Coilover Angle

[basemodel67]

So I am going to put my truck on coilovers, and I will start making the mounts for it soon. I have looked at a bunch of different setups and was wondering if there is an optimum angle they should be mounted at for best control. Some are straight up, and others are at about a 30 degree slant. Any help?

[draggin86]

there is some missing info here how much travel does the coil over have? are you going to be mounting it with some leverage or just behind the axle.. you should would be safe mounting them straight at 0 degrees.. you sure can mount it at 30 degrees that is the max that i would do.. i just did some shockwaves at 30 degree they are levered off the control arms..

[LONGHAIR]

For a coil-over I would get it as close to vertical as possible. The shocks are also the suspension in this case. So they work best in opposition to the direction of the suspension travel. Spring-rate is far easier to calculate, etc.

[Wild83C10]

As longhair stated as veritcal as possible and as close to the wheel as possible.

[noonzor]

http://www.qa1.net/qa1_motorsports/images/drag_tech.pdf

good info there.

[basemodel67]

Thanks for the info guys! I am going more for handling, so I want to get things set up with that in mind. If anyone has some insight on autocross suspension or tips for setting up a 67-72 with trailing arm rear suspension to handle, I'm interested in hearing what you have to say...

[Mike Bradbury]

Before you start welding Contact Steve Duck at http://www.racecardynamics.com/class...hr/indexhr.htm
He really knows his stuff as far as coil overs go.

I am going the same route with them mounted behind the axle and saw his presentation at the Good Guys Swap meet. He recommends an angle of about 20* on coil overs. I would not go with anything but Bilstein after seeing his demonstration on the differences.

[basemodel67]

Thanks for the info. I will definitely be going with Bilsteins anyway because I can get them at cost.

I am approaching the suspension on my truck with the reasoning that if NASCAR uses it and they can handle pretty good, why can't I make my truck do the same. Drag racing is fun, but driving is better!

[Wild83C10]

Originally Posted by Mike Bradbury

Before you start welding Contact Steve Duck at http://www.racecardynamics.com/class...hr/indexhr.htm
He really knows his stuff as far as coil overs go.

I am going the same route with them mounted behind the axle and saw his presentation at the Good Guys Swap meet. He recommends an angle of about 20* on coil overs. I would not go with anything but Bilstein after seeing his demonstration on the differences.

Why did he recommend a 20* angle?

[Mike Bradbury]

I believe it has to do with how the trailing arm supension moves vs other types. But I am not sure I just remember that number. I am working on a lincoln 9 that I am putting trailing arms and coilovers on so I will be calling him soon and will ask specifically why, Because I as well have heard that the more angle the less effective the shock is.

[DKN]

Coil over type spring and shock have very little travel when compared to conventional coil spring and shock. By mounting the coil over on angle you can get more wheel travel than if it was mounted vertical. The more angle the less effect the spring and shock have. When mounting the coil over on an angle you will need to run a stiffer spring and shock to have the same “wheel rate” as a coil over that is mounted vertically. Some other factors you may want to consider: A spring wound on a larger diameter mandrel will have much less stress than a spring wound on a small mandrel. The larger diameter spring will provide more wheel travel and have a longer service life than a small diameter spring. If you have looked under a modern strut suspension you will find most cars use a very large diameter spring mounted above the top of the tire. This makes a light weight low stress long life spring. You may want to get the largest diameter coil over you can. I have engineering many suspensions and it is rare to get better performance from a coil over that has been retrofit in place of a regular coil spring, however, a coil over does offer adjustability.

Danny Nix
CPP

[Wild83C10]

Originally Posted by DKN

Coil over type spring and shock have very little travel when compared to conventional coil spring and shock. By mounting the coil over on angle you can get more wheel travel than if it was mounted vertical. The more angle the less effect the spring and shock have. When mounting the coil over on an angle you will need to run a stiffer spring and shock to have the same “wheel rate” as a coil over that is mounted vertically. Some other factors you may want to consider: A spring wound on a larger diameter mandrel will have much less stress than a spring wound on a small mandrel. The larger diameter spring will provide more wheel travel and have a longer service life than a small diameter spring. If you have looked under a modern strut suspension you will find most cars use a very large diameter spring mounted above the top of the tire. This makes a light weight low stress long life spring. You may want to get the largest diameter coil over you can. I have engineering many suspensions and it is rare to get better performance from a coil over that has been retrofit in place of a regular coil spring, however, a coil over does offer adjustability.

