Another guy asking for suspension info. *Long first post*

[Sijonda]

Ok. I dug around and talked to a mechanic who isn't really a Nissan guy but has some track experience with this 80s Supra but is mostly a Honda guy so I'm looking to ask some 240sx owners their opinion on what I should get for coilovers on my car. After everything I've read about what different people have and use I understand there are a whole bunch of options I can work with but as for reliability I think I'll work with a higher budget and stick with TEIN instead of any of the other companies. My goal here is a 300-350 whp “at the most” track car. Currently I'm avoiding working on the engine because I know I need to work on my suspension first and I can work on wheels and tires later when I'm ready to get serious with it but I'd like to get some info on fitment on this as well. I know what wheel sizes and tires I want I just want to know if there are any reasons why I should't go with what I've decided on.

Now what I have currently is a 91 240sx SE with the HICAS lockup bar in place and a pretty much stock SR20 blacktop with a Greddy intercooler and a 3” full Tanabe exhaust with a high flow CAT. I'm not worried about power here I know I need to work on my suspension right now before power. As for what I've already replaced, I have Megan lower control arms and tensioners on the front only from replacting the factory set which I pretty much ripped in half from curbing the car last year. I was on a budget so I know I could have done better but it's already been done. I also have aftermarket sway bar end links and a new steering rack and new tie rod ends. On the way back from the track today I noticed my front passenger side wheel is a little lose and tends to jerk my car left or right wile driving so I'll handle that myself. I know I must have knocked something loose or broke something else.

I just came back from Carlise this weekend and I seriously realized I was the only guy there with stock suspension and my times showed it (was about 6 seconds slower than the quickest guy there) so I'm looking to work toward a ciruit track/autocross car and I still plan on driving it to and from work on sunny days (not my main car but I do love driving it as often as possible). I tried out drifting with it and it was really fun but I get the impression I'm just beating the piss out of my drivetrain and engine which kinda puts a hamper on the fun factor once I actually get out of the car and take a look at how the car handled it. So I'm going to keep out of drifting at least until I feel the car is upgraded enough to handle such stress.
Now on to the questions. Hopefully most of the people who managed to read through all of that are the ones who can give me some solid answers.

1. Coilovers: I'm looking to get a set of TEIN Flex Coilovers but I saw a few notes on them mentioning I may need wheel spacers if I'm using the stock wheels and tires. I'm not planning on spending the cash on wheels and tires until I'm done with my suspension upgrades (currently stock wheels with 205/60/R15 on the front and 215/60/R15 on the back) I don't want to need to use wheel spacers with my stock setup or after I get wider wheels all around (I'm stuck between 225 or 245 in the front. Reason being I found a whole bunch of tire options for the sizes I want) So I'm split between the Flex and the Super Street coilovers. I'm not worried about having a super hard ride. I rode in a friends civic with some seriously siff suspension and yea it was annoying but I could live with it if that's where I need to be.

2. Wheels and Tires: I'm looking to fit 245/45 R17 tires on a 17x8 or 17x9 wheel on the back of the car. I don't want to go any bigger than that and I feel that should handle my power goal just fine. What I'm stuck on is the tires size for the front wheels. I understand the car is balanced 50/50 so the question here is would it be a bad idea to fit identical tires on the front or should I go with something like 225/45 R17 tires? I want to run the 45 wall height in the back because the speedometer seems to read correctly with taller tires vs 205/60/R15 tires where it reads like 5 over what I'm actually doing and just gets worse the faster I go. Plus when I got the car there were 215/65R15 tires on the back and seemed to fit perfectly fine.

3. Differential gear ratio: Currently I know I've got a 4.03 ratio as the stock VLSD diff for a 240sx. What I want to switch to is a 3.7 or 3.6 from a Q45 or something like that. I've read that when looking for diffs I should stay away from the NA 300ZX rear diff because it will “slow down” my car. From what I've seen it has the same 3.7 ratio as the Q45 does so I'm assuming this is in reference to being not as quick through the gears as opposed to actual speed. I'm looking to stretch out my gears and gain speed as opposed to closing the gap between them so incrase acceleration. I think I should work on increasing power to compensate for the longer gears instead of shortening everything up so I just want to see if there is anything I'm not considering or if I'm not looking at this the right way. I'm taking into account that I'll be mostly driving the car to all of the events and tracks I will be attending so I'm also considering cruising speed in 5th.


I hope this wasn't too much of a novel but I wanted to put down as much info as I could think of.
Thanks in advance for any answeres I get back.

