Suspension upgrade - Step 1
02-14-2006 | 05:23 AM
#16
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From: Los Angeles
Originally Posted by Porschefile
Eh, it's not exactly "soft" per se. It's decently stiff and feels like any 240sx with coilovers I've ever been in. Although, many of the coilover 240sx's I've been in ride much smoother when set at full soft due to more optimal valving for the specfic spring rates. Though, if I set it to full stiff it's plenty stiff for the street. After seeing the pics you posted, it looks like you have TONS of bodyroll and nosedive. Let me assure you, 400# fronts will completely solve this. I'm still on stock sways and there is very little body roll now, and no noticeable nosedive. If you do much street driving, it's really not necessary to go stiffer than 400# fronts. However, if you are doing lots of track work, alot of this won't apply as it really depends on what type of track use.
I wouldn't go much over 400# on our cars, for regular street use. From everything I understand, the stock Koni yellow valving is optimal for up to ~400# rates. After that, I'm not sure if it wears them out more quickly, but it's not supposed to be optimal valving performance wise at least. I daily drive my car, and the roads here can get pretty bad so having the stiffest suspension isn't the best idea.
Eyal 951, just to give you some basics so you don't have to research too much, rear coilover springs when used with torsion bars are only ~56% effective. The front springs are supposedly ~90% effective. What you want to do is calculate the effective wheel rate. All you do is multiply the rate by either .9 or .56 (whether it's front or rear). With a 400# front, that should equal ~360# front wheel rate. After lots of research, I'm basing my setup off the rates used by many of the Turbo Cup cars. I believe they used progressive 410# front springs and ~30mm torsion bars (335#). If you calculate that you get a 369# front and 335# rear wheel rate. If you have rear coilovers with stock torsion bars (126# for a non S 951), you could run a 375# rear spring to come up with a 336# rear wheel rate. A 600# spring also equals a 336# rear wheel rate if you're not using torsion bars. With upgraded sways, those rates should make for a nice, fairly neutral setup. I figure, since the turbo cup cars used these rates, add ~300-400lbs of weight for a street car and those same rates should be fairly road compliant. Rates are subjective though, and it all depends on how you like your car to drive (over/understeer,etc).
To give you an example, I'm only using 200# rear springs w/ the stock torsion bars right now. This comes out to a 360# frt wheel rate and 238# rear wheel rate. Let me just say that it understeers ALOT! If you run 400# fronts, I'd try to go with somewhere between a 280-340# rear wheel rate. The lower end of that range should give you a decent amount of understeer, while the upper end should give you a little oversteer at the limit.
Everything I mentioned is just what I understand from my research. If my math or info is incorrect, please correct me.
I wouldn't go much over 400# on our cars, for regular street use. From everything I understand, the stock Koni yellow valving is optimal for up to ~400# rates. After that, I'm not sure if it wears them out more quickly, but it's not supposed to be optimal valving performance wise at least. I daily drive my car, and the roads here can get pretty bad so having the stiffest suspension isn't the best idea.
Eyal 951, just to give you some basics so you don't have to research too much, rear coilover springs when used with torsion bars are only ~56% effective. The front springs are supposedly ~90% effective. What you want to do is calculate the effective wheel rate. All you do is multiply the rate by either .9 or .56 (whether it's front or rear). With a 400# front, that should equal ~360# front wheel rate. After lots of research, I'm basing my setup off the rates used by many of the Turbo Cup cars. I believe they used progressive 410# front springs and ~30mm torsion bars (335#). If you calculate that you get a 369# front and 335# rear wheel rate. If you have rear coilovers with stock torsion bars (126# for a non S 951), you could run a 375# rear spring to come up with a 336# rear wheel rate. A 600# spring also equals a 336# rear wheel rate if you're not using torsion bars. With upgraded sways, those rates should make for a nice, fairly neutral setup. I figure, since the turbo cup cars used these rates, add ~300-400lbs of weight for a street car and those same rates should be fairly road compliant. Rates are subjective though, and it all depends on how you like your car to drive (over/understeer,etc).
To give you an example, I'm only using 200# rear springs w/ the stock torsion bars right now. This comes out to a 360# frt wheel rate and 238# rear wheel rate. Let me just say that it understeers ALOT! If you run 400# fronts, I'd try to go with somewhere between a 280-340# rear wheel rate. The lower end of that range should give you a decent amount of understeer, while the upper end should give you a little oversteer at the limit.
Everything I mentioned is just what I understand from my research. If my math or info is incorrect, please correct me.
The car is intended for track performance, with street fun every once and a while, plus I can hanlde stiff springs. I may go with 500f and like 450 effective rear depending on lots of stuff.
