No, if you make them as long as possible you'll be sitting with the shock bottomed out at ride height and the car will handle like garbage. You need to set your compression/droop ratio by adjusting damper length and then you adjust ride height with the lower spring perch. Most Fortune dampers are 90mm travel but some are 110mm. Rule of thumb is 1/3 stroke goes for droop and 2/3 goes towards compression. Easiest to figure out installed lengths by setting them up in the car with no spring installed, you'll have to compensate some for spring compression but it gets you in the ballpark.

I usually check my damper stroke lengths by measuring them in my press.

 

Thanks, My head was more around 'longest' will be good for tripod'ing situations.I was thinking I'd arrive around the same perch height with my helper springs (from KW v3) installed. The stroke from the helper springs is the 'considerable' droop stroke, not much stroke from 5" 950lb springs.
Would you guys say having a set up with helper springs is not good? and prefer having springs loaded and have minimal droop? I haven't tried the latter in any of the coilovers I've had so I have no idea what that feels like for street or race.
Looks harder to adjust ride height.

 

For the shock height the witness hole is there as an indicator of minimum amount of threads in safety. so id say your on the bare minimum in that picture. However, As mentioned you want 1/3 of the shock travel for droop. and you need to set this up on the car with the spring removed. Helper springs just keep the main spring from being captive when at full extension. if you have the correct length springs you dont need them. The overall height of the shock just sets your droop ratio, The spring perch sets your ride height, and the spring rate controls the hardness of the suspension. then you need the shock valving to match the spring rate otherwise they wont work together e.g the shock wont keep up with the spring etc.

With the shock longer the car will still tripod and youd probably make this worse without droop as the suspension will have no travel in rebound when the tyre unloads as the opposite side thats in compression will have way more travel than normal due to the droop ratio and the outside suspension will compress way further. if anything youd want more droop and less compression to stop the outside shock compressing too much but the danger is if the strut hits its bump stop the shock rate essentially goes to inifinity which can cause major issues. think of slowly squashing a piece of foam or rubber till it gets to the point it doesnt squash anymore suddenly it becomes very hard. Youll induce major understeer and unpredictability at high speed.

Regarding the helper springs,
The helper spring will be fully compressed with the cars weight on it, the only time they extend is when the spring becomes fully unloaded. their only use really is to stop the spring falling out of its perch when unloaded and uncaptive. You cant really load a spring on a strut as the spring rate doesnt change when you wind the tension up due to the common type of spring cars use(constant rate springs). e.g if you have a 200mm long spring and its 1000lb, and you compress it to 180mm it will still have a 1000lb spring rate. no matter how compressed the spring is it will still have the same spring rate. compressing the spring doesnt do anything to the rate of the suspension (unless it runs out of travel and binds) or anything it just adjusts the ride height.

You need to set your droop ratio first without the spring on. then you fit the spring and you adjust the ride height via the spring perch offset(compressing the spring) if you cant achieve this and the spring is slightly slack in full droop you can add a helper spring to keep the spring loaded under full droop. If the helper spring still doesnt allow you to keep the spring captive you need to get a longer spring. If the spring binds or runs out of compression travel on full bump then you need a shorter spring.

I think what your understanding a keeper springs role is more what a dual rate spring would do, Im assuming the springs you have are constant rate. generally only see progressive or dual rate springs in very high level professional GT/ time attack cars or pick up trucks. a Dual rate spring has essentially 2 spring rates or you can use 2 separate springs with the idea being that the lower spring rate is the cars spring rate at neutral loading and then during roll in a corner the strut will dip into the higher spring rate coils which can act like another anti rollbar essentially and help with roll control. or in the case of a pick up when the deck is unloaded the truck will ride on the lower spring rate but when you put stuff in the back it will compress and use the stiffer spring rate.

It would be quite interesting to see somebody play around with dual rate springs in an evo and see if it helps with the tripod issue but youd probably need a degree in motorsport suspension to get it right haha. You see it being used on professional time attack cars with big aero as the car at low speed cornering will sit on the softer spring rate but when the aero presses the car to the track at high speed the stiffer rate stops the car from bottoming out on the bump stops and provides better ride height control. think turn 1 at eastern creek for WTAC as an example where you would need this.

 

Thanks gents. I do believe I understand the helper springs 1) To keep the actual spring in place when unloaded & 2) it becomes a 3/4"ish spacer when fully compressed. For street use and in general, the helper springs may aid in certain aspects, maybe around the sound (and preserving the finishes) going up ramps and cruising ... it has some hard plastic seats (aka isolators) top and bottom, it does not impact spring performance.

