tonycharger72 Posted May 25, 2009 Share Posted May 25, 2009 Hey guys, just thought I would post some pics of my new front suspension and steering rack, it has a bit of everything thrown in , I have used a highly modified RX7 S4/S5 Crossmember, RX7 S5 Lower Control Arms, stub axles and lower portion of the strut tube, top half of a 240z strut tube and some TTT threaded collars for a 51mm ID tube, Just so I could bolt it all in place I have used the stock rubber insulators! Initially I mounted the crossmember slightly to low and the LCA's were about at horizontal when the car was at rest, so I cut 25mm of the top of the Crossmember, which effectively moved the LCA pivots upwards 25mm, I would have just re-drilled the LCA pivot, but couldnt because the design of the RX7 Lower Control Arm! Enjoy! Top of the Z Strut! Sticking them together! Ground down! Snap-Ring for the Threaded Collars, All Together and in the car! & the LCA Angle! Quote Link to comment Share on other sites More sharing options...
bart628 Posted May 25, 2009 Share Posted May 25, 2009 Looks good. Lovin' the aluminum FC lower control arms. Quote Link to comment Share on other sites More sharing options...
blaze73 Posted May 25, 2009 Share Posted May 25, 2009 Nicely done. Any more pics of the cross member mounting and how it looks in the engine bay? Are you using the rx7 rack or the Z one? Any idea what this does to the front track width (hub to hub)? http://www.cardomain.com/ride/563982/3 This guy used the same control arms while retaining the stock struts and xmember.....sort of. Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted May 25, 2009 Author Share Posted May 25, 2009 This guy used the same control arms while retaining the stock struts and xmember.....sort of. That fellow is running a VH45 and (I assume) for similar reasons he wanted to use a crossmember that was shaped like a "K" so you more easily mount the engine as the mounts are far back on the block! Mine sort of evoled from there, I originally built a crossmember very similar to his, but then got my hands on an RX7 crossmember and decided it would fit nicely - with massive mods ! I was going to try and use S4 RX7 LCA's but it was awfully difficult to fine a balljoint that I could use with the Z strut, he mentions a "Mitsubishi" ball-joint, but no local parts stores had anything on the shelf, so ditched that idea and used the lower half of the RX7 strut and upper half from a 240z! Nicely done. Any more pics of the cross member mounting and how it looks in the engine bay? Are you using the rx7 rack or the Z one? Any idea what this does to the front track width (hub to hub)? I am using a Subaru Rack - the RX7 crossmember is way to wide, so I cut a section out and changed the LCA pivots to be 630mm apart, 30mm increase over stock Z crossmember LCA pivots, 15mm increase a side - this was to suit the Subaru Rack, then I removed 25mm from the top of the RX7 crossmember because the LCA pivots were about 105mm down from the chassis rails, which gave the LCA's a near horizontal plain, as you can see from the above pics they slope downwards to the balljoint after removing 25mm! The RX7 LCA's are pretty much identical to the Z in length and the hub offset is very similar to that of the Z, overall there was an increase because I kept the LCA pivot distance to 630mm, not 600mm (which is what they are on original Z crossmember is), so track change should be slightly wider than original, with relative increases in camber! I will post some pics of it's transformation of the crossmember! Quote Link to comment Share on other sites More sharing options...
blaze73 Posted May 26, 2009 Share Posted May 26, 2009 Cool beans man. I will be running a VH and would like to use a subaru rack as well and seeing as the stock crossmember will have to be modded for both the motor and the rack I am considering just making a custom one....of course that opens up the possibility of using different LCA's and struts and....well its really easy to fall into the "while i'm at it" trap! Looking forward to seeing how this works out for you! On a side note....do you think it would be possible to use the entire RX7 strut instead of merging the two by essentially welding in an RX7 camber plate on Z's strut tower? Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted May 26, 2009 Author Share Posted May 26, 2009 Here is some pics of the RX7 Crossmember! This is some of the Mods I made to it! Like it was never apart ! Here is some pics of the RX7 Crossmember in the car, this is before I cut 25mm of the top, but it is basically the same! I kept the Subaru Rack in the same position as the RX7 rack, which positions the rack ends quite a bit higher than the LCA pivots, in-built bump steer I guess! This was my original design, which would have worked I guess - but once I saw the RX7 Crossmember and took some measurements decided to go down that path! On a side note....do you think it would be possible to use the entire RX7 strut instead of merging the two by essentially welding in an RX7 camber plate on Z's strut tower? Not really, the stock struts from the RX7 have very wide springs - they are very wide at the top, plus the RX7 strut tops are massive, easily twice as big as the Z strut tops - the overall length was pretty close though, You couldn't just bolt the RX7 struts in, BUT...........you could do this easily enough, Just a custom spring! I didn't bother going down this path because I wanted the adjustable collars and I will eventually throw in some Koni's! But you could also look at getting some Teins and using them with Z camber plates! Quote Link to comment Share on other sites More sharing options...
