dj paul Posted January 24, 2006 Share Posted January 24, 2006 Hey guys, I was just wondering. i know the 240sx rear subframe has been done and even an r33. but is there any way for us to design, without swapping the rear subframe, to get a design not exactly like this, but similar? for some reason, it doesnt seem like it would be that hard to me to do. especially the upper arm. we might not need the rest, but as discussed in the other thread, some people are getting some forward movement of the rear tires on hard launches. now im pretty good at fabricating, and whatever i cant do my friend can. just let me know is this possible? with just some fabbing? i am going to school for engineering so i can get some friends to do stress testing and help me design stuff. i just think this upper arm would help greatly in the strength of our rears, allowing better grip for better launches.since the 240sx rear subframe can be put in our cars with some fabbing, i would think that this can be done. i know the actual stub axle does not have this stuff on it but it could be welded on correct? like say, use 2 monoballs on both joints of that rear upper control arm? and if it would help, the forward link. im not sure if we would even need the toe link, or am i wrong in thinking this. i think this would be great for cheap assess on our cars and would greatly spread out stress. my car is eventually going to have around 400-500 rwhp. and while im down here, (hmmm...... where have i heard that before? ) and i have the entire car torn down, id like to see if i can desing something liek this. any questions, comments, motivations speeches(lol) etc. would be greatly appreciated. Thanks in advance! Paul Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 24, 2006 Share Posted January 24, 2006 I'd think it would be easier to just weld in some clevises and adapt the rear control arms and uprights from something like the Cobra IRS or the C5 Vette IRS arms. Basically the same thought, but well proven in strength for much higher HP and torque loads, and on heavier cars. You could also look through the catalogs and check out some of the upper and lower control arms sold for race car fabrication. Mike Quote Link to comment Share on other sites More sharing options...
dj paul Posted January 24, 2006 Author Share Posted January 24, 2006 thanks man. anyone happen to have any pictures of those irs' similar in view to mine above? i tried google search but couldnt really find good ones. so you think that would be better/easier? cuz im thinking what i see above would be fairly easy. im just looking to impede any movement except for up and down. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 24, 2006 Share Posted January 24, 2006 Here's the most recent thread about this subject, and it has links to maichor's project. Maichor's suspension swap is done and seems to work. http://forums.hybridz.org/showthread.php?t=106726 Quote Link to comment Share on other sites More sharing options...
dj paul Posted January 24, 2006 Author Share Posted January 24, 2006 oh ive seen that, what im trying to accomplish is a similar, stronger setup that i could make myself with some fabbing. not the whole rear end but just some of those components you see in the picture i posted for adjustability and strength in the outer portions of the arms. im poor as hell right now so im either looking to do something like this, or at least get some 280z rear control arms since they are supposedly stronger but i cant find any for sale. Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted January 24, 2006 Share Posted January 24, 2006 Check out the factory five cobra set up http://parts.factoryfive.com/newcatalog/chassis/irs.htm It does look like it could be a good basis for a design. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 24, 2006 Share Posted January 24, 2006 http://www.davidfarmerracing.com/c6b.html These pics are of Dave's conversion of his car to the C6 racing platform, but the parts are the exact same, as this particular tub is I believe a C5 converted. Dave Farmer is one of the regulars over in the road race section on corvetteforum.com, along with lou gigliati from LG Racing, and the acquolette boys from Phoenix Performance. Based on how compact the double Aarm design is, I don't see there being a huge issue with retrofitting these parts to a Zcar, espescially in the rear. You could do away with the composite leaf spring by going with coil over shocks with the threaded shock bodies. Mike Quote Link to comment Share on other sites More sharing options...
dj paul Posted January 24, 2006 Author Share Posted January 24, 2006 both look like good places to get ideas from, thanks guys. what im thinking about doing..... when i build the frame for my fuel cell, im going to tie it in to either side of the rear subframe (you know on either side of the spare tire well?) and box it in. im thinking about making a gusset attached to this to get the upper arms with a bent arm like on the 240sx. this the gains from this would be worth it? i dont even believe it would be that hard as im pretty good with this stuff. and one more question, use monoballs? if i do this i will def post step by step stuff so you all can use it, youll just have to stamp "DJ PAULS IDEA" on each of the bars. lol... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 24, 2006 Share Posted January 24, 2006 I don't mean to insult your intelligence, but you realize that the 240SX suspension uses a rear spindle, right? So you'd have to cut the strut tube off, and make or find a rear spindle for your new arm to attach to. If you just attached an arm to the existing strut tube it would either have to follow the existing arc of the strut tube exactly (which means that it doesn't do anything) or it would bind horrendously and break stuff. So what you're talking about is finding a coilover shock that attaches top and bottom, figuring a way to attach this to a spindle and then designing and locating links to attach to the spindle so that the suspension stays within a certain camber and toe range throughout the travel. Simpler to cut the whole subframe off a 240SX and get that in the rear of your Z I would think, by a long shot. Quote Link to comment Share on other sites More sharing options...
