tonycharger72 Posted January 22, 2009 Share Posted January 22, 2009 I have had good look around on Hybridz and can only find one example of a Double-A Arm front suspenion modification in a Z, fellow put Lexus front end into his Z, Has anyone else done this conversion on their Z? Be interested to see what setups were used and how fitiment issues were tackled!!! Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 22, 2009 Share Posted January 22, 2009 Cool question. I just breifly thought about it. It would require some modification but certainly not beyond the scope of some people on this site. Design a feasible layout using the stock Z strut tubes and lower suspension. Cut off the top of the stock strut housings at the correct height, weld on a machined pivot and bearing boss for an upper A-arm. Weld some reinforced mount points on the inner fender for the inner A-arm bushings. The toughest part is finding a spring strut combo that can fit diagonally from the outer LCA to the inner A-arm. It would be really cool to see. Quote Link to comment Share on other sites More sharing options...
NZeder Posted January 22, 2009 Share Posted January 22, 2009 Lots of MX5 around (miata) and they have a front mounted rack too. Track increases issues might be a problem for some countries if the car is going to be road legal. Stock 260z front track 1359mm (I chose 260z as both you and I have 260z ) Mx5 front track 1410 for the NA and NB with the NC at 1405mm. I can't find a pic of the MX5 front suspension setup on it own.... Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 22, 2009 Share Posted January 22, 2009 Design a feasible layout using the stock Z strut tubes and lower suspension. Cut off the top of the stock strut housings at the correct height, weld on a machined pivot and bearing boss for an upper A-arm. Weld some reinforced mount points on the inner fender for the inner A-arm bushings. The toughest part is finding a spring strut combo that can fit diagonally from the outer LCA to the inner A-arm. The problem with this approach is you will have very close to the same king pin inclination (KPI) as the stock strut. The shock isn't that much of an issue. This has been done on a similar cars and doesn't really end up giving the jump in performance that you may expect. It's cool and sooner or later it will be done. Cary Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted January 22, 2009 Author Share Posted January 22, 2009 The problem with this approach is you will have very close to the same king pin inclination (KPI) as the stock strut. The shock isn't that much of an issue. This has been done on a similar cars and doesn't really end up giving the jump in performance that you may expect. It's cool and sooner or later it will be done. If you slapped in some other cars front suspension into the Z strut towers and its Kingpin inclination has now changed to suit the Z's, wouldn't you be stuffing around with that car's suspension that you transplanted, primarily its scrub radius - most likely making it worse and end up with a crappy conversion? Unless you could modify the stock strut towers so you could more or less mount the shocks in the same location as they were found from the donor vehicle, you would probably be better of whipping up your own design? Quote Link to comment Share on other sites More sharing options...
zguy36 Posted January 22, 2009 Share Posted January 22, 2009 I am in process of putting an '88 fiero front suspension into a 1600 roadster. I would imagine that it would be fairly easy to do the same swap into a Z. This suspension is 'self contained' and does not require strut towers. Instead of a strut, the spring is located between the upper and lower control arms, similar to a mustang II. These are also front steer. Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted January 22, 2009 Author Share Posted January 22, 2009 Ooppss, measursing Kingpin inclination through the ball-joints, Macpherson strut (like the Z's) measure this angle through the top of the strut tower as it doesnt have a upper ball-joint, on a double A-Arm setup you have two ball-joints so strut tower placement isnt as critical right?, even if your donor's vechiles strut was moved about to suit the Z wouldn't cause all that many issues? I would actually prefer to stick the rack behind the crossmember if possible, make my engine conversion easy I think !!! Quote Link to comment Share on other sites More sharing options...
