zclubhouse Posted March 2, 2010 Share Posted March 2, 2010 I finally took the plunge this winter and cut out my rusting away front frame. I built a replacement front frame and thought it was a good time to modify the suspension for my needs. After spending hours on here researching different approaches, I decided to explore the blank slate I had to start from and try something different from stock. I kept the factory crossmember but changed the pivot point as many have done here. I scrapped the radius arm/tension control rod bucket concept and instead used a shock mounting tab. The reasoning behind this idea was to use rod ends at both pivots and have the bracket in shear instead of tension. Its welded to a reinforcement plate to spread out any forces applied to it. I also changed how the cross member attaches to the subframe. I drilled a new set of holes and welded two sandwich style plates on the frame so that I could bolt it directly through the frame instead of hanging it from a tab. The control arms are made from DOM tubing, QA-1 rod ends and circle track style screw in ball joints. I have order military spec bolts for installation, however for mockup purposes they were held together with any old thing laying around, so dont worry! I am having a local machine shop make a piece similar in appearance to the AZC steering knuckles which will serve the purpose of adapting this larger taper to the strut housing. I will update further as I complete the install. Let me know what you guys think, I appreciate any feedback. Thanks. Quote Link to comment Share on other sites More sharing options...
doublexl240z Posted March 2, 2010 Share Posted March 2, 2010 Looks awesome!! Great minds think alike!! Nice work! My project. Quote Link to comment Share on other sites More sharing options...
bjhines Posted March 2, 2010 Share Posted March 2, 2010 ok.. There is nothing to keep the control arm from rolling around with the sway bar action(or am I just crazy?). The "Hockey Stick" on the factory control arm kept it level. Yours has rod ends everywhere. The aftermarket kits have a rigid dogleg attched by a rigid clevis(mounted further out with a longer moment arm) that can only pivot in one plane. This design also holds the control arm level. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted March 2, 2010 Share Posted March 2, 2010 (edited) I think you have too many degrees of freedom in your lower control arm / TC rod. The rod end at the junction between the control arm and TC rod needs to be a solid end and not a spherical bearing. Otherwise, the effective length of your TC rod will change as the control arm rotates about its long axis. Oops, BJhines beat me to it... Edited March 2, 2010 by 74_5.0L_Z Quote Link to comment Share on other sites More sharing options...
heavy85 Posted March 2, 2010 Share Posted March 2, 2010 ok.. There is nothing to keep the control arm from rolling around with the sway bar action(or am I just crazy?). The "Hockey Stick" on the factory control arm kept it level. Plus the factory arms put the swaybar mounting in the middle of the arm so that it does not try and rotate it. This minimizes twist put into the T/C rod. Cameron Quote Link to comment Share on other sites More sharing options...
zclubhouse Posted March 2, 2010 Author Share Posted March 2, 2010 I think you have too many degrees of freedom in your lower control arm / TC rod. The rod end at the junction between the control arm and TC rod needs to be a solid end and not a spherical bearing. Otherwise, the effective length of your TC rod will change as the control arm rotates about its long axis. Oops, BJhines beat me to it... I apologize I did not describe the design properly. The LCA/TC rod junction is effectively a solid rod eye. I used a forged rod end for the pull strength and thread application, but I have machined spacers that sit flush against the rod end housing, therefore it acts like a solid joint. This eliminates any sway bar "twisting" and limits the functional motion to the frame/crossmember attached pivots only (with the exception of the ball joint itself.) I hope this clears it up, otherwise I certainly missed something major?! Thanks for the input guys. Quote Link to comment Share on other sites More sharing options...
doublexl240z Posted March 2, 2010 Share Posted March 2, 2010 I hope this is the general idea?!Sway bar mount is not drilled yet, but will be in center. Not trying to highjack. Quote Link to comment Share on other sites More sharing options...
zclubhouse Posted March 3, 2010 Author Share Posted March 3, 2010 I hope this is the general idea?!Sway bar mount is not drilled yet, but will be in center. Not trying to highjack. That looks good, I like the idea of reusing the stock ball joint attachment points but changing the rest of the design. I also really liked seeing your chassis work so far. That approach crossed my mind but lack of time, space and talent persuaded me otherwise! Do you mind sending me some pictures of the top shock mounting area? I'm curious to see your approach given the tube frame idea. Thanks Quote Link to comment Share on other sites More sharing options...
piston Posted March 4, 2010 Share Posted March 4, 2010 the new frame looks like it centers the cross member but the rear end diff is still offset? which means you will also have to center the rear diff also for drive shaft angle correction. Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted March 4, 2010 Share Posted March 4, 2010 Instead of turning your rod end into a clevis... would attaching the sway bar directly to the strut housing eliminate the control arm from rotating? Quote Link to comment Share on other sites More sharing options...
doublexl240z Posted March 5, 2010 Share Posted March 5, 2010 Here is a few pics from the strut tower and bracing. I cleaned most of the dust for you guys!! The motor will be slightly right of center for "alignment " purposes... not weight distribution.( LOL) Quote Link to comment Share on other sites More sharing options...
doublexl240z Posted March 5, 2010 Share Posted March 5, 2010 The camber plate is from ISC racing, they are Mazda shop in Lakeland Fl. they sell ther plates for about 110 bucks. I can't see spending 300 on the set of aluminum ones!! Quote Link to comment Share on other sites More sharing options...