Eyal
02-14-2006 | 09:07 AM
#17
Nordschleife Master
Joined: Jun 2003
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From: San Diego, CA
Z-Man, looks like a great setup. I hope to make it to a few of the NNJ events this season. Look out for me.
Seeing the picture of those struts which Skip posted makes me want to repaint my strut housing. They are yellow..but they also have about 10k miles of paint chips, sand, dirt and road grime on them. Needless to say they are beat to hell. Not to mention i should remove that spring perch since i will be lowering my car a little more once i do the ball joints.
Seeing the picture of those struts which Skip posted makes me want to repaint my strut housing. They are yellow..but they also have about 10k miles of paint chips, sand, dirt and road grime on them. Needless to say they are beat to hell. Not to mention i should remove that spring perch since i will be lowering my car a little more once i do the ball joints.
02-14-2006 | 11:49 AM
#18
Pro
Joined: Sep 2003
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From: New Jersey
great info, i gotta find out what my spring rates are on the S2, i think they're only 250 
If so i might just stick with 29mm until i get the cashola to get 400 pound spring. I really don't care about harsh ride, i have 500 springs in my 1800pound Rabbit, i keep only one seat in the car because noone would ride with me... 
Vlad.
If so i might just stick with 29mm until i get the cashola to get 400 pound spring. I really don't care about harsh ride, i have 500 springs in my 1800pound Rabbit, i keep only one seat in the car because noone would ride with me... Vlad.
02-14-2006 | 12:06 PM
#19
Thread Starter
Race Director
Joined: Jan 2002
Posts: 10,170
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From: North NJ, USA
Vlad:
Just make sure that your suspension upgrade is balanced - shocks & springs, front to rear - all must work in harmony - otherwise, you'll have a car that has unpredictable handling characteristics. Doing the research up front will save you frustrations and money in the end.
Techno: the NNJR AX season opener is tentatively set for April 30 - hope to see you there!
-Z.
-Z-man.
Just make sure that your suspension upgrade is balanced - shocks & springs, front to rear - all must work in harmony - otherwise, you'll have a car that has unpredictable handling characteristics. Doing the research up front will save you frustrations and money in the end.
Techno: the NNJR AX season opener is tentatively set for April 30 - hope to see you there!
-Z.
-Z-man.
02-14-2006 | 12:10 PM
#21
RL Community Team
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From: Toronto
Hey Z-man, that stuff looks great. All this discussion is interesting. I have bought similar items from Paragon for my car. I went a little softer though. Like you I'm using the Konis and ARHK, but have opted for 300 lb/in springs up front and 28 mm solid torsion bars in the rear.
I have removed the majority of the old spring perch on the housing and it certainly will improve access to the lower adj. perch. Now I just have to get my home powder coating set-up going to finish my housings...
Do you have any plans for your bushings etc.?
I have removed the majority of the old spring perch on the housing and it certainly will improve access to the lower adj. perch. Now I just have to get my home powder coating set-up going to finish my housings...
Do you have any plans for your bushings etc.?
02-14-2006 | 12:18 PM
#22
Pro
Joined: Sep 2003
Posts: 685
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From: New Jersey
yup, harmony is key, currently the car understeers pretty badly with quick inputs i think with 250pound front springs 28-29mm t-bars should be just right...I have Koni shocks in the rear too. but then if i want to upgrader later i'll already have wasted cash/time to put in the smaller t-bars.. might just as well upgrade all together. Hopefully i won't have to revavle shocks for 400 pound springs.
I def. haven't researched the 944 susp. as much as i will when it comes to buying. I'm REALLY concerned about screwed up front geometry when it's lowered. Basicly the front design on 944's is the same as my Rabbit and VW racers never lower the front unless they go with custom a-arms or modified strut towers.
Here's a good read:
http://forums.vwvortex.com/zerothread?id=1363022
Not 944 specific but a lot of good info.
Vlad.
I def. haven't researched the 944 susp. as much as i will when it comes to buying. I'm REALLY concerned about screwed up front geometry when it's lowered. Basicly the front design on 944's is the same as my Rabbit and VW racers never lower the front unless they go with custom a-arms or modified strut towers.
Here's a good read:
http://forums.vwvortex.com/zerothread?id=1363022
Not 944 specific but a lot of good info.
Vlad.
02-14-2006 | 04:34 PM
#23
Thread Starter
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Joined: Jan 2002
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From: North NJ, USA
Originally Posted by amjf088
Do you have any plans for your bushings etc.?
Need advise & comments, and part numbers from you all.
So far, I have the following plans:
1. I plan on keeping my stock (2 year old) A-arms, but getting the ball joints that have the longer arm (Elephant racing? )
2. I think I want to go with solid bushings where appropriate. (Help!)
3. Camber plates - solid or adjustable?
Comments & recommendations greatly appreciated.
