johnc Posted July 1, 2004 Share Posted July 1, 2004 In theory, the strut towers would remain at a constant distance, but they could both be pivoting in parallel The strut towers tops move in towards each other under suspension load and they also twist - clockwise for the driver's side and counter-clockwise for the passenger side. Lateral strut tower braces stop the inward movement but do little for the twisting. Quote Link to comment Share on other sites More sharing options...
v8dats Posted July 1, 2004 Share Posted July 1, 2004 hey i noticed that the ultimate strut brace didnt have a price listed on the site. anybody know how much they are going for? and any updates on the fiberglass dash(off topic i'm sorry)? Quote Link to comment Share on other sites More sharing options...
rc's240z Posted July 1, 2004 Share Posted July 1, 2004 There is pricing on the strutbar on the PDK web page...I believe that it is $249.00 You will have to ask the guys about an update on the dash. Ron Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 1, 2004 Share Posted July 1, 2004 The strut towers tops move in towards each other under suspension load and they also twist - clockwise for the driver's side and counter-clockwise for the passenger side. That's what I always thought until I read a magazine article that used a dial indicator with a tell tale function to measure the movement. The strut towers actually move OUT on the loaded side of the car, and in on the other side (at least on the 944 that was the test car). Surprised the crap outta me too. Quote Link to comment Share on other sites More sharing options...
rc's240z Posted July 1, 2004 Share Posted July 1, 2004 I cant speak in regards to a porsche...but John Coffey did a lot of development work on his car to find out what a Z unibody does under severe stress. Ron Quote Link to comment Share on other sites More sharing options...
Drax240z Posted July 1, 2004 Share Posted July 1, 2004 Just a point that might be missed in all this, is that a rear strut tower bar can also have a VERY positive effect on the Z chassis, especially if you have stiffer than stock suspension installed. The 'cockpit' area of the Z seems to move quite a lot and bracing between the strut towers seems to limit this noticably. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 1, 2004 Share Posted July 1, 2004 Just a little backup for my point, this was the only site I could find that had any reasoning as to what the chassis does under load: http://e30m3performance.com/myths/Strutbar_Theory/strut_bar_theory.htm Quote Link to comment Share on other sites More sharing options...
johnc Posted July 1, 2004 Share Posted July 1, 2004 The BMW link example above ignores the vertical loading on the strut (spring). Bill Savage has a pretty cool modeling system that can do some finite element analysis and he came up with the effects I mentioned above when modeling the strut tower braces installed on my 240Z. I think Keith Thomas (katman) has also done some modeling while developing Chet Whittle's ITS 240Z. I'm no engineer (well, a monkey see-monkey do engineer) so I"m just repeating what I've been told. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 1, 2004 Share Posted July 1, 2004 If you read the second page he talks about hitting bumps while going straight flexing the towers in, but under cornering load, flexing out. I'm sure our Z's are worse than most cars, and are probably really bad when you've got heavy springs in. It's really not a big deal which is right, as long as it gets fixed. I just thought it was interesting, and like I said before, suprised me a lot when I learned why and how. Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted July 1, 2004 Share Posted July 1, 2004 Great thread! While on the topic of 4130 alloy steel. JohnC, do you or do you recommend heat treating crmo for a small project like a strut tower brace? I've never welded 4130 and have been alittle hesitant because of what I've been taught about it. I would use it more if I knew more about welding it. Quote Link to comment Share on other sites More sharing options...
johnc Posted July 1, 2004 Share Posted July 1, 2004 For thicknesses up to .120 welding 4130 sheet or tubing is basically the same as welding mild steel. You don't need any pre-heat although the steel should be at room temperature and if you're in a really humid environment, pre-heating to 100F should get the moisture off the metal. For thicknesses over .120 you'll need to pre-heat to 300F-400F and stress relieve after welding at 1,100F for tubing. Its also important to keep interpass temperature over 300F-400F during the welding process. FYI... there isn't a part I can think of on a car where you would need 4130 anything thicker then .120. Use ER80S-D2 filler if the welds need to be as strong as the base metal. Use ER70S-2 or ER70S-6 if the elongation is more important. You can also use 310 or 312 stainless. As always, cleanliness is important and you must remove the green scale that most 4130 tubing comes with. No need to backpurge tubing and absolutely never quench 4130. Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted July 2, 2004 Share Posted July 2, 2004 John, Thank you! I have much respect for your knowledge and accomplishments. I hope you don't stop hanging out here if you do sell the Old Rusty Datsun. Quote Link to comment Share on other sites More sharing options...
johnc Posted July 2, 2004 Share Posted July 2, 2004 I was all scared to weld 4130 because of what I had read in the trade mags about it. But when I took the Motorsports Welding class at Lincoln Electric they said the trade mags are all concerned with welding 1/2 plate. For our uses 4130 isn't a big deal. You can screw it up with bad technique (like anything), but if you've been MIG or TIG welding for a year or two your technique should be fine. FYI... Lincoln is working with NASCAR and Tony Gibbs Racing to develop a certification for welding 4130 and DOM tubing. While I was at the Lincoln Motorsports school they asked a few of use to stay late one evening and TIG weld a bunch of 1.5" .095 wall 4130 round tubing joints. I ended up welding 50 - 90 and 45 degree joints. A few months ago I got a certificate in the mail from Lincoln saying I'm certified to weld 4130 steel tubing. They put all the welded joints in a fixture that pulled and bent the things to failure and all of mine passed. They still don't have the NASCAR wedling certification process done yet. 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.