Shorter Spring on Ground Control?

[tek_88]

Hey guys I need some input or thoughts before I go ahead and do this so please feel free to chime in. Okay, so right now my car is sitting on ground control+agx and I like em but the fronts just don't drop low enough for me. So I'm planning to switch out the current springs which are 5" with 7.5kg spring rate to a lower 4" spring with a 6.5kg rate. My question is will the shorter spring bind at that rate or the will shocks will bottom out first?

And yes I can get real coilovers but these work just fine for me and the springs are only gonna cost me $100 or so, thanks in advance.

[nismoman]

the front has very little travel with that setup as it is, so yes the shocks will bottom out. you need coilovers or modified strut mounts like some of the guys running konis use.

[Future240]

Bottom out feels like ass btw. Do not do it. Save the money get coils. If low is all you care about get something like pbm $1000 done and done. Hell you could probably catch some for sale cheaper than that.

[tek_88]

thanks for the replies...yeah I'm not all about getting low, just looking to close the gap between the fender and wheels a bit. And yeah I'll probably build a set of koni or get some front coilovers later on then...

Also have another question my car likes to grab to the left and right when I'm changing lanes or I'm on uneven pavement. Is this because of the tension rods? or something else?

[Perfect Balance]

thanks for the replies...yeah I'm not all about getting low, just looking to close the gap between the fender and wheels a bit. And yeah I'll probably build a set of koni or get some front coilovers later on then...

Also have another question my car likes to grab to the left and right when I'm changing lanes or I'm on uneven pavement. Is this because of the tension rods? or something else?If you've got wheels with a low offset, or an aggressive alignment, this will happen due to the nature of these things, but regardless, any kind of improvement to the suspension should help counter this, or at least minimize it.

[tek_88]

thanks...i'm running xxr 962 17x9 +35, but Im planning on selling them and getting different rims soon. But in the mean time I'll go ahead and start working on my suspension setup

[240sxScores]

Also have another question my car likes to grab to the left and right when I'm changing lanes or I'm on uneven pavement. Is this because of the tension rods? or something else?


Could be bumpsteer you're experiencing. Google it if you don't know.

[tek_88]

^^^possibly that too, but my car is old and wasn't really taken care of by the previous owners...has 315***miles right now and most of the bushing and stuff are destroyed.

[nismoman]

busted tension rod bushings can cause that problem too, as well as instability while braking.

[drift freaq]

If you've got wheels with a low offset, or an aggressive alignment, this will happen due to the nature of these things, but regardless, any kind of improvement to the suspension should help counter this, or at least minimize it.

Please do not respond to questions if you really do not know what the fuck you are talking about.
First off low offsets wheels are not going to make your car pull one way or the other. Second off an aggressive alignment will most likely not cause it either.

Third saying an improvement on suspension should help counter it, is a vague non answer that shouts " I do not know fuck about suspension but I am going to answer anyways".

He is experiencing bump steer, in part due to the fact that he has altered his roll center to an unfavorable for handling point.
It has also affected the steering angle on his tie rod ends.

When you you lower a car anytime your control arms and tie rod ends wind up pointing upwards at the wheel, you will have bump steer and it will fuck your handling.

If you want to go low and not have bump steer and a bad roll center you have to invest money into corrected knuckles, roll center correctors, or other pieces to correct it.

To the OP do not put a shorter spring on your Ground Controls. It will just make matters worse.
If you want to A: go lower then a custom setup is in order. KYB's are not that special anyways. I would do a custom setup with Koni's.

Oh and if you have a lot of shot bushings in your suspension? Fix them. You area basically in scatter shot mode here.
You have a ton of stuff that needs to be fixed contributing to the problem and your making it worse by doing things with not addressing those issues.

As far as the roll center stuff goes you should take a look at the roll center thread in tech. If you really want to get even more in depth? Go over to Nissan road racing forum. That is pretty much were all the guys that really have the suspension sorted for our cars hang out.

[Perfect Balance]

Please do not respond to questions if you really do not know what the fuck you are talking about.
First off low offsets wheels are not going to make your car pull one way or the other. Second off an aggressive alignment will most likely not cause it either.Lets pick this apart one part at a time.
Low offset wheels increase your scrub radius. A positive scrub radius makes the wheels respond more to bumps on the road due to the simple leverage effect it increases. This is why you can feel the painted lines on the road just from putting on a set of low offset wheels, and why the dips in the road made by tractor trailers at intersections want to pull your steering wheel around. He did specifically mention switching lanes and uneven pavement.

Third saying an improvement on suspension should help counter it, is a vague non answer that shouts " I do not know fuck about suspension but I am going to answer anyways".Right.

He is experiencing bump steer, in part due to the fact that he has altered his roll center to an unfavorable for handling point.
It has also affected the steering angle on his tie rod ends. He is not experiencing bump steer. What he is describing is called steering kick-back. Bump steer doesn't jerk your wheel around. Bump steer is when the toe alignment changes because of bumps at a given steering angle, it doesn't actually twist the steering wheel in your hands. I actually ran into this 2 weeks ago when I installed my SPL tie rod ends on my car, and stacked too many spacers on it. I had terrible bump steer. I would go into a banked corner, and as soon as the suspension compressed the car would go straight, and the opposite was true for when I came over the crest of a hill, the car would actually swerve at the slightest amount of steering angle. During a single corner, the car would serve or straighten out during the course of the turn, without ever changing how much I was turning the steering wheel, my brother in law could feel it from the passenger seat.

