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350z Street Suspension Upgrade (springs and shocks, not coil-over)

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350z Street Suspension Upgrade (springs and shocks, not coil-over)

Old 02-16-2015, 12:12 PM
  #21  
DarkZ03
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It's the weight transfer and also physics, you accelerate out of a corner the car will squat, if it is even (ride height) it will ramp up the front end allowing air to lift it further and take weight off of the front wheels. It is set up the way it is to prevent that.
I will have to read that thread when I'm bored, but I most likely wont do the mod because I know better. I think I will opt to go with a diffuser instead to visually bring the rear down.
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Old 02-16-2015, 03:53 PM
  #22  
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Originally Posted by Spike100 View Post
^^ Mic... Looking forward to the comparison report. That will be very interesting. --Spike
First observation: I am still subject to irrational joy. Keep telling myself that grown men are NOT supposed to get this excited about packages from Fed Ex. The kind the wife shakes her head at and mutters, "More car stuff?? And it's not for mine??"



On first name basis with the Fed Ex delivery guy.

I keep getting that buyer's remorse kinda feeling.... the kind where I've got my suspension nice and dialed in with the 'Steins and I'm going to f' something up. Heh heh. Naaaaahhhhh, no worries. I'll swap and test before I give the "old" (if you can call 18 months "old") shocks to my kid. Hell, he might end up with Konis! Tough break for the brat, right? Hahahahahahaha!
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Old 02-16-2015, 04:06 PM
  #23  
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Actually very curious as well, personally I hold Bilstein higher in terms of perception as a suspension company but that's NOT backed up by fact, just because they are used on so many cars over at the 'ring
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Old 02-16-2015, 05:32 PM
  #24  
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Mic... Keep us posted on the project. I was thinking going the other direction and keeping my Bilsteins but swapping in some Hotchkis Sport Springs to compare with the Teins I have on now.

It's unusual seeing this type comparison since few owners swap out shocks and springs before they are very worn. We might end up posting some very useful info for the community.
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Old 02-16-2015, 09:31 PM
  #25  
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Originally Posted by Spike100 View Post
Mic... Keep us posted on the project. I was thinking going the other direction and keeping my Bilsteins but swapping in some Hotchkis Sport Springs to compare with the Teins I have on now.

It's unusual seeing this type comparison since few owners swap out shocks and springs before they are very worn. We might end up posting some very useful info for the community.
Absolutely! Wasn't sure how the Bilsteins would do on our Z's - my experience with them were all on my Euro cars (Volvo, BMW, Benz) but happy to report, they've been great! (That's why I want my son to have 'em on his. He was going to go budget, being a college student and all (junk shocks, no names named) but I told him "Dude, your dad is an exacting and **** retentive car-o-phile..... and good dads don't let their kids drive on junk!"

Funny, I didn't hear him complain at all. (And even though he was going to buy his own springs and such, I just decided to get those for him as well...)

Besides, I've not run Konis in MANY years (last car I had 'em on was my racecar and on a 240Z) so I want to satisfy my curiosity. Even if they don't work as well as the 'Steins, I KNOW they're not the junk shocks my kid was going to get. Oy...

I'm having them installed professionally next week since my whole new set up (camber adjustment stuff) is requiring an alignment and I can't do that. But aside from bringing camber back into the middle of nominal range, my bars will remain as they were and the shocks will start out on mid-firm and I'll dial it in from there.

Oh, and if you do go with the Hotchkis springs, I'll be very curious how that will work out. I debated on going linear but I've been using Eibach Pro Kit successfully since the '80s and really like them for the way they ride and perform when needed so. But am curious because I'm betting the Bilsteins will take the edge off the linearly firmness of the Hotchkis units.

Last edited by MicVelo; 02-16-2015 at 09:34 PM. Reason: Additional info
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Old 02-16-2015, 10:07 PM
  #26  
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Originally Posted by RobPhoboS View Post
Actually very curious as well, personally I hold Bilstein higher in terms of perception as a suspension company but that's NOT backed up by fact, just because they are used on so many cars over at the 'ring
RobPhoboS, I'll say this right now (and no, I don't work for them), Bilstein shocks are a world standard and there's no denying that they work. Well!

