Last year I purchased a coil-over set up from Arruart motorsports. The directions are a little vague, but I wanted to run this by those who have some experience with coil-overs to see if this looks correct. The first pic shows the QA1 shock all the way compressed. I have about 4 1/4 inches of room between the spring perch on the cradle and the spring perch on the shock. The shocks perch is all the way down, and can't be moved any further. The second picture shows the shock in the full extended position and I have approx 7 3/4 inch perch-to-perch. The third pic shows the provided shock, its 10 inches uncompressed.
My question is this. I have koni struts on the back with coil-overs and 10 inch springs. I know that the back and front are different but I was under the impression that I would not have 10 inch springs on the front, I say this because with the shock perch all the way in the bottom position I still only have 7 3/4 inch to play with. The 10 inch spring will compress, sure, but how much? Before I can even install them, I have to compress them 3 inches, and this will still put the suspension at the full "Top" ride height. Do you think I will get the spring to compress enough? And after is does compress because of the weigh of the car, I don't see it really allowing me to "lower" the shock perch to "lower" the car. I'm not looking for much anyway, i am running 1 1/2 dropped spindles on the front, I was looking at using the coil-over to help "fine tune" the ride height.
So for those with knowledge of springs, shocks and coil-overs, does this all add up? Should I get the springs compressed and put some heavy duty zip ties on them so i can get the spring on the shocks? Do you all think the 10 inch spring will compress enough to fit into the 7 3/4 space and sill lower a little so that I can have a decent ride height?
Oh yea, and doing this with the front cradle off the car was a bad idea. The weight of the car is your friend when you need to compress the spring....... dah!
Thanks in advance.
Rob.
[This message has been edited by qwikgta (edited 11-16-2013).]
2.25" is going to be a lot of preload. What mount are you using for the top of the QA1 Promastar (bayonet adapter, bushing, or rod end) and what is the spring rate you want?
[This message has been edited by Zac88GT (edited 11-16-2013).]
2.25" is going to be a lot of preload. What mount are you using for the top of the QA1 Promastar (bayonet , bushing, or rod end) and what is the spring rate you want?
The kit comes with stock QA1 shocks, and includes a set of Fiero style tops. You remove the originals and install the Fiero ones. But this is not the issue, the issue that I see is that when using a coil-over, the benefit is that you can adjust the perch to raise/lower the ride height. As I see it now, with a 10 inch spring I have to squeeze it down to between 4.25" and 7.75", again that is the upper/lower limit of the shock. I just don't see how a 10" spring is going to fit and be useful loaded up that much.
Thanks for this thread. I had looked at it a long time ago, and forgot that he installed the same kit (almost). Later in the thread there was some discussion about using a 8" or 10" spring. I'll have to do some additional reading and maybe contact those guys to ask some specific questions.
OK, so i'm not going to do anything just yet, but this is what I am thinking. The benefit of a coil-over system is that you can run a shorter spring and if you need to you can adjust the shock perch up/down to raise the ride height. In other words, if the spring was only 8" and i installed them with the shock perch all the way down, I'd just adjust the perch up a little and the ride height would change. This is how i see the coil-over thing working. So even if I decided that the 10" spring I have now is too long, I could cut off a few coils to make it smaller, then install them. If the ride height is too low with the perch all the way down, I just adjust the perch up a little and the height goes up. I know it is that simple, so i'm trying to figure out why I just don't go out into the garage and cut the springs?
And for those who think I will be changing the spring rate if I cut the spring, that is not true. These springs are made from a huge, long,coil of metal, they are cut to a specific length and removing a coil or two will not change the rate, just the height. The main reason I just don't go out and do it is that springs have kicked my butt in the past. I know I need to let them settle after install, the last time I did a spring change I didn't like the ride height after I installed some 1.5" dropped springs so I pulled them and cut off 1/2 a coil. The car looked great, but after a few hundred miles the springs settled in and the car was then too low.