Adjusting droop ratio first, OK thanks. I will go for 1/3 droop, likely with helper springs. I will get right to it as soon as I install WL upper control arm bushings
what i was saying previously was "the FA spring perch might end up where the purple KW spring perch is relative to the top mount" - when the same 60mm springs are moved to the FAs and overall mount-to-mount distance is the same

i'm wondering why ayoustin needs a shop press. I guess i will find out

 

Anybody looking to ugrade and selling a used wavetrac? I got my backup TC and will send this to TRE as soon as mine comes back (I dont want to pack a box again).. I know I broke and paid for an upgraded output shaft once. Was that TC or trans part? Sorry

I already ordered a new dust cap

 

Like Brad said, preload is a big of a misnomer term. It's technically preload because you are loading the spring when you compress it to raise the car with the lower spring perch but you're not changing the spring rate. Helper springs do not do anything for useful spring rate, their spring rate is so low that it basically does nothing. When you stack springs in series the effective spring rate is the same as electricity in parallel it's the sum of the square roots of each spring rate, which often means you get a very very soft spring rate. Progressive springs are very tricky to get right and honestly not worth the headache when you can achieve the same result with properly selected linear springs and bump stops. In the past couple of years, the top tier TA teams have had a major focus towards bump stop tuning over spring rate tuning but that's how it be when your car's performance is heavily aero dependent.

I use a press because FA dampers are nitrogen charged so they're not easily compressed by hand. Gas charged dampers also act differently than non gas charged units. The gas charge can alter spring rates and it has an effect on cavitation properties.

 

Sorry its hard to judge what knowledge each person has so hope i wasnt teaching you how to suck eggs.

One application i missed with the helper spring which i missed is they can assist in very fast bump and rebound movements to dampen the effect as you touched on. e.g a very bumpy road or cracks in the road etc it can help absorb them.


Yep if your using the same springs youll find that they will probably end up in around the same position, The position of the spring perch on the shock is mostly irrelevant as long as the spring isnt binding or stopping the shock from travelling. Youll also find if you corner weight the car youll be adjusting the spring perches individually anyway.

 

Damn moneybags here going to load up a spare TC with a wavetrac? haha i just pray that if i blow a TC the wavetrac survives otherwise ill just run stock diff till i can replace the wavetrac.

The output shaft is probably classified as a transfer case part as its basically the drive from the front diff to the axle. If your talking about the solid shaft that you pull out when you pull the TC off the diff.

 

NP. Thanks for everyone's patience. This is a family issue for me... 8 lone wolf coder/developer ESL siblings (+Dad) and everyone is bad at conveying their thoughts lol

Yeah, I've seen a few cars clicking whenever they transfer weight from one side to the other. I dont want that lol

LOL I thought that's how the pro-solo guys have it. They can replace a TC in a few hours. I assume they wont reuse the bearings due to the shrapnel.
I already sent my 2nd/backup rear diff to TRE. 1st one is in the car, My original one had a ring gear bolt back out and was junked
I haven't autocrossed in 3 years (also no restaurants) so I'm thinking I have some budget lol

what about that spline that goes to the yoke? is that weak & upgradable? Thanks

 

nothing new to share today. just this... I always wondered why there usually a lizard or a spider on my tires

 

need to pull that box out it looks 60 years old hahaha.

Im guessing your car has been on salted roads at some point?

 

That's actually freshly assembled maybe 300miles ago. before that check up it was built and painted by ShepTrans . I think that paint had chipped off thats why it looked like it lived underwater lol. I have full splash shields/plastics so this area does not get rinsed. We dont get snow or salt water in Houston. My car is parked outside tho. I will pressure wash it when my axles are in

 

Along the same vein:

My coilover builder recommends 35-45mm droop travel, and I had 36mm droop (110mm shock travel) with the coilover as is. I decided to lengthen the shock 20mm at the shock housing to raise ride height 20mm and increase my droop to 40mm. My shock travel also increased to 120mm in the process. Did I take away any compression travel?

I'm using 6in 11K Main Springs up front with 2.8in 4K Helper Springs (all Swift). I took all my measurements with just the bumpstop on the shock (no springs at all) and did it all on the car with the wheels on to ensure I had appropriate clearance compressed and extended. Just making sure I did the fronts correctly to do the rears next.

 

did you lower it -20mm from the spring perch to get back to previous ride height? that would be minus 20mm compression, plus 20 droop
if you just lengthened the shock body (never moved the spring perch) then compression/droop ratio stayed the same

 

In case you want to remember what Whiteline RSB bushings were like