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Grant Galloway
06-17-2016, 02:13 PM
The 06-11 Honda Civic has inboard springs in the rear, this setup has an individual spring and an individual shock that work together.

I was recently advised by a Canadian Race Team that they are not running the stock spring locations, in favour of running a coil over setup where the actul rear dampener is located.

This setup allows greater spring rate affect and gives you better direct feel from the rear.

My question is this...

Would the stock factory dampening locations hold up to this kind of abusive force from the springs now being in a different location? Or do you think it would require some reinforcement to that part of the car?

Anyone else come across this?

Grant

wparsons
06-17-2016, 02:46 PM
With absolutely no data to back this up, I think you would be ok with the coilover. Over any bump/compression, the factory mount points currently have to deal with the force being applied through the shock which is likely comparable to the spring force. At rest the shock isn't exerting much force on the body, but the forces at rest are much lower than over a bump or loading in a corner.

All that said, you'll want to make sure the shock is valved correctly for the spring rate you're running since you're changing the spring motion ratio relative to the shock motion ratio. You'll need a lower spring rate than you currently have, or more damping.

3wheeler
06-17-2016, 03:23 PM
With absolutely no data to back this up, I think you would be ok with the coilover. Over any bump/compression, the factory mount points currently have to deal with the force being applied through the shock which is likely comparable to the spring force. At rest the shock isn't exerting much force on the body, but the forces at rest are much lower than over a bump or loading in a corner.

All that said, you'll want to make sure the shock is valved correctly for the spring rate you're running since you're changing the spring motion ratio relative to the shock motion ratio. You'll need a higher spring rate than you currently have, or less damping.

I have pointed Grant towards an awesome builder by the name of Sean Asselin who happens to make these modifications on CTCC race cars. So if anyone else is looking to do this, PM me for contact info. He does cage work as well!

I also want to clear up a couple things with the above post.

First, the shock does exert an incredible amount of force on its mounts but no where near the same force as the spring. The shock is responsible solely for dampening. A very simple test to prove this would be to remove your shocks while leaving the spring in place. Ride height will change very little if at all. Now, leave the shock in place, and remove the spring. You will find that the shock cannot support the weight of the car. Note: Please don't actually try that. :D When moving to a true coilover suspension you must reinforce the shock mount area to ensure you do not suffer a failure due to relatively thin metal normally used in this area.

Secondly, when going to a true coilover suspension, you are almost always changing the motion ratio for the better(meaning closer to 1:1). As you get closer to 1:1, your spring rate will go down as a result. The reason for this is that you decrease the leverage on the spring during compression by moving the lower shock/spring mount closer to the wheel. The more inboard the lower shock/spring mount is, the more leverage you have, thus requiring a higher the spring rate.

I hope that makes sense to everyone! :)

wparsons
06-17-2016, 04:47 PM
I have pointed Grant towards an awesome builder by the name of Sean Asselin who happens to make these modifications on CTCC race cars. So if anyone else is looking to do this, PM me for contact info. He does cage work as well!

I also want to clear up a couple things with the above post.

First, the shock does exert an incredible amount of force on its mounts but no where near the same force as the spring. The shock is responsible solely for dampening. A very simple test to prove this would be to remove your shocks while leaving the spring in place. Ride height will change very little if at all. Now, leave the shock in place, and remove the spring. You will find that the shock cannot support the weight of the car. Note: Please don't actually try that. :D When moving to a true coilover suspension you must reinforce the shock mount area to ensure you do not suffer a failure due to relatively thin metal normally used in this area.

Secondly, when going to a true coilover suspension, you are almost always changing the motion ratio for the better(meaning closer to 1:1). As you get closer to 1:1, your spring rate will go down as a result. The reason for this is that you decrease the leverage on the spring during compression by moving the lower shock/spring mount closer to the wheel. The more inboard the lower shock/spring mount is, the more leverage you have, thus requiring a higher the spring rate.

I hope that makes sense to everyone! :)

I had a typo/logic fail on the spring/damping rate when moving to a coilover... corrected now :D

I disagree on the forces on the shock while being compressed though, there is a lot of force exerted on/by the shock while resisting compression or rebound. How much will depend on how close to critically damped the suspension is, but it's definitely not trivial.

You're right that at rest the shock won't hold up the car, but without the shock you'd have almost zero motion control over a bump or when loading the suspension. All the force from any resistance to body motion is going through the shock mounting points.

I'm not going to suggest that it shouldn't be reinforced if people that have done it say it should be done, but it will likely depend on spring/damper rates. A race team is likely running much higher spring/damper rates since they're on slicks.

You could probably make a strong case for reinforcing OEM mount points even if not changing spring position when running significantly stiffer springs/shocks as well, but hardly anyone does that.

3wheeler
06-17-2016, 05:16 PM
I had a typo/logic fail on the spring/damping rate when moving to a coilover... corrected now :D

I disagree on the forces on the shock while being compressed though, there is a lot of force exerted on/by the shock while resisting compression or rebound. How much will depend on how close to critically damped the suspension is, but it's definitely not trivial.

You're right that at rest the shock won't hold up the car, but without the shock you'd have almost zero motion control over a bump or when loading the suspension. All the force from any resistance to body motion is going through the shock mounting points.

I'm not going to suggest that it shouldn't be reinforced if people that have done it say it should be done, but it will likely depend on spring/damper rates. A race team is likely running much higher spring/damper rates since they're on slicks.

You could probably make a strong case for reinforcing OEM mount points even if not changing spring position when running significantly stiffer springs/shocks as well, but hardly anyone does that.

Its all good, Will!

I did say that the shock exerts an "incredible amount of force", so we agree there. My point was that the spring mount is built much beefier compared to a shock mount, and the reason being that it supports the weight of the car. Combing the two is playing with fire. Maybe it will hold up, maybe it won't. Anyone using non OEM coilover conversion typically reinforce the shock mount as it was never designed to handle the combined forces of a spring AND shock. My E36 was a great example of that but the shock alone could punch through on that car in some case...Usually because the shock is blown and they hit the bump stops though. A good way of looking at it is, the shock does not control how far a cars suspension will travel, it instead controls how quick it does(rebound too, except that is dependant on how long the shock is).

As for shock dampening, I wasn't stating you should run without a shock. I was only using that as an example to show that a shock doesn't hold the weight of a car on its own. So, we agree on that too. How much dampening is a whole other topic..

So to sum up what I am trying to say; If you plan on going to a true coilover setup, it would be in your best interest to reinforce the new mount unless the manufacture has already done this for you.

Grant Galloway
06-17-2016, 06:03 PM
Yeah I will side with Corey on this, I will definitely be reinforcing the factory setup!

Thanks Corey, it all makes sense from what I know about suspension!

Ziploc
06-18-2016, 12:47 PM
I've seen people do this with E36 M3s as well.

http://i405.photobucket.com/albums/pp137/steve23002/Image376.jpg

to

http://i957.photobucket.com/albums/ae55/PerkM3/CIMG0490.jpg

which leads to

http://i.imgur.com/PS2EIY2.jpg