MECF_728x90_top

Collapse

Announcement

Collapse

Official C8 Owners Manual, Build and Price, Visualizer, Pricing, and Ordering Information

See more
See less

Lowering a C8 With Both E60 & Z51 Options!

Collapse
This is a sticky topic.
X
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Originally posted by Teamzr1 View Post

    Neil,
    How many miles on this C8 when measured ?

    was the height measured when brand new and then again after maybe 5,000 miles to see how much the coil-over springs settle down

    Also any difference in cold weather over hot summer heat ?
    When measured (yesterday), the car has 600 km/400 mi.
    Like I mentioned, I measured after bouncing it, driving it, after lifting/lowering it a few times and it always returned to perfect gaps.
    I did not measure it when it arrived at the dealer, but the gaps always looked the same and have not changed and there was not extra weight in the car, like in either trunk.
    I doubt it will ever change that much but I will keep and eye on it.

    For reference, my car has Z51 with E60 and MRC.

    It would be interesting to know what the tolerance is in the wheel alignment specs for ride height.
    That would give us an indication of what GM expects for changes in ride height over time, and we should not expect any changes to exceed that.

    If the tire is concentric in the body wheel opening, the only way to decrease that gap while still being concentric is to go to a taller tire and to not change the ride height.
    I also understand that some like a lot less gap at the top than the front and back of the tire, that is their style and nothing wrong with it, that is just not my style for my car.
    The real beauty is that we live in a time that we can make changes to cars in pretty much any area and in any system to get to the individual style that we like.
    TPW March 2. 3LT, Z51, FE4, Black GBA, ZZ3, Black interior with Red seats/red stitch HU0 & 2 tone TU7, E60, J6N, RIK, Q8Q, etc.
    Medicine Hat, Alberta, Canada

    Comment


    • Originally posted by Neil H View Post

      When measured (yesterday), the car has 600 km/400 mi.
      Like I mentioned, I measured after bouncing it, driving it, after lifting/lowering it a few times and it always returned to perfect gaps.
      I did not measure it when it arrived at the dealer, but the gaps always looked the same and have not changed and there was not extra weight in the car, like in either trunk.
      I doubt it will ever change that much but I will keep and eye on it.

      For reference, my car has Z51 with E60 and MRC.

      It would be interesting to know what the tolerance is in the wheel alignment specs for ride height.
      That would give us an indication of what GM expects for changes in ride height over time, and we should not expect any changes to exceed that.

      If the tire is concentric in the body wheel opening, the only way to decrease that gap while still being concentric is to go to a taller tire and to not change the ride height.
      I also understand that some like a lot less gap at the top than the front and back of the tire, that is their style and nothing wrong with it, that is just not my style for my car.
      The real beauty is that we live in a time that we can make changes to cars in pretty much any area and in any system to get to the individual style that we like.
      If you go with a taller tire it will throw off the speedo and likely mess with other speed sensitive electronics. Generally not recommended. I think if you want to keep the gap to the fender the same all around the tire, you probably need to keep everything stock.
      2020 C8 | Torch Red | Z51 | 3LT | Carbon | Comp Seats
      2016 Porsche GT4 | Black everything ... sold
      2016 BMW M2 | Blue | MT ... sold
      2014 C7 | Torch Red | Z51 | 2LT ... sold

      Comment


      • Originally posted by Frenzy36 View Post

        Thanks for that tidbit of knowledge. Would you know how the MSRC plays into this ?
        I can understand for most people take granted what a shock does but yes any time vehicle height changes or the rate the spring reacts and recovers
        that then effects the design of the specific design of the shocks ( in this case MRC)

        Shock design, setup, calibration and settings can win or lose a race but also how car responds on **** roads we have today

        How complex in choosing a shock or how it was designed takes some real thought before changes are made

        In my case for my C5, the car height was lowered first and then lots of time selecting a shock system that fit the changed C5 height
        and type of driving and racing would be done

        The Penske shocks in my C5 are shorter then stock were due to lowered chassis height
        they are mounted UPsideDown for less unsprung weight and have bump stops at bottom of shock

