What do you get with LSS and a Lathe?

[flyguyskt]

i guess i will have to look at the stock shock and figure out what it is you are doing. doesn't make sense to me...i see the groove and the ring in the first pic but that means nothing to my brain without reference to how it "lowers" the car??

[turbophil]

Originally Posted by flyguyskt

i guess i will have to look at the stock shock and figure out what it is you are doing. doesn't make sense to me...i see the groove and the ring in the first pic but that means nothing to my brain without reference to how it "lowers" the car??

Imagine the spring is on the shock. It is secured to the shock body with a collar. That collar is secured to the shock body with a little "jesus clip". By machining a new groove for said "jesus clip" further up on the shock body, it will allow one to locate the upper spring collar further *up* on the shock body. That means the spring itself will rest higher up on the body, and subsequently lower the car... I wish I had a picture... If someone doesn't post one, I'll try to come up with one at home...it'll be later in the evening though

Best,

Phil

[turbophil]

Originally Posted by fpitas

Phil,

Looking at my base coilovers, it looks like it would be possible to machine new spring seats to fit standard 2 1/4" ID springs. That would make changing spring rates much easier, although the coilovers would no longer be SCCA stock.

You've about got it...There's actually a slick little adapter ring that eibach sells which will keep the ever so slightly larger springs centered. It's only a few dollars and probably makes more sense than machining a whole new collar or modifying the existing one. It will also keep the stock shock collar in tact so that one could switch back to OE springs if ever desired.

The mod is two levels, I figure.

1) Simply cut either LSS or standard shock and lower to desired height... cheapest sollution, yet effective.

2) Swap in stiffer Eibach springs on to either shock style and cut respective ring into shock body. This is a little more complex as the stiffer spring will require an entirely new locating groove regardless of desired ride height, but that's not a big deal as I know how to derrive that location... This would cost a bit more as there's about $250 worth of additional spring cost here...

Again, I see these mods as a nice middle ground for the "value shopper"

Best,

Phil

[R T]

[fpitas]

BTW, for those with base suspensions, they can be lowered a few mm. My Bilsteins have another groove below the normal setting.

[fpitas]

Originally Posted by turbophil

You've about got it...There's actually a slick little adapter ring that eibach sells which will keep the ever so slightly larger springs centered. It's only a few dollars and probably makes more sense than machining a whole new collar or modifying the existing one. It will also keep the stock shock collar in tact so that one could switch back to OE springs if ever desired.

The mod is two levels, I figure.

1) Simply cut either LSS or standard shock and lower to desired height... cheapest sollution, yet effective.

2) Swap in stiffer Eibach springs on to either shock style and cut respective ring into shock body. This is a little more complex as the stiffer spring will require an entirely new locating groove regardless of desired ride height, but that's not a big deal as I know how to derrive that location... This would cost a bit more as there's about $250 worth of additional spring cost here...

Again, I see these mods as a nice middle ground for the "value shopper"

Best,

Phil

If you equipped the Bilsteins with stiffer springs, and revalved them with a bit less bump and perhaps more rebound (depending on the spring rate) you might have a winning package for "budget racing". Like you said, the springs will be about $250 for four, here's the best place I've found to get them:

www.eshocks.com

They have Eibach & Hyperco, both of which are excellent springs.

[turbophil]

I think a nice improvment is attained just by lowering the factory suspension as RT and I have done -- we both feel so anyway

New stiffer springs may be *just* that much better for a track car. I'm -content- with the valving for now. If I got to the point where I felt the I couldn't live with valving and my driving ability exceeded the improvement made to the stock bilstein dampeners, then I would likely buy the higher price nitrons or similar. The idea here is bang for the buck and a happy medium

My suggestion is to lower as much as reasonable for your driving style and roads. Also run a slight rake on the chassis, especially for the more powerful cars that will squat the suspension more (super charged for example) under accel and heavier drivers, etc... The flat bottom of the car should NEVER be pointing up going forward in relationship to the road or your Cdf may go positive I run about a cm lower up front than in the back. I question whether that's even enough with the soft stock springs (Lotus seems to think it's OK), but it will do for now or until I can proove otherwise.

Regarding lowering, studies have shown that well a designed underbody (like the one we have, could be better in places though) will substantially pick up Cdf (i.e. lose underbody pressure resulting from an increase in velocity of the air under the car) from ~10cm to ~2cm of ride height and the Cdf falls off a bit above 10cm. Below 2cm the boundry layers are apparently thick enough to begin to kill much of the ground effects. Of course 2cm isn't reasonable and 10cm is about at the threshold of too low for a street car.... That's why I say as low as you can reasonably go for your area and style of driving.

We have to remember that It Is OK to Change what the Lotus engineers gave us on a case-by-case scenario. They had to deliver a car that could clear driveway entries of all kinds, meet DOT regs, go over speed bumps etc... Well for some of us, we can take some of the civility out of the car for the betterment of handling, ground effects, etc...

Couple more pennies for the jar...

Best,

Phil

[xtn]

Originally Posted by turbophil

XTN,

You're right, it is not the case It's a straight piece of tube of uniform wall thickness. There's no buldge on the outside and the inside must be uniform to allow for piston travel.

Okay I gotcha. I didn't know the piston went that far, so I guessed at the possibility.

xtn

[R T]

Phil, preload is going to become an issue when you go to a stiffer spring at your lowered ride height. You are either going to have to limit the full extension length of the shock (droop) or you're going to need to get the stiff springs wound shorter than stock and use tender springs to keep the springs seated on the cups/perches at full suspension droop.

[turbophil]

Originally Posted by R T

Phil, preload is going to become an issue when you go to a stiffer spring at your lowered ride height. You are either going to have to limit the full extension length of the shock (droop) or you're going to need to get the stiff springs wound shorter than stock and use tender springs to keep the springs seated on the cups/perches at full suspension droop.

I follow what you're saying, but I'm only talking 10-20% stiffer springs. Much stiffer and I would worry about over power the shock valving...Since we can adjust the collar to where ever we want, we should be able to dial in ride height and still have enough preload the keep the spring seated at full droop. There are several shocks that can be purchased in off-road racing that have virtually no preload, just enough to keep the spring seated in jump and that's it (past experience)...Arguably, we don't even need that unless we plan to jump the car There's also a nice set of equations that help determine the appropriate free length of the spring for just such a project I bet the free length comes out to be about the same as stock, however...

I'll keep ya posted as I get closer to purchasing the springs, as I know you want to play too

Best,

Phil