blueovalz 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, 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. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 24, 2006 Share Posted January 24, 2006 Bingo Terry! You're on to something there... Need to get a couple of rear uprights and hack them up. Unfortunately I gave the last good pair I had to Michael for his bigblock Z. Mike Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 24, 2006 Share Posted January 24, 2006 Have you ever tried to cut those uprights? Better have several good blades, and a 55 gallon drum of spinach close at hand! Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 24, 2006 Share Posted January 24, 2006 One more comment about what I perceived as what got this string started in the first place: A holeshot using the OEM parts causing the wheel to move forward. I find it hard to believe the metal or construction of the arm itself is responsible for anything but a negligible deflection. I find it much more likely that the bushings (rubber or polyurethane) are whats giving way. 4 bushings, all compressing a small amount add up to a large deflection. Then add some high offset wheels where the leverage against these bushings has been increased, and I cannot imagine the noted deflection not taking place. But, the Z only has these 4 bushings (plus the one at the top of the strut tower). The OEM SX/ZX suspension has 8 (if I counted correctly) that can contribute to the same issue. I would find it hard to believe that the SX/ZX suspension would be any stiffer in this regards than the Z suspension (provided using equal types of bushings), but I've been wrong many many times. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 24, 2006 Share Posted January 24, 2006 I saw an autox car about 10 years ago in CA that had a built Pinto engine and some funky front end. The rear suspension was 280Z with the strut chopped off about midway and a custom upper control arm just like your drawing Terry. That's a much better idea IMO than trying to make a DIY 5 link. Quote Link to comment Share on other sites More sharing options...
Hypertek Posted January 24, 2006 Share Posted January 24, 2006 i think one reason why teh 240sx subframe would be easier to do for some is becuase 240s are cheaper and mroe plentiful. Ive yet to see a C6 in a junk yard, or even anything from 1999 and above lol. But im not sayin this cuz I have a 240sx, but becuase no one ever really modifies the subframe. Simular suspension found on the skylines and 300zx. Usually a desired must for the rear is the rear upper control arms for camber adjustments, and rear toe arm to correct the toe from modified ride hieghts. and usually these upgrades consist of using ball pivot joints instead of bushings as the stock arms are. So I think its a good mod for someone who doesnt want to spend all thier time doing homework and or fabricating, or like the average joe like me, who just wants something effective,affordible and just drive. Quote Link to comment Share on other sites More sharing options...
dj paul Posted January 24, 2006 Author Share Posted January 24, 2006 i was wondering something like this, im thinkin since noones done this yet (as it seems a bit simple) im guessing that for some reason it wont work, or just wont make ne difference at all. now keep in mind here im not worried about adjusting camber, i just want a stronger rear end. everythings gonna be poly bushings so that will help a lot. as you can see there is a little bracket that is welded onto the strut tube itself, and right off of it is a monoball to allow vertical movement and that attaches to a similar setup on the upper rear subframe. is this even worth it? i dont even think it would be too hard and it would be kind of fun to do. but would this just be added weight? or would it actually help strengthen it. Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 24, 2006 Share Posted January 24, 2006 This is something I have considered as a project later on if I decide I have too much time on my hands. Basically, 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. If you do this turn them upside down. The lower mount them becomes an a-arm to the old strut tube the the top is a reverse a-arm and toe-link. This will make getting the geometry right a little easier while letting you burry the upright into the wheel. Here's a pic of the idea. Cary Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 24, 2006 Share Posted January 24, 2006 i was wondering something like this, im thinkin since noones done this yet (as it seems a bit simple) im guessing that for some reason it wont work, or just wont make ne difference at all. Older supras and MR2s had a strut suspension with additional arms that located the strut to take bending loads off. As John mentioned you need to figure out the anlges and articulation so you don't bind things. Another option for drag only would be what they do the front of many FWD cars. Those funky traction bars. As long as everything was in rubber or poly you could use those to keep the arms from moving, again assuming that's the real issue. If not then you need to look at making the bushings less compressible. The only option is then a monoball or heim. And since someone is good at fabrication it sounds like they would just build new tubular lower arms with heims/monoballs. Not that those are cheap. But before this all gets carried away some simple tests need to be done to understand what the problem is. cary Quote Link to comment Share on other sites More sharing options...
dj paul Posted January 24, 2006 Author Share Posted January 24, 2006 well im not having the problem yet. my cars not even road worthy. i have my entire car apart right now and am just having "while im down here" syndrome. if angles were correct would either of these setups have any benefit? or should i just leave this crap alone? like i said my car is going to be around 500rwh and i dont wanna do this stuff again (spindle pins) for a while. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 24, 2006 Share Posted January 24, 2006 The C5 and C6 suspension arms are interchangable and the C5 aluminum arms are available for $140 each from GM, inclouding bushings, ball joints and hardware. However, there are parts available elsewhere from stock car and race car suppliers that would work much better I'd think. Getting the geometry correct would be the key. I've always hated the stupid strut insert design of the original S30. Mike Quote Link to comment Share on other sites More sharing options...
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