NZeder Posted January 22, 2009 Share Posted January 22, 2009 There a many Lotus 7 Replica manufactures around maybe they might have a solution that could work in kit set form. I see an number of them are now doing inboard front setups (might be a problem on the zed as the engine will be in the way) but these inboard setup do have advantages. Inboard Front Suspension A major failing of the conventional placement of the spring/shock absorber is called falling rate suspension. As the wheel progresses through its bump travel the spring becomes increasingly horizontal and thereby becoming softer in the vertical direction (the one that matters). At absolutely horizontal of course the effective spring rate is 0. By introducing a pushrod and rocker assembly, carefully engineered, the angle of the pushrod to rocker and rocker to shock can be maintained as a near right angle at ride height therefore introducing rising rate suspension. This is of course more desirable giving a more linear wheel deflection and better control. It has resulted in much lighter springs being required to do the same job. There is significantly less unsprung weight in replacing the coil/shock with a pushrod. Ride height is easily adjusted with pushrod length. Option 4, Race set up, uses: * Triumph uprights for liteweight (new or second hand) * Triumph trunnion replaced with lower spherical joint conversion * Widetrack / Inboard * Alloy Hubs cast for 4 1/4" P.C.D. * Provision for 4 pot vented rotor brake kit * A very lightweight effective design for the ultimate * Inboard Front susp is inclusive The above is from one of the local NZ Lotus 7 Replica builders on their front suspension setup. Would be a lot of work but doable I guess. Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 22, 2009 Share Posted January 22, 2009 Inboard Front Suspension A major failing of the conventional placement of the spring/shock absorber is called falling rate suspension. As the wheel progresses through its bump travel the spring becomes increasingly horizontal and thereby becoming softer in the vertical direction (the one that matters). At absolutely horizontal of course the effective spring rate is 0. Also true in with the strut. And with a rocker it's very hard to get a linear range over the travel a street car generally has. There is significantly less unsprung weight in replacing the coil/shock with a pushrod. I hear this one often used as a selling point. But I don't think it's correct. While technically the shock and spring are now bolted to the car they still move when the wheel is raised and lowered. So I'm not seeing how this is less unsprung weight. Perhaps by some definition it is. It is more intertia that needs to move and more friction because of additional joints. Quote Link to comment Share on other sites More sharing options...
260DET Posted January 23, 2009 Share Posted January 23, 2009 Unless you are going to build the ultimate S30 then the cost/benefit return from changing to double A arms at the front is dubious. Strut design has progressed a long way since the S30's, you could do a lot worse than changing to a S13/14/15 setup, the latter two for a gratis five stud conversion. Plus you get a more Ackerman friendly rear mount steering rack and PS if you want that. Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted January 24, 2009 Author Share Posted January 24, 2009 Unless you are going to build the ultimate S30 then the cost/benefit return from changing to double A arms at the front is dubious. Strut design has progressed a long way since the S30's, you could do a lot worse than changing to a S13/14/15 setup, the latter two for a gratis five stud conversion. Plus you get a more Ackerman friendly rear mount steering rack and PS if you want that. Not really the point of the thread mate , sure there is lots of stuff folks do to their Z's that is probably a bit wasteful, like the two weeks after work I spent making fibreglass guards to evnentually decide I would prefer to just stick with stock wheel flares (made fibreglass guards with integrated ZG flares) I am interested to see how many people have actually done this and what they did to make it all work! I got my hands on an MX5 Crossmember, funny looking little thing! But, I really think it would fit, the distance between the LCA' is about 630mm, not to different from the Z, however you would most likely have to shorten the Miata Control arms if you wanted to run anything more than 185mm tyres and keep them under the guards, Enjoy guys!!! Arrows point to the Upper and Lower control arm mount points - the 810mm measurement is where the crossmember bolts to the frame and the 710mm measurement is for the Upper Control Arm mounting points, weird design, sits in-bound of where the crossmember bolts to the chassis! Pic from the front, It would certainly be easier to use the Miata Rack with this setup ! & this is what I think would be required to get the MX5 into your Z, I think it would be far to difficult to use the MX5 crossmember though, be probably a lot easier to build ur own crossmember and use the MX5 arms maybe! Quote Link to comment Share on other sites More sharing options...
NZeder Posted January 26, 2009 Share Posted January 26, 2009 Maybe you could fab up a frame like these guy do for the MX5 for installing a V8 see there production section http://www.v8roadsters.com/Products/ Quote Link to comment Share on other sites More sharing options...
