Author Topic: Robert's Reventon Chassis Works build. Freaking finally  (Read 38831 times)

plans4sale

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #45 on: June 23, 2014, 03:24:22 PM »
Thank you everyone for your input. I am always humble to those more knowledgeable than me.
I crunched numbers last night, ran out to the garage with my tape measure several times.
The wheels are 18x9.5 with a 2.2 off set, tires 18/285zr30 11.5 width. I will have to cheat the length of the lower control arm a little. 14" lower control arm is the best I can do. I will have to trim the quarter panel lip a little.
http://www.vsusp.com/#0.8%26project_name%3Adefault%20values%26trim%7Bbody_roll_angle%3A0%7Cfront.left_bump%3A-8600%7Crear.left_bump%3A0%7Cfront.right_bump%3A-8600%7Crear.right_bump%3A0%7D%26front%7Bframe.susp_type%3A0%7Cframe.bottom_y%3A0%7Cframe.center_to_upper_mount_x%3A0%7Cframe.bottom_to_upper_mount_y%3A0%7Cframe.center_to_lower_mount_x%3A0%7Cframe.bottom_to_lower_mount_y%3A0%7Ccontrol_arms.upper_length%3A24800%7Ccontrol_arms.lower_length%3A37500%7Cknuckles.hub_to_upper_x%3A15000%7Cknuckles.hub_to_lower_x%3A13000%7Cknuckles.hub_to_lower_y%3A13000%7Cknuckles.hub_to_upper_y%3A13000%7Cknuckles.hub_to_strut_axis%3A14000%7Cknuckles.strut_incl%3A8000%7Cwheels.offset%3A0%7Cwheels.diameter%3A1800%7Cwheels.diameter_expl%3A35000%7Ctires.size_convention%3A1%7Ctires.section_width%3A33500%7Ctires.aspect_ratio%3A3000%7Ctires.diameter_expl%3A50000%7Ctires.width_expl%3A7620%7D%26rear%7Bframe.susp_type%3A0%7Cframe.bottom_y%3A15238%7Cframe.center_to_upper_mount_x%3A51587%7Cframe.bottom_to_upper_mount_y%3A26670%7Cframe.center_to_lower_mount_x%3A48158%7Cframe.bottom_to_lower_mount_y%3A1904%7Ccontrol_arms.upper_length%3A23393%7Ccontrol_arms.lower_length%3A35560%7Cknuckles.hub_to_upper_x%3A17881%7Cknuckles.hub_to_lower_x%3A9207%7Cknuckles.hub_to_lower_y%3A12011%7Cknuckles.hub_to_upper_y%3A11244%7Cknuckles.hub_to_strut_axis%3A14000%7Cknuckles.strut_incl%3A8000%7Cwheels.offset%3A5588%7Cwheels.diameter%3A1800%7Cwheels.diameter_expl%3A35000%7Ctires.size_convention%3A0%7Ctires.section_width%3A28500%7Ctires.aspect_ratio%3A3000%7Ctires.diameter_expl%3A50000%7Ctires.width_expl%3A7620%7D%26pref%7Bdiag1.px_per_mm%3A200%7Cdiag1.front_or_rear%3Arear%7Ctab.active%3A1%7Cunits%3A0%7Cshow.f%3A1%7Cshow.ca%3A1%7Cshow.k%3A1%7Cshow.w%3A1%7Cshow.t%3A1%7Cshow.rc%3A1%7Cshow.ic%3A1%7Cshow.fvsa%3A1%7Cshow.tl%3A1%7Cshow.kpil%3A1%7Credraw_during_drag%3A1%7Cchart.x_axis_center%3A0%7Cchart.x_axis_window%3A10%7Cchart.x_axis_num_steps%3A21%7Cchart.x_axis_field%3A%5BFR%5D.wheels.diameter%7Cchart.y_axis_fields%3A%5BFR%5D.general.roll_center.y%7D


