Raise shock mount or raise entire frame
12-21-2013, 10:27 PM
#1
Le Mans Master
Thread Starter
Raise shock mount or raise entire frame
Hey,
So as you may have seen in my previous topic about ride height I have settled with a rocker height of 4" front 4.25" rear which keeps stock incline angle.
Now I have 3 ways to get there and I need to know what's best. I can not afford to blow the budget on drop spindles so that's not one.
Stock height is 6-6.25" respectively. So I need to obtain a 2" approx total drop of the car.
1- keep ride height bolt stock, cut frame, raise front and rear sections by 2", weld back up, enjoy car with stock suspension travel etc etc
2- lower ride height bolt by 2" requiring longer rear bolt and cutting rubber in front, cut upper shock mount, raise up 1.5" (motion ratio is approx 70% wheel to shock) so this retains stock levels of shock travel and weld, no hitting bump stops and screwing with handling.
3- lower ride height bolts 1", raise shock mounts 0.75" up, cut And weld frame up 1".
#1 would have benefit of the body sitting lower, better aero, more down force, but the engine and trans etc sit stock height so it does not really help a TON with center of gravity but does retain stock suspension which people say is best for some reason I do not understand.
#2 seems best in my opinion. Lowers everything 2" so the cg lowers 2". Puts suspension into much more aggressive camber curve, toe is constant so it's still the same bump as stock height, roll center lowers 2.2", anti squat and dive increase by around 4% IIRC, outside tire gets less negative camber in a turn vs stock height, and raising the shocks makes it have the same suspension travel stock to avoid bump stop issues.
#3 uses the magic 1" drop number but I do not know if I believe it's magic. Roll center lowers 1.1" camber is more aggressive than stock but not as much as 2" less linear. Raise shock to get stock bump/droop travel, but only get a cg change of 1" due to frame coming up on the body 1" to get 4" ride height.
Now I have modeled the suspension using suspension analyzer with their corvette c5 saved file. I made screen shot images of the plotted graphs to back up the curve claims.
Which way is best? I don't want to do this twice.
I'm voting #2 but maybe someone else here has ideas to back up what they believe would be fastest on a track? I've seen pfatd post that their short coil over and lowering down is best for handling which follows my train of thought and the geometry I obtained from the program.
Perhaps race cars are not allowed modding suspension mounting points which is why they do a drop spindle?
Going 3" down makes roll center go pretty much into the ground which I do not want. Maybe race cars like the DRM use drop spindle for 1" and drop 2" to give total drop of 3" because those cars sure look lower than 4"...
Anyone know their height?
Anyhow
Food for thought! Let me know what you think. I don't want to know about a guy that slammed stock bolts and rides on bump stops and handles terrible and grandma's dentures fall out because of harsh ride.
That's all fixed with changing where the shock mounts.
Thanks!
-Chris
So as you may have seen in my previous topic about ride height I have settled with a rocker height of 4" front 4.25" rear which keeps stock incline angle.
Now I have 3 ways to get there and I need to know what's best. I can not afford to blow the budget on drop spindles so that's not one.
Stock height is 6-6.25" respectively. So I need to obtain a 2" approx total drop of the car.
1- keep ride height bolt stock, cut frame, raise front and rear sections by 2", weld back up, enjoy car with stock suspension travel etc etc
2- lower ride height bolt by 2" requiring longer rear bolt and cutting rubber in front, cut upper shock mount, raise up 1.5" (motion ratio is approx 70% wheel to shock) so this retains stock levels of shock travel and weld, no hitting bump stops and screwing with handling.
3- lower ride height bolts 1", raise shock mounts 0.75" up, cut And weld frame up 1".
#1 would have benefit of the body sitting lower, better aero, more down force, but the engine and trans etc sit stock height so it does not really help a TON with center of gravity but does retain stock suspension which people say is best for some reason I do not understand.
#2 seems best in my opinion. Lowers everything 2" so the cg lowers 2". Puts suspension into much more aggressive camber curve, toe is constant so it's still the same bump as stock height, roll center lowers 2.2", anti squat and dive increase by around 4% IIRC, outside tire gets less negative camber in a turn vs stock height, and raising the shocks makes it have the same suspension travel stock to avoid bump stop issues.
#3 uses the magic 1" drop number but I do not know if I believe it's magic. Roll center lowers 1.1" camber is more aggressive than stock but not as much as 2" less linear. Raise shock to get stock bump/droop travel, but only get a cg change of 1" due to frame coming up on the body 1" to get 4" ride height.
Now I have modeled the suspension using suspension analyzer with their corvette c5 saved file. I made screen shot images of the plotted graphs to back up the curve claims.
Which way is best? I don't want to do this twice.
I'm voting #2 but maybe someone else here has ideas to back up what they believe would be fastest on a track? I've seen pfatd post that their short coil over and lowering down is best for handling which follows my train of thought and the geometry I obtained from the program.
Perhaps race cars are not allowed modding suspension mounting points which is why they do a drop spindle?
Going 3" down makes roll center go pretty much into the ground which I do not want. Maybe race cars like the DRM use drop spindle for 1" and drop 2" to give total drop of 3" because those cars sure look lower than 4"...
Anyone know their height?
Anyhow
Food for thought! Let me know what you think. I don't want to know about a guy that slammed stock bolts and rides on bump stops and handles terrible and grandma's dentures fall out because of harsh ride.
That's all fixed with changing where the shock mounts.
Thanks!
-Chris
Last edited by Apocolipse; 12-21-2013 at 10:52 PM.
12-21-2013, 10:44 PM
#2
Drifting
Member Since: Dec 2005
Location: Dayton, OH
Posts: 1,822
Likes: 0
Received 0 Likes
on
0 Posts
I basically did #2 but I have coilovers and run a soft wheel rate. I love it! My car sits about 3 1/4" front and rear at the frame rails but it is a race car only.
12-22-2013, 12:01 PM
#3
Le Mans Master
Thread Starter
How's it handle the turns and throttle mid way through the turns? I am curious about roll center migration when lowered that much then apply throttle after diving through an apex.
I also watched them talk about their drop spindle on the car, they mentioned they drop 1" from spindle then they said 1" through coil over or leaf adjustment.
Now this could be due to not being allowed to move shock mount up? So that's only way to stay off bump? Or is there some magic with 1" drop I have not been able to find yet.
I also watched them talk about their drop spindle on the car, they mentioned they drop 1" from spindle then they said 1" through coil over or leaf adjustment.
Now this could be due to not being allowed to move shock mount up? So that's only way to stay off bump? Or is there some magic with 1" drop I have not been able to find yet.
12-22-2013, 07:55 PM
#4
Melting Slicks
What are your intentions with the car? Unless your racing this car for position or time, I don't see why all this matters. I'm all for modifying, but cutting frame or moving shock mounts seem excessive. Lower the car 1" and put on the best tires you can. If you want to go lower, then buy coilovers. If that's not low enough, then add drop spindles. No matter what you decide, you still have to balance the car for understeer vs. oversteer. Great driving and Hoosiers will net more time gained then any other mod. All this other stuff only equals tenths of seconds. Good luck with your project. 
Steve A.
Steve A.
12-22-2013, 08:48 PM
#5
Le Mans Master
Thread Starter
I'm building the car from scratch so I have the ability to change things now which is why I'm asking in advance. I'll put pics up of progress but right now I'm getting it ready to install the rear frame rails which is why I need to know if I'm to lower it by raising the rails or use suspension points.
It's super easy to do it now vs later
It's super easy to do it now vs later