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tie rod/z31 strut conversion complete


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I need some ideas on this..... when i modded the struts for the z31 lower half i used the z31 sterring knuckle. unfortunatly this made my tie rod ends too short .. by about 3 inches on both sides. Heres what im thinking.

 

1st option... research and find a stock type tie rod that is long enough to work with the stock rack <img border="0" alt="[eek2]" title="" src="graemlins/eek2.gif" />

 

option number 2... build a custom setup with spherical rod ends.... this option sounds shaky to me for a daily driver. <img border="0" alt="[shifty]" title="" src="graemlins/shifty.gif" />

 

option 3... cut reverse and reweld the steering knuckles so the stock tie rods will fit. my concerns here are strength... <img border="0" title="" alt="[Confused]" src="confused.gif" /> Im not too sure this will be safe, will it break? can it be done with a normal mig or does it need to be a special type welder. <img border="0" alt="[ugg]" title="" src="graemlins/ugg.gif" />

 

thanks in advance

<img border="0" alt="[rockon]" title="" src="graemlins/rockon.gif" />

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Guest AlsoRanFPrepared

I would recommend that you build some new tire rod ends using spherical rod ends. I am in the same position with respect to tie rod length as I have increased the front track on my car and changed the ackerman. As long as you buy good quality rod ends there should be no problem with using them in this setup. This is commonly used to correct bumpsteer and is used on cars set up for racing. The only issue is the need to drill and tap the rack side of the new tie rod to 14-1.5 (as I recall you should check to be sure) right and left hand threads to accept a stock rack. Those taps are available at McMaster-Carr for about $25 each. The knuckle is commonly drilled out to accept a 5/8 bolt and 5/8 rod ends are use on the outer end of the new tie rod.

 

I would be leary about welding on the knuckle as it is relatively thick and not very large.

 

-Mark

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I've done much the same thing using spherical rod ends (but for a different reason). Good quality rod ends are available that will be stronger than you will ever need. I took a slightly different approach though. I instead used a grade 8, 1/2" bolt through the steering rod (Ackerman) instead of drilling the hole out larger. The reasoning was that 5/8" seemed to be a bit of overkill, the 1/2" was almost a perfect fit (the hole is slightly bigger), and lastly, if I later did decide to use a conventional rod end, the unmodified Ackerman rod would still be usable. I found that with good quality washers, the 1/2" bolt is very well suited for this usage. I then made an adapter to match the steering rack ends to the spherical rod ends. With this set-up, bump steer can also be improved upon. This set-up has worked well for many years. I the below photo, I used nuts as spacers to adjust the bump-steer height. Once I found a good length as far as bump-steer spacing, I made a nicer looking single spacer. standard.jpg

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ok sounds good.... but im really interested in the cutting and rewelding the arm so i can use the stock z rack tierods. i was planning on cutting them grinding the weld seam at an angle, fill in with weld then grind it down. i sectioned the struts so the top have is S30 and the bottem half is z31. im not to concerned with being able to use it in stock configuation later if i need to i will replace the entire strut housing. rockon.gif

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Tim has many good as well as valid points and concerns here. In fact, many years later (not because I had any problems) I fabricated cylindrical wedges to would slip into the wedge gap of the Akermans, and "crush" into place when the 1/2" bolt was torqued down sufficiently. It was not anything that I felt was needed. The binding rod end is very important. The first time I did this, yes, the rod was binding at full droop. This problem was cured by chamfering the spacer so that the ball had minimal contact surface with the spacers. Lastly, I do have a set of Akermans that I did cut in two, and weld back together. The welding was done in such a manner that heat throughout the process was not cycled and the piece was kept cherry red from start of welding process to the finish. Once the weld was completed I used a press as well as a large hammer and attempted to destroy the weld. Lastly, the piece was normalized (don't know for sure if this really was of any benefit). I used it for many years successfully too. But these are only experiences and may not be an "SAE approved" method. Thanks Tim for bringing up the safety aspects of these mods.