Danny Nix
CPP

How do you get more wheel travel with a coil over mounted at an increased angle? If you are comparing this to a coilover with the same spring rate mounted at different angles then I you would have more wheel travel. If you use the same rate to compensate for the angle the wheel should travel the same distance.
How does a large diameter spring provide more wheel travel when compared to a small dia. spring if they have the same spring rate?

[DKN]

Originally Posted by Wild83C10

How do you get more wheel travel with a coil over mounted at an increased angle? If you are comparing this to a coilover with the same spring rate mounted at different angles then I you would have more wheel travel. If you use the same rate to compensate for the angle the wheel should travel the same distance.
How does a large diameter spring provide more wheel travel when compared to a small dia. spring if they have the same spring rate?

When the coil over is mounted at an angle the vertical change in length is less than the coil over change in length. Imagine a coil over mounted horizontal (level to the ground). As one end moves up the coil over would have very little change in length while it would pivot at both ends. This is similar to the track bar on an axle. The axle could move up down 12 inches, while the side to side movement is less than 1 inch. If you mounted a coil over in the same location as a track bar the axle could move vertical 12 inches while the coil over only moved 1 inch. Of coarse coil overs are not mounted at a 90deg. angle, but this extreme example explains how the angle changes how much wheel travel can be achieved. This horizontal coil over would provide no vertical force. The vertical force will change as the angle changes. You can use basic trigonometry to calculate the exact amount of vertical force for any angle the shock is mounted at. In short, the more angle the more wheel travel, and the less vertical load.

Springs are made by winding wire over a mandrel, or a roller. When the diameter of the mandrel/roller is larger the body of the spring is larger. With a larger diameter body the spring can have more travel with less internal stress. The internal stress is the limiting factor of any spring. The lower the stress the longer the life. CPP made coil springs are designed to have a service life of at least 1,000,000 cycles. Our springs meet or exceed all GM standards and exceed Ford and MOPAR requirements. I have worked with other spring manufactures that have produced springs that will begin to fail (sag) after the suspension has bottomed out in travel as few as 10 times. Part of my duties designing new springs is to make sure CPP springs can with stand being bottomed out at least 1,000,000 times. Most coil over springs do not meet this standard because the small body diameter limits how much travel the spring can have, and limits the design to a lower service life.

Spring design is much more involved than this over simplifcaton, I’m just sharing some basic info.

Danny Nix
CPP

[basemodel67]

Your over-simplification is like a Rubik's cube to Helen Keller - Way to complicated for me. I seem to learn best with pictures. But, since you probably know a pantload more about suspension geometry and setups, is it best to mount the rear coilovers behind or in front of the axle, with both being the same distance off axle centerline? Also, I am OK with a firm ride, but how much actual suspension travel is needed to not drop a kidney out of my bung - 4"? 6"? Your expert opinion is greatly appreciated.

[basemodel67]

Bump for some help! Also, what about a cantilevered setup with horizontally mounted coilovers, like a Ferrari F50? I heard not every kind of c/o shock can be mounted horizontal. Anyone know?

[DKN]

In front or in back of the axle will not make much difference with a 4 link or traling arm set up. With only 4" of travel I would try to get 3" compression to 1" extension. 1" extension from ride hieght will top out often but that is much smoother than when you bottom out. Bottoming out also puts a lot more stress thru the truck. 3" compression is not very much but will work for most average roads. It will need to be firm to avoid constant bottoming. Use as tall a side wall as you can and a soft seat cussion. All single tube shocks with a dividing piston can be mounted at any angle. Twin tube shocks that use a closed cell foam instead of an air buble can also be mounted at any angle. All other shocks need to be mounted body down. Not all coil overs shocks are single tube, and not all single tube shocks use a dividing piston. Check with the manufacture to find out how its made.

Danny Nix
CPP

[basemodel67]

Thanks DKN! You gave me more info in a short paragraph than I could find searching the web for 4 hours. I love this place!

[Wild83C10]

I would shoot for more then 4" of suspension travel. 1" of extension will more then likely tear the shocks up on a street drive vehicle.

[basemodel67]

I think most shocks have a cushion internally to keep them from being damaged by overextending. And, 4" should be plenty of wheel travel. I doubt a new Corvette even has 2" of suspension travel, and lots of people drive them everyday.