ZCC JDM Outer tie rod issue

[Rob L]

So I decided to consult with my brother in law who is a full time mechanic ....he was telling me that these tie rods should be able to be used with all types of different spacers as ride height is adjusted you must adjust the spacing inbetween the tie rod and steering knuckle to keep the rods parallel to alleviate the bump steer .....whats every bodies thoughts on using different spacing ...which in turn might clear my rim as well .

[JMortensen]

This is why I was saying if you don't know how it works, let someone who does fix it. Your BIL is right, but you would need to measure it to find out what spacer is necessary, and if you buy a similar kit for a Porsche or some other car, they've already measured it and come up with a generic recommendation based on that.

 

I don't know how big your spacers are, but I moved the LCA pivots up about 7/16" to minimize my bumpsteer, so if yours are about that tall then you're probably in the ballpark. Changing the size of the spacer to make it fit is not the way to deal with this. Wheel spacers are a better solution.

[m1ghtymaxXx]

The spacer won't be a "one size fits all" solution. The proper length of that spacer will vary with ride height. Look at the picture I posted on first page. It's the same sort of setup up, but rather than a spacer, there's a nut on either side of the rod end for unlimited adjust ability. You could simply replace the spacer with nuts, figure out your spacing, and trim any excess threaded rod.

 

Perhaps someone can come up with a simple way to figure how to eliminate bumpsteer, but It could be done by removing the front springs, setting the car at ride height on a floor jack, checking toe, lowering the car on the jack, check toe again. Adjust until the toe change from ride height to full compression is minimal. 

[Rob L]

This is why I was saying if you don't know how it works, let someone who does fix it. Your BIL is right, but you would need to measure it to find out what spacer is necessary, and if you buy a similar kit for a Porsche or some other car, they've already measured it and come up with a generic recommendation based on that.

 

I don't know how big your spacers are, but I moved the LCA pivots up about 7/16" to minimize my bumpsteer, so if yours are about that tall then you're probably in the ballpark. Changing the size of the spacer to make it fit is not the way to deal with this. Wheel spacers are a better solution.

 

Yes i already planned on my brother in law looking everything over ....i just wanted to get my hands dirty too you know what i mean

As for the different spacers first i will figure out my ride height then i will deal with the proper spacing .......i dont want to use wheel spacers unfortunately.....and worse comes to worse i will just put the old tie rods back on which is last resort.

[Rob L]

The spacer won't be a "one size fits all" solution. The proper length of that spacer will vary with ride height. Look at the picture I posted on first page. It's the same sort of setup up, but rather than a spacer, there's a nut on either side of the rod end for unlimited adjust ability. You could simply replace the spacer with nuts, figure out your spacing, and trim any excess threaded rod.

 

Perhaps someone can come up with a simple way to figure how to eliminate bumpsteer, but It could be done by removing the front springs, setting the car at ride height on a floor jack, checking toe, lowering the car on the jack, check toe again. Adjust until the toe change from ride height to full compression is minimal. 

 

 

Yes the way you did it in the picture is the exact way i will try it....thanks for the pic.

 

Im assuming those are tie rods from Brian from zcc jdm?......im gonna hit up the fastener store and see if i can mimic what you've done in that pic.

Edited April 21, 2014 by theatriks

[m1ghtymaxXx]

Yes the way you did it in the picture is the exact way i will try it....thanks for the pic.

 

Im assuming those are tie rods from Brian from zcc jdm?......im gonna hit up the fastener store and see if i can mimic what you've done in that pic.

 

 

That pic is just the first Google result I got for "bumpsteer adjustable tie rod end" and doesn't look to be an S30. I've never owned such a part, but the concept is the same across the board. Replacing the spacer with a nut will give unlimited adjustment, and if you find the ideal length is less than with the spacer, it means you can trim some meat off the shaft and get your clearance back. 

[azcarbum]

I'm pretty sure at this point, that its a offset issue also…. I've never ran into this issue with any customers.

 

I'm going to shorten the spacer just a hair for him, and that should get it to clear the wheel. How it will effect the dumpster, is the question. Its only going to be 3/8-1/4" max, but still…

 

B.

Edited April 26, 2014 by azcarbum

[RebekahsZ]

99% of the Z cars left on the planet have goofed up bump steer-what are the chances most drivers (including myself) will even recognize a problem? We have a lot more trouble with wide tires following cracks in the road. Get it to clear the wheel and drive it.

[johnc]

At stock ride height the bump steer is pretty good on the S30.

[TimZ]

99% of the Z cars left on the planet have goofed up bump steer-what are the chances most drivers (including myself) will even recognize a problem? 