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A couple of things should be mentioned here...

 

First, all rod ends have a limit as to their range of angular travel. You need to make absolutely sure that your rod end does not bind anywhere in the suspension's range of travel. I can't emphasize enough the importance of this. Okay, maybe I can - otherwise, TIE ROD FAILURE WILL RESULT.

 

Generally, the geometry of the Z's front suspension (at least on mine, which has nothing terribly unusual in this regard) does not result in the rod end being in the middle of it's travel when the suspension is in the middle of it's travel. On my car, I had to introduce a bend in the middle of the tie rod in order to allow it to be in the appropriate orientation to prevent binding throughout the suspension's range of travel.

 

There are heim joints available that have an increased range of angularity - they generally use an undersized hole - i.e., the rod end is the same size as a normal 5/8" end, but uses a 1/2" bolt.

 

Regardless of what rod end you use, you really need to make sure that it isn't going to bind.

 

Second, I don't particularly like the idea of using a bolt in a tapered hole - this just sounds like asking for trouble, especially when we are talking about a safety critical component. Apparently it has been working okay for Terry, but that is not a configuration that I would recommend. Maybe if the spacer had a chamfer machined into the end that contacts the knuckle to keep the bolt centered, but I'd still prefer a straight bore hole.

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  • 1 month later...

Ok lets try this again... Im done with the front end z31 conversion.

 

2227size_differ.jpg

size comparison between the s30 stock brakes and the z31 stock brakes

222700_00019.jpg

z31 strut cut ready to cut s30 strut

222700_00019.JPG

extention on rack to fit the z31 spindle

2227z32_calipers.jpg

struts welded up ready to go

 

 

the caster was a little mor positive then the stock s30 struts but i should be ablt to adjust it negative with arizona z car a-rms i have installed ;> :rockon:

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Basically here’s what I did.

 

I got a set of z31 struts and cut them just above the bracket that holds the brake line. Then I measured the s30 struts that I have converted to coilovers. I measured the z31 struts and determined how much to cut off the top of the s30 coilovers. I clamped them together in angle iron to keep them straight and welded the top half of the s30 struts to the bottem of the z31 struts.

 

Here’s what I’m not sure on for other cars. I have tubular a arms and not sure if they have the same ball joints as other z's but they probably do. They are slightly smaller then the z31 ball joints so I had to use a couple of washers to pull the ball joint up further into the hole. This worked fine with no binding.

 

Second obstacle was the tie rod thing that as soon as I figure out the damn length they need to be ill be ok just have to mod the rack to the right length like I described above.

 

With the z31 bottom halves in place the z32 calipers bolt right up using the z31 rotor. The z31 rotors are the same size as the z32 but the z32 rotors are thinker with bigger vents but have a different offset and can’t be used in this application without being modded.

 

Another thing for people to consider is these struts have more positive caster then the stock s30 struts but i should be able to adjust this out with the custom aarms

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  • 2 months later...

ok i hit the alignment shop to day and was able to tune the caster back to normal levels with the TC rod and toe measurements are all within specs :D

 

As for the brakes they are awesome. for those of you that have stock brakes still youll know what im talking about. before i took a good stomp to lock all 4 and a steady amount of pressure to stop quickly. I would also feel alittle fad slowing from 120+ for the turnoff at the track.

 

Now with very slight toe pressure the car wants to stop on a dime. Im sure its not as good as some of the wilwood or other big brake kits but it works fine for me. I drove a friends 350z the other day with the brembo brake option and my car no shit felt as good if not better in the stopping area then it. so all in all im very happy with the results.

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  • 2 years later...
  • 1 month later...

How did you resolve the bumpsteer issue. I know many with the S30 use a bumpsteer spacer to correct the geometry of the tie rod ends. Is there an equivalent spacer for the Z31? I couldn't find one available. Still a bit confused and wanted to know how you solved this problem.

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