 Robert, if it was mine build, I would use a bit different setting just to make sure the outer wheel's camber angle is not affected by more than 1,5 degrees during high-speed cornering, where the car's body usually rolls by about 3 degrees. While your setup from the link above have very nice settings to keeping both wheels vertical while crossing bumps or holes simultaneously, the camber angle of the outer wheel while cornering and say 3 degrees of body roll is 2,976 degrees. The latter means that this settings basically act nearly identical to equal A-arm setup and makes it easier to lose control over the car and wear the outer tyre protector quicker than normal. If it's not possible to change the wheel hub and the length of either A-arms on your suspension, I would recommend to slightly lower the joints of the upper A-arm connecting to the chassis. Under the "Frame" settings bar, if you change the "Frame bottom to upper mount Y" from the current 10,5 inches to 9,25 inches (i.e. 1,25 inches down), the outer wheels camber angle will be affected in the following way:

Car body roll of 0 degrees --> outer wheel's camber = -0,751 degrees (it's always good to have about 0,5-0,75 degrees negative camber while in neutral position)
Car body roll of 1 degree --> outer wheel's camber = -0,127 degrees
Car body roll of 2 degrees --> outer wheel's camber = 0,399 degrees (2 degrees is the most common roll angle)
Car body roll of 3 degrees --> outer wheel's camber = 0,888 degrees
Car body roll of 4 degrees --> outer wheel's camber = 1,309 degrees (really agressive high-speed cornering)

 Of course, we should not forget the caster angle, which additionally helps to gain some extra negative camber while cornering, so the above numbers are just to giving a rough idea and will not represent the actual camber of the wheels.

9,25 inch
« Last Edit: June 23, 2014, 03:31:05 PM by plans4sale »
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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #44 on: June 22, 2014, 02:53:19 AM »
 I need a new phone, the lense is scratched. Here is a little progress.
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76mx

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #43 on: May 11, 2014, 11:18:02 AM »
Right again 01, when a driver says that a car handles like a dream, be certian that there is no such thing. Just like a chain, when a suspension is pushed to it's limit, it will show you what charactoristics need improvement. What the driver is really saying is that they have reached their limits well before the car did. That is why with a rookie racecar test we put an experienced driver in first to get a baseline. That way we know whether to work on the rookie or the racecar.
« Last Edit: May 11, 2014, 06:19:40 PM by 76mx »

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #42 on: May 11, 2014, 11:16:11 AM »
Just to add to the confusion of suspension design, especially on the front, a line drawn vertically through the inner pivot points of the front a-arms will not intersect the inner pivot of the tie rod.  This is because  most street vehicles have ackerman built into the design.  This places the outer tie rod center out past the upper and lower ball joints on the spindle.  It is the length and vertical placement of the tie rods that determines bump steer, not that they intersect the line of the ball joints and inner pivot.  For more information about this read the Carroll Smith books and "How to make your car handle" by Fred Puhn.