260DET Posted January 26, 2009 Share Posted January 26, 2009 Not trying to discourage anyone from doing a double A arm conversion, provided they aware of the challenges involved. Really to do it properly the car would need to be put on an alignment frame so the new mounting points can be located accurately so its not really your average DIY project. There have been previous discussions on this same topic with pics and measurements of various possible donor parts. It would also be possible to make up a front end from parts available from those stockcar race places. Anyway, here is a sketch of a double A arm conversion of a stock rear strut I took from this forum years ago. Sorry don't know who the original poster was, perhaps something similar could be done for the front. From memory someone actually did this conversion. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 26, 2009 Share Posted January 26, 2009 That sketch is Terry's. I don't think he ever actually fabbed that up though. In fact, I think he went full monoball in the rear and that was that. Pics here: http://www.fototime.com/ftweb/bin/ft.dll/pictures?userid={7DC317B0-8EDB-4B2E-A837-F708D07C9769}&inv=9C67398D46D99D9&userid={7DC317B0-8EDB-4B2E-A837-F708D07C9769}&AlbumId={D383C2E2-8DC2-4EBF-A7B7-068689BD893D}&inv=9C67398D46D99D9&GroupId={6D2BD180-CD3C-43B3-B9F2-1BEB95FCD9B5}&nt=a Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted January 27, 2009 Author Share Posted January 27, 2009 Not trying to discourage anyone from doing a double A arm conversion, provided they aware of the challenges involved. Really to do it properly the car would need to be put on an alignment frame so the new mounting points can be located accurately so its not really your average DIY project. There have been previous discussions on this same topic with pics and measurements of various possible donor parts. It would also be possible to make up a front end from parts available from those stockcar race places. Anyway, here is a sketch of a double A arm conversion of a stock rear strut I took from this forum years ago. Sorry don't know who the original poster was, perhaps something similar could be done for the front. From memory someone actually did this conversion. All you have to do is have a good look at the Z suspension, a crossmember from a Double A-Arm car and you will quickly see there are some challenges involved !!! But your right, something like this wouldn't be like slotting your LCA pivots, But for the folks who have installed R32/S13/S14 rear ends, I really don't think there is that much more involved as far as fabrication is concerned, providing you can find a suitable donor car so you are not fabricating everything from scratch!!! Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted January 27, 2009 Author Share Posted January 27, 2009 I think this might be a more likely candiate for a double A-Arm setup - its from an Rx7 - I think the scrub radius is still determined via the top of the strut, not the upper ball-joint - the upper arms kinda hang and would be just bolted up to the inner guards, so would be able to avoid creating new chassis rails, just reinforce the inner guards where the upper arms would be bolted to! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 27, 2009 Share Posted January 27, 2009 I think this might be a more likely candiate for a double A-Arm setup - its from an Rx7 - I think the scrub radius is still determined via the top of the strut, not the upper ball-joint - the upper arms kinda hang and would be just bolted up to the inner guards, so would be able to avoid creating new chassis rails, just reinforce the inner guards where the upper arms would be bolted to! I think the strut there doesn't really have anything to do with the suspension angles, caster, camber, etc. and also wouldn't affect scrub. That strut is just bolted in with a pivot at each end, so it moves independently of the upright (spindle). The spindle's angle is controlled by the upper and lower ball joints and so the control arms are doing the work of setting and controlling angles. Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted January 27, 2009 Author Share Posted January 27, 2009 It does certainly look that way, this is from a Series 6 I think, maybe its more like the Z in the series 4/5, local Rotary/RX7 guy told me about the upper arms being more of a brace, so besides really early RX7 suspension (which from memory looks pretty much the same as stock Z stuff) and that picture, I have limited first hand knowledge, However, even if the Scrub isn't controlled via the top of the strut tube and its just there to keep the car at height, the design still looks very adaptable to the Z just because of the mountings for the upper arms - I will have to look at a late 80's, early 90's RX7 and see what the upper-control arm mounting points look like! Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 28, 2009 Share Posted January 28, 2009 I am trying to understand why that RX-7 setup is any better than any of the other double wishbone setups we have seen so far (Lexus, Miata, cut up stock stuff, etc...). Just trying to understand why it is/was proposed? Am I missing something? Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted January 28, 2009 Author Share Posted January 28, 2009 I am trying to understand why that RX-7 setup is any better than any of the other double wishbone setups we have seen so far (Lexus, Miata, cut up stock stuff, etc...). Just trying to understand why it is/was proposed? Am I missing something? Sorry - the stuff I have measured from the RX7 is shorter , The MX5 lower arms are really long, the Lexus stuff looks very wide to me - the RX7 lower arms are almost the same length as the Z lower arms, about 300mm instead of around 285-290mm, Also the Lower Control Arms from the Mazda will bolt into the Z crossmember with the help of two 2mm washers (the LCA/Part mount is 60mm as opposed to the Z's 64mm width), Then you just away with the TC bucket and make a mount to suit the rear of the RX7 control arm, Then you would most likely just install some sort of reinforcement on the inner side of the guards, then mount a couple of clevis's to hold the Upper Control arms of the RX7 in place, Then mount in the struts, a fellow in Australia seems to have modified the RX7 strut tower to mate the Z strut tops in place, So hey-presto, double-A Arms that maintain close to original track width and geometry, Seems a bit easier, in theory, than hacking up the chassis rails for the Miata or Lexus stuff 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.