Suspension Suggestions...Project

[mhl0521]

I am in the process of gethering up components for a project car.

Using a 240Z shell and building a GT1/Trans Am style square tube chassis. Car will probably be 99% street toy but might gravitate towards some track days or something.

Anyway, doing the build myself and as low buck as possible with no high dollar components and minimal new aftermarket...race classifieds, Craigslist and Ebay will be my main shopping source.

Plans are to use a VQ35DE engine and 6 speed.

I want to use conventional upper and lower control arms and coil overs front and rear and OEM hubs and spindles. I will go with aftermarket control arms if available. 5x114.3 wheel bolt pattern.

I am going to pull the front fenders and rear quarters out approximately 3" per side depending on variables when that time comes, so I do not need to stay within the current 240z body confines.

I picked up a Q45 VLSD with a 3:71 gear on the cheap so I want to use that which I believe lends itself to going ahead and using 240sx suspension in the rear...anybody confirm this as a decent choice and which models 240sx would be best to source...13/14/15? I understand the rear is multi-link.

Are there any Nissan options for front suspension that are not strut?
I have been thinking about Toyota Supra front suspension.

Thanks for any input!!

[Tower240sx]

Z32 front is not strut, I do believe it is double wishbone, also skylines.

rear suspensions are all so similar, only differences as far as fitting goes are the width differences of 5mm (per side) between the s13 and the s14/15, also Z32 rear suspension becomes a clear option aswell basically the same just a width difference again,

IF alot of power is in the works I believe the Z32 TT had a slightly larger Diff (R230 right??) that may be worth a look since you are starting at scratch anyway...

[Matt93SE]

The R200 should be plenty strong enough to hold whatever he's going to put on it for a street car. guys running 600+hp are still drag racing on them. I wouldn't worry about that part.

Supposedly the S14/S15 rear subframe is a bit better than the S13, but yeah the Z32 subframe is several inches wider- arms are the same length though. I'm goign to guess you proabbly want to look at an S13 or S14 subframe due to the track width. depends on how wide you're going to make the car in the end.

on that note, widening a subframe is easy enough if you're doing that much fab work.

and do you really want to keep an IRS? It would be much easier to go to a 3 or 4 link rear suspsneion at that point and stick a 9" ford back there. but yeah, an independent susp will be cooler. not as easy to set up though.

For fronts.. the Z32 or Z33 is probably your best bet for a nissan application. Z31 and all S-chassis use McStrut suspensions.
Before you mess with that, I'd look at the front end off a Corvette or Camaro or something if you have the room. it's way lighter than a Z setup and easier to buy go fast parts for.

[Tower240sx]

matt...did you really just suggest a solid rear axle, and then infer that GM could possibly engineer something stiffer than a noodle and have it weigh less than equivalent nissan parts?

Please return after therapy or coffee which ever is appropriate...

[spent]

If you're doing q45 rearend and VQ swap, I'd recommend the 3.54 fd. I have VQ and 3.9 J30 diff and I'm now switching to 3.54 q45. If something taller was readily avaliable, I'd personally would go taller, especially if you plan on FI down the road. Traction will be a problem with street tires even with stock hp.

[240sxTTC]

It's so funny I'm running a 4.90 gear set and it's perfect for NA. However I liked the 4.08 with the turbo motor on the track.

[CodyAce]

matt...did you really just suggest a solid rear axle, and then infer that GM could possibly engineer something stiffer than a noodle and have it weigh less than equivalent nissan parts?

Please return after therapy or coffee which ever is appropriate...

C4 setup would probably be close to same weight, what's required to fab it in though into an older Z is beyond me having never really worked on an old Z. Knowing Z guys there may even be a kit available lol




....let me know, as I'd love to do a V8/vette suspension in a Z someday...sigh why did I ever start with the S14

[WorkInProgressK]

matt...did you really just suggest a solid rear axle, and then infer that GM could possibly engineer something stiffer than a noodle and have it weigh less than equivalent nissan parts?

Please return after therapy or coffee which ever is appropriate...

In before: I said front end.

For the rear parts : s14 definitively :P less anti squat and none of them have Hi-cas, S15 are problably more expensive and harder to find at JDM and local scrap yards.

[josh18_2k]

miata or FD rx7 suspension might do you well. FD stuff is gonna be hard to find, but definaely works well. miata stuff is abundant, and pretty small/light so packaging should be easy

[Def]

S13/S14 subframes are relatively easy to swap into these cars. They didn't change the basic frame structure too much, so it's some "minor" cut/weld/fab to get the subframe studs in there.

I think a 3/4-link would be a little more involved once you get down to trying to figure out your roll center/roll center migration etc.

