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Tech Talk Technical Discussion About The Nissan 240SX and Nissan Z Cars


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Old 12-11-2006, 05:04 PM   #1
drew935
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Bumpsteer

Who has this problem? What have you done to remedy it? Does the S14/15 have this problem or is it just more common on the 13s? I know that 13s don't run a upper A-arm in the front. Does the 14/15?

I will be replacing my tires soon. This week maybe w/ Bridgestones.
My setup is Cusco Zero2 coilovers w/ Swift springs 6/4kg.
Shocks are on 2-fr/ 1-rear.
I have a 2.2 finger gap in the front and about a 3 in the rear.
1.5 neg camber front/ 1.6 neg rear
Running stock tie rods. Replaced the outer with OEM.
Running S14Se wheels w/ 20mm KICS spacer adapters.
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Old 12-11-2006, 07:05 PM   #2
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What are your toe settings?

Band-aids:
- if you have toe out, less aggressive toe (toe-in or neutral toe)
- run non-directional tires - seems directional tires tend to follow the grooves of the road and make bumpsteer worse, just observation - I may be wrong
- raise the car
- soften the suspension dampening
- increasing positive caster may help

The only "true" way to fix bump steer issues is to get an aftermarket outer tie rod, such as the kazama one.

Let's you adjust the tie rod to be relative to the steering rack so that it moves correctly when you hit a dip/bump.

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Old 12-11-2006, 07:11 PM   #3
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I wouldn't put Kazama outer tie rods on my car even if someone gave them to me for free. PURE SHIT!!!
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Old 12-11-2006, 09:03 PM   #4
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I ran Kazama outers on my car for about a year including several events (running over cones at full lock, bouncing over curbing, dealing with the horrendous surface on the Streets before they repaved it) and never had a problem. However, there are much better ends out there for similar money. SPL is great, Ikeya looks good as well, Peak's also good if they ever get around to remembering us Nissan guys. The shites stopped making Pro 5-lug hubs, leaving me with the ordinary hubs. Grumble.

I run adjustable lower control arms front and rear in addition to adjustable tie rod ends to reduce bumpsteer. I'm still messing around with the geometry but the car is infinitely better than it used to be. The rear is absolutely planted but I still have a little bumpsteer up front.
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Old 12-12-2006, 12:17 AM   #5
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my car feels fine pretty low stock tie rod ends, with a spacer on the inner(suppost to make "bump steer" worse

i think bump steer is a scam, shit most of the people on this forum (not this thread suprisingly) dont even drive their car past work. i dont really notice bumpsteer, maybe its becuase im dookie though.
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Old 12-12-2006, 12:20 AM   #6
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people confuse bad aligment and tramlining with bumpsteer.
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Old 12-12-2006, 01:00 AM   #7
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From many people's perspectives kazama seems to suck nuts and the heim joints wear out on them in like a month.
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Old 12-12-2006, 01:27 AM   #8
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Get aligned, then feel out bumpsteer. If it's REALLY bad then get the adj. ends.

I definately have no issues now, after I got an alignment.

I'm running

Peak Performance PRO inners.
Kazama Outers (because at the time I didn't know any better.)
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Old 12-12-2006, 12:27 PM   #9
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Quote:
Originally Posted by McRussellPants
people confuse bad aligment and tramlining with bumpsteer.
Someone with common sense.

Bump steer isn't quite as it's name emplys. Bump Steer is when your wheels steer themselves without input from the steering wheel. The undesirable steering is caused by bumps in the track interacting with improper length or angle of your suspension and steering linkages.

In order to accomplish zero bump steer, the tie rod must fall between an imaginary line that runs from the upper ball joint through the lower ball joint and an imaginary line that runs through the upper a-arm pivot and the lower control arm pivot. In addition, the centerline of the tie rod must intersect with the instant center created by the upper a-arm and the lower control arm.

The instant center is an imaginary point that is created by drawing a line from the upper a-arm ball joint through the a-arm pivot where it is intersected by an imaginary line that extends from the lower ball joint through the inner control arm pivot. Where the two imaginary lines intersect is the instant center.

S14/S15's have similar suspension geometry as the s13. There is no real front upper control arm.


Purchase angle adjustable tie rod ends. They will allow you to run the tie rod parallel to the ball joint. By the sounds of it, you also need alignment.


Pm me if you have anymore questions.
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Old 12-12-2006, 12:45 PM   #10
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I had the bumpsteer after I changed the springs which made it lower due to a softer spring and that was after an alignment as well. That is when I started to get bumpsteer. It looks like the outer ties are what I need. I'll just get SPLs.

So I'm looking at getting an alignment when I get the tires as well. But maybe I'll get the ties first
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Old 12-13-2006, 01:27 AM   #11
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Quote:
Originally Posted by !Zar!
Someone with common sense.

