Robert's Reventon Chassis Works build. Freaking finally

[76mx]

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. 

[RT]

Just keep in mind the travel distance of the shock is not the same as the travel distance of the wheel/tire.
For the travel distance to be identical, the shock would have to be attached to the A-arm at the outer ball joint and the shock would have to be vertical.  This is not the case.  The shock is attached inside from the outer ball joint so that location does not travel as far as the wheel/tire.  ALSO, the shock is leaning inward at the top.  That produces even less travel because of the angle.  (You are basically shortening the one side of the triangle formed by the shock and A-arm pivots.)
This not only affects the travel but if your spring is over the shock, the compression forces are not linear also.

RT

[76mx]

   Eric, that is true but in my opinion it becomes less true the shorter the shock travel becomes. That would put the sweet spot at 12-2/3", allowing only 1-1/3" of expansion before topping out in that direction. I think if Robert ran the numbers with his simulator, he would find that it does not take much weight transfer at all to get to that. I used Aldan Eagles on my Cobra and mounted them that way and it tops out hard all the time. Maybe that is just my driving but there is not much weight in that car to transfer to begin with.

[Robert]

   Robert, that is what I suspected, you have 4" travel shocks (14" extended minus 10" compressed), just make sure that the chassis is designed for that travel. If so, when the car is at ride height, the shock should be in it's "Sweet Spot" of 12", allowing 2" of travel in extension and 2" in compression. The extreme camber gain over 4" of compression is a mute point as the shock bottoms out at 2". This shock is hard to work with because there is not much room for error. You need to know your geometry, ride height, and tire and wheel size right now in order to hang it. A 5 travel shock does not seem much different but it is much easier to work with (insert joke here). The 4 shock will not take any spring over 8" long so the 5 has a much better spring selection as well. Either way your spring rates are back in the ballpark.
   I have a set of those Chassisworks plans but it has been a while since I looked at them. If I remember right they were based on C5 geometry. If I also remember correctly, they just need to have a little dive taken out and a little more squat put in to allow for the larger rear weight percentage.
   P.S. Here is the problem with 8" springs. If you use say a 200lb spring and there is say 600lbs of car on that corner, the spring will compress 3" to be 5" tall. It will coil bind at 4", giving only 1" of suspension travel regardless of your shock travel. A 10" spring still coil binds at 4" but it would have 3" of travel. 

Thank you very much for your advise! I will definitely use it.

[aeauto]

Aldan recommends that the shocks be compressed 1/3 their travel at normal ride height.  You will use more compression than extension during normal driving.

[76mx]

   Robert, that is what I suspected, you have 4" travel shocks (14" extended minus 10" compressed), just make sure that the chassis is designed for that travel. If so, when the car is at ride height, the shock should be in it's "Sweet Spot" of 12", allowing 2" of travel in extension and 2" in compression. The extreme camber gain over 4" of compression is a mute point as the shock bottoms out at 2". This shock is hard to work with because there is not much room for error. You need to know your geometry, ride height, and tire and wheel size right now in order to hang it. A 5 travel shock does not seem much different but it is much easier to work with (insert joke here). The 4 shock will not take any spring over 8" long so the 5 has a much better spring selection as well. Either way your spring rates are back in the ballpark.
   I have a set of those Chassisworks plans but it has been a while since I looked at them. If I remember right they were based on C5 geometry. If I also remember correctly, they just need to have a little dive taken out and a little more squat put in to allow for the larger rear weight percentage.
   P.S. Here is the problem with 8" springs. If you use say a 200lb spring and there is say 600lbs of car on that corner, the spring will compress 3" to be 5" tall. It will coil bind at 4", giving only 1" of suspension travel regardless of your shock travel. A 10" spring still coil binds at 4" but it would have 3" of travel. 

[Robert]

I just measured a c6 corvette lower control arm to ground clearance. From the center of the inside pivot point, it measures 6.75" from the ground. The body in front of the rear wheel has 5.625" ground clearance.

[Robert]

This is the chassis I purchased prints for. I had to change it for the LS4 drivetrain.  I do not have dimensions for a C5.

  I'll play around with the data input, and lower it.

[01Lambiero]

Wouldn't it simplify things if you just went with the C5 suspension all around?  You wouldn't have to micro-tune every spec.  I would question your ride height at 8".  At 5.5", my chassis is 1" higher than stock.  A reventon has to be around 4.5", right?  Or is 8" just the ride height of the lower A pivot to the ground?
Ah!!  we all love to build, don't we.  Jim

[Robert]

From my experience -.5 to -1.5 is good for the street. Up to -2.5 for racing applications. Also the rear should be half of the front...

