74_5.0L_Z Posted April 17, 2004 Share Posted April 17, 2004 I just finished making some Chromoloy Adjustable rear control arms. They are a direct bolt-in replacement for the stock control arms and feature Aurora XAM10T rod ends. The complete control arm(rod ends included) weighs in at 6 pounds. The factory control arms weigh 10 lbs. In the process of building my control arms, I fabricated a fixture so that I can build more if I desire. Is anyone interested in purchasing control arm sets if I decide to make them? I will post pictures and a price soon. Quote Link to comment Share on other sites More sharing options...
280Zone Posted April 17, 2004 Share Posted April 17, 2004 Just waiting to see pictures and prices. Quote Link to comment Share on other sites More sharing options...
tannji Posted April 17, 2004 Share Posted April 17, 2004 yeah, lets see some pics..... and perhaps some testing? Quote Link to comment Share on other sites More sharing options...
ToplessZ Posted April 18, 2004 Share Posted April 18, 2004 Im open to hear some prices and testing. If it is a reliable budget alternative to some of the other offerings I would be interested. Quote Link to comment Share on other sites More sharing options...
Guest ON3GO Posted April 18, 2004 Share Posted April 18, 2004 i would also like to see some pics and get some prices on them... i already have the front i just need the rear now... thanks mike Quote Link to comment Share on other sites More sharing options...
zguy95135 Posted April 18, 2004 Share Posted April 18, 2004 how much were the fronts? Quote Link to comment Share on other sites More sharing options...
Owen Posted April 19, 2004 Share Posted April 19, 2004 watching this thread... Quote Link to comment Share on other sites More sharing options...
Guest ON3GO Posted April 19, 2004 Share Posted April 19, 2004 my fronts are Mike kellys ZF racing control arms... i think i paid 300 but he is no longer selling or making them... i love them mike Quote Link to comment Share on other sites More sharing options...
jgkurz Posted April 19, 2004 Share Posted April 19, 2004 I'd be interested in the rear control arms. Especially if they bolt up to all the stock locations. Definatley need pics. Are the 240z, 260z and 280z arms all the same? Quote Link to comment Share on other sites More sharing options...
Guest ON3GO Posted April 19, 2004 Share Posted April 19, 2004 yeah there all the same.. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted April 19, 2004 Author Share Posted April 19, 2004 I will post pictures as soon as I have some(next week). I was supposed to get them welded on Saturday, but the guy who does my welding was ill(aircraft certified welder who does welding on space shuttle and space station components at KSC). I performed a quick and dirty stress analysis just based on statics and strength of materials. Based on this analysis these control arms have at least a factor of safety of 4. Still, real life doesn't look at the equations, so I plan to install them on my car and run a few autocross events and a track day before making them available. Speeder, do you have access to some strain rosettes? Maybe we could instrument the tubing to get some data. Quote Link to comment Share on other sites More sharing options...