-Z.
Last edited by Z-man; 02-14-2006 at 05:25 PM.
02-14-2006 | 05:20 PM
#25
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From: Northern NJ
Z--You are a mad man! Hope you can endure the ride to the track with those stiff springs! Also, I recall the roads being kinda rough around Rutt's Hutt!
Good luck with the upgrades. Glad you finally got a new suspension after your "problems".
Good luck with the upgrades. Glad you finally got a new suspension after your "problems".
02-14-2006 | 06:59 PM
#26
Three Wheelin'
Joined: Aug 2004
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From: Austin, TX
To those that are interested, I would highly recommend looking at Nissan 240sx coilover setups just to become more familiar with spring rates. I can give you guys links if you'd like. Those cars are similar enough that I've tried to base my suspension and rates off of what many people do to those cars. There are tons of factors to take into account, such as suspension fulcrum points, spring location, vehicle weight, etc. You can't exactly use the same rates and expect the same outcome, but it's helped me to get a general idea of rates by seeing what is run on 240sx's.
For an example, the Tein Flex coilovers for '95-98 240sx's run 336# front and 280# rears. These are anywhere from a 2750-2900lb car depending on the options (I think some can get closer to 3000lbs). That's close to what a 951 weighs, so similar rates should work fairly well. Just remember to take into account the differences in suspension geometry between both cars. I believe both cars have a similar effective wheel rate percentage in the front (~90% I believe), and I believe 240sx's are closer to ~90-100% in the rear as opposed to the ~56% of coil springs on the rear of a 951. Does anyone happen to know the effective percentage of torsion bars on our cars? I would think it should be ~90-100% seeing as it is located at the fulcrum point.
Check this page to see some more examples of coilover spring rates on those cars Tein USA. If you notice, the first listings are just for springs. The 1st is 210# front and 180# rear. The ones below are listed as "luxury" and have 180/160# rates, so those are definitely soft. Those should be fairly comparable to 200# and 250# springs available for our cars. Most of the street coilovers are anywhere from 340-450# rates, and the track based setups are 450-560# rates.
For an example, the Tein Flex coilovers for '95-98 240sx's run 336# front and 280# rears. These are anywhere from a 2750-2900lb car depending on the options (I think some can get closer to 3000lbs). That's close to what a 951 weighs, so similar rates should work fairly well. Just remember to take into account the differences in suspension geometry between both cars. I believe both cars have a similar effective wheel rate percentage in the front (~90% I believe), and I believe 240sx's are closer to ~90-100% in the rear as opposed to the ~56% of coil springs on the rear of a 951. Does anyone happen to know the effective percentage of torsion bars on our cars? I would think it should be ~90-100% seeing as it is located at the fulcrum point.
Check this page to see some more examples of coilover spring rates on those cars Tein USA. If you notice, the first listings are just for springs. The 1st is 210# front and 180# rear. The ones below are listed as "luxury" and have 180/160# rates, so those are definitely soft. Those should be fairly comparable to 200# and 250# springs available for our cars. Most of the street coilovers are anywhere from 340-450# rates, and the track based setups are 450-560# rates.
02-14-2006 | 08:08 PM
#27
Drifting
Joined: Jul 2002
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From: Cleveland, OH
Originally Posted by Z-man
...That is my understanding. If I find there's too much understeer in the setup, I can always adjust my Welt rear sway bar a little, or if I can't dial it out that way, I can dump down to a less-stiff spring - like a 350lb unit. Balance front the rear is more important than overall stiffness, IMHO.
02-15-2006 | 03:03 AM
#28
Three Wheelin'
Joined: May 2004
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From: Chicago
All this talk bout springs. What do stock NAs comes with. I have a 85.5 and bought red Konis upfront and yellow for the rears. What springs should I get for the front and do I need to do anything to the rears. I do feel the rear drop a little bit still even with the Konis. Eventually Id like to track her sometime this year.
02-15-2006 | 04:45 AM
#29
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Originally Posted by chitown944
All this talk bout springs. What do stock NAs comes with. I have a 85.5 and bought red Konis upfront and yellow for the rears. What springs should I get for the front and do I need to do anything to the rears. I do feel the rear drop a little bit still even with the Konis. Eventually Id like to track her sometime this year.
02-15-2006 | 08:28 AM
#30
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From: San Diego, CA
Originally Posted by chitown944
All this talk bout springs. What do stock NAs comes with. I have a 85.5 and bought red Konis upfront and yellow for the rears. What springs should I get for the front and do I need to do anything to the rears. I do feel the rear drop a little bit still even with the Konis. Eventually Id like to track her sometime this year.