Strange "handling" issue, need feedback...

[AZhitman]

93 240, S-Techs, AGX's, CP tri strut bar and lower rear tie brace...

Car handles SO much nicer with these mods, however, I notice that when I go over some rough pavement, the rear end "hops" noticeably to the right (and only to the right).

Any thoughts?

Thanks guys!

[ralphdig]

S13 ´93 hicas original suspension.

Mine does the same plus when hard cornering, only to the left, the rear goes out and i have a lot of oversteering, i ordered a set of Energy Suspension Master bushing set and will install new Tokiko springs & struts, new tierods&ends are to be upgraded whith Tein.I hope this will fix the bad handling.Right now the rack and right tie-rod has a lot of play i think this is the cause for the dance movements.Let you know after improvments.

[InsanityInc]

maybe it just needs an alignment? Or possibly some of the bushings are shot.

Also, do the S-Techs and the AGX's play well together? I was considering getting that combo.

[Dano]

Greg... did u make sure u had the same amount of threads on both sides on that tie bar? your toe on your rear wheel could be out, pullin u to the right. u should get an alignment, haha... i can do em next week at school. other than that... have u checked to see that none of the suspension pieces are bent back there?

-Dan

[BuudWeizErr]

you didn't even get an alignment and you're asking questions like this? come on greg, you should know better.

think about subframe spacers now.

[Exar-Kun]

1. lose lower tie bar....useless for a 240.

2. sell lower tie bar to another baka who likes to waste money

3. buy a rear STB

4. Check alignment and suspension peices.

5. come back with report.

-chet

[AZhitman]

OK - Tie bar is goign byebye.

Alignment pending - Dan, that'd be awesome!

CD, what's the purpose of the subframe spacers?

Lastly, RSTB will be tough as the vert has a topmotor in the way...

[Nismo_Freak]

Bumpsteer... check the bushing on the front most arm in the rear as well as the bushing on the spindle coresponding to it.

[AsanBBoy]

This "hop" is exactly what I have. Very scary, Infact this is the very thing that lead me into an accident with the median wall on the interstate (I guess i hit a bump going 70mph and rear end slid to the right bad, so i had to countersteer.... or something like that), resaulting to two bent control(driver front and rear) arms, mad rim scratch, and one long sratch on the driver's side of the car. I'm lucky I didn't hit anyone. Good thing I have a parts car to get suspension parts off of. This is also probably because of my blown struts, but i'm werry of other bad suspension parts too. Thanks for the tips. Do you have any sugestions of where or what (brand) I should buy as some good bushings and a stb. I plan to get some coilovers to replace the blown sturts, I have some ideas of what i want but any sugestions would nice.

[AZhitman]

Alan, you're probably right as it doesn't "bumpsteer" in the front, only once the rear tires hit the bump - then it "pitches" the rear to the side (and I was mistaken - it ONLY pitches it to the left).

[Nismo_Freak]

Alan, you're probably right as it doesn't "bumpsteer" in the front, only once the rear tires hit the bump - then it "pitches" the rear to the side (and I was mistaken - it ONLY pitches it to the left).

After you get your alignment, drive the car around a bumpy road and see if you can get it to reproduce it. Try to hit different bumps with the different rear wheels (ie. left bump, right bump). If you have 0 cross toe the car shouldn't want to rotate after it hits the bump (toe will move inwards for stability). However if your bushings in the two toe related arms (rear toe arm and rear traction arm (forward link)) have enough play in them they can have excessive bump to the point it creates toe out which will make the car feel as if it wants to rotate (a la HICAS haha).

Now... on the other hand if you bump the right rear and the car pitches left then you have excessive toe in as a result of the bump.

Thats why we sell the traction rods in the rear... you can vary their length to add or subtract the dynamic toe change in the rear.

[Hijacker]

3. buy a rear STB

I wish.



The part labelled "Center Rear Seat Back Support" is in the way of installing a rear STB. Not only that, but there is next to no room with the top down to wedge a bar in there, and there are miscellaneous relays taped to the top and side of it.

Thirdly, since it is welded to the rear towers, it is effectively a rear STB in itself.

Alan, with the SPL rear toe arm parts, would you recommend an alignment shop install and set them or could any joe schmoe pull the old arm, use the original to gauge where to set the new one and reinstall it?

Also, ho exactly does it eliminate dynamic toe change? is it because it doesn't have rubber bushings that can shift?

[aither]

That kind of reminds me of the 350Z's rear frame structure.

[Hijacker]

here are some better shots of the rear support





not only is the support in the way, but the seat belts take up what space is left. I could barely fit the breaker bar in there. Gear wrenches are an essential tool in a convertible owner's toolbox

[Nismo_Freak]

Alan, with the SPL rear toe arm parts, would you recommend an alignment shop install and set them or could any joe schmoe pull the old arm, use the original to gauge where to set the new one and reinstall it?

Also, ho exactly does it eliminate dynamic toe change? is it because it doesn't have rubber bushings that can shift?

For toe I would highly suggest an alignment shop, a very small amount off and the toe will be off enough to cause a pull, wear out tires, and/or handle funky. Plus when loaded you have to keep in mind that the OEM arm absorbs some load into it's bushing by compressing it. You won't be able to accurately gauge how much compression is in the bushing under standing load and this will make your toe off as well.

As far as dynamic toe change, it's very hard for me to describe without a visual.



Here you can make out the RUCA, Traction Rod, and the Toe Arm is hidin behind the brakes.

Basically when the suspension compresses, the arms are not equal length so you will get a twisting force in the suspension and this is what creates toe-in under load to stabilize the car under acceleration, and when cornering.

However, when you increase the length of the traction arm in relation to the toe arm you end up with greater equality between the two which reduces dynamic toe change. If you can prevent excessive toe change in the corner you can improve the pivot ability of the car and thus the steering response and overall handling can improve.

[Q45tech]

When you study the rear suspension you'll see dynamic vs. static [alignment toe] is designed to toe in on deceleration whether brake or engine created and toe out on severe acceleration and be neutral at the 55-65 mpg range to reduce rolling tire friction.

They only work this way when all bushings are new, not unsual to see different toe changes on different sides under load.

This is in addition to the BUMP [toe] STEER.

This can really only be checked on a lab rolling road or dyno.

If you replace rubber with urethane you must create new toe specifications and accept constant toe from load/unloaded fore aft wheel position

[Hijacker]

how harsh would using heim joints in the rear make the ride? As compared to say a set of Nismo bushings?

[aither]

building on this, if you have a relatively stiff rear spring rate, to where there is little suspension movement in cornering, and fully adjustable, metal bushing links, you will have less toe change under all conditions, right? So less suspsion movement under cornering = less toe change? Is it possible to eliminate toe change under acceleration?