They're the shocks I would NEVER hesitate to buy over and over. But....for the reasons I cited about adjustability (and my son's need for shocks, laff), I'm game to experiment with another "go-to" brand, Koni.

There are very few shocks I've NOT used on my cars from KYB to Koni to Bils to Tokics (oh and Gabriel Hijackers, laff!!!). Koni and Bilstein are in that rarified air of "Can't go wrong."

My opinion of course (and I have NO experience on coilovers) and YMMV, but 40 years of using these and still buyin' them, well....
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Old 02-17-2015, 04:52 AM
  #27  
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I'm looking forward to seeing how they compare, and especially if Spike tries out the Hotchkis springs, obviously I've just bought my parts so no needs to replace anything here. Just more bits on the shopping list to help aid it for the street
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Old 02-17-2015, 01:50 PM
  #28  
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Originally Posted by RobPhoboS View Post
I'm looking forward to seeing how they compare, and especially if Spike tries out the Hotchkis springs, obviously I've just bought my parts so no needs to replace anything here. Just more bits on the shopping list to help aid it for the street
Rob… I am toying with swapping in Hotchkis springs with the Bilstein shocks. The Hotchkis springs lower the car a little more and they have a great reputation, but I am concerned mounting a linear spring. I worry that I may end up with a stiff and harsh (i.e., uncomfortable) ride on public streets with the linear Hotchkis springs. I think (but am guessing) that a superior shock (such as the Bilstein) will mitigate (but not completely eliminate) the harsh ride you get with linear springs (the Hotchkis springs as an example).

Right now I have the Bilsteins with Tein S-Tech Springs, and the ride is comfortable with very good handling on city streets. I would say that the Tein S-Tech Springs are a hybrid progressive/linear design.



A typical linear spring (Notice that the coils are uniform)



A typical progressive spring (Notice that the coils are wider at one end)



Hotchkis Springs (Notice the coils are uniform indicating a linear spring)



Tein S-Tech Springs (Notice that coils are not uniform but more tight than progressive)

The Tein S-Tech Springs are somewhere between the typical configurations for linear and progressive springs. That is why I define Tein S-Tech Springs as hybrids.

ADDITIONAL NOTES: Linear springs – aka Straight springs, have a spring rate that is consistent along the entire length of the spring as it is compressed. Progressive springs on the other hand, have a spring rate that increases or changes with the compression of the spring.

Last edited by Spike100; 02-17-2015 at 02:05 PM.
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Old 02-17-2015, 04:03 PM
  #29  
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I'm sure you know this but just in case anyone reading this doesn't:

Be aware that the B6 shocks aren't designed for a big drop.

copied from the Bilstein Q&A page

B6's specifically:

'Down to which lowering level can I go with BILSTEIN B6 sports shock absorbers (not shortened) in conjunction with shorter springs?'
Down to 30mm
That is what is typically offered for new vehicles straight from the factory.
Any lower and a shock absorber with a shortened stroke has to be fitted, so that the spring tension - which ensures the required distance between the car body and the wheel - is maintained, whatever the driving situation.
Otherwise the spring may slip out of its fitting and the vehicle will abruptly go out of control.

B8's specifically:
'Down to which lowering level can the BILSTEIN B8 Sprint shock absorber be fitted?'
Down to 50mm.
The ideal depth for driving dynamics is however between 30mm and 40mm; any lower and the driving performance becomes poorer again, unless a major adjustment of the entire vehicle is carried out.

And in regards to Linear or Progressive, you'd have seen this post but seems like the less progressive or linear the better (Tein has small progression on the front F:"327"-386/R:402 guessed "") but that's just an opinion of course:

https://my350z.com/forum/brakes-and-...l#post10218808

I would just send Bilstein an email and ask them.
No harm in that
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Old 02-17-2015, 04:53 PM
  #30  
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^^ Maybe just go with the Bilstein B8 shocks.. They provide an incredible result.
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Old 02-17-2015, 07:21 PM
  #31  
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Originally Posted by RobPhoboS View Post
I'm sure you know this but just in case anyone reading this doesn't:

Be aware that the B6 shocks aren't designed for a big drop.

copied from the Bilstein Q&A page

B6's specifically:

'Down to which lowering level can I go with BILSTEIN B6 sports shock absorbers (not shortened) in conjunction with shorter springs?'
Down to 30mm
That is what is typically offered for new vehicles straight from the factory.
Any lower and a shock absorber with a shortened stroke has to be fitted, so that the spring tension - which ensures the required distance between the car body and the wheel - is maintained, whatever the driving situation.
Otherwise the spring may slip out of its fitting and the vehicle will abruptly go out of control.

