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FWIW, Bilstein has a whole line of inverted shocks. I don't know if they can be set up as adjustable, but they can be custom valved. Seems like it would be possible to make an early C4 coilover kit based on those.
The Bilstein stuff is very nice, but also very expensive, anything in adjustable and gas charged is at least double the price, so it depends on your budget i guess ? Also its difficult to set up compressed and extended length with stud top and t bar bottom to suit c4.
If you wanted to spend the money, could be done tho.
check out this link, its almost like suspension **** !
I made a bending tool by cutting a slot in some steel bar to bend out the sides of the shock tower,
After widening the towers I had the unfortunate realization that the cap and spring are just not going to fit inside the top of the tower. The spring is quite wide being a 600 lb and made of thick wire.
To others that are considering coil overs on early c4 I would be looking at buying the thin shock or upside down setups if you dont want to be spending lots of time in the garage cutting and grinding !
After much deliberation I have decided that the only way forward is to relocate the top of the shock further out in the tower. I am going to make a brace to weld/bolt to the tower.
after some drilling, cutting and grinding,
This is how the coilover looks with a test fit. still need to organise sway bar end links and make a tower bracket to strengthen it.
Two things are important for that brace you fab. First, it will need to be really strong. The shock tower sees very high transient loads from the damper (far higher than the load the spring will put on it). And obviously a failure here could cause you to have a really bad day. I don't know how to advise you to design it, but you're going to have to pay close attention to its load capacity.
Second, you should consider modelling the proposed new suspension geometry before you do all this. As I'm envisioning this, I think moving the the top of the shock outward runs the risk of having a falling wheel rate as the suspension moves through its compression travel. This is not a good thing, usually. You'll want to keep it as close the stock location as possible.
here is my custom coilover hat I made a 'sandwich for the hat'
I put a wash on the top of the hat like you did, but also used that custom machined piece (silver).. These were FX3 Bilstein Shocks and they have been on the car like that for 3 years at least
here is my custom coilover hat I made a 'sandwich for the hat'
I put a wash on the top of the hat like you did, but also used that custom machined piece (silver).. These were FX3 Bilstein Shocks and they have been on the car like that for 3 years at least
Thanks for the pics Jeff, its always good to see how others have done it, what spring rate are you using ?
thanks for that link boots, there is a lot of good info and links on it,
ld85 had to get serious to get his coilovers in, I might just make a brace to go over the top of my tower.
The spring is .55 inch diameter, its 9/16" with the powdercoat on it.
Last edited by blackozvet; Jan 4, 2016 at 09:43 PM.
Two things are important for that brace you fab. First, it will need to be really strong. The shock tower sees very high transient loads from the damper (far higher than the load the spring will put on it). And obviously a failure here could cause you to have a really bad day. I don't know how to advise you to design it, but you're going to have to pay close attention to its load capacity.
Second, you should consider modelling the proposed new suspension geometry before you do all this. As I'm envisioning this, I think moving the the top of the shock outward runs the risk of having a falling wheel rate as the suspension moves through its compression travel. This is not a good thing, usually. You'll want to keep it as close the stock location as possible.
I agree, you dont want the front end collapsing, thats for sure !
There is some comfort in the fact that the GM engineers would have over engineered the front shock tower, that is supported by the number of people who have put coilovers in by just widening that tower, and have years of untroubled use.
By bracing, or in the case of LD85 - a complete re-engineering of the tower, will add some insurance to the deal, particularly if you track your car.
Moving the shock unit out will increase the actual spring rate at the wheel by lessening the angle, but I think that if thats what you have to do to make it fit, then thats what you have to do.
Moving the shock unit out will increase the actual spring rate at the wheel by lessening the angle, but I think that if thats what you have to do to make it fit, then thats what you have to do.
I agree that the initial rate from static ride height will be increased a bit. But the more inclined the springs and dampers are toward the center, the more the rate increases as the suspension compresses. It's a rising rate geometry. As you decrease that inclination, the rise in rate decreases, and at some point of lessened inclination the rate actually begins to fall. Seeing how little the mount had to be moved, I doubt it will be an issue though.
Blackoz i would make a new thicker tower ,i remember a forum member build ,his towers were very thick,a massive amount of steel, large enough to fit the big QA1 coils that are really fat.Some guys here say you are safe with stock towers...may be ,but safety is never enough,i would make new towers....
Blackoz i would make a new thicker tower ,i remember a forum member build ,his towers were very thick,a massive amount of steel, large enough to fit the big QA1 coils that are really fat.Some guys here say you are safe with stock towers...may be ,but safety is never enough,i would make new towers....
I am making tower braces now, and this has been the most time consuming part of the whole project so far !
Using 5 mm thick steel and surrounding the stock shock tower, I have had to cut and weld the top to match the angle of the stock top. this is a pic of the Mark2 version (just to give you an idea where Im heading), I have changed it a bit since - straightened bottom and extended, I want to keep the original tower in place so that it can be reverted if necessary.
The left side brace is done, Mark 3 version !
I have decided to bolt the brace on, 1 bolt each side at the bottom that goes thru the bottom part of the shock tower where it is attached to the top of the tower.
This way the tower can be easily removed if necessary.
It will have 2 bolts at the top, one thru the old shock hole and one via the shock stud itself.
it has been time consuming doing this brace because the shock tower and chassis at that point is angled back in line with the top a-arm and the top of the tower is angled back in line with the shock angle. So basically nothing is straight !
Pic of the tower in place, note nothing has been tightened up in this pic.
with the coil over sitting in place,
for the right side Im thinking I might use 4mm plate instead of 5mm and see how that goes.
While Im waiting for some 4mm bar, Ive had an idea on how to do it better, so I did a practice with some 3 mm.
6 1/2" for each side and 4 1/4" across the top (which is slightly wider than the Mk3 version)
Then make an angle on the top (come in about 2/8" each side) see the marks.
so when you bend it, it automatically has the correct angle to suit the top of the shock tower,
I will make the Mk4 version for the right hand side this way from 4 mm bar.
This is what I see when I look out from under the car, do you think he is trying to tell me something ?
thanks for the picture,
I see that you removed the shock tower and built another one, Im still wrestling with making braces, Ive got nearly 2 weeks invested in them so I guess I better keep going !
What did you do with your swaybar, did you grind a radius around the back of it to clear the spring, or move it forward ?
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