... even if I decided that the 10" spring I have now is too long, I could cut off a few coils to make it smaller, then install them. If the ride height is too low with the perch all the way down, I just adjust the perch up a little and the height goes up. I know it is that simple, so i'm trying to figure out why I just don't go out into the garage and cut the springs?
What's the rush? Phone them and get the right springs so you can do it right.
Make sure you have enough shock travel with that short of spring. I remember these coilovers from back in the day and if you ran them at their lowest setting you wouldn't have enough shock travel for street use... I believe that was with a 8" spring.
[This message has been edited by The Aura (edited 11-17-2013).]
While I don't have this style of coilover, I am using 8" springs, stock fiero spindles ( I removed drop spindles), and adjusted to the mid point on the sleeve.. and it works out to be about a 1.5" drop.
I also removed 8" springs from the rear of the car and replaced them with 10" units that another member gave me for free. I will pass on the same deal, if you need the 8" chrome springs from my kit.. You pay shipping and they are yours. PM me and I'll take pictures and tell you the #'s. That is if they don't supply you with the right size springs.
Originally posted by qwikgta: so i'm trying to figure out why I just don't go out into the garage and cut the springs? Rob
Once you cut them, you won't be able to get them replaced by the vendors, but cutting them would resolve the issue much, much quicker. You could even cut them to find the approximate length you need and then buy new ones. The only issue with cutting them is you will end up with a non-flat end and neither the upper or lower seats are designed to accept it.
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Originally posted by qwikgta: And for those who think I will be changing the spring rate if I cut the spring, that is not true. Rob
Cutting them will in fact change the spring rate. All spring rate calculations are based on wire diameter, coil diameter of the spring and # of active coils. Reduce active coils and the rate will increase. Here is just one of the spring rate calculators.
As for the length of the springs... they are too long. The stock 88 front spring is about 12" in length and has a load height of about 7.87" and is resisting about 910 lbs at that compression.
With a 350 lb/in spring the 910lbs will require 2.6" of spring compression at ride height. So if you install an 8" spring, it will be compressed 1/4" just to install the shock, then another 2 1/4" to settle at ride height. This will give you about 1 1/4" of upward travel at the shock, 2 1/2" at the wheel before bottoming out the shock. Then you could use the adjuster to raise the front if needed. Since the collapsed picture shows the lower a-arm sitting on the crossmember w/o any bumpstop, then at that point the tire will likely be into the fender (with stock spindles, so you will indeed need to raise the front end up some to compensate for your lowering spindles).
For a 350 lb/in spring, 8" is probably the proper size.
[This message has been edited by fieroguru (edited 11-17-2013).]
Rob, Cutting coils will change the spring rate. The rate of each coil does not change, but the rate of the spring as a whole goes up as you remove coils. Think about it this way: if your 10" spring has 10 coils, each coil only compresses 1/10 of an inch for each inch of spring compression. If you remove 2 coils, now each of the 8 remaining coils must compress 1/8 inch for each inch of spring compression. The wire and coil sizes didn't change, so the force required to compress each coil 0.125" instead of 0.100" is higher. You shortened the spring by 20% but increased the rate by 25%.
Rob, Cutting coils will change the spring rate. The rate of each coil does not change, but the rate of the spring as a whole goes up as you remove coils. Think about it this way: if your 10" spring has 10 coils, each coil only compresses 1/10 of an inch for each inch of spring compression. If you remove 2 coils, now each of the 8 remaining coils must compress 1/8 inch for each inch of spring compression. The wire and coil sizes didn't change, so the force required to compress each coil 0.125" instead of 0.100" is higher. You shortened the spring by 20% but increased the rate by 25%.
Marty
OK, reading it that way it makes sense.
I am going to wait to talk to Richard at Aurrat Motorsports. I hate that I have to send another set of parts off to get powder coated, I've already got $50 into these getting them powder coated red as is. Hopfully Richard will send some 8" springs so I can get this back on track.
Rob
[This message has been edited by qwikgta (edited 11-18-2013).]
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