        Get a idea how complex a shock design is view the owners PDF to see what it all about and how complex it is even in changing the shock's rod
        even if only lowering car 1/2 inch

        This shock design, though expensive in the start allow the vehicle owner to rebuild, modify and calibrate each shock on their own without
        having to send them to some shop to do

        http://teamzr1.com/penskemanual.pdf

        Here is a few of the specs, look at how many adjustments there is
        • Triple Adjustable – 25 Clicks Low Speed Compression, 17
        • Clicks High Speed Compression, 30 Clicks Rebound
        • 6 setting for compression rates via Nitrogen
        • Extended Lengths from 10.0″ through 24.0″ or Custom Lengths
        • Piggyback or Remote Reservoir
        • 45mm or 55mm Bore Body
        • 2.00″, 2.25″, 2.50″ Spring Hardware
        • Various Piston Options
        • Built to Customer Specifications
        • Custom-Valved for Driver Feel or Chassis Set-Up
        • Owner Rebuildable
        • Consistent Performance

        100% Engineered, Manufactured, and Hand Built in the USA

        Review other shock models
        https://www.penskeshocks.com/product...ar-automotive/


        Click image for larger version

Name:	8760seriestripleadjustable.jpg
Views:	120
Size:	80.0 KB
ID:	145649
        Corvettes owned, wrenched on and raced since 1975:
        1974,75,77,84,87,89,91,93,94 ZR-1 & 1999 Mallett 435

        Comment


        • Originally posted by Neil H View Post

          When measured (yesterday), the car has 600 km/400 mi.
          Like I mentioned, I measured after bouncing it, driving it, after lifting/lowering it a few times and it always returned to perfect gaps.
          I did not measure it when it arrived at the dealer, but the gaps always looked the same and have not changed and there was not extra weight in the car, like in either trunk.
          I doubt it will ever change that much but I will keep and eye on it.

          For reference, my car has Z51 with E60 and MRC.

          It would be interesting to know what the tolerance is in the wheel alignment specs for ride height.
          That would give us an indication of what GM expects for changes in ride height over time, and we should not expect any changes to exceed that.

          If the tire is concentric in the body wheel opening, the only way to decrease that gap while still being concentric is to go to a taller tire and to not change the ride height.
          I also understand that some like a lot less gap at the top than the front and back of the tire, that is their style and nothing wrong with it, that is just not my style for my car.
          The real beauty is that we live in a time that we can make changes to cars in pretty much any area and in any system to get to the individual style that we like.
          Part of the thought process of people changing the car's lower height is not thinking about when there is a shift of weight and balance
          In part if launching hard there is a weight transfer and as one end lifts, the other is forced lower
          Which then depending on the tire type and the amount of air pressure by lowering the car can induce the top or sidewall to then scrape on the inner fender well

          As example use like a drag tire with like only 24 PSI and *** end squats, and if car is lowered too much the tires will hit.

          GM also has to consider all types of **** road conditions where there will be lots of shock travel so reason a base C8 has more tire to inner fender free gap
          Corvettes owned, wrenched on and raced since 1975:
          1974,75,77,84,87,89,91,93,94 ZR-1 & 1999 Mallett 435

          Comment


          • Originally posted by gthal View Post

            If you go with a taller tire it will throw off the speedo and likely mess with other speed sensitive electronics. Generally not recommended. I think if you want to keep the gap to the fender the same all around the tire, you probably need to keep everything stock.
            I agree.
            The systems that are affected are ones like ABS, MRC, speedometer, traction/stability control system, transmission shifting, active restraint system (air bags), etc.
            TPW March 2. 3LT, Z51, FE4, Black GBA, ZZ3, Black interior with Red seats/red stitch HU0 & 2 tone TU7, E60, J6N, RIK, Q8Q, etc.
            Medicine Hat, Alberta, Canada

            Comment


            • This tire size calculator may come in handy.

              https://www.discounttire.com/learn/tire-size-calculator
              Black over Sky Cool Gray.....2LT.....Z51.....FE4.....E60.....