Turbo7MN Posted May 31, 2009 Share Posted May 31, 2009 I come from the RX-7 forums to the Z forums and I'm still seeing things that look familiar . Excellent work. Quote Link to comment Share on other sites More sharing options...
shika805 Posted June 1, 2009 Share Posted June 1, 2009 i have a S5 rx7... thats really interesting... i never thought that work out, thats an easy swap. Will have to take a look at this next time. I'm guessing you have to customize a sway bar though. wouldnt be hard if you had the right tools Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted June 1, 2009 Author Share Posted June 1, 2009 i have a S5 rx7... thats really interesting... i never thought that work out, thats an easy swap. Will have to take a look at this next time. I'm guessing you have to customize a sway bar though. wouldnt be hard if you had the right tools Yeah, it's a bit of stuffing around, but overall really not that bad at all!!! But using the RX7 crossmember actually worked out easier than making my own deisgn! Haven't even tried connecting it up yet, but the RX7 LCA's are pretty much identical in length to the Z LCA's so sway-bar wouldn't be far of fitting................maybe ! Quote Link to comment Share on other sites More sharing options...
shika805 Posted June 2, 2009 Share Posted June 2, 2009 wow if i had my rx7 as a donner car and had all the tool to do this, i would in a heart beat... its a perfect swap to a five lug from a S5 rx7 and plus using the brake set up that the rx7 has would be awesome for the 240z. the rx7 comes with a pretty decent front 4 piston calipers... what model ground controls are you using, i know its not for the 240z (the thread looks longer) and i know thats not for a rx7, i have ground controls on my 7 and look nothing like that?... Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted June 3, 2009 Author Share Posted June 3, 2009 wow if i had my rx7 as a donner car and had all the tool to do this, i would in a heart beat... Besides my welder, which is a middle of the road, 10 year old piece of equipment, which really needs more settings , all of my equipment is mostly hand tools! I have been ummming and arrrggghhing about purchasing a mill or decent drill press, horizontal bandsaw and lathe - but this is all hobby stuff, so its tricky to justify all the expensive, so I just give my Ryobi angle grinder a real workout - go through them every 3mths or so - but just take it back to Bunnings (Local Hardware Store) and get a new one as its still under warranty! Different story with my Metabo items, nothing it seems is covered under warranty!!! But all of this stuff is trial and error, I used to take me at least 2-3 goes to get most things right, well it would annoy me and I would have to re-do it, but I find that now, just with practise I am getting much better at this sort of thing, usually get it right the first time! its a perfect swap to a five lug from a S5 rx7 and plus using the brake set up that the rx7 has would be awesome for the 240z. the rx7 comes with a pretty decent front 4 piston calipers... Yeah, and the RX7 has a couple of degrees of built in Caster, I haven't measured accurately yet, but from memory its about 3deg on the RX7, its a bit tricky to tell from the above photos, but there is certainly some caster already in those struts! Camber is really up to how much you cut out of the RX7 crossmember as the LCA's for the RX7 are pretty much identical in length to the Z LCA's and the wheel offset is very similar as well! I am using some BA Falcon Rotors I had lying around, they are 298x28mm, I just opened up the centre to suit the RX7 hub - but if you wanted to you could use the RX7 S4/S5 brakes or even buy a big brake kit for these things - have seen a few kicking around on EBAY, but lots of options there which ever way you go with it!!! what model ground controls are you using, i know its not for the 240z (the thread looks longer) and i know thats not for a rx7, i have ground controls on my 7 and look nothing like that?... The coilover kits I am using are a 10" spring with a 7" collar that are suited to a 51mm OD strut, I bought them from Gab at TTT (awesome customer service) to suit originally my 240z style struts! Just so happened they were also the perfect diameter for the RX7 strut tubes, just to long! But once I found a suitable insert, the Celica 1989-94 Fronts, I was able to graft the top of the 240z strut to the bottom of the RX7 strut, which gave me adequate length for the 7" threaded collar! Gab would have done a swap for me if needed slightly shorter threaded collars, which was awesome, but as it turned out that wasnt required because of the Celica inserts I ended up using! The celica inserts