Well, phooey...

[Pentalab]

If you haven't tried increased spring rates, better dampers, etc., without lowering the car, then how do you really know that lowering the car really is good?

Proper testing means changing one, and only one, variable at a time. Unfortunately, it takes a better driver than me to actually detect anything more than major improvements, since improvement detection requires driving consistency on the order of a couple of tenths of a second per lap on the track.


That's why, while I'm annoyed that I'm "forced" to go with this solution for now, I'm not too bent out of shape about it. Certainly, it is essentially forcing me to change one variable at a time!

Without going to the megabuck coil overs, who makes stock ride height springs...that are stiffer than oem ? And if you do lower it, it has to be stiffer, so it doesn't bottom out. I couldn't find any stock ride height, but stiffer springs back in the spring + summer of 2011. But I didn't look as hard as I should. After a month of on + off looking, I gave up.

Dunno how much the lower CG from a 1.125" to 1.25" drop really makes. Everybody that does it, also uses stiffer lowering springs, so its not an apples to apples comparison. Stiffer stock ride height coils and better dampers vs same but lower coils would be a real fair comparison.

My guess is, for DD use, the stiffer, stock ride height coils would suffice. Then tweak the sway bar rates + camber. I'm sure the car could be made to handle quite well. Lowering is fine up to a point..until clearance issues arise. My PA auto tranny pan is 2.1" deeper than oem. Its the lowest thing under there. Then toss in high flow catted H and 4" diam resonators just b4 the axle. The cats are ok, but the resonators are down a bit...the saving grace being the rake of the car means more clearance. It all works, but had to be carefully thought out.

If I ever had a flat in the rear, my BMR lca relocate brackets would bottom out. They are aprx 3.5" above the ground. A 285-40-18 has a 114mm sidewall. I'm tempted to do what skwerl did, and cut the un-used lower portion off... or use the WL version. WL version is the same as using the center hole on the BMR (both have a 3" drop)

 

[Norm Peterson]

Dunno how much the lower CG from a 1.125" to 1.25" drop really makes. Everybody that does it, also uses stiffer lowering springs, so its not an apples to apples comparison. Stiffer stock ride height coils and better dampers vs same but lower coils would be a real fair comparison.

This is the crux of the matter.

Lowering a 20" CG height to 19" buys you . . . 5% less lateral load transfer. But that is not the same thing as increasing cornering grip by 5% (which would be huge). Your outside tires do go to a slightly better situation, but since that is due to less load transferring off the inside tires, the inside tires are a little worse off. Overall, you're probably gaining on the order of 1% in terms of cornering g's.

I suspect that most of the observed improvement is due to the increase in spring rate - the car takes a quicker set due to the higher spring rates and remains closer to linear longer, and that an improvement in driver confidence results makes it easier to drive the car closer to its ultimate limits consistently. But I doubt that anybody has even tried to separate a diminishing-returns amount of ultimate cornering g's from those.

Sure, at the pointy end of competition where there may be a tire contingency at stake and where lowering really does amount to low hanging fruit in terms of difficulty, it still makes sense to chase a 1% thing. Even with significant "give-backs", as long as you can band-aid them with the rest of your setup - spring & bar stiffnesses, static alignment specs, etc. Marginally streetable track car vs moderately trackable street car kind of mod, maybe.


I do have a little experience with lowering a strut-suspended car . . . and promptly ran into a tire rub problem in roll but not in ride (bumps, brake dive). That was with shorter than OE tires in the same width on wheels of similar offset, which tells me that the roll center height sacrifice was significant (and bad enough that the then-slower rate of camber gain was irrelevant).


Maybe my '08 is a freak in yet another way, but I know if I lowered its rear 1.5" from where it sits - it still is on its original springs - that there would be little (if any) free bump travel left. I do expect the bump stops to get involved during extreme maneuvers, but I sure as hell wouldn't want to put up with the car living on them all the time. Might as well go buy a pair of >500 lb/in rear springs and get the Tokico Illumina team to revalve the bump damping on my Konis to their hearts' content. Ugh.


Norm

 

[Pentalab]

This is the crux of the matter.


Marginally streetable track car vs moderately trackable street car kind of mod, maybe.