              Comment


              • Originally posted by Neil H View Post

                I agree.
                The systems that are affected are ones like ABS, MRC, speedometer, traction/stability control system, transmission shifting, active restraint system (air bags), etc.
                Far common issue I see with my custom performance tuning customers either complaining their automatic tranny shifting is not right or worse they do not know it
                So I require a testrun with a GPS that also reports MPH and then compare it to what speedo reports

                Worse is people buying a used Corvette and find out maybe the hard way by a stop by a cop for speeding that their speedo is reporting is not correct
                that past owner had made changes that effects the VSS signal

                In past Corvettes or even other GM models
                If the vehicle has a auto tranny the VSS signal comes from it to supply to other controllers in vehicle
                So it has no way of knowing if the rearend gear, wheels or tire sizes were changed

                IF a manual tranny, the VSS sensor is in the rearend and can count the revolutions so changing tire and/or wheel size changes can be seen and no
                changes in controllers needed

                Consider a C7 Corvette the TCM (controller) for the auto tranny calibration is around 4 Meg bytes, that is a lot of tuning variables GM set in the tune
                so changing tire/wheel sizes the TCM is still commanding everything related to all it's functions still by the GM VSS values

                This gets even worse if the transaxle gear is changed as many with auto tranny do not a stock 2.56 gear and change to like a 3.42 or 4.11 ratio
                and with a tire and/or wheel size change compounds the problems even more to the controllers
                which can effect many other functions like auto volume control of radio, cruise control, speedo, all up and down shifts for the several driving modes
                the auto tranny has today

                Here I just made one change, the tire size
                Look closely at the stock (left) to larger tire (right) at the value changes just related to doing that
                Now figure other controllers like PCM, TCM, ABS, eLSD all also needing to know about the changes made.

                With no way to tune any controllers of C8 at this time, if changing tire sizes it better be close to what stock was.
                There is some slop allowed before ABS or torque management in older Corvettes but unknown as of today what C8 is allowed to


                Click image for larger version

Name:	speedo.jpg
Views:	116
Size:	303.5 KB
ID:	145688
                Corvettes owned, wrenched on and raced since 1975:
                1974,75,77,84,87,89,91,93,94 ZR-1 & 1999 Mallett 435

                Comment


                • This thread is getting a lot of great input but I am still waiting for Cicio Performance to post installation pix as they said they would. Waiting....

                  Comment


                  • They were posted. Here are The pictures Cicio Performance posted on a Z51 with E60 with stock wheels and tires.

                    Click image for larger version  Name:	00E30AF7-5BAE-4FBC-8094-E83927CA1229.jpeg Views:	0 Size:	751.3 KB ID:	145734Click image for larger version  Name:	3D224111-FEB1-41C8-B294-5B3986979435.jpeg Views:	0 Size:	800.2 KB ID:	145735Click image for larger version  Name:	BFCD3EEC-A440-40FA-A31B-DB8E5F82C931.jpeg Views:	0 Size:	957.5 KB ID:	145736
                    GBA Black; HTO Twilight/Tension interior; Z51 & Mag Ride; E60 lift; 5VM visible carbon fiber package; 5ZZ high wing; FA5 interior vis CF; ZZ3 engine appearance; 3LT; Q8T Spectra Gray Tridents; J6N Edge Red Calipers; SNG Edge Red Hashmarks; VQK Splash Guards; RCC Edge Red engine cover; VJR illuminated sill plates.Lifetime, annual contributors, and 22 year members of National Corvette Museum. Home is the beautiful Pacific Northwest.

                    Comment


                    • They just posted the installation instructions on the other thread. Here's the link to download the PDF

                      https://cicioperformance.com/product...-lowering-kit/
                      Last edited by pksjc; 05-11-2020, 08:31 PM. Reason: Fixed link that was broken

                      Comment


                      • Thanks pksjc

                        Comment

                        MECF_728x90_bottom

                        Collapse
                        Working...
                        X