are great as well, you can purchase them in Koni's, AGX's, and plain old KYB Excel-G's! Also - there is a few companies that do cheapy coilovers - they are sh#t apparently, but Ksport will sell you bits and pieces individually! Here is a link! http://cgi.ebay.com/ebaymotors/85-91-RX-7-FC3S-Ksport-Pro-Coilovers-Springs-Shocks_W0QQcmdZViewItemQQ_trkparmsZ72Q3a570Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem58810908d3QQitemZ380121974995QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories What I was going to do originally was purchase the shocks from these guys and the lower hub spindle mount - the massive benefit to this setup is you cut out the strut insert, just like you would if you were installing Koni's in a stock RX7 S4/S5 strut tube (Koni has instructions on their website of the process), but the strut tube is threaded so you are able to raise and lower the ride height of the vehicle without changing the relationship with the spring collar and the insert itself! They also have adjustment in the hub spindle bolt holes, which allow for a little bit of camber adjustment! However, these are illegal locally and I would find it very difficult to get my car registered with them on my car! Quote Link to comment Share on other sites More sharing options...
shika805 Posted June 3, 2009 Share Posted June 3, 2009 yeah the ksports are really popular on my the rx7 forums probably be a good choice for a swap like this... good info man... i will be definitely be taking a look at this project. update us more on this later when you get everything set up!!! Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted June 7, 2009 Author Share Posted June 7, 2009 Shika805, what series RX7 have you got? I was under a lowered S5 RX7 the other day, which didn't have an engine in it and the Lower Control Arm Angles were pretty bad, they were angled upwards at maybe 15-20 degs, I am just curious as to what other S4/S5 RX7 LCA's angles look like! Quote Link to comment Share on other sites More sharing options...
bart628 Posted June 7, 2009 Share Posted June 7, 2009 From my old S4 Turbo II (KTS Coilovers, Mazdatrix outer tie-rods, Lowered about 1"). Would've corrected it by adding a spacer above the front ball joint, but sold the car before then. Compression on Macpherson strut with positive LCA angle equals positive camber; so I dialed in some negative static camber to compensate. Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted June 7, 2009 Author Share Posted June 7, 2009 Thanks for the pic mate!!! Those LCA angles are the same as the RX7 I was looking at the other day, very odd that.................. This is Jmortensen answering a question I had in another thread! Tony, you could put bumpsteer spacers on a Z at stock height and what that will do is raise the roll center. Where to set the roll center is not a clear cut thing. The suspension gets acted on differently by lateral forces depending on the roll center. When the LCA goes past horizontal, then lateral forces try to COMPRESS the outside suspension, basically making body roll worse. If the LCA is totally horizontal then there are no jacking forces on the suspension. If the LCA points down then lateral forces try to raise the outer suspension. If it's really pointing down then lateral forces can tip the car over, a la jacked up Baja Bug. If you add the bumpsteer spacer to a stock Z then as Pete said you'd put the car into another part of the bumpsteer curve, and the curve works out to be pretty gradual in the middle but fairly extreme at the ends of the suspension's travel, so you might not like the results. You can run the car with a roll center that is very low, but you need to run very heavy springs and shocks that can control those springs. For less body roll most agree that you want to run the control arms pointing "slightly down". If you're running softer springs, you'd want it pointing down a bit more. It is a trial and error thing, and you can fix the resultant body roll issues with more spring, more sway bar, or higher roll center. You aren't limited to one or the other. King Springs sell a lowering spring for the RX7 that is (from memory) about 200lbs, which dosen't appear as if it is particulary heavy, plus from what I have heard the S4/S5 RX7 is a good handling car, with an LCA angle like that you would think would be riding around on its door handles ! This is the original angle of the RX7 LCA's in my car, so I trimmed an 1" of the top of the crossmember so the angle changed from this, To this! What am I missing here? from the way I understand it, having the LCA's pointing up like that shouldn't be a good thing? Quote Link to comment Share on other sites More sharing options...