B8's specifically:
'Down to which lowering level can the BILSTEIN B8 Sprint shock absorber be fitted?'
Down to 50mm.
The ideal depth for driving dynamics is however between 30mm and 40mm; any lower and the driving performance becomes poorer again, unless a major adjustment of the entire vehicle is carried out.

And in regards to Linear or Progressive, you'd have seen this post but seems like the less progressive or linear the better (Tein has small progression on the front F:"327"-386/R:402 guessed "") but that's just an opinion of course:

https://my350z.com/forum/brakes-and-...l#post10218808

I would just send Bilstein an email and ask them.
No harm in that
Good info for a la carte shoppers, Rob.

That's one of the reasons Bilstein teamed with Eibach to develop the matched set "B12 ProKit" series. ProKit springs lower most of the cars they're offered for only a small amount (~15-30mm dep. on application).

Mic
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Old 02-17-2015, 07:32 PM
  #32  
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Helper springs??? (To keep the spring from falling out of its fitting...if they can be found in that diameter)

Doesn't sound like the shocks care one way or the other. - at least not from that particular warning.

Last edited by Z1NONLY; 02-17-2015 at 07:33 PM.
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Old 02-19-2015, 04:33 PM
  #33  
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Originally Posted by MicVelo View Post
Good info for a la carte shoppers, Rob.

That's one of the reasons Bilstein teamed with Eibach to develop the matched set "B12 ProKit" series. ProKit springs lower most of the cars they're offered for only a small amount (~15-30mm dep. on application).

Mic
Rob and Mic… You describe the reason I was initially interested in the Nismo 350z S-Tune Suspension Kit (Spring/Shock setup). The kit was expensive. You pay a premium for Nissan tests (insuring the components were compatible) and the “Nismo” logo. I didn’t buy this setup because it is now very difficult to find; that wasn’t the case in 2003.

I did the research for my Bilstein B8 Shocks and Tein S-Tech Springs combination. I was trying to match the specs for the Nismo 350z S-Tune Suspension Kit. As it turns out, the Bilstein/Tein setup was better.
--Spike
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Old 02-19-2015, 11:32 PM
  #34  
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^ That's why I got my S-tune kit, I got it new for a steal, I think there are very little (if any) suspensions I could have gotten for the price I paid.
If I did not find that deal I probably would have bought coilovers.
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Old 02-22-2015, 02:20 PM
  #35  
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^^ I could be wrong, but I believe that JDM is Nissan’s OEM supplier for the 350z’s Nismo S-Tune Suspension Kit.

Initially at the 350z’s release (in 2003 to 2005), the demand for the Nismo S-Tune Suspension Kit was strong. However, that is no longer the case. JDM waits for orders from individual dealers before producing units of the Nismo S-Tune Suspension Kit. In other words, the Nismo S-Tune Suspension Kit is a custom order. Dealers list the product; but when you order, you are notified that it is a 6-9 week time before fulfillment.
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Old 02-23-2015, 07:45 PM
  #36  
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I just received a Private Message (PM) from a my350z.com member asking if there is a requirement to add camber arms and/or other adjustment pieces if you swap the stock springs for Tein S-Tech springs.

The answer is NO.

Tein S-Tech springs lower the car 0.6”. That is a very modest drop that allows you to maintain factory alignment specifications without adding hardware (i.e., camber arms). I did do an alignment after installing new shocks and springs, but that is routine in this case.

--Spike
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Old 02-24-2015, 03:42 AM
  #37  
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An alignment is a must !