Essentially zero if you never measure the bumpsteer.  If you already have the suspension apart and are modifying it, measuring the bumpsteer isn't that difficult to do, and you can make your own gauge for maybe $5 - Google "homemade bump steer gauge".

 

The kind of spacer that you have with this setup is intended to be used to adjust the bumpsteer by changing it's length to achieve the desired bumpsteer curve.  If you just install it (or any "bumpsteer spacer" for that matter) the only thing that you know for sure is that you have _changed_ your bumpsteer, but you won't know if you've made it better or worse.

[Rob L]

Hey im all for getting it to clear and just driving .....Brian from zcc jdm is a great guy to work with and as stated will work with you to make sure your happy in the end.......looking forward to receiving the shortened spacers and hitting the road.

[JMortensen]

Essentially zero if you never measure the bumpsteer.  If you already have the suspension apart and are modifying it, measuring the bumpsteer isn't that difficult to do, and you can make your own gauge for maybe $5 - Google "homemade bump steer gauge".

I don't think this is true at all. If you lower the car a lot (which seems to be the trend) then it can be REALLY bad, and fixing it is a good idea. On my Z with stock length struts run at about an inch off the bumpstops, there was one part of a particular track where my car was doing an emergency lane change maneuver all by itself. Some might argue that I was pushing harder than most people would, but the issue with bumpsteer isn't how hard you push, it's where the suspension is in its travel. You get some of these guys who are running the super short struts to get lower and they have to be lower than I was, so they're probably driving around town in a spot in the curve that is worse than what I had going on at the track. And when you start talking bumpsteer a lot of them seem to want to come back with "I put in bumpsteer spacers" to end the criticism. Those of us who know better are aware that doesn't fix the issue.

 

It's likely that if the car is lowered, using a bumpsteer kit manufactured by someone who knew WTF they were doing is going to improve things, just as the JTR up 3/4" out 1/4" xmember mod probably improves things without being exactly the right answer. To really know you have to measure, it's true. Also true that it doesn't take a lot of $$$ to measure.

[Rob L]

 using a bumpsteer kit manufactured by someone who knew WTF they were doing is going to improve things

 

You sound like you know what your doing maybe its time to get into custom bumpsteer kit manufacturing lol......like you said lots of people are lowering there Zs...maybe theres a market for a proper bumpsteer kit.

[JMortensen]

The kit you have probably is a proper bumpsteer kit. 

[TimZ]

I don't think this is true at all. If you lower the car a lot (which seems to be the trend) then it can be REALLY bad, and fixing it is a good idea. On my Z with stock length struts run at about an inch off the bumpstops, there was one part of a particular track where my car was doing an emergency lane change maneuver all by itself. Some might argue that I was pushing harder than most people would, but the issue with bumpsteer isn't how hard you push, it's where the suspension is in its travel. You get some of these guys who are running the super short struts to get lower and they have to be lower than I was, so they're probably driving around town in a spot in the curve that is worse than what I had going on at the track. And when you start talking bumpsteer a lot of them seem to want to come back with "I put in bumpsteer spacers" to end the criticism. Those of us who know better are aware that doesn't fix the issue.

 

It's likely that if the car is lowered, using a bumpsteer kit manufactured by someone who knew WTF they were doing is going to improve things, just as the JTR up 3/4" out 1/4" xmember mod probably improves things without being exactly the right answer. To really know you have to measure, it's true. Also true that it doesn't take a lot of $$$ to measure.

It sounds as if we agree - which part isn't true at all?

 

Just to elaborate a bit more, in simplest terms, bumpsteer is a measurement of how much your toe changes over the travel of the suspension.  It's not a number, but a plotted curve of suspension displacement vs. toe.   This curve is affected whenever you change the relationship between the arc that the lower control arm follows vs the arc that the tie rod follows.  Sounds simple enough, but both arcs travel in 3 dimensions, not two, so "eyeballing" the relationship isn't as easy as you might think, and it takes surprisingly little to change the curve from "(" to ")" to "S". 

 

Now consider that the front suspension on these cars were only adjustable for toe, and the way suspension shops generally "fixed" camber problems due to something getting tweaked or just the addition of lowering springs was to cut the spot welds on the crossmember mounting points and move the inner control arm pivot point around until they got the camber they wanted and re-weld it.  Also consider that the NEWEST S30 is now ~37 years old and very few of us are origninal owners and know the car's full history so if you've never measured it, you don't really know how close to stock your suspension geometry is.  There is no way that anybody can claim that there is a one size-fits-all solution that will "correct" your bumpsteer, especially given that they have NO IDEA where any given car is starting from.  

 

If you were tuning an engine this would be pretty much like saying "I know you have an SBC and a Holley 4-barrel, so you should increase your main jets by 20%", without knowing what jets you have or the displacement or cam being used.

