titanjc

iTrader: (11)

Here's kind of an odd question. After putting 19's on my car, I don't like how high the rear sits, but the front is fine. I have a set of Tein S-Tech springs that I was going to throw on with the stock wheels, but now I'm worried that I won't like the drop in the front. Would it hurt anything if I lowered just the rear? Obviously this would be for aesthetic reasons, not performance. Just wondering if this has been done before.

jreiter

iTrader: (6)

I know that the Hotchkis springs lower the back a tiny bit more than the front. Other than that I think all the springs out ther lower both ends evenly, or even do the front a bit more. I agree with you, though, I don't like how the rear of the Z sits a bit higher than the front.

You definitely don't want to mix different models of springs. You should always use 4 springs which are designed to work together. So, other than getting coilovers, I suppose the easiest (and cheapest) way to lower the back is to maybe cut the rear springs a tiny bit. (I know a lot of people might say that's ghetto, but I don't see why it's a problem if you're only doing a tiny bit and have it done properly.)

I don't know the proper way to cut springs, but I'm sure a good shop might know what's up. You'd want to make sure you're using linear springs, though. If you cut progressive springs, you'll affect their spring rates. If you do that, you might want to get opinions from knowledgeable people on which end to cut: the soft end or the stiff end. That could get a little more complicated. But anway, I believe the S-Techs for the 350Z are linear, so you should be okay.

The nice thing is that the rear springs and shocks are so darn easy to remove. You'll probably need a little trial and error when cutting the springs before you find the right height. Just remember not to cut too much, because it's a one way trip!

skank-a-holic

Regardless of what others may say... I would do just the s-techs in the rear and leave it at that.

If you cut the rear springs you now have screwed up the tension and weight ratio of the rear springs which would not be matched up with the front anyway.

The front are not matched with the rear anyway being that they have to support the weight of the engine.

Swap out the rears!!!

*Im no mechanic... just my $0.02*

del105

iTrader: (4)

you will be fine swapping only the rears. At worst it will make the rear have an slightly more traction, because you will be tipping the weight of the car more toward the rear.

jreiter

iTrader: (6)

When I said springs are matched I didn't mean they have equal spring rates. I meant they have springs rates that are designed to give the car a certain balance. My concern with using aftermarket springs in the rear and stockers up front would be that balance. I believe the S-Techs increase the rear stiffness quite a bit over stock. So if you use the S-Techs in the rear and the stockers up front, you'll have transferred a *huge* amount of roll stiffness to the rear. This might result in way too much oversteer. I'm just guessing here based on the posted spring rates on the sites, but it seems like something to consider.

I believe the S-Techs would drop the rear way too much if you kept the stock front springs. I bet it would look goofy. I mean heck, the rear is only a tiny bit higher than the front with the stock springs. Having the S-Techs in the rear only would drop the rear by .6". That'd just look goofy. You might consider going with a completely different spring set. The Hotchkis springs lower the rear about 4mm more than the front specifically to address what we're discussing here, and give the car a pretty level look. I have the RSR Ti2000 springs, which are fantastic. While they don't drop the rear more than front (they drop equally), they do result in a reasonably balanced look. It would be nice to drop that addtional few millimeters off the back, but it's not bad.

As far as messing with the tension and weight ratio by cutting the rear springs, would that really be the case here? I mean, we're only talking a few millimeters. I'm not an engineer so I don't know the math, but it doesn't seem like a few millimeters would mess it up that much, especially for a street car. On a hard core track car, yeah, that kind of minute adjustment can make a noticeable difference... but driving around on the street?

NORCALSTI

in rear on top of the bumpstop you can grind away the rubber and that will lower the back. 1/2 inch off top off the top of the bumpstop will equal 1/2 inch drop. imdiong this on my g35 coupe next week

Strife350z

iTrader: (4)

norcalsti... interesting, i didn't know that... are there any drawbacks to grinding away the bumpstop?

jreiter

iTrader: (6)

Interesting. I wasn't paying much attention to that when my installer did my suspension. So the bump stop actually supports the spring (and thus grinding it a bit shorter lowers the car)?

35oZephyR

iTrader: (4)

Buy some Tein H-Tech springs...they're dirt cheap.

Put those in front since they barely drop the car at all. Install the S-techs in back and both front and back will at least be stiffer than stock.

