AST 4150

[AFRichZC6]

Originally Posted by Lincoln Logs

The helper is full compressed at static and under load, it's length is much shorter than the main spring, and in reality it spends most of it's time compressed and does not contribute the helper's rate to the total spring pack. The helper comes into play during droop travel and helps keep the tire on the ground. Given a set up with and without helpers, I'll take the helpers.

The Whiteline coilovers only have a helper up front, don't recall the rate off hand but it isn't zero. I'd like to add a helper to the rear at some point too.

You're right. The helpers that come with the Whiteline coilover are not zero rate tender springs. They are usually 2-4 kg/mm. Tender springs usually have very flat and thin spring coils - thinner than what you have pictured.

The point of using a tender (zero rate) spring is only to keep the spring fully seated when the damper is under droop. It doesn't help keep the tire on the ground. A helper spring has some rate less than the main spring to create a dual spring setup (not to be confused with progressive spring rates), usually for ride comfort.

Preload/height adjustment doesn't affect the extension travel of the shock but only droop travel at the wheel. If you are fully compressing a helper or tender spring while the damper is in full extension/droop, then that just indicates you shouldn't need a helper/tender spring. If you are compressing the helper while static, then you're right - it is no longer doing the job of a helper but a tender spring at this point. You would only need a tender spring if whatever ride height you set requires the spring perch to be set in a position that offers less than zero spring preload when under full droop.

I haven't driven a twin with a 5/5 kg/mm setup so I don't have any firsthand experience on whether or not any pitching is apparent, but the math checks out and says it should pitch some amount if your helpers in front are not a factor. 5 kg/mm in the rear for these cars makes for a very low wheel rate and ride frequency, so maybe it's soft enough to not notice any pitching or excess oscillation (good!). The pitching was apparent to me with higher rates like 7/7, 7/8, or 8/8 (no helpers).

[Racecomp Engineering]

Just a note...in general "tender" or "assist" springs refer to springs with some actual spring rate while "helper" springs refer to springs with zero rate.

"Helper" spring is kind of the general term, but it is more correct to refer to a "helper" as a zero rate spring and a "tender" as one with some spring rate.

A lot of tender springs will still be fully compressed at normal ride height. They can still have a noticeable effect on ride over certain types of surfaces (as well as keeping everything seated at full extension).

I will almost always use a helper or a tender on a single height adjustable coilover at both ends of the car.

With the higher damping ratios of most performance coilovers, ride frequencies that meet the "flat ride" criteria are not nearly as noticeable as it is on a car with a damping ratio of say...0.25. At 0.65 there is minimal overshoot in response. Excessively high rebound damping can cause a "pitchiness" too if the suspension is just jacked down and not working. Lack of compression travel can also give a similar feeling of crappiness.

I'm not saying that "flat ride" doesn't matter, but it is not the only thing that matters for ride or handling.

Hope that helps.

- Andrew