stony Posted May 2, 2003 Share Posted May 2, 2003 Ok you guys asked for it here it is. This is how I basically swap my suspension stuff for a z31 front and rear suspension and axles. First a friend of mine got a hold of a really low mileage wrecked 1988 turbo z31. He sold me every bit of suspension stuff I wanted for 200 bucks. I started thinking about the 500rwhp z31 I have seen still running the stock axles without any problems and decided this was the cheapest way to go. The front…… To get the bigger brakes of the z31 on my s30 I first made a few measurements…. Then I reluctantly cut the z 31 struts and the s30 struts so when put together they measured the same length as the original s30. I guess if you were going to use custom shocks any length would do. So now I have the top have of my s30 coilover and the bottom have of the z31 disc brake setup. I carefully ensured the 2 pieces were together straight and welded the together. The first obstacle was the steering knuckle. The s30 didn’t fit on the bottom of the z31 strut. So I reinstalled the z31 knuckle and pressed hoping I could make it work. The second obstacle. The AZC control arm ball joint was smaller then the z31. When I tried to bolt it in the bolt shanked out on the shaft of the ball joint. I played around with it for a while and looked for a ball joint that I could use. Then just when I was going to scrap everything and go with a set of something else my friend suggested I use a couple washers to pull the ball joint up a little more. IT WORKED. The taper is the same and the washer allowed the nut to pull the ball joint up into the socket to specified torque level with no binding. So that problem was solved. Now obstacle number 3. The steering knuckles are bent different. The s30 basically comes straight out and the z31 bends out towards the rotor. This meant the s 30 rack was going to be too short. I researched using a different rack but came up with having to mod just about anything I found. I decided to mod the s30 rack. I cut the output rods where there are no threads under the boot and added the length with chomoly tubing. It took me two times to get the right length .The first time I didn’t take into account the angle of the knuckle was going to require additional length. I measured it as if the knuckle was horizontal with the ground. At any rate once the length was right my welder used a piece of chromoly tubing that fit tight over the shafts and welded them in place. Ok now the brakes. On the front the z31 calipers were scraped for a set of z32 4 puck units and a set of metal pads. I had to retain the z31 rotors because the z32 rotors offset was wrong and didn’t fit ;<. I bent a 6 inch long piece of hard line so it lined up with the clip on in the strut, I just so happened to have a set a braided lines from my rx-7 days that fit perfect. I tried a set of z32 braided lines but the front lines were too long. And rears were too short. Another problem I had was the stock caster of the z31 strut was different then the s30 and when I put the wheels on you could see the wheel was not centered in the wheelwell. I took it to the alignment shop and tuned as much out as we could with the TC rod (AZC control arms). The measurement is 4.5 degrees now so you experts out there tell me is that good or should I go some more. That is the front in a nut shell now the back, Before I decided to start this I knew I was going to need a custom set of axles. I also had an r-200 swap already done so apply that to this before you start. I also had the AZC rear control arms, which greatly increased this working due to their adjustability. I took my strut housings to the machinist and told him I wanted to put the z31 stubs in the s30 strut housing. He said he would take a look and let me know. What I wanted to do was find a bearing that would fit the housing and the stub, but since one was metric and one was standard couldn’t do that. What we did was machine the housing to accept bigger bearings that would fit on the z31 stubs. Once this was done I installed the struts and measured from the diff seal to the flange on the strut. Then sent my z31 axles and measurements to the driveshaft shop in new York and they made me a set of chromoly axles specifically for drag racing and guarantied the shafts for 600hp. I’m sure the cvs will break before the axles do; > The calipers were done by the same machinist that did the housing here in Alaska , he basically took a piece of thick metal and welded it to the caliper base and picked up the holes to mount them on the strut. I can’t explain this process as I didn’t do it but it worked. I again made a 6 inch hard line to the bracket on the strut and used the rx7 rear lines with banjo fittings and it all worked. Does it work???? So far yes … im very happy with how the brakes work and the axles are very smooth. I will be on the dyno for some test runs and at the track within the month to see how they hold up. Wish me luck. more pics at 240z.org in my gallery (stony) Quote Link to comment Share on other sites More sharing options...
j260z Posted May 2, 2003 Share Posted May 2, 2003 awesome!!! Quote Link to comment Share on other sites More sharing options...
Guest Zachb55 Posted May 3, 2003 Share Posted May 3, 2003 i dont even understand a lot of that, and i probly wouldnt wit ha manual and all the parts in front of me so oh well, what parts exactly were made stronger or changed? i know the axles are different, but what about the suspension? did you like put new struts and springs in there too or did you weld the Z31 stuff onto the bottom of the s30 strut housing? im sure you said that up there but i dont remember... looks really great though, how much did the machining and stuff cost you? hope you have great luck with those parts, cant wait to see some low tens out of that car -Zach Quote Link to comment Share on other sites More sharing options...
stony Posted May 3, 2003 Author Share Posted May 3, 2003 i basically welded the top of the s30 struts to the bottem of the z31 struts. all in all what the conversion did was allowed me to run custom chromoly z31 turbo z axles without and adapter and converted to bigger disc brakes all at all 4 corners. so i should be able to go faster and stop quicker Quote Link to comment Share on other sites More sharing options...
j260z Posted May 6, 2003 Share Posted May 6, 2003 stony, when you did the swap did you check to see if the width between the hubs changed between the stock and the modded versions. i would be very interested to see if it changed the fronts and/or rears. the reason i ask is that i am changing over my front hubs to 5 bolts from a 300zxt but it changes the offset on the front wheels by 3/4" outward while the rears stay the same because i'm just getting them redrilled. the measurement is 2 15/16" for the 4 bolt the measurement is 3 11/16" for the 5 bolt if after all the mods your front and rear measurements are the same i would do this to my vehicle also. Quote Link to comment Share on other sites More sharing options...