 

The JTR "up 3/4" and out 1/4" and the "bumpsteer spacers" that relocate the outer pivot point of the lower control arm are in reality used to correct camber gain and roll center on a lowered car, and these are generally desirable things to do.  Both of these definitely _change_ the bumpsteer characteristics, but neither is really intended to "correct" bumpsteer.

 

The ZCCJDM piece pictured earlier is intended specifically to adjust the bumpsteer curve, by trimming the length of the spacer.  This changes bumpsteer independently, and does not affect camber gain or roll center, so it's really the preferable way to dial in your bumpsteer curve.  However, just installing it without checking the actual curve is a total crapshoot as to whether you will end up with a "good" curve or not. Besides, given that you just spent a bunch of cash on this nifty adjustable part and you can make your own gauge for next to nothing, why on earth would you NOT want to get it right?  If checking it is too much work then you have picked the wrong hobby.

[JMortensen]

It sounds as if we agree - which part isn't true at all?

The part that I bolded previously is untrue IMO; that your chance of noticing bumpsteer is essentially zero if you don't measure it. I haven't driving one of these excessively lowered cars personally, but I have to imagine that there is a problem just based on my own experience.

 

FWIW, I bumpsteered my car by slotting the front xmember and then moving the pivots up until the bumpsteer was minimized on the gauge. Took about 7/16" movement in my case. You seem to be saying that it is a bad idea to move the LCA pivot to make this adjustment. Yeah, it affects the roll center, but the benefit of reducing severe bumpsteer overshadowed the literally unnoticeable effect of the increased roll resistance or jacking that came from the higher roll center. In theory, it really should be the same for every Z that shares the same chassis geometry, and that is why you will find similar kits for all sorts of different cars, but as you said, Z's are mostly bent or modded at this point. You really can dial in the bumpsteer just by moving the LCA pivot if you do it correctly with a gauge and all that. And for the OP, I did it just the way someone suggested. Pulled the springs, jacked the xmember up and down and used dial indicators on the rotor (but a $5 DIY wood tool which uses a feeler gauge to measure change would work just as well).

 

I totally agree that if you're buying this part you should measure it and dial it in.

Edited April 26, 2014 by JMortensen

[Rob L]

The kit you have probably is a proper bumpsteer kit.

 

 

 

Ya the outer tie rods I have from Brian are crazy compared to stock ...I love them ....that's why I'm super happy he's trying to make it work for me .....what I meant is someone should come up with a outer tie rod .....RCA ...steering knuckle all in one kit it would probably be a big hit .

[TimZ]

The part that I bolded previously is untrue IMO; that your chance of noticing bumpsteer is essentially zero if you don't measure it. I haven't driving one of these excessively lowered cars personally, but I have to imagine that there is a problem just based on my own experience.

 

FWIW, I bumpsteered my car by slotting the front xmember and then moving the pivots up until the bumpsteer was minimized on the gauge. Took about 7/16" movement in my case. You seem to be saying that it is a bad idea to move the LCA pivot to make this adjustment. Yeah, it affects the roll center, but the benefit of reducing severe bumpsteer overshadowed the literally unnoticeable effect of the increased roll resistance or jacking that came from the higher roll center. In theory, it really should be the same for every Z that shares the same chassis geometry, and that is why you will find similar kits for all sorts of different cars, but as you said, Z's are mostly bent or modded at this point. You really can dial in the bumpsteer just by moving the LCA pivot if you do it correctly with a gauge and all that. And for the OP, I did it just the way someone suggested. Pulled the springs, jacked the xmember up and down and used dial indicators on the rotor (but a $5 DIY wood tool which uses a feeler gauge to measure change would work just as well).

 

I totally agree that if you're buying this part you should measure it and dial it in.

I guess what I was getting at was that if you don't have any idea what your starting point is, you can't properly diagnose any maladies that you might notice.  Lots of things get attributed to "bumpsteer" that aren't actually bumpsteer.  

 

Roll center might be a bit esoteric, but camber gain isn't.  Again, I think that this is the main benefit to be gained by the JTR mod or bumpsteer spacers.  By your own account if you had moved the pivot point by 3/4" up and 1/4" out (or the 1" up that most spacers essentially provide) instead of he 7/16" that you actually needed you likely would have been as bad or worse bumpsteer-wise than when you started.

 

I'm not saying that moving the inner pivot point won't work - clearly it can work.  But it does couple in other factors that would be better if you could keep them separate.  For instance, if you ended up needing a different vertical relocation from right to left, now you've got different camber gains right to left, which would not be that desirable.  What I would advocate would be to go ahead and do the JTR pivot point relocation or something similar and only pay attention to getting the camber gain where you want it for both sides.  Then use the shims on the outer tie rod ends to bring the bumpsteer back to zero.