Bump steer isn't quite as it's name emplys. Bump Steer is when your wheels steer themselves without input from the steering wheel. The undesirable steering is caused by bumps in the track interacting with improper length or angle of your suspension and steering linkages.
Uh, if you say bump steer isn't what its name implies and then define it with exactly what its name implies isn't that a bit... simple?

Bump steer is dynamic toe change. The toe "steers" the car.
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Old 12-13-2006, 01:57 AM   #12
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Quote:
Originally Posted by KA24DESOneThree
Uh, if you say bump steer isn't what its name implies and then define it with exactly what its name implies isn't that a bit... simple?

Bump steer is dynamic toe change. The toe "steers" the car.
It was towards people who have bad alignment and how they automatically blame the problem they are having on bump steer.
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Old 12-13-2006, 06:02 PM   #13
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once you get your alignment, if the problem is not fixed, check your ball joints. then tend to get alittle play with age so check to make sure they are packed tight
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Old 02-13-2007, 05:09 PM   #14
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ok, to follow-up with my orginal post;
I have replaced the inner and outer tie rods from SPL and have replaced the bushings with ES bushings all around and had the alignment done. I am not satisfied with any of the the parts. It turns very well and tracks good enough but the steering still has a bit of bumpsteer. I have it aligned to -1.2 front/ -1.5 rear camber. Tie rods are parallel to the ground. I actually raised the car to about 3finger gap all around. I even took off my spacers on the front to see if there is a difference.

What I am thinking is that maybe it's the wheels? When I had the stock 7 spokes on there, it was fine. But I was running an 10k spring in the front. Now with the s14se wheels, I'm running a 6k spring. Gees, I might just get rid of the coilovers and go shocks and springs...who knows.

I'm not complaining about the situation, but am still looking for a fix for it.
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Old 02-13-2007, 05:12 PM   #15
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lca's and tie rods...
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Old 02-13-2007, 05:22 PM   #16
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Quote:
Originally Posted by s13gold
lca's and tie rods...
Well I already have the tie rods.

Now do you have those installed on your car?
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Old 02-13-2007, 05:25 PM   #17
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what are your toe & caster settings?

what size tires are you running?
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Old 02-13-2007, 07:28 PM   #18
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Do some research. Bumpsteer is generally used to refer to a condition when one wheel hits a bump and the steering wheel is jerked out of your hand. This is caused by a positive scrub radius, as described above. Use google and search.

What you're experiencing may or may not be bumpsteer. I don't know.

Generally try to keep your suspension arms parallel to the ground so you zero out the scrub angle.

Alignment is aso key.
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Old 02-13-2007, 07:45 PM   #19
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Quote:
Originally Posted by ughzilvian
ok, to follow-up with my orginal post;
I have replaced the inner and outer tie rods from SPL and have replaced the bushings with ES bushings all around and had the alignment done. I am not satisfied with any of the the parts. It turns very well and tracks good enough but the steering still has a bit of bumpsteer. I have it aligned to -1.2 front/ -1.5 rear camber. Tie rods are parallel to the ground. I actually raised the car to about 3finger gap all around. I even took off my spacers on the front to see if there is a difference.

What I am thinking is that maybe it's the wheels? When I had the stock 7 spokes on there, it was fine. But I was running an 10k spring in the front. Now with the s14se wheels, I'm running a 6k spring. Gees, I might just get rid of the coilovers and go shocks and springs...who knows.

I'm not complaining about the situation, but am still looking for a fix for it.

Quote:
Originally Posted by McRussellPants
people confuse bad alignment and tramlining with bumpsteer.
done.

you're feeling the SEs, smaller sidewalls track the road more.

run monster truck tires if your gonna be a bitch about it.

Furthermore Tie rods are supposed to be parralel with the LCA not the ground.
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Old 02-13-2007, 09:22 PM   #20
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I forgot that about the LCA and tie rods parallel deal.

Btw, I do know bumpsteer is as I went to school learning to work on cars so stop defining it. Also no ones bitching. Just looking for a fix...as this is the tech section.
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Old 02-14-2007, 08:53 PM   #21
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Quote:
Originally Posted by g6civcx
Do some research. Bumpsteer is generally used to refer to a condition when one wheel hits a bump and the steering wheel is jerked out of your hand. This is caused by a positive scrub radius, as described above. Use google and search.

What you're experiencing may or may not be bumpsteer. I don't know.

Generally try to keep your suspension arms parallel to the ground so you zero out the scrub angle.

Alignment is aso key.
None of that was even close to right. Take your own advice and do some research.
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Old 02-14-2007, 11:13 PM   #22
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I already explained it...
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