I tend to think any changes to suspension I think it's worth doing anyway, the car always feels nicer afterwards

Last edited by RobPhoboS; 02-24-2015 at 10:06 AM.
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Old 02-24-2015, 03:53 PM
  #38  
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Originally Posted by Spike100 View Post
A typical linear spring (Notice that the coils are uniform)


A typical progressive spring (Notice that the coils are wider at one end)
I'd be interested to see some data on how many of these progressive springs are actually coil-bound at normal ride height, effectively making them a linear spring. It's my understanding that some manufacturers (Swift, to name one) do this to keep the spring in the seat at full damper travel, since the stiffer/shorter spring is often slightly too short for the shock at full droop. The progressive portion becomes, in effect, just a helper spring.

Originally Posted by spike100
I think (but am guessing) that a superior shock (such as the Bilstein) will mitigate (but not completely eliminate) the harsh ride you get with linear springs (the Hotchkis springs as an example).
The harshness is largely in the dampers to begin with, not the springs. None of these springs are considerably stiffer than stock (which are linear). The harshness comes from poor high speed damping, which tends to transmit even the smallest bumps into the chassis instead of soaking it up like the dampers should (overdamped as opposed to critically damped). Bilstein is probably the best in the world at tuning high speed damping. You should be able to increase the spring rate without gaining harshness with Bilsteins. I'm getting anxious for mine to show up, but they're probably sitting in one of those container ships parked off the west coast.
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Old 02-24-2015, 05:01 PM
  #39  
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Originally Posted by kilogram View Post
I'd be interested to see some data on how many of these progressive springs are actually coil-bound at normal ride height, effectively making them a linear spring. It's my understanding that some manufacturers (Swift, to name one) do this to keep the spring in the seat at full damper travel, since the stiffer/shorter spring is often slightly too short for the shock at full droop. The progressive portion becomes, in effect, just a helper spring.

Interesting thought Kilogram but a true progressive spring is NOT coil bound at static height (or at least it's not supposed to be). With Eibach, for example, when the car is at rest and with the spring fully weighted (with 25% of the theoretical weight of the car sitting on it, the gap in the soft end of the spring is still visible. Again, "at least it's supposed to be."

However, what you suggested does exist. Take a look at a square end spring and you'll note that it appears that the last 10% of the spring's length appears to be coil bound but that's intentionally done for the exact reason you mention, to give the spring the proper curvature to remain in full contact with a flatter type spring perch.


The harshness is largely in the dampers to begin with, not the springs. None of these springs are considerably stiffer than stock (which are linear). The harshness comes from poor high speed damping, which tends to transmit even the smallest bumps into the chassis instead of soaking it up like the dampers should (overdamped as opposed to critically damped). Bilstein is probably the best in the world at tuning high speed damping. You should be able to increase the spring rate without gaining harshness with Bilsteins. I'm getting anxious for mine to show up, but they're probably sitting in one of those container ships parked off the west coast.
Absolutely right! Especially if one considers that this is the primary function of the shock absorber.

You're also right about the Bilsteins being one of the best for DECREASING harshness. After switching over any/all of my cars that used Bilsteins as replacements, that's the first thing you notice.... the small deflection but high frequency oscillations of the stock OR aftermarket springs disappears.

One thing to note to all who lower their cars with name-your-brand springs mated with Bilsteins, you might be disappointed that the "drop that was advertised by the spring mfgr" isn't as low with Bilsteins as they have the tendency to RAISE the car back up, on average, about .25" (or more) in typical applications.
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Old 02-24-2015, 06:24 PM
  #40  
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Linear vs. progressive (variable rate) springs could be an entirely new and interesting discussion.

I am under the impression that a linear spring has a consistent rate making this type of spring more easily matched to a damper. Conversely the progressive rate spring (or a dual spring setup) presents a problem (mainly handling) when the spring goes out of the optimum dampening range of a shock absorber.

It’s like everything else in life. You sacrifice something to gain in another area. You are going to get better handling with a linear spring, but possible at the cost of comfort when driving on the street. On the track you again get better handling with linear springs, and the smooth tarmac on a racetrack keeps the ride comfortable (so you can have your cake and eat it too).
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