Robby

I posted this on the main board- just X-posting for more response...

Long story, but, essentially, I just put Ledas on my Turbo S- non-adj w/225lb springs- I ALSO bought 27mm T-bars, but, NEVER installed the T-bars- used 100lb helpers instead- if anyone's interested, I'll sell them for less than cost- they are in PERFECT condition...

Karl (Racer's Edge) told my mech to tighten the helpers on the rear shocks enough to keep them from rattling- my mech added 1" of preload after measuring actual stiffness of the spring, etc so, they are now installed w/1" of preload- the car feels very sketchy- leans toward oversteer, but, I get the feeling the rear end WANTS to snap around- I don't think it'll oversteer to THAT degree, but, it's definately not reassuring. Many people on this board know that I'm not afraid to point out negative aspects of these cars, but one excellent thing about them, I've ALWAYS maintained, is their excellent on-center feel- they seem to keep direction well & feel VERY stable at ALL speeds- this feeling is non-existent at the moment...

I was just wondering if anyone had experimented w/preload on helpers or anything thereof- what about front coil-overs (Koni's, Ledas, Bilsteins, etc?)? Do you add pre-load there? Pre-load is something I had never really considered before now- I'm just wondering if the pre-loaded helpers could be causing more pressure on the rears- since they're already compressed 1", then, do I already have 100lbs of pressure, so, compressing another inch would be 200lbs? IF so, at rest, w/1" of pre-load, it seems as if I would be adding to my 25.5mm T-bars to give ~275lb effective rear rate- this could cause oversteer since the fronts are ~225lbs- &- the 225lb springs are not 100% effective themselves, so the dif is probably a tiny bit greater toward the rear, but, I'm sure it's not much.... Any input?

thanks a lot,

Wormhole

I use helper springs and have experimented with many different combinations of preload, spring rates, and torsion bar indexing. I can tell you it does change the effective rate and is extremely complicated to find the right balance between index and preload as many factors need to be considered that will change the geometry, such as ride height, torsion bar index point, spring plate height, spring rates, shock damper rate, etc. Karl gave good advice in that you shouldn’t use much preload on the spring. When this happens the torsion bars are indexed up too much and the geometry is placing most of the load on the springs, and not enough on the T bars. Then as the wheel is compressed the wheel rate is more of a progressive rate. I guess that’s why the cup cars had progressive springs in the front to balance things out since they used helpers.

Given that you are only using a 100lb spring and one inch of preload I would not be concerned. Changing the preload to less would actually make your car overstreer more.

Your rear effective rate is more like ~231, and your front effective rate is ~200. That’s like a 115% rear/front differential. Try using 275lb or 300lb front springs to dial out the oversteer, that will put you at 86% and closer to the stock balance. That’s assuming I interpreted your post correctly and you have 25.5mm T bars with 100lb helpers.

Robby

You have it right- I knew the rear would end up a hair more than the front, but, didn't think it would be too noticeable- I may have been wrong- I'm thinking alignment has something to do w/my prob here though, but, the rear feels a good bit stiffer- I would think it would be the opposite on the pre-load, as, compressing them some already- 1" / 100lbs- would make it so any more compression- say another 1" / would make it 200lbs- would ADD even MORE pressure- it would be like STARTING w/100lbs & ANY compression above that would be additional... ???

Thanks for the input- not sure if my mech has finished or not, but- I MAY try to get some weaker helpers OR stiffer fronts... I guess the easiest way would be to get 250lb fronts, but, I'm trying to stay a little on the side of caution- there's too much initial impact as it is, yet not enough roll control- maybe larger sways, but I don't believe it for a second- my '89 Integra was MUCH easier to dial in & would out-hang this car w/out question, plus, be more tolerant of bumpy terrain- this w/simple Tokico 5-points & Eibachs basically thrown on... I just really didn't expect to have to mess w/it this much when buying this stuff or wouldn't have done it...