Guest AlsoRanFPrepared Posted April 19, 2004 Share Posted April 19, 2004 Now when you did your quick and dirty stress analysis you did not look at fatigue correct? Did you focus on the location with the highest stress concentration? Depending on the loads you assumed and the cyclic nature of suspension loading you may need much more than a safety factor of 4 for a reasonable life. For a race only part that gets inspected frequently it may be just fine. If someone is planning on using this as a daily driver part without inspection there could be issues. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted April 20, 2004 Author Share Posted April 20, 2004 The intended purpose of these is for racing applications with limited street use. I made these for myself because the primary purpose of the car is more and more race oriented, and because I have not had the best of luck with the adjustable aluminum delrin bushings offered by some of the aftermarket. They are a pain to adjust, and after less than a year, one of the holes in bushing became elongated enough to cause slop in the rear suspenison and an annoying thud every I hit a bump. The analysis I ran was very conservative for static loads. I assumed 2500 lbs simultaneously in the lateral and longitudinal directions. I have yet to do a fatigue analysis. I am working on Pro-E model, and later perhaps a Catia FEA analysis as time on my lunch hour permits. Regardless, I plan to test them on my car first. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 20, 2004 Share Posted April 20, 2004 I'll caution you here... Our test mule 240Z weighs 1950# and runs on full slicks only, uses extremely stuff springs, stiff sway bars, and solid mounts in most locations. The car ran for 2+ years in this configuration on a 10 month California sunshine season with two drivers hammering the car most weekends... The car sees some track events, but mostly solo1 & solo2 events... Three weeks ago Steve and Ian had a failure on the control arm at the outboard side of the arm at the location of the spindlepin mount. A weld failed due to stress... Fortunately it was the very first set, and saw extreme stresses under hard conditions... You can't measure fatigue stress accurately... We had done some serious stress analysis on these parts, and knew we would have an issue creep up in a stress related area. the constant cyclic abuse on the parts and the weld was something that, coupled with the added stress from hard suspension mounts and large sway bars, simply put a mulitplier unimaginable on the parts... And you have no control over how a driver will configure his or her car. Good luck! Mike Kelly 8) Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted April 20, 2004 Author Share Posted April 20, 2004 Thanks Mike, The issue that you have encountered, as well as marginal profits that are to be had from making these parts (compared to the amount of work that goes into making them) has me wondering if it's worth the effort. My set is essentially complete (less welding). After some time has elapsed, I may offer them to others. If I do offer them, it will be as a company, and the control arms will be designated race only. In any case, I'll post pictures when they're available. Quote Link to comment Share on other sites More sharing options...
gramercyjam Posted April 20, 2004 Share Posted April 20, 2004 FWIW, I did something the other day that clearly illustrated cyclic stress and related fatigue failure better than any textbook ever did for me. Not being able to find one in any local stores, I welded up a 4" wide chisel out of 1/4" mild steel for my impact hammer to scrape old glued on wood parque tile from an oak floor. In my mind, not a particuarly demanding job for the chisel. After only a few minutes use, the chisel shattered into glass like shards and chunks. I was utterly suprised so I made several of these chisels to better understand what the mode of failure was and how it progressed. The failure was not gradual. It appeared to be fine, without cracks observeable to the naked eye right up to the point of catastropic failure. I think you are up against a similar situation when you are making control arms. It would seem that heat treatment to relieve residual stresses in the welded up parts would be necessary to help prevent this mode of failure. My .02 Quote Link to comment Share on other sites More sharing options...
Drax240z Posted April 20, 2004 Share Posted April 20, 2004 It would seem that heat treatment to relieve residual stresses in the welded up parts would be necessary to help prevent this mode of failure. And doubly so when using 4130. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted April 25, 2004 Author Share Posted April 25, 2004 (edited) I got the control arms welded thursday, and I am very happy with the way they came out. I spent Saturday morning cleaning off the remainder of the mill scale from the cromoloy and getting them ready to paint and install. After I finished sanding, I had some doubts about whether to paint them of just clear coat.Rick Bowers(speeder) was nice enough to come by to take a look and to take a few pictures. Tell me what you think. The control arms have since been painted black and installed. I'll test drive them sometime next week. I am considering forming an LLC to sell these if there is interest. NOTE: Edited because links to old pictures were broken. Edited August 1, 2015 by 74_5.0L_Z Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted May 12, 2004 Author Share Posted May 12, 2004 (edited) Well, I've got the control arms installed and have taken a few pictures. I only have room in my album for one. I have driven it on the street a bit since installing them, and I am quite happy. I installed them 1/8" longer than stock to increase camber. I am running an autocross on May 22, and plan to put them through a beating. NOTE: Edited because links to old pictures were broken. Edited August 1, 2015 by 74_5.0L_Z Quote Link to comment Share on other sites More sharing options...
speeder Posted May 12, 2004 Share Posted May 12, 2004 Those look really nice on the car... The workmanship is so good that it's a shame to paint them. It would be nice to instrument and test, but sadly I have no connections to get strain gauges. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.