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #41 on: May 11, 2014, 11:09:48 AM »
Thank you everyone for your input. I am always humble to those more knowledgeable than me.
I crunched numbers last night, ran out to the garage with my tape measure several times.
The wheels are 18x9.5 with a 2.2 off set, tires 18/285zr30 11.5 width. I will have to cheat the length of the lower control arm a little. 14" lower control arm is the best I can do. I will have to trim the quarter panel lip a little.
http://www.vsusp.com/#0.8%26project_name%3Adefault%20values%26trim%7Bbody_roll_angle%3A0%7Cfront.left_bump%3A-8600%7Crear.left_bump%3A0%7Cfront.right_bump%3A-8600%7Crear.right_bump%3A0%7D%26front%7Bframe.susp_type%3A0%7Cframe.bottom_y%3A0%7Cframe.center_to_upper_mount_x%3A0%7Cframe.bottom_to_upper_mount_y%3A0%7Cframe.center_to_lower_mount_x%3A0%7Cframe.bottom_to_lower_mount_y%3A0%7Ccontrol_arms.upper_length%3A24800%7Ccontrol_arms.lower_length%3A37500%7Cknuckles.hub_to_upper_x%3A15000%7Cknuckles.hub_to_lower_x%3A13000%7Cknuckles.hub_to_lower_y%3A13000%7Cknuckles.hub_to_upper_y%3A13000%7Cknuckles.hub_to_strut_axis%3A14000%7Cknuckles.strut_incl%3A8000%7Cwheels.offset%3A0%7Cwheels.diameter%3A1800%7Cwheels.diameter_expl%3A35000%7Ctires.size_convention%3A1%7Ctires.section_width%3A33500%7Ctires.aspect_ratio%3A3000%7Ctires.diameter_expl%3A50000%7Ctires.width_expl%3A7620%7D%26rear%7Bframe.susp_type%3A0%7Cframe.bottom_y%3A15238%7Cframe.center_to_upper_mount_x%3A51587%7Cframe.bottom_to_upper_mount_y%3A26670%7Cframe.center_to_lower_mount_x%3A48158%7Cframe.bottom_to_lower_mount_y%3A1904%7Ccontrol_arms.upper_length%3A23393%7Ccontrol_arms.lower_length%3A35560%7Cknuckles.hub_to_upper_x%3A17881%7Cknuckles.hub_to_lower_x%3A9207%7Cknuckles.hub_to_lower_y%3A12011%7Cknuckles.hub_to_upper_y%3A11244%7Cknuckles.hub_to_strut_axis%3A14000%7Cknuckles.strut_incl%3A8000%7Cwheels.offset%3A5588%7Cwheels.diameter%3A1800%7Cwheels.diameter_expl%3A35000%7Ctires.size_convention%3A0%7Ctires.section_width%3A28500%7Ctires.aspect_ratio%3A3000%7Ctires.diameter_expl%3A50000%7Ctires.width_expl%3A7620%7D%26pref%7Bdiag1.px_per_mm%3A200%7Cdiag1.front_or_rear%3Arear%7Ctab.active%3A1%7Cunits%3A0%7Cshow.f%3A1%7Cshow.ca%3A1%7Cshow.k%3A1%7Cshow.w%3A1%7Cshow.t%3A1%7Cshow.rc%3A1%7Cshow.ic%3A1%7Cshow.fvsa%3A1%7Cshow.tl%3A1%7Cshow.kpil%3A1%7Credraw_during_drag%3A1%7Cchart.x_axis_center%3A0%7Cchart.x_axis_window%3A10%7Cchart.x_axis_num_steps%3A21%7Cchart.x_axis_field%3A%5BFR%5D.wheels.diameter%7Cchart.y_axis_fields%3A%5BFR%5D.general.roll_center.y%7D
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01Lambiero

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #40 on: May 11, 2014, 07:40:08 AM »
O.K. then and thank you. I thought we were on the same page here. As you play with the 15-10, keep this in mind. All suspensions are compromises, there is no perfect setup. How the compromises are handled determines the quality of it. You are looking for it to be consistent and predictable. That makes it driveable. It does not matter as much where the graph lines of the travel are, but that they are in consistant patterns without quirky directional changes. Now I have a few questions. First, how did you get your last reply INSIDE the quote box? And second, What is an expirimental mechanic and painter?
[/quote

He left off the bracket after "[/quote"   
He left off the bracket after "[/quote".
I just said that.  I know you did.   ::headbang
Now that we have opened up the can of unpredictability, we have to say that two more factors enter the picture relating to how well the suspension design will still fail.  DRIVER ABILITY and the SPEED OF THE VEHICLE.
« Last Edit: May 11, 2014, 07:49:32 AM by 01Lambiero »
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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #39 on: May 11, 2014, 01:32:50 AM »
O.K. then and thank you. I thought we were on the same page here. As you play with the 15-10, keep this in mind. All suspensions are compromises, there is no perfect setup. How the compromises are handled determines the quality of it. You are looking for it to be consistent and predictable. That makes it driveable. It does not matter as much where the graph lines of the travel are, but that they are in consistant patterns without quirky directional changes. Now I have a few questions. First, how did you get your last reply INSIDE the quote box? And second, What is an expirimental mechanic and painter?

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #38 on: May 11, 2014, 12:07:25 AM »
Robert, now I am confused about which theory is kept and which is thrown away. If you are trying to copy the Chassisworks plans, it does not matter if it is C4 or C5, either one is well capable of accomplishing O1's idea of not having to reinvent it. If on the other hand you are trying to design your own suspension using the simulator, hopefully this is useful.
[/quote 76, you have been a great advisor! You are the expert on this forum!. I have the 15/10 calculated.
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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #37 on: May 10, 2014, 11:20:06 PM »
Robert, now I am confused about which theory is kept and which is thrown away. If you are trying to copy the Chassisworks plans, it does not matter if it is C4 or C5, either one is well capable of accomplishing O1's idea of not having to reinvent it. If on the other hand you are trying to design your own suspension using the simulator, hopefully this is useful.