Thank you Alan!

[Robert]

Robert, how about some clarification on your shock travel.  Are you saying that you have 2" up and 2" down?  Your camber would be set at ride height, right?  What are you trying to do with this car?  What are you trying to achieve?  What knuckle and A-arms are you going to use on the fronts?  What suspension components are you going to use in the rear?

Jim

Thank you Jim. Check  the vsusp link.

[Robert]

In the sim, try raising the inner mount of the upper arms, that should change the gain #'s

Does it calculate squat, anti-squat, dive and anti-dive numbers, what about bump

Thank you for trying! If you have time, look at the above link.

[Robert]

In the sim, try raising the inner mount of the upper arms, that should change the gain #'s

Does it calculate squat, anti-squat, dive and anti-dive numbers, what about bump

Robert, I  agree with 01L that we need more info to help but what info we already have just does not seem right. Four inches of shock travel in compression? It would have to be all compression to yield NEGATIVE camber. What is the total travel of your shock? What spring rate are you using that would allow that much weight transfer and compression? You would have to get down to a 100lb spring which you just do not want and then it would have to be a 12 inch spring to have any compression left at ride height and then it would have to be at least a 7 inch travel shock to fit the 12 spring and 7 shocks just do not work on these cars, and the issues continue to compound from there. Four inches of travel at the shock would be five or even six at the wheel and you would have bottomed out and ripped a fender off way before camber angles ever became an issue. Consider what your gain is at about 1-1/2 inches of travel, which would be 2 or so at the tire (depending on the motion ratio of the shock mount), and this would be all of the travel that you would want or need. Also, verify that your lower arm is close to parallel with the ground plane at ride height so that the upper arm does all of the gain. AB is right about raising the inner mount of the upper arm, and a longer arm will also be less gain. A general rule of thumb is that the upper arm wants to be 2/3 of the lower arm length, and the lower length is generally set by the limitations of the steering linkage.   

Thank you 76, coils overs are QA!1 ur 4855p. Brand:QA1 Precision Products
Manufacturer's Part Number:UR4855P
Part Type:Coil-Over Shocks and Struts
Product Line:QA1 Ultra Ride Coil-Over Shocks
Summit Racing Part Number:HAL-UR4855P

UPC:806990000293
Coil-Over Shock Type:Single-adjustable
Shock Body Material:Aluminum
Shock Body Finish:Clear anodized
Adjustable Valving:Yes
Number of Valving Selections:12
Extended Length (in):14.000 in.
Collapsed Length (in):10.130 in.
Upper Mount:Eyelet
Lower Mount:Eyelet
Gas Charged:No
Bushing Material:Polyurethane
Bushing Color:Black
Coil-Over Springs Included:No
Recommended Spring Diameter (in):2.500 in.

The lower control arms will be parallel with the frame. Let know what you think, thank you!

[76mx]

Robert, I  agree with 01L that we need more info to help but what info we already have just does not seem right. Four inches of shock travel in compression? It would have to be all compression to yield NEGATIVE camber. What is the total travel of your shock? What spring rate are you using that would allow that much weight transfer and compression? You would have to get down to a 100lb spring which you just do not want and then it would have to be a 12 inch spring to have any compression left at ride height and then it would have to be at least a 7 inch travel shock to fit the 12 spring and 7 shocks just do not work on these cars, and the issues continue to compound from there. Four inches of travel at the shock would be five or even six at the wheel and you would have bottomed out and ripped a fender off way before camber angles ever became an issue. Consider what your gain is at about 1-1/2 inches of travel, which would be 2 or so at the tire (depending on the motion ratio of the shock mount), and this would be all of the travel that you would want or need. Also, verify that your lower arm is close to parallel with the ground plane at ride height so that the upper arm does all of the gain. AB is right about raising the inner mount of the upper arm, and a longer arm will also be less gain. A general rule of thumb is that the upper arm wants to be 2/3 of the lower arm length, and the lower length is generally set by the limitations of the steering linkage.   

[AdrianBurton]

In the sim, try raising the inner mount of the upper arms, that should change the gain #'s

Does it calculate squat, anti-squat, dive and anti-dive numbers, what about bump