 

It probably didn't sound like it, but I was agreeing with RebekahsZ - the OP was worried about "screwing up the geometry" by shortening the spacer to get it to clear the wheel, and Brian was going to shorten the spacer by 1/4" to 3/8" to get it to clear but wasn't sure what effect it would have on bumpsteer.  My point was that we really don't know what effect it had _before_ shortening it because nobody has checked.  For all we know shortening the spacer might very well make things better.  If you are not going to check it then just make it clear the wheel and forget about it, as neither arbitrary spacer length is more likely to be "right" than the other, and they are probably both wrong.

Edited April 27, 2014 by TimZ

[TimZ]

Ya the outer tie rods I have from Brian are crazy compared to stock ...I love them ....that's why I'm super happy he's trying to make it work for me .....what I meant is someone should come up with a outer tie rod .....RCA ...steering knuckle all in one kit it would probably be a big hit .

This still wouldn't guarantee "correct" bumpsteer.  If you think about it another way, setting toe-in is WAY easier than setting bumpsteer characteristics, yet nobody would ever dream of replacing a tie rod and not checking the toe after installation.  Why would you assume that bumpsteer would be any different?

 

While we are talking about the tie rods, while running the suspension through it's travel for the bumpsteer measurement, you should also keep an eye on the outer heim joint and make sure that it isn't binding at any point in the suspension travel.  Heim joints have a limited angular range of travel.  This is normally enough, but if your particular installation and range of travel put the heim joint out of its range of travel at any point you could end of failing the heim joint at some point in the not-too-distant future.  THIS WOULD MAKE A VERY BAD DAY FOR YOU.  

 

I'm not ragging on Brian's parts in any way, btw - they look like they are well made.  As I've been trying to point out, he has NO WAY of knowing what your actual suspension geometry is.  When you start making lots of suspension mods it's really up to you to verify things like "Is anything binding?" and "is everything adjusted properly?".  The Heim joint binding thing is safety critical - don't f*ck around with that.

Edited April 27, 2014 by TimZ

[JMortensen]

Roll center might be a bit esoteric, but camber gain isn't.  Again, I think that this is the main benefit to be gained by the JTR mod or bumpsteer spacers.  By your own account if you had moved the pivot point by 3/4" up and 1/4" out (or the 1" up that most spacers essentially provide) instead of he 7/16" that you actually needed you likely would have been as bad or worse bumpsteer-wise than when you started.

 

I'm not saying that moving the inner pivot point won't work - clearly it can work.  But it does couple in other factors that would be better if you could keep them separate.  For instance, if you ended up needing a different vertical relocation from right to left, now you've got different camber gains right to left, which would not be that desirable.  What I would advocate would be to go ahead and do the JTR pivot point relocation or something similar and only pay attention to getting the camber gain where you want it for both sides.  Then use the shims on the outer tie rod ends to bring the bumpsteer back to zero.

Camber gain will hardly change at all by adding a bumpsteer spacer. Check out the graph that Dan McGrath produced. It's pretty damn linear. Adding a bumpsteer spacer just moves you up or down the graph 3/4 or one inch depending on which spacer you use. The spacer moves BOTH outer pivots (ball joint and tie rod) the same amount, so it doesn't adjust bumpsteer, it only adjusts where on the bumpsteer curve you're driving. The spacer is a roll center adjuster more than a bumpsteer changer. 

 

http://album.hybridz.org/data/500/Camber_curves.JPG

 

Moving the LCA pivot is not at all the same as using a spacer. Moving the LCA pivot changes the relationship between the LCA and tie rod. It will change the camber gain, but again, without actually having a graph to prove it, I think you're vastly overestimating the effect. 

 

You compared tie rods to bumpsteer spacers, and that's a bad analogy. Setting toe is different than bumpsteer because bumpsteer is determined by the non-adjustable geometry in the front end. If you know the geometry (LCA vs inner tie rod height, ball joint vs outer tie rod height for strut suspension), you really can make a tie rod that adjusts out bumpsteer pretty closely. It might not be optimized for a particular car at a particular ride height, but there is no question that if the suspension isn't bent or modified, you can vastly improve things. Put a non-adjustable bumpsteer kit on a mid 80s 911. It'll get better. Been there, done that.

 

If you had a front end that was free of bumpsteer, in theory toe could be adjusted the same way. You might buy one set of tie rods that would give you 0 toe, a slightly longer set that would give you 1/8" toe out, or a shorter that gives 1/8" toe in. Since Z's have a lot of bumpsteer, setting toe that way isn't the best idea because ride height would change the static toe setting (not to mention the issues involved in getting the wheel straight).

Edited April 27, 2014 by JMortensen