[adrianfromthecastle]

so exactly what kind of driving are you intending on doing? occasional drifting? autox? drag?

Personally, I'm running Dmax coilovers with a spring rate of 8kg/6kg front/rears respectively. I've been dailying this thing with the occasional drift events for the past 3 years and have no complaints what so ever. Actually, a bunch of my friends with similar spring rates always compliment my ride feel when they drive in it. If I can recommend a set to get, these would be the ones, or at least something similar (inverted monotube type coilovers).

[Sijonda]

so exactly what kind of driving are you intending on doing? occasional drifting? autox? drag?

Personally, I'm running Dmax coilovers with a spring rate of 8kg/6kg front/rears respectively. I've been dailying this thing with the occasional drift events for the past 3 years and have no complaints what so ever. Actually, a bunch of my friends with similar spring rates always compliment my ride feel when they drive in it. If I can recommend a set to get, these would be the ones, or at least something similar (inverted monotube type coilovers).

Mostly track use. The car will probably spend 80% of it's life on the street as casual driving but I want it setup as a "basic" circuit track car.

I'll dig around and see what I can find on how "monotube" coilovers work. I saw a few people mention that design but I don't know what it's supposed to be. Thanks for the info, I got some digging around to do now . I'll keep in mind the 8kg/6kg setup. I figured I would stay away from anything above 10kg since that seems to be for heavy racing only. Not where I want to be.

Again thanks for the info.

[Sijonda]

Found an excellent thread on the differences between monotube and twintube.
http://www.clublexus.com/forums/suspens ... -tein.html

So I'll keep an eye out for 8kg/6kg TEIN twintube coilovers. I'm still worried about hear I may need wheel spacers though. Still hoping someone can snuff that out for me so I won't have to worry about it.

[adrianfromthecastle]

yup no prob.

as far as diff, if you want vlsd... I'd just go with a j30. its practically a direct drop in (you have to swap the axles too) and i believe the gear ratio is like 3.9 or something close.
http://www.ka24development.com/vlsd.html

I have a j30 sitting in my rear subframe with SPL diff bushings and I must say, for a vlsd, its really not bad. I mean, it should suffice until I get a clutch type lsd.

[Sijonda]

Ok. Looks like I'll hang onto my stock VLSD diff for a wile then. It still works, just wanted the longer ratio. I'll see if I can find anything on trying to figure out if it's possible to change the guts out but that was also something that looked to be not possible for the VLSD compared to the open diff.

[compactfean]

^^^??? Very possible. I'm running the q45 guts in my stock housing.

[Sijonda]

^^^??? Very possible. I'm running the q45 guts in my stock housing.

Really???? which diff did you have? The open diff or did you bave a VLSD in the 240 and swapped in the guts from the VLSD of the Q45? I'm extremely interested in this. What was involved? I'm sure there are plenty of people wanting this answer since I've never heard of someone changing the guts on the VLSD from a different version of R200V.

[compactfean]

I used the vlsd section and output shafts and installed it into my stock non vlsd with the 4.08 gears. I did this for 2 reasons, 1 so I wouldn't have to spend the money on the solid diff.bushings and 2,.q45 final drive ratio sucks for turbo!. And if you have a j30 diff ou didn't like that gear ratio either, even though they are pretty close I noticed a difference and didn't match well with my gt3071r turbo.

[compactfean]

Another good reason would be because the j30//q45 diffs are abs which for some cars.requires a shorter driveshaft. here is a link with some good info from when I did mine. I was gonna do a wright up on it but didn't have much interest. hybrid-q45-diff-swap-which-housing-and-why-t550129.html

[Sijonda]

Another good reason would be because the j30//q45 diffs are abs which for some cars.requires a shorter driveshaft. here is a link with some good info from when I did mine. I was gonna do a wright up on it but didn't have much interest. hybrid-q45-diff-swap-which-housing-and-why-t550129.html

Ok, I've heard people say the Q45 ratio sucks in a 240 and I do hace an SR20 swapped in but in what way does the longer ratio actually suck? Just takes longer to accelerate or does it bog down the engine really bad until the turbo spools up? These were also the questions I had before that nobody explains othr than a short "Don't do it". The plan is to get up to 300whp but I know that regardless of how much power I'll be pushing with the turbo I'll still be working with a regular 2.0L 4 cylinder engine until the turbo spools which for driving around town isn't often for my relaxed driving (I get mid high 20s in MPG). My 240 had every option you could think of except for the HUD since it's a hatch so I already have the shorter drive shaft but I need to change it out anyway because the joints may be getting loose. So it sounds like because I already have a VLSD I can't swap the guts so I'm stuck with swapping the entire thing out with an open diff housing and rebuild that with what I want before putting it in or swapping it out with something else. If having the longer ratios will seriously hamper my acceleration to where it just puts stress on the engine then I won't do it but I need an explanation before I agree with anyone.