When you you lower a car anytime your control arms and tie rod ends wind up pointing upwards at the wheel, you will have bump steer and it will fuck your handling.Indeed, although the reason he's getting bumpsteer isn't because the arms are pointed upwards. I actually didn't think this through when correcting my bumpsteer. I got as far as "all arms should be parallel with the ground to minimize the change in effective length under suspension compression", and didn't keep in mind that the control arm angle also needed to be corrected for that to work. I ended up stacking all the spacers SPL gives you with their kit (which are simply to adjust for aftermarket knuckles), and that was what caused my extreme bumpsteer. To correct suspension geometry, yes the arms need to move down, but to correct bumpsteer, the tie rod angle simply has to match the angle of the lower control arm, so they move at the same arc. The end result remains that both arms are still pointing upwards, but they move at the same arc, therefore they "get shorter" the same amount under compression, and the alignment doesn't change. The only problem with this is that the tie rods and lower control arm aren't the same length, so it's impossible to get rid of bumpsteer completely, but you can minimize it to have the least amount for the current operation range of the suspension. This is what Nissan did for a stock 240sx, but once it's lowered, the tie rods needs to be moved down about a 1/4 inch. (with stock lower ball joints)

If you want to go low and not have bump steer and a bad roll center you have to invest money into corrected knuckles, roll center correctors, or other pieces to correct it. Agreed. That's something everyone should keep in mind. You can have all these parts and still have horrible bumpsteer. To get rid of bumpsteer, the objective is to always have the lower control arm and tie rod parallel with each other. Moving them all down fixes the other problems with the geometry, like the fact that a lowered 240sx actually gets more positive camber under compression at those heights.

To the OP do not put a shorter spring on your Ground Controls. It will just make matters worse.
If you want to A: go lower then a custom setup is in order. KYB's are not that special anyways. I would do a custom setup with Koni's.

Oh and if you have a lot of shot bushings in your suspension? Fix them. You area basically in scatter shot mode here.
You have a ton of stuff that needs to be fixed contributing to the problem and your making it worse by doing things with not addressing those issues.

As far as the roll center stuff goes you should take a look at the roll center thread in tech. If you really want to get even more in depth? Go over to Nissan road racing forum. That is pretty much were all the guys that really have the suspension sorted for our cars hang out. Agreed.

Don't assume that I'm a fucking retard. You can look up every single one of my points and confirm them to be true. It's kind of ironic to start out a post telling someone off and then find out you made the same misconception everyone else makes about what bump steer actually is.

[drift freaq]

lots of stuff deleted just to get to the gist

Don't assume that I'm a fucking retard. You can look up every single one of my points and confirm them to be true. It's kind of ironic to start out a post telling someone off and then find out you made the same misconception everyone else makes about what bump steer actually is.

I did not assume you are fucking retard. Those are your words. What I did do was correct your statement about low offset wheels on our cars affecting steering the way you were claiming.

What I did do was call foul on your comment because it was not exactly correct and only after I did that, did you post some correct info and some incorrect info.


Our cars can run offsets as low as +5 on a 9.5 rim up front and have no scrub radius issues.
With a proper alignment.

Plus the kid is running 18x9 +35 offsets which are not exactly crazy or super low offsets. Oh and he does not have a crazy alignment. Bad alignment? Most likely.LOL

As far as bump steer goes, it can cause a steering wheel reaction. The name is pretty self explanatory BUMP STEER,. It will steer your car, which can pull your steering wheel in the direction of the steer. On some cars its less pronounced on others its more.

I have seen bump steer on 510's 240Z's, Roadsters, 240sx's Etc.. how many cars do you have experience with?
I have no misconceptions of bump steer.

I also pointed out that the problem could be bump steer but he had a lot of other factors involved, something you were willing to note and admit.

Perhaps you are one that should not assume.

[tek_88]

Thanks to both of you for your input it's really helpful, and no I haven't really read up on any of the roll center threads or any threads about suspension tuning because I'm alway working on the engine most of the time, hahah. Yes, my car does have a slight alignment problem and I'm aware that a lot of different factors can be causing my bump-steer or kick-back. I'll be fixing those with brand new arms, rucas, bushing, etc after I sell the ground control and rims.

[Perfect Balance]

snipFair enough.


As far as bump steer goes, it can cause a steering wheel reaction. The name is pretty self explanatory BUMP STEER,. It will steer your car, which can pull your steering wheel in the direction of the steer. On some cars its less pronounced on others its more. This was the misconception I was referring to. The name bump steer is somewhat misleading. The "steer" part refers to the actual wheels on the car "steering" in a different direction, it doesn't actually have anything to do with the steering wheel itself, since it's caused simply by the upward or downward movement of the suspension, and not like kick-back, which is actually force applied horizontally into the steering rack itself. Theoretically, you could have a car with extreme bumpsteer but not have more than the slightest vibration in the steering wheel, and vice versa. In fact, most properly set up race cars will have a bit of steering kick-back, even though (at least ideally) there is little, if any bumpsteer. Some kick-back is usually what lets you feel what the car is doing.

I think what causes confusion is the simple fact that typically a bump that causes the suspension to compress and cause bump steer, is also one that causes some kick-back as well, so while you do get some movement in the steering wheel, the root cause of both issues isn't necessarily the same.

I have seen bump steer on 510's 240Z's, Roadsters, 240sx's Etc.. how many cars do you have experience with?
I have no misconceptions of bump steer. I work as a tech for a car dealership that also sells used cars. I've driven hundreds (if not over a thousand by now) of different cars, many of them modified, a lot of them very improperly modified.

snip
Agreed. My bad.


Only word of advice I can offer to the OP is do coilovers, and when you get around to adjusting your roll centers, do a lot of measuring and make sure everything is being adjusted the same amount.