Front end bouncing everywhere

[Goobdog]

I replaced my struts because when I launched the front end would get stuck up and would take forever to go back down. I went to AutoZone and bought some struts and these things bounce everywhere. I know I shouldnt have bought them but I really didnt have a choice. If im going down the highway and hit a bump I can get the front end to bounch for a good 1/4 mile if I keep blipping the throttle. So anyway I need some new front struts that can handle lowering springs and not bounce me out of the car.

 

[UCSLugRacerX]

Your lowering springs have too high a spring rate than your shock can accomodate. Your shock has to match the spring rate, if not it will causes a pogo effect. Also, it might be that upon fully extended rebound of your shock, your spring is too short, and does not extend with it. Also, you might be hitting your bump stops.

Remedy: get stiff shocks, i.e. Konis, and find a way to extend the spring, so there is no gap between the spring, and the top of the shock.

 

[JDMFirstGen]

If you put on lowering springs and did not cut the bump stops you are riding on them and you need to cut them.

 

[UCSLugRacerX]

If you put on lowering springs and did not cut the bump stops you are riding on them and you need to cut them.

I disagree. You shouldn't be cutting anything. The reason why the bumpstop is there is to protect the shock assembly when fully bottoming out. (And to make a valiant attempt to increase the spring rate.) In one sense, it's the suspensions' last line of defense before all the energy from the bump travel is transferred to the chassis.
The shock and spring assembly's purpose is to dampen the energy from vertical wheel movement from road force. Hence the word “dampener.” If that bumpstop is cut, the shock will bottom-out sooner, and the spring rate will instantly go to infinity, as the top of the shock smacks against the chassis. (A very BAD thing.)

 

[UCSLugRacerX]

Jtmcindy--can you comment?

 

[92awddsm]

I disagree. You shouldn't be cutting anything. The reason why the bumpstop is there is to protect the shock assembly when fully bottoming out. (And to make a valiant attempt to increase the spring rate.) In one sense, it's the suspensions' last line of defense before all the energy from the bump travel is transferred to the chassis.
The shock and spring assembly's purpose is to dampen the energy from vertical wheel movement from road force. Hence the word “dampener.” If that bumpstop is cut, the shock will bottom-out sooner, and the spring rate will instantly go to infinity, as the top of the shock smacks against the chassis. (A very BAD thing.)

If your theory is correct, why does eibach tell you to cut the bumpstops slightly when installing their springs? I understand what you are trying to say but in some cases, you are wrong. I have pro kits and gr2's with new, cut bumpstops and I have no pogo, or ill effects. I also never have bottomed out my struts but Im sure it is possible with some of the cheaper lowering springs or coil overs.

IMHO, the cheap struts you have are the cause of your evil. I would take them back and exchange for the better version or get your money back and invest in either a kyg gr2 stock replacement or save for some konis or better.

 

[RamenPride]

most manufacturers tell you to trim/cut the bumpstops when you install lowering springs to "recover" some of the lost travel from lowering the car.

 

[UCSLugRacerX]

I still think bump-stop cutting is side-stepping the problem. Ideally, the shock travel should try to be increased when lowered, and not the other way around. Yes a low C.G. is good, but reducing bump travel is not neccesarily good. We're still driving the same car over the same bumpy roads aren't we?
Also the reason why your Eibach Pro-kit springs are not letting you bottom out, is because they are stiff racing springs. Also, when you installed the Pro-kits on the GR-2's, did you have to use a spring compressor? If so, that means that as of now, the top of your spring extends with your shock upon full rebound. Doing this will negate the pogo effect.

 

[jtmcinder]

If that bumpstop is cut, the shock will bottom-out sooner...

It's the opposite. The reason for cutting the bumpstops is to delay when the shock bottoms out. Yes, when it does finally bottom out, you'll hit harder, but if the extra travel gained from cutting the bumpstops is enough to prevent contact, then the gains outweigh any losses.

Back to the original point: if the problem is that the nose stays up after acceleration, then you have too little rebound, too much compression, or both. On the other hand, if the problem is all-the-time bounciness, then you're underdamped or banging the bumpstops. But since we're talking about a 1G (right?) unless you are slammed, you don't have the suspension-travel issues that those of us with 2Gs have, so I'd be suspecting the damping.

- Jtoby

ps. my car is named Cinder, not Cindy