NORCALSTI

if you take out rear springs (this takes 10 minutes at most) you will notice how the spring sits on the bumpstop mount. well when youpull the spring out you can just pull that rubber bumpstop out. now up top you can cut 1 inch off and that will lower the car 1 inch. you still have enough meat there to support the spring no problem. im going to prob cut about 1/2 inch in 2-3 weeks to make sure the springs settled in all the way. ill get it on a vice with the portion i want to cut off sticking out then get a cut off wheel and cut threw the rubber

tony

skank-a-holic

Yes

It sounds like he needs more then a "few millimeters" (dont think thats going to make much of a difference) to get the appearance hes looking for. He's at least going to need a 1/2 inch +

Pedal Pusher

I have "rear only" Tein H-Tech springs for a G35 Coupe for sale. They will lower the rear about .3 inch and reduce the rear spring rate which will take some of the rough ride out of the car. I use a combination of H-Tech fronts and S-Tech rears. Therefore, the H-Tech rears are not going to be used. They are boxed and ready for shipment. $70

skank-a-holic

Very

NORCALSTI

just cut the bumpstop mount like i said

jreiter

iTrader: (6)

Yeah, I'd have to agree. If it's just that easy, then it definitely seems like the best bet in this situation.

Strife350z

iTrader: (4)

has any one else performed the bumpstop mod before? this is the first time i've heard of it... but it sounds very promising... it seems like a quick way to eliminate that "jacked up" look people get when they run a lighter exhaust or run without a spare (removing weight from the rear)

as long as it's safe and reliable...

Gsedan35

iTrader: (10)

This is my idea gentleman, I've done 3 set's of them. I have them on my car, I made a set for a G35 coupe running oem Z springs in the front and oem coupe springs in the rear and set for a member here has them on his Z with Zeal coilovers.

1. These are rear upper spring seat's, bump stop's are on the rear shocks your local Nissan part's department call's them something yet again totally different even though the FSM defines them as "upper seat".
2. Using a rotor saw is a very dangerious idea, these are basically solid chunks of what amount's to a car tire. Even if you are able to control the saw, the heat it generates unvulcanize's the rubber and will spite out a super stickly gooey mess that stick's to everything and resists attempts to wash it off. I know, my first set was cut down with a rotor saw on a dremel, which was must tiny blade no bigger then a quater and about as thick as a razor. That was the one and only time I used that method to cut them.
3. The shape of this part and what it's made from will defy anyone's attempt to make a percise cut. Since it's made of rubber, correcting error's in cutting are extreamly difficult, either you get powdered rubber that goes everwhere, your clothes ect or a gooey mess, either way it's painfully slow going. Your best success will come from mounting what you can of the seat in a vise and use a hacksaw and cut along where the ribs meet up with solid rubber. Use a screw driver to pry open your cut as you go deeper and saturate it with wd40 or your blade will lock up. Rotate the part in the vise to work the cut around.

Strife350z

iTrader: (4)

gsedan... great idea and thanks for the detailed info!

btw - do you offer these "upper seats" premade? If so... how much? also, any problems from the cars you've modified in the past? ride quality, I'm assuming, stays stock correct?

jreiter

iTrader: (6)

The Hotchkis spring installs I've seen leveled the car out perfectly, and they only drop the rear 4mm more than the front. (15mm in the front, 19mm in the back.) If he goes with the spring seat trimming route, I'd say be conservative at first just so he doesn't over do it. It's amazing how much lower a car can look with only a little bit of drop. Gsedan35, how much did you cut off of the spring seats you've done, and what springs were they used with? I guess if they are combined with a spring set that lowers the front more than the rear you'd have to cut more off, but if using a spring set that lowers evenly, you'd cut less off.

fahrenheit350

iTrader: (15)

I found this thread very helpful in my pursuit to make the rear end look so high but keep the stock springs on there. I have the 04.5 springs in the rear with the higher spring rate (314fr/427rr) compared to 03-04 and I like the ride the way it is.

After getting 19’s with 35/275 tires, I was disappointed with the fender gap in the rear and made it look “4x4-ish.” I was debating on getting the RSR TI 2000 springs but could not afford to drop the car since I was already scraping everything (I live in Irvine, go figure). So I searched around and found the “upper seat” or “bump stop” mod intriguing and decided to give it a go. I consulted Steve from Corner3 Garage in Lake Forest is there is any negative ramifications from this adjustment and he agreed that he did not see any issues; only that some weight will be transferred to the rear.. but even that is a not a bad idea.

Steve went ahead and dropped the rear end and took a couple of bolts out that held the control arm in place. Took the spring out then proceeded to pull the upper seat out. The upper seat looked like a big donut that was 2” think. He took a hacksaw to it and cut it in half till it was 1”. The way he did it was clean with no gummy mess. Slap the seats back in, springs and bolt it back.

So here are some numbers:

Rr Fender gap before mod: 2.33”
Rr Fender gap after mod: 1.4”

I am happy.

Here are some before pics: (I will have 'After' shots when I get home and when they settle just a tab bit more)