260DET Posted June 8, 2009 Share Posted June 8, 2009 Don't forget the relationship between the front and rear roll centers, basically the rear center should be higher than the front, not a lot higher but some. Getting the roll centers right is more important than getting the C of G down a bit by lowering the car so leave some room to adjust them in the overall design. Nice discovery by the way, lot of advantages in using late model steering/suspension. Oh and on your query above, the outer part of the LCA should be lower than the inner ie the arms should slope down from the inner pivot point to the outer. Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted June 8, 2009 Author Share Posted June 8, 2009 Don't forget the relationship between the front and rear roll centers, basically the rear center should be higher than the front, not a lot higher but some. Getting the roll centers right is more important than getting the C of G down a bit by lowering the car so leave some room to adjust them in the overall design. Just by taking a breif look at the rear suspension, which is basically still 100% stock, the angle of the rear LCA's is more steeply angled than that of the fronts, I will keep this in mind when it comes to designing my rear suspension! Very difficult to built in any adjustment for the roll centres - if I assume, it can really only be done by lowering/raising the LCA inner/outter pivot point and by shortening/extending the strut itselt - the RX7 LCA basically combines the Radius Rod and LCA, so unlike the Z design, I can't just shift up the LCA inner pivot point, not without also moving up the rear of the LCA, Nice discovery by the way, lot of advantages in using late model steering/suspension. Thanks Richard, for a suspension and brake upgrade this RX7 gear would be a good cheap improvement to the stock Z stuff - the fellow who's struts I pictured above just modified his LCA's to accept the RX7 ball-joint, so he still retained the stock Radius Rods - therefore, if you mixed what I did with the struts, which allows full ride height adjustability and selection of Koni, AGX or simple KYB Excel G shocks from a 1989-94 celica with a 240lb pound spring stock so the valving would be a pretty good starting point right out of the box and just that fellows idea for the modified Datsun LCA to accept the RX7 ball-joint - you would have a fairly simple and easy conversion which also provides you with alluminium hubs, 5 stud and a brake setup with 4-pot Sumitono's (thats what the S4/S5 RX7 used for front brakes) By doing this you would be able to retain Radius Rods that allow much greater adjustability that what I have in my setup - there is some caster built into the RX7 LCA's, but no real adjustment is available to me! Oh and on your query above, the outer part of the LCA should be lower than the inner ie the arms should slope down from the inner pivot point to the Thanks for that! I had a quick look around on some RX7 forums and it seems quite a few of them have S4/S5 RX7's with more horizontal looking LCA's, I think this might just be an issue with this vehicles suspension once you lower it - actually I am sure it is an issue with lots of Mac strut cars once you lower them more than a certain amount! Quote Link to comment Share on other sites More sharing options...
260DET Posted June 9, 2009 Share Posted June 9, 2009 Yeh, many cars are lowered without considering the effect on roll centers, its a very important consideration. Of course the easiest way to adjust those centers is to raise/lower the car, I'd suggest aiming to have them where you think they should be with the car in rake. By that I mean with the front of the car a bit lower than the rear, which incidentially promotes good airflow around the rear of the car. Quote Link to comment Share on other sites More sharing options...
shika805 Posted June 9, 2009 Share Posted June 9, 2009 Shika805, what series RX7 have you got? I was under a lowered S5 RX7 the other day, which didn't have an engine in it and the Lower Control Arm Angles were pretty bad, they were angled upwards at maybe 15-20 degs, I am just curious as to what other S4/S5 RX7 LCA's angles look like! not much different from S4 to S5, all the suspension is interchangable between the 2nd gens. i'm not sure about 15 to 20 degrees but they are little more aggresive than other cars i've worked on, the S4 and S5 suspensions are is very ahead of its time. Plus mazda's main goal was to enhance suspension techniques for the RX7. What other car out there, you gonna find 50/50 weight ratio distribution. Quote Link to comment Share on other sites More sharing options...
shika805 Posted June 9, 2009 Share Posted June 9, 2009 oh yeah i have a S5 rx7. Quote Link to comment Share on other sites More sharing options...
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