[compactfean]

Gear ratios aren't something that are just good or bad, you have to find out where your peak torque is (dyno results from similar builds will help in your gear ratio choice. Notice how I haven't said don't do it! Lol. For my personal build with the rev limit that I have and the turbo that I have with the size of tires I have in the rear, every time I shifted (when drag racing) then next gear I would fall out of boost and have to waite to recover pressure. Im now back to the 4.08 gears and tuned it another 500 rpm more on thr rev limit and don't fall out of boost anymore (this is with 26” tires). If you have a vlsd already in the car you can still swap the guts but I don't understand why you would want to. If its just to keep your stock gear ratio and your vlsd is toast, than yeah swap the guts, otherwise if you want whatever gear ratio that is in the diff you purchased, just swap the entire diff. For example, lets say you build your sr with a some very quick spooling cams and turbo so your power kicks in very soon (2800 rpm) and falls off by 6000 rpms. Id would set my rev limit to 6500 rpms and choose a final drive that would keep me in that rpm range after every shift. Its possible that a 3.5 or a 3.7 gear ratio may benefit your build. there is more to it then ” this gear ratio is best”. There are many v8 swapped 240sx that actually seak the q45 diff specifically for its longer ratio and the fact that with 4.08 gears and the v8, its spin city till like 4th gear on the street.

[compactfean]

That's just One example. Another would be that Mazworx uses a 4.6 gear ratio on there drag sr20, which for most would be too short, but they rev there motor to 11k and boost doesn't even kick in till like 5k. See why they choose that ratio? To keep them in the rpm range needed to keep the turbo spooling.

[Sijonda]

Yep, I totally got that. I'm hoping to not need to go with anything bigger than the T28 from an S15 since I hear quite a few good things about what you can do with them and still get a quick low rpm boost as long as you don't expect to get high power or pressure from them. Cams seemed to be out of the question since wherever I looked it seemed people were saying most cams will increase higher rpm power and work with a turbo better at the higher rpm but end up losing lower end power and can cause the SR a harder time to start up. This is why I'm specifically pointing out it's going to always spend most if it's life on the street since I have a tendency to drive whichever I like best. If there are cams that are designed to help spool up my turbo quicker then I'll need to dig around a lot more on this and see what I can find.

In the end I'm trying to stay away from getting serious with getting performance out of my car, I feel like it's just going to kill the fun in driving it. Peek power isn't really my goal here it's the mid rpm range I'd like to work on.

[compactfean]

Id stick with the 4.08 gears and look into tomei 256 pon cams with that setup. The gear ratio from a j30 (3.916) wouldn't cause boost to fall off either. I wouldn't try going any taller of a gear ratio without a pretty decent amount of power. Also are you sure you have vlsd? And what excactly are you wanting to do with the diff?

[Sijonda]

Currently it's used for autocross when I'm not driving it to and from work (5 miles total each day) when the weather is clear. What I want is to take it to track days and of full circuit tracks for performance training classes and see how I do. Then see where it takes me from there. I'm not much of a drag racer since I enjoy maneuvering around obstacles as opposed to going in a straight line but I also enjoy high speed. I figure I can just change out the tire height whenever I need to change my gear ratios.

My 240 is a 1991 Hatch SE with HICAS and ABS. If it doesn't have the VLSD I'd be surprised and I'm pretty darn sure it does since it's quite easy to kick the back out on wet roads. Just tap the throttle in 1st at around 2.5k rpm.

It's too bad I can't see what the VIN number can tell me since it looks like the S13s don't have codes for the options on the car other than the body type and engine used. I've been under the car a few times and I don't really see an orange sticker anywhere on the diff but I usually don't look for it.

[compactfean]

If you have hicas you have vlsd with 4.08 gears. Id leave it alone. Maybe shim it if your
Want the vlsd to be engaged a little harder but that's it.

[Sijonda]

Ok. Then I believe that pretty much sums up all my questions. Thanks guys/gals for the great info. I believe I'm very solid on what I'll do about my drivetrain and suspension now. Tires I think I know What I'll do. As for my engine I've just done a few hours of digging arround and think I know how I'll start handling turbo response for starters.

Again thanks a bunch.