dj paul Posted January 24, 2006 Author Share Posted January 24, 2006 well i guess i might just put all this effort into making some custom rear lca's. my sway bar end link hole on one rlca got tore up i could prob just weld plates in there and a strong washer but i like the look of those custom rlca's (but dont have money!) Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 24, 2006 Share Posted January 24, 2006 I plan to come up with something that will incorporate a custom control arm and a custom rear subframe to carry the Q45 rear. This will be something similar to what Jamie T. has come up with in his design, but a little more robust. Mike Quote Link to comment Share on other sites More sharing options...
BlackBeaut Posted January 24, 2006 Share Posted January 24, 2006 Try this again (original post did not make it through). This is something I have considered as a project later on if I decide I have too much time on my hands. Basically' date=' retain the OEM lower control arm and bearing carrier boss, but cut the strut tube short, and assemble an upper arm onto this shortened tube. My goal was vastly increased backspacing, but the wheel well inner lining will prevent a wheel with much more the 7" of backspacing. The objective was minimal fabrication, and maximum use of the OEM parts as possible, but still have an unequal length upper and lower control arm assembly that did not require extensive (a relative term) modifications. [img']http://www.fototime.com/A67D60CE66CC292/standard.jpg[/img] Looks very interesting, also looks like it could be easily translated to the front end of the car. Anyone got any good reading links on why wishbones should be unequal length, something I've not got around to getting my head around, "suspension for dummies" would be good Cheers, Rob Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 25, 2006 Share Posted January 25, 2006 The unequal length arms allow a more favorable camber change with suspension movement (but mounting location and configuration is important). This same advantage can be had with equal lenth arms, but mounting on anything other than a purpose built race car makes this option unattractive. I've considered this for the front end as well, but am a bit concerned about the OEM unibody support for it up front verses the rear. I did not want to start adding a lot of support for the upper arm in the front being its not got a lot of supporting structure in the first place (where an upper arm would be located). The rear end though has the subframe in the immediate area of the upper arm location which keeps the weight and fabrication time down somewhat. Also, using the rear lower OEM control arm in its current configuration ensures factory strength where needed. Obviously, the OEM designed strut tower mount helps locate the hub, but it provides no twisting resistance (as viewed from the top of the strut). A triangle type of upper arm, with the ball joint bolted to the top of the shortened strut tube should ensure sufficient strength to prevent any unwanted movement (at the top of this shortened tube) in the horizontal plane, provided it is properly designed. Quote Link to comment Share on other sites More sharing options...
dj paul Posted January 25, 2006 Author Share Posted January 25, 2006 i have access to an industrial tig and a jig and chromoly tubing. could someone with either the arizona zcar or msa adjustable rear control arms give me some detailed drawings? if not ill just have to figure it out on my own =( lol. i dont think anything like i was drawing above would be needed now that i think about it. i just thought it would be kind of fun. Terry's idea seems interesting but does seem like it wouldnt be needed anyways unless on a pure track car. thanks paul Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 25, 2006 Share Posted January 25, 2006 I don't think anyone has a drawing of either part. I wouldn't recommend using them anyway. Basically all you need to do is take the pickup points off the existing controll arm as your parameters, and go from there. Building a rear control arm isn't that hard. Building one that won't fail is VERY hard. Mike Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted January 25, 2006 Share Posted January 25, 2006 Here is another thought use a jag suspension in the back. Relatively cheap to get at the local yard or about $200 on eBay. Looks like mounting could done without major headaches. They use them in Cobra kits for years so power should be no problem. http://images.google.com/imgres?imgurl=http://www.jcna.com/library/tech/images/tech0009b.jpg&imgrefurl=http://www.jcna.com/library/tech/tech0009.html&h=450&w=600&sz=38&tbnid=3byh4ax2S2-YRM:&tbnh=99&tbnw=133&hl=en&start=9&prev=/images%3Fq%3Djaguar%2Bsuspension%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DG http://cgi.ebay.com/ebaymotors/Jaguar-Rear-End-Differential-with-inboard-disk-brakes_W0QQcmdZViewItemQQcategoryZ33731QQitemZ8031755132QQrdZ1QQsspagenameZWDVW Quote Link to comment Share on other sites More sharing options...
dj paul Posted January 25, 2006 Author Share Posted January 25, 2006 lol, its alright. im going to draw up a few designs and put them into a stress calculation program and see the weak points under certain forces. we are currently doing the same thing at school for a dune buggy project. we try and make the stuff fail so we see design flaws and such. their ca's are a bit different though, lol. also i appreciate the suggestion about the jag piece, but that thing's ugly as balls. i dont want that under my car! lol. id rather just design my own piece and put my in training engineering skills to work! Quote Link to comment Share on other sites More sharing options...