AkumaNoZeta Posted March 5, 2010 Share Posted March 5, 2010 Instead of turning your rod end into a clevis... would attaching the sway bar directly to the strut housing eliminate the control arm from rotating? I've seen other set-ups where they did that with the sway bar in one of my suspension books, there wasn't any mention of any downsides. Quote Link to comment Share on other sites More sharing options...
zclubhouse Posted March 6, 2010 Author Share Posted March 6, 2010 How much force do you guys think I will be dealing with in regards to the twisting of the control arm from the sway bar? This is some seat-o-the pants hillbilly physics talking here, but I figure that a 2000lb car cornering at 1G putting sway bar torque motion through a 1 inch effective "lever" (sway bar bracket) doesn't add up to enough to harm the radius rod by twisting it. Or are you guys thinking that not mounting the bar in the middle of the control arm will load the suspension in some adverse manner, causing the car to be a handful when turning? Thanks again for the input. doublexl, thanks for the pictures. Interesting design. Definitely interested in your progress, its a cool project. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted March 6, 2010 Administrators Share Posted March 6, 2010 the new frame looks like it centers the cross member but the rear end diff is still offset? which means you will also have to center the rear diff also for drive shaft angle correction. The crossmember in a stock car is also centered. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 6, 2010 Share Posted March 6, 2010 How much force do you guys think I will be dealing with in regards to the twisting of the control arm from the sway bar? This is some seat-o-the pants hillbilly physics talking here, but I figure that a 2000lb car cornering at 1G putting sway bar torque motion through a 1 inch effective "lever" (sway bar bracket) doesn't add up to enough to harm the radius rod by twisting it. Or are you guys thinking that not mounting the bar in the middle of the control arm will load the suspension in some adverse manner, causing the car to be a handful when turning? Thanks again for the input. doublexl, thanks for the pictures. Interesting design. Definitely interested in your progress, its a cool project. 1" sway bar has an effective rate of 300-something lbs/in. Its in Dan's (74_5.0L_Z) sticky thread in this forum. Attaching the sway bar to the strut housing is a good way to go if you can figure it all out. I looked at it for about 5 minutes and then made a more traditional sway bar setup. Quote Link to comment Share on other sites More sharing options...
piston Posted March 6, 2010 Share Posted March 6, 2010 The crossmember in a stock car is also centered. duh, i knew that. lol, j/k. forgive me, i didnt even realize that until i looked at mine earlier. haha Quote Link to comment Share on other sites More sharing options...
zclubhouse Posted March 6, 2010 Author Share Posted March 6, 2010 1" sway bar has an effective rate of 300-something lbs/in. Its in Dan's (74_5.0L_Z) sticky thread in this forum. Attaching the sway bar to the strut housing is a good way to go if you can figure it all out. I looked at it for about 5 minutes and then made a more traditional sway bar setup. I wasn't talking about the stiffness of the sway bar, I meant to describe the offset of the sway bar bracket as the "lever" that would allow the sway bar action to apply twist to the control arm. I think I will avoid the method of attaching it to the strut housing, as I want to keep the sway bar I already have and I cannot see how I would be able to perform this modification without purchasing a different sway bar? Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted March 7, 2010 Share Posted March 7, 2010 (edited) I don't think you would have to change your sway bar. Maybe modify it a little but, it shouldn't be that difficult considering you made those control arms yourself. If I were to do it I would have an adjustable rod with rod ends on both ends that bolted to the strut housing and sway bar with adjustable mounting points. here's what most bimmers look like Edited March 7, 2010 by EMWHYR0HEN Quote Link to comment Share on other sites More sharing options...
zclubhouse Posted March 7, 2010 Author Share Posted March 7, 2010 I don't think you would have to change your sway bar. Maybe modify it a little but, it shouldn't be that difficult considering you made those control arms yourself. If I were to do it I would have an adjustable rod with rod ends on both ends that bolted to the strut housing and sway bar with adjustable mounting points. here's what most bimmers look like Very interesting! Thanks for the input and provided example, now I can better visualize what you were talking about. I like your idea of the adjustable link. I'll have to chew on that idea a bit, see if I should go that direction with my set up. Thanks again. Quote Link to comment Share on other sites More sharing options...
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