Front suspension... I'd probably just keep it easy and try to do an S13 front. If I were doing a dual A-arm setup, I think I'd just make the crap from scratch and forget trying to adapt heavy stock components that will probably need to be endlessly fiddled with to get good camber and toe curves.

[spent]

It's so funny I'm running a 4.90 gear set and it's perfect for NA. However I liked the 4.08 with the turbo motor on the track.

The 6 speed out of a 350z has much shorter gears than a 5 speed 240sx.

For example, using your 4.08 as a comparison...

1st 4.08 x 3.321 240sx = FD x 3.794 350z
350z FD equivalent = 3.58


2nd 4.08 x 1.902 240sx = FD x 2.324 350z
350z FD equivalent = 3.34


3rd 4.08 x 1.308 240sx = FD x 1.624 350z
350z FD equivalent = 3.27


4th 4.08 x 1.0 240sx = FD x 1.271 350z
350z FD equivalent = 3.21


5th 4.08 x .759 240sx = FD x 1 350z
350z FD equivalent = 3.09

Not only does the 350z 6 speed have more shorter gears, but it is also going to have more lowend torque than any turbo KA or SR that revs to a decent RPM without running out of steam...

I really think you would enjoy the car with a taller FD... just my opinion. I have a basically stock VQ and the 3.9 is too short for my application, autocross. Off the line I have to start easy to not smoke the tires and I have to shift to third in mid/low 50s and that is with the RPM limiter bumped up to 7k...

[mhl0521]

OK...I also wonder about 350Z rear suspension...snooping on Ebay that stuff can be had quite reasonable and they are aluminum uprights. I guessing someone makes an aftermarket lower control arm so I could go with a coilover setup...or fab up a lower.

Actually it also would appear that the front suspension from the 350z would be a good candidate.

I know I posted in the wrong part of the forum to maybe get much input on this but maybe somebody could chime in.

I need to talk to a CV shop to see if axles can be made that will work with the Q45...unless I go with something else. Maybe the 350z diff should be considered...or stick with whatever diff I end up using for rear suspension and quit trying to complicate things?


I don't THINK I will use front or rear subframes but will work all the mounting points into the chassis design. Am I correct in thinking that I should be able to get all the suspension mounting dims/location points from a frame shop? I messed with a project years ago and seem to remember we did that?

I just have to settle in on front and rear suspension in the next month or so as I hope to be ready to start with the chassis by then. Currently gutting the car and building a chassis jig.

and thanks for all the input so far...I am still digesting it.

[Def]

The 350Z stock stuff is pretty horrible for tearing up bushings, and the parts to replace all the bushings are $$$. The aluminum subframe is thick as hell, so I doubt it's going to save all that much weight over the somewhat smaller steel S13/S14 subframe.

As for the FD, lots of Z33 guys go to 4.08 gears in the rear. I'd think a 3.9 would be perfectly fine, especially with some slightly taller tires.

[Def]

The 6 speed out of a 350z has much shorter gears than a 5 speed 240sx.

For example, using your 4.08 as a comparison...

1st 4.08 x 3.321 240sx = FD x 3.794 350z
350z FD equivalent = 3.58


2nd 4.08 x 1.902 240sx = FD x 2.324 350z
350z FD equivalent = 3.34


3rd 4.08 x 1.308 240sx = FD x 1.624 350z
350z FD equivalent = 3.27


4th 4.08 x 1.0 240sx = FD x 1.271 350z
350z FD equivalent = 3.21


5th 4.08 x .759 240sx = FD x 1 350z
350z FD equivalent = 3.09

Not only does the 350z 6 speed have more shorter gears, but it is also going to have more lowend torque than any turbo KA or SR that revs to a decent RPM without running out of steam...

I really think you would enjoy the car with a taller FD... just my opinion. I have a basically stock VQ and the 3.9 is too short for my application, autocross. Off the line I have to start easy to not smoke the tires and I have to shift to third in mid/low 50s and that is with the RPM limiter bumped up to 7k...

Keep in mind a Z33 has larger diameter tires stock than an S13/S14. I hated my car with a 4.08 - gears were way too long with 255/40-17s. With a 4.36 it's still a little long in some gears, especially 5th. Lots of guys use a 4.6 with no problem.


Might not work great for autox since you typically want a longer 2nd gear just to eliminate shifts, but for anything else shorter gears are typically a better match.

[mhl0521]

I actually just bought the drivers side front and rear upright/hub off ebay. Snooping around to see who makes what for tubular control arms...at least before I buy the OEM ones wich are a nice looking piece anyway.