260DET Posted January 26, 2006 Share Posted January 26, 2006 Try this again (original post did not make it through). This is something I have considered as a project later on if I decide I have too much time on my hands. Basically' date=' retain the OEM lower control arm and bearing carrier boss, but cut the strut tube short, and assemble an upper arm onto this shortened tube. My goal was vastly increased backspacing, but the wheel well inner lining will prevent a wheel with much more the 7" of backspacing. The objective was minimal fabrication, and maximum use of the OEM parts as possible, but still have an unequal length upper and lower control arm assembly that did not require extensive (a relative term) modifications. [img']http://www.fototime.com/A67D60CE66CC292/standard.jpg[/img] I like that idea and may do a variation of it for the front suspension on the S130 project. The variation would be similar to the Mazda RX8 front setup where the coilover shock bottom mounts a bit higher up than shown on the sketch above. That should allow the top of the coilover shock to bolt up into the existing strut tower top. Not sure how it would work on the rear though without a fair bit of fabrication to make a frame for the upper A arm to mount to? Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 26, 2006 Share Posted January 26, 2006 Just remember when starting with a strut as an upright you should fix the high SIA/KPI. Cary Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 26, 2006 Share Posted January 26, 2006 :confused: Oh, kingpin inclination? On the back that would not be an issue, correct? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 26, 2006 Share Posted January 26, 2006 I think he meant SAI and KPI. Steering Axis Inclination and Kinpin Inclination. As to an explanation of those measurements, I'll leave that to someone who actually knows what they mean... Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted January 26, 2006 Share Posted January 26, 2006 I think you need to examine how the stressed are distributed now through the strut itself. Draw a moment diagram of all that is going on. I think you will see that the bending moment is supported by the strut and not the housing. To do you design I think you will need to machine a solid piece to replace the strut housing. But I am a field mechanical piping engineer and not into machine design. I will be interested in what you come up with using the FE program and what forces you use. Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 26, 2006 Share Posted January 26, 2006 :confused: Oh, kingpin inclination? On the back that would not be an issue, correct? It does matter to a degree in the back but not as much as the front, which is what I was thinking about. Here's a pic of how this is commonly done on GT cars. Cary Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 26, 2006 Share Posted January 26, 2006 Excellent photo...exactly what I had in mind. BUT, this photo (to my minds eye) does not indicate the KPI has been changed much. If they had offset the upper mount over toward the wheel side of the remaining strut tube, I could understand it a little better. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted January 27, 2006 Share Posted January 27, 2006 I've been thinking of this topic for several weeks. The people on this forum always seem to read my mind. I began thinking in terms of doing the rear suspension to increase the amount of backspace available in the rear wheel wells. I drew up some ideas, and decided to analyze the suspension I currently had before making modifications. What I came up with is that the front needs alot more help than the rear. The front suspension gains about 0.75 degrees of negative camber per inch of bump, gains positive camber in a deminishing non-linear fashion as the wheel rebounds past the point where the LCA is level, and has a really high KPI (~13.5 degrees) The rear suspension gains about 1.7 degrees of negative camber per inch of bump, and is linear over the entire stroke of the damper. I decided that I will modify the front suspension rather than the rear. I may do the rear later after I have improved the front. What I am trying to decide is how much KPI to design around. I can run a longer upper control arm by using a smaller KPI (5 to 8 degrees), and I feel that a longer UCA is better because the roll center will move around less. I am also trying to decide how tall to make the upright. I am currently leaning towards going with the tallest upright height that will allow the ball joint to fit inside the wheel. Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 27, 2006 Share Posted January 27, 2006 Excellent photo...exactly what I had in mind. BUT, this photo (to my minds eye) does not indicate the KPI has been changed much. If they had offset the upper mount over toward the wheel side of the remaining strut tube, I could understand it a little better. It was changed very little with offset at the top and the bottom. This car features custome built steering arms that move the lower mounting point towards the center of the car. The wheels in this case were something bolted on so the car could move. The race wheels are snug up to this upright. If I recall correctly they have about a half inch of scrub and less than ten degrees of KPI, but my memory isn't the best these days. Cary Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 27, 2006 Share Posted January 27, 2006 What I am trying to decide is how much KPI to design around. I can run a longer upper control arm by using a smaller KPI (5 to 8 degrees), and I feel that a longer UCA is better because the roll center will move around less. I am also trying to decide how tall to make the upright. I am currently leaning towards going with the tallest upright height that will allow the ball joint to fit inside the wheel. Sounds like you have a good start to me. Try and keep caster trail less than three quarters of an inch and scrub less 1.5 inches. A lot of the other numbers will fall into place. When looking at RC/ICs remember to look at their velocity rather than where they end up. The rate of change is what we call feel and are sensitive to. All manner of variations can be made to work and are dependent on tire/driver/use characteristics. Don't let RCs go through a tire or the ground or a tire under normal operating parameters. Bad things happen then. Cary Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted January 27, 2006 Share Posted January 27, 2006 Thanks, Would you mind clarifying the last sentence? What kind of bad things? Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 27, 2006 Share Posted January 27, 2006 A momentary traction loss. As in sudden and no warning. Cary Quote Link to comment Share on other sites More sharing options...
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