Maybe my '08 is a freak in yet another way, but I know if I lowered its rear 1.5" from where it sits - it still is on its original springs - that there would be little (if any) free bump travel left. I do expect the bump stops to get involved during extreme maneuvers, but I sure as hell wouldn't want to put up with the car living on them all the time. Might as well go buy a pair of >500 lb/in rear springs and get the Tokico Illumina team to revalve the bump damping on my Konis to their hearts' content. Ugh.


Norm

"Marginally streetable track car vs moderately trackable street car kind of mod, maybe." Never heard it put that way. That adds some perspective to the ultimate goals for the car. IE: if it's used 95% of the time as a DD, then factor that into the mod equation. Factor in local road condx.

The typ lowering kits include new, lower, rear bump stops. But you still lose 1.25-1.5" of travel on the rear shocks provided in the typ lowering kits..since most of em use oem length shocks.

 

[Norm Peterson]

Shorter bump stops help . . . sort of. When you eventually do hit them, you hit them harder because they're stiffer, which tends to upset the car worse than initial contact with a softer bump stop.


Norm

 

[Mineral_'01]

All this talk lately between this thread and mine concerning ride height really makes me wonder what I am going to end up with installing the coilover kit from Ground Control I ordered. In my instructions to GC, I specified a kit that would go from stock ride height and down to a max drop height of 2". However looking at my invoice/packing list, I see they have my struts listed as the "shortened Koni housings" which makes me wonder exactly how high I can go. I bet even if it is possible to get that kit up to near stock height, my shock/strut travel will be almost fully maxed out on rebound travel. Really wish I had done more research on these coilover kits before I spent the cash.

Anyone with experience running the Ground Control coilover kit and shortened housings know what max height I can hope to achieve with a 7" 430lbs/in spring?

Hope I am not thread jacking this

 

[zeroescape]

All this talk lately between this thread and mine concerning ride height really makes me wonder what I am going to end up with installing the coilover kit from Ground Control I ordered. In my instructions to GC, I specified a kit that would go from stock ride height and down to a max drop height of 2". However looking at my invoice/packing list, I see they have my struts listed as the "shortened Koni housings" which makes me wonder exactly how high I can go. I bet even if it is possible to get that kit up to near stock height, my shock/strut travel will be almost fully maxed out on rebound travel. Really wish I had done more research on these coilover kits before I spent the cash.

Anyone with experience running the Ground Control coilover kit and shortened housings know what max height I can hope to achieve with a 7" 430lbs/in spring?

Hope I am not thread jacking this

Since you already have the strut, you can just mock it up. Remove the spring or drop the collar so the spring wont compress. Jack the control arm up and down and measure how much movement you have.

 

[Mineral_'01]

Since you already have the strut, you can just mock it up. Remove the spring or drop the collar so the spring wont compress. Jack the control arm up and down and measure how much movement you have.

Yes, I think that method would work great; however I should have mentioned, and the reason for my question is, I am overseas and it will be about one month and a half before I can install it.

 

[kcbrown]

All this talk lately between this thread and mine concerning ride height really makes me wonder what I am going to end up with installing the coilover kit from Ground Control I ordered. In my instructions to GC, I specified a kit that would go from stock ride height and down to a max drop height of 2". However looking at my invoice/packing list, I see they have my struts listed as the "shortened Koni housings" which makes me wonder exactly how high I can go. I bet even if it is possible to get that kit up to near stock height, my shock/strut travel will be almost fully maxed out on rebound travel. Really wish I had done more research on these coilover kits before I spent the cash.

This is precisely why I ordered custom made coilovers. My specifications included that the dampers' shaft extension must be at or very near the halfway point with the car at stock ride height.

Vorshlag advertises that the struts in their Bilstein kit are explicitly designed around lowering springs, and that lowering the car without struts that are designed that way will put the struts at a suboptimal part of their travel at the lowered ride height. Well, that goes both ways: if you're at stock ride height, you need struts or coilovers that are designed to be at the optimal part of their travel at the ride height you choose. Since most struts are designed for the stock ride height, that isn't much of a problem if you're going to run straight-up struts. But I know of no coilover system which is designed around the stock ride height.

Anyone with experience running the Ground Control coilover kit and shortened housings know what max height I can hope to achieve with a 7" 430lbs/in spring?

Hope I am not thread jacking this

No worries on thread jacking here.

The issue you raise goes straight to the heart of the matter. I, for one, think it's highly appropriate.