had in his 55 frame would cover all the labor on my interior but in doing this job for him he said he'll do whatever I want on my interior until it's the way I want it.....no charge. He's very meticulous and I need to get him going on my stuff soon.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  10. #20
    Banned
    Join Date
    Nov 2015

    Member #:2775
    Posts
    1,426
    The chassis you modified looks great, and will probably work fine on a lightweight C1 on a smooth road, but I am thinking as far as track width goes, sometimes maybe a narrower tire might work better? After all, anytime you try and put a wider tire inside the bodywork of any car you are narrowing the track width, which I would visualize that it messes with the roll centers, which don't get discussed much. And I don't have a clue as to how all of the factors that work into it along the front/rear roll-axis, roll-stifness, etc.??? Drawing lines on paper will get you close, but actually dynamic testing of any tire/suspension setup is just important. An IRS makes it even more complicated. Testing would explain it better instead of just coloring inside the lines. Big wheels/tires look the best, but
    simply just stand with your big feet together, and lean.
    Here is a great technical paper by Michelin that will tell you more than you ever want to know about tire grip, and all the variables. I was surprised at a lot of things about tires I still don't know.

    https://www.paradigmshiftracing.com/...p-michelin.pdf
    Last edited by 55 Rescue Dog; 10-04-2019 at 09:52 AM.

Page 2 of 3 FirstFirst 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •