# Road race spring rates?



## Jackson Diamond (Apr 30, 2002)

Right now i have 300lb up front and 200lb in the rear on a fmax 200sx. I have a chance to swap to 450lb up front and 400lb in the rear. THis swap is free and will cost me only the time to do it. THe car is rarly driven on the street. My question is how will this set up handle in the corners. Will my ass end be coming out at every corner?

these are on a 200sx


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## Geo (Apr 30, 2002)

You don't say which chassis you have.

We are currently running these spring rates in our SCCA ITS SE-R with AGX dampers.

We still are not getting major oversteer. If you don't have a welded cage, the rear spring rates are going to be too high. The strut towers will flex a great deal. We are still hitting the bump stops with those rates and we are not at the legal lowering limit.

We are planning on going up a fair bit higher in rates as soon as we have our proper race dampers (double adjustable Konis).

BTW, these will be murder on the street.


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## AznVirus (May 8, 2002)

wow George Roffe visits this forums?  remember me from the automotive forums?  nice to see the diversity.


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## morepower2 (Apr 19, 2002)

Geo said:


> *You don't say which chassis you have.
> 
> 
> 
> BTW, these will be murder on the street. *


I drive 500 in/lb front and 400 in/lb rear on the street and they are uh murder!

Mike


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## morepower2 (Apr 19, 2002)

Jackson Diamond said:


> *Right now i have 300lb up front and 200lb in the rear on a fmax 200sx. I have a chance to swap to 450lb up front and 400lb in the rear. THis swap is free and will cost me only the time to do it. THe car is rarly driven on the street. My question is how will this set up handle in the corners. Will my ass end be coming out at every corner?
> 
> these are on a 200sx *


On a B14 they will probably work pretty well. In fact I am going up to those spring rates on my street 200SX. I curently run 350/250 and they are too soft and too much understeer. Car rides pretty smooth with these rates.

For instance I run 600 in/lbs front, 500 in/lbs rear on my race B14.

Mike


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## barnoun (May 7, 2002)

morepower2 said:


> *I drive 500 in/lb front and 400 in/lb rear on the street and they are uh murder!
> 
> Mike *


Do the strut towers flex like Geo says? ...or do you have a cage in the street car to stiffen it up. Is it that the b14 can handle those rates but the b13 can't unless it has a cage?


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## morepower2 (Apr 19, 2002)

barnoun said:


> *Do the strut towers flex like Geo says? ...or do you have a cage in the street car to stiffen it up. Is it that the b14 can handle those rates but the b13 can't unless it has a cage? *


My street car has upper and lower front and rear STB's plus a strucutral foam filled chassis so its quite a bit stiffer than a normal B13. My race car has a welded in cage and a triangulated STB.

Mike


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## barnoun (May 7, 2002)

So you don't think rates of 500in/lb front and 400in/lb rear can be tolerated by a street b14 without any type of structural reinforcement? Or can the chassis take it but the passenger can't


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## morepower2 (Apr 19, 2002)

barnoun said:


> *So you don't think rates of 500in/lb front and 400in/lb rear can be tolerated by a street b14 without any type of structural reinforcement? Or can the chassis take it but the passenger can't *


The chassis can take it but it is sort of brutal for daily driving. I mean I dirve on the street like that but some of my friends complain about the ride, well the ones that do are my wife, the other a girl I know. My guy friends don't seem to mind.

Mike


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## barnoun (May 7, 2002)

Good to hear the chassis can take it...girls can complain all they want Don't want to ask a dumb question, but can these rates be used with AGXs, or do special race shocks/struts have to be acquired?


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## morepower2 (Apr 19, 2002)

barnoun said:


> *Good to hear the chassis can take it...girls can complain all they want Don't want to ask a dumb question, but can these rates be used with AGXs, or do special race shocks/struts have to be acquired? *


AGX's don't have anywhere close to enough damping to take these spring rates. You need Real Race shocks, like the Shigspeed Koni 8611, Ground Control Advance Design and Truechoice.

Mike


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## PatScottAKA99XE (Apr 30, 2002)

Somebody is gonna have to teach me about that chassis foam thing. I dont know if I will do it to this car, but the idea intrests me greatly.


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## barnoun (May 7, 2002)

morepower2 said:


> *AGX's don't have anywhere close to enough damping to take these spring rates. You need Real Race shocks, like the Shigspeed Koni 8611, Ground Control Advance Design and Truechoice.
> 
> Mike *


Good to know...thanks man.


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## Geo (Apr 30, 2002)

PatScottAKA99XE said:


> *Somebody is gonna have to teach me about that chassis foam thing. I dont know if I will do it to this car, but the idea intrests me greatly. *


Mike wrote an article about putting in his 300ZX in SCC about 3 years ago. I don't know the issue off-hand, but if you or a friend have an extensive collection of back issues, you will be able to find it with no trouble.


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## Geo (Apr 30, 2002)

barnoun said:


> *Do the strut towers flex like Geo says? ...or do you have a cage in the street car to stiffen it up. Is it that the b14 can handle those rates but the b13 can't unless it has a cage? *


Yep. Just like Geo says.

I've personally watched someone grab a strub in a B13 that was attached to the top of the strut tower and not the upright and wiggle it around. The amount the coachwork moves around will stand your hair on end. OK, maybe that's an over statement, but not by much. I was truly shocked (no pun intended).

The foam Mike is talking about will help a great deal, but still won't keep the the metal of the strut tower from flexing. For that you need a rear STB or a rollbar. 

Best solution for a track car is a welded cage, but don't even think about running one on the street. They are dangerous without a race seat, 5 point harness and most of all, a helmet.


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## barnoun (May 7, 2002)

Geo said:


> *Yep. Just like Geo says.
> 
> I've personally watched someone grab a strub in a B13 that was attached to the top of the strut tower and not the upright and wiggle it around. The amount the coachwork moves around will stand your hair on end. OK, maybe that's an over statement, but not by much. I was truly shocked (no pun intended)...
> 
> *


Is it the independant rear suspension that makes the b13 so flexible and the b14's lack of irs that makes it stiffer?


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## Geo (Apr 30, 2002)

barnoun said:


> *Is it the independant rear suspension that makes the b13 so flexible and the b14's lack of irs that makes it stiffer? *


It's just the chassis design, not the suspension design.

BTW, sorry to keep talking about the B13. I see now that you specified that you have a B14.


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## barnoun (May 7, 2002)

Alright, so it's just the chassis in general that's stiffer. Glad I don't have a b13 then(not really, you guys have the good suspension)


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## PatScottAKA99XE (Apr 30, 2002)

barnoun said:


> *Alright, so it's just the chassis in general that's stiffer. Glad I don't have a b13 then(not really, you guys have the good suspension) *


Hey, there is nothing wrong with B14 rear suspension. Do a little reseach about it and see what you come up with. SE-R.net has a good article about it. But I can never find the link. If I find it I'll post it here.


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## Geo (Apr 30, 2002)

PatScottAKA99XE said:


> *Hey, there is nothing wrong with B14 rear suspension. Do a little reseach about it and see what you come up with. SE-R.net has a good article about it. But I can never find the link. If I find it I'll post it here. *


I'll take the B13 suspension any day of the week and twice on Sunday if for no other reason that adjustability (tunability).


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## PatScottAKA99XE (Apr 30, 2002)

SLAM!
You got me, and I thought I was gonna get away with that. Point(adj.) well taken.

Guess Ill I have to take my Beam to the bending shop.


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## shmuck90 (Oct 28, 2002)

*Dropzones*

does anyone know the spring rates for the dropzone springs, or at least know if they are pretty stiff or not?

thanks


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## hpro123 (Apr 30, 2002)

Close to stock and short. Forget it.

If you get them at a very good price (i.e. <$80) you can keep the mounting hardware, throw away the springs (or eBay them) and get Eibach ERSs to your liking.

Chris


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## shmuck90 (Oct 28, 2002)

hey hbpro are you talking to me? and nothing came with them except the springs what are you talking about the mounting hardware? damn are you sure those springs are that bad? thanks


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## hpro123 (Apr 30, 2002)

Sorry I had coilovers in my mind (this is where the "mounting hardware" came from).

As far as the lowering springs are concerned, it has been discussed very often in several lists/forums that practically ALL of the lowering springs for Sentras available in retail stores (i.e. not from special orders or whatever) are very close to the stock spring rates (maybe +20%).

In our cars that have limited travel, this almost always means trouble. Short springs and not enough spring rate make the car look right and drive aufully due to continuous bottoming.

Chris


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## shmuck90 (Oct 28, 2002)

do you think sprint springs are better than the dropzones or stiffer? just worried, i dont know what to get, eibach are pretty expensive


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## hpro123 (Apr 30, 2002)

Sorry, I do not know the specific rates and since I have a B13 I do not have 1st hand knowledge about B14s.

In any case try as hard as you can to find out the spring rates. Anything that lowers the car should be really stiff (at least 190/160 lb/inch front/rear) or you are about to be surprised.

Check the Suspension pageas at www.sentra.net and you will be enlightened.


Chris


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## shmuck90 (Oct 28, 2002)

ok what if i get b13 front shocks (kyb gr2) and b14 rear agx (kyb)struts and also got low profile bumpstops (energy suspension), will that help reduce bottoming out? thanks alot youve helped me alot


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