eibach springs question
 

hey fellas

okay so i have a quick question. I have a '02 gt conv. with 18 inch saleen wheels, and looking to get the Eibach springs. now i have two choices the sportline vs the pro kit.. now the sportline, lowers the car about 2 inches as for the Pro kit lowers the car about 1.3 to 1.5 inches. im looking to get the sportline.. but will that lower my rear to much with the extra weight of the convertible. most sites that sell the springs will not offer the Sportline for convertible's...


thank you
for you're time
Dan....

I personally think anything lower than 1.5" is just dumb since anything below 1" starts to destroy handling. Plus, the Eibach springs lower your car but don't have the increased spring rate so if you're worried about bottoming out, then get some H&R springs since they have increased spring rates w/ their drops.

If you get the sportlines, plan on doing things the will help correct the steering geometry. Like bassman said, "it starts to destroy handling", which I don't completely agree with, but there is some truth in it. I'm lowered 1.75" and my handling is much better than stock, so I don't see how it destroys handling, but steering geometry is compromised. Steeda Bumpsteer kit, and X2 ball joints might be needed, along with caster camber plates, and ofcourse upgraded dampers. Handling will be improved rather than destroyed. The lower you go, the more problems that you could have.

I know that anything lower than 1" screws up the front end geometry and the fact that I can take corners at a faster speed w/ my Mach 1 springs vs. my old Eibach Pro-Kit springs. This is why I say handling is compromised since anything lower than 1" is a point of diminishing returns.

That's about the gist of it. Bassman was right though and I'll splain below.

Generally more than 1.5" of lowering in front pushes you past the point of diminishing returns and starts directly causing handling problems you didn't have before. Some of those problems are really hard to identify but they're easy as hell to feel if you know what it can be like and it becomes obvious in any hard driving like racing or tear-assin'... things like increased tread squirm, increased push and a below-ground roll center, blah blah blah. Suffice it to say that unless you go the whole coil over and tubular arm route that more than 1.5" drop is a no-no. If it doesn't impact your daily driving... cool, but I'd call it at the 1.5 mark.

Below an inch you'll start feeling the negative effects and the extra half inch is pushing things to what I'd call a streetable limit. It's not a question of what's possible it's a question of what'll last and perform and the two don't often meet.

As for Eibach... meh... some good some not. I prefer either FRPP F springs or H&R Sport. Consult the spring rate guide in this forum for an idea of what's what.

But can things like, below ground roll center and the other things be fixed? I think if they can be fixed then there shouldn't be a problem with lowering to 2". Or is it really impossible to fix without total overhaul?

you have to relocate suspension pickup points in order to do that. That's why it's easy with coil overs and tubular everything... the makers of those parts setup the tubular arms with different pickup points that work better on lowered cars (well... most of them). Otherwise fixing requires un-doing what's causing it and a lot of times it's something that's been welded into place from the factory.

Oh ok. So you basically have to fix it, which is just doing what you should have done in the first place to mod the suspension. Or change the suspension to where it doesn't become a problem, basically leaving it alone. You can't really keep moding yourself back into proper steering geometry, I think I understand.
Do it right, or don't do it at all?

Edit: So is it impossible to have a perfect >1.5" drop with coil springs, dampers and stock-like related stuff?

not to hijack the thread but r3d had a quick question. Was going to replace the springs on mine this summer and was going to get either for F springs or the H&R sport mostly because I don't want the hardcore drop and have to replace most of the suspension. Now I've looked some stuff up and found a lot of times CC plates are not needed to be upgraded with a 1-1.5" drop (i know thats kind of hit and miss you may need them may not). What about the shocks and struts how much of a drop can the stock ones take without putting to much pressure on them? could they handle a between a 1-1.5" drop?