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #36 on: May 10, 2014, 07:17:08 PM »
I guess that threw the theory out the window.

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #35 on: May 10, 2014, 03:33:14 PM »
Robert, I hope our input is incouraging to you rather than discouraging. I am very glad to try and help someone that is making an effort to help theirself....but....that design will never work. Your lower a-arms are way too short, which makes your upper a-arms way too shorter (?). They need to be around 15" and 10". The short arcs of the short arms will make everything happen way too fast and your graphs of them will go off of the chart. As I mentioned earlier, the front lower a-arm design is usually detirmined by the limitations of the steering linkage, so let us look at that one first. 24-1/2" inches is a magic number here, it does not matter what you are building. That is the knuckle to knuckle distance on all of the Mustang type aftermarket rack and pinions. Since the inner lower a-arm pivit should be directly in line with this to avoid bumpsteer, use this to establish that point. Going from there out to the spindle should be in that 15" range. Now use the spindle to establish the upper outer ball joint and work back from there to locate the inner mount to give a correct upper arm length. Remember, a chassis is designed from the outside in, not from the chassis out. Once you have these locations, put the chassis wherever it needs to go in order to attach them. Now, at the back of the car, there should be plenty of room outside the engine cradle to use the same lower a-arm length (depending on wheel offset and others) with the same 24-1/2" centerlines and the same upper a-arm location procedure. If you can, not only do you have economy of parts but your roll centers are as simple as they can get.
Thank you 76, the front is factory C4 upper and lower arms.
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76mx

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #34 on: May 10, 2014, 11:37:28 AM »
Robert, I hope our input is incouraging to you rather than discouraging. I am very glad to try and help someone that is making an effort to help theirself....but....that design will never work. Your lower a-arms are way too short, which makes your upper a-arms way too shorter (?). They need to be around 15" and 10". The short arcs of the short arms will make everything happen way too fast and your graphs of them will go off of the chart. As I mentioned earlier, the front lower a-arm design is usually detirmined by the limitations of the steering linkage, so let us look at that one first. 24-1/2" inches is a magic number here, it does not matter what you are building. That is the knuckle to knuckle distance on all of the Mustang type aftermarket rack and pinions. Since the inner lower a-arm pivit should be directly in line with this to avoid bumpsteer, use this to establish that point. Going from there out to the spindle should be in that 15" range. Now use the spindle to establish the upper outer ball joint and work back from there to locate the inner mount to give a correct upper arm length. Remember, a chassis is designed from the outside in, not from the chassis out. Once you have these locations, put the chassis wherever it needs to go in order to attach them. Now, at the back of the car, there should be plenty of room outside the engine cradle to use the same lower a-arm length (depending on wheel offset and others) with the same 24-1/2" centerlines and the same upper a-arm location procedure. If you can, not only do you have economy of parts but your roll centers are as simple as they can get.
« Last Edit: May 10, 2014, 12:28:50 PM by 76mx »

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #33 on: May 09, 2014, 08:42:33 AM »
All well and good info, BUT...when you get all of the data and pieces of this puzzle together and it doesn't quite ride like you thought it should, then what?  There are more complex potholes in a build than this that will cause you to pull your hair out.  Don't forget to design the ability to repair components of your car after the body gets glued on and positive bump stops so that your tires don't hit your wheelwell liners.  IMHO. ::help

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #32 on: May 09, 2014, 02:49:06 AM »
guys I had this salted away it could prove useful
« Last Edit: May 09, 2014, 02:54:05 AM by lambo »

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Re: Robert's Reventon Chassis Works build. Freaking finally
« Reply #31 on: May 09, 2014, 02:39:23 AM »
Absolutely right RT, that goes back to what I was saying about motion ratios in my first answer. Look at Afco Racing Products and there are simple and well illustrated examples of this with some basic calculation tables. It is probably too late now but those Afco shocks are everything that the QA1 is but right at half the price. 
I will check them out!
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