stony Posted May 7, 2003 Author Share Posted May 7, 2003 you are probably right considering i completely swapped the bottem half of the strut . im running skinny tires up front and 10 inch wheels with 275 50 15 on the rear so for me it wont make a big difference Quote Link to comment Share on other sites More sharing options...
j260z Posted May 7, 2003 Share Posted May 7, 2003 if you get the chance do you think you could measure those widths up for me? i think they would be a good reference to have for anyone considering this mod. Quote Link to comment Share on other sites More sharing options...
stony Posted May 7, 2003 Author Share Posted May 7, 2003 i have the brakes on and i take them off to measure them i will have to bleed them... sorry but whenever i take them apart again i will measure them. if your really interested all youd have to do is go to a junkyard and measure it on a z31. 1988 to be exact. Quote Link to comment Share on other sites More sharing options...
stony Posted May 7, 2003 Author Share Posted May 7, 2003 no actually now that i look at the pics again the 2 hubs are on the s30 spindle. i have teh z31 wheels on which have 5.5 inch backspacing and they just bearing clear teh struts ..... i tried a set of 4 lug wheels with a similar offset with similar results.. they just bearly clear the struts. so im thinking the offset are about the same between the z31 and s30. i may be wrong. what is the concern here really? if the wheel base changes you can fix it with wheel offset. right? Quote Link to comment Share on other sites More sharing options...
j260z Posted May 7, 2003 Share Posted May 7, 2003 yeah you could fix it with offsetting the wheels. i was trying to come up with a way to get all four rims to have the same offset without having to use spacers on the rears. the other reason is i'm not fond of the gap left on the spindle with the 5 bolt hub, it looks like dirt could get in there a lot easier. Quote Link to comment Share on other sites More sharing options...
stony Posted May 7, 2003 Author Share Posted May 7, 2003 remember i didnt use the s30 spindle for that reason... mine is a z31 spindle which does not have that space. Quote Link to comment Share on other sites More sharing options...
j260z Posted May 7, 2003 Share Posted May 7, 2003 exactly!! and that is why i like your attitude and attention to detail. first class!! Quote Link to comment Share on other sites More sharing options...
j260z Posted May 13, 2003 Share Posted May 13, 2003 stony, can you remember what size socket fits on the stub axle nut on your z31's. i'm thinking it's about a 30mm but they are so recessed that it's hard to measure. i don't have a socket that large and would like to buy the right one right off the bat. Quote Link to comment Share on other sites More sharing options...
stony Posted May 13, 2003 Author Share Posted May 13, 2003 sorry i didnt have one either we took it apart at my friends shop Quote Link to comment Share on other sites More sharing options...
j260z Posted May 14, 2003 Share Posted May 14, 2003 the bolt size is 30mm. when i picked up the front suspension from a 85 z31t today i noticed that the steering knuckles pointed towards the engine. granted the steering is set up behind the control arm unlike the s30 which is in front. my question is why did you set up your system with the knuckles pointing outward rather than just swapping them side to side and have them pointing inward. would this make your steering too long? lastly, do you know how long you lengthened your steering by? Quote Link to comment Share on other sites More sharing options...
stony Posted May 14, 2003 Author Share Posted May 14, 2003 You can’t swap them so they point in... They have to point out. You will have to trim the brake shielding for them to fit. You will also more then likely have to use a washer to pull the ball joint up hi enough into the socket. As for the length of the extension I’m not sure. heres what I did. I cut the tierod and put a small tack weld on the surface of the rod. then I slipped a piece of chomoly tubing over the rod . this allowed the tube to fit tight enough that I had to use slight force with a hammer to get the adjustment right. you could also put a small crease or something to get it to bind Alltel. Now I assembled the tierods and bolted them together and adjusted the toe till I had a slight amount of toe out and enough threads to adjust it out and still have good thread engagement. Once I was satisfied everything was right I removed the rack and took it back to the welder and had it tig welded. Something you also have to be concerned with is if your using stock control arms you may get allot or extra camber as I think the stock z31 control arms are longer then the stock s30. Also the caster is different ... so much so you can actually see that the wheels moved aft in the wheelwell. I just adjusted this out with the TC rod on the AZC control arms. Initial measurements looked good on the alignment machine. I will have final measurement by the end of the week when I have my new wheels installed and the car sitting at the ride height I want. Let me know how it goes. fell free to ask questions, as you need to this is still fresh in my head ;> Quote Link to comment Share on other sites More sharing options...
stony Posted May 14, 2003 Author Share Posted May 14, 2003 the piece of tubing that was welded in measures 3 inches but like i said both ends of the cut tierod were hammered about and 1/8 of an inch into the tubing. Quote Link to comment Share on other sites More sharing options...
j260z Posted May 14, 2003 Share Posted May 14, 2003 did you lengthen both rods the same amount or did you only do one side? Quote Link to comment Share on other sites More sharing options...
stony Posted May 15, 2003 Author Share Posted May 15, 2003 both sides equally Quote Link to comment Share on other sites More sharing options...
j260z Posted May 15, 2003 Share Posted May 15, 2003 the reason i ask is because i'm looking at trying to put a power steering rack in and with the rack being an inch longer to begin with the tie rods would end up being shorter than the ones on the stock unit which isn't possible. with this setup, between the knuckles adding length and using the shorter subaru tie rod ends, i should gain roughly 5" on either side. cool! what do you think of cutting off the whole tube on the z31 strut and repositioning the s30 tube so as to bring the camber back? i'm not sure you could do anything about the caster except lengthen the t/c arms. by the way, which rotors and calipers are you using on your rear setup? your input is much appreciated!! Quote Link to comment Share on other sites More sharing options...
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