Coil Overs For My R34 Sedan. What Spring Rate.

[2lord]

Hey all.

i know there is a hundred threads in here about coil overs but most aren't directed to where i am looking.

i have a R34 Sedan and was wondering if anyone knew what the spring rate of the standard springs would be??

i am looking to upgrade to coil overs.

However, i dont want to comprimise to much on the ride.

I want the coil overs to lower my car and offer adjustability etc. i do not want these springs to offer better handling etc.

So on that note i want the spring rates to be friendly to my car as i've had rough stiff spring cars and i certainly don't want that.

i seen that Hsd HS series are f8 r7.

unsure if this would be to hard or not?

i noticed that tein super streets are at about 5kg, but i am not a fan of the old school design of the super streets as the length of the stroke gets shorter the lower you go, so when i lower the car it will inturn get rougher.

ISC's are about the only company that offer's any spring rates you want. However unsure to what rate i would want.

any help would be apprechiated.

cheers

[Yawn]

Id hazard a guess at 4-5kg will be what you want, slightly stiffer than stock but not too harsh.

[2lord]

yer unsure what stock is so can't really say what harder will be.

only thing i am unsure on is some brands when u lower then alot (which is what i want) the stroke of the actual suspension gets shorter ie making the spring harder.

so unsure if brands like tein super street that although offer a softer spring rate at the height i want i am unsure if they would be harder than a coilover with say 7kg spring rates but with longer stroke at lower heights.

hmnnn.

[Yawn]

Id say stock is around 3ish. And id say that the ride getting stiffer the lower you go is actually an advantage, or else you're gonna get your wheel hitting the guard etc. And I must say the Tein SS are a very comfortable ride, although other people make think otherwise.

[Sydneykid]

Hey all.

i know there is a hundred threads in here about coil overs but most aren't directed to where i am looking.

Try a search on "Sydneykid" and "spring+rates"

i have a R34 Sedan and was wondering if anyone knew what the spring rate of the standard springs would be??

~3kg/mm

i am looking to upgrade to coil overs.

R32/33/34's come standard with coil overs

However, i dont want to comprimise to much on the ride.

Then why change the springs at all?

I want the coil overs to lower my car and offer adjustability etc.

The most effective way to lower it and retain the standazd ride comfort is by changing the shocks. The Bilsteins in the Group Buy come with additional circlip grooves which enable you to lower it using the standard springs. Around 16 to 24 mm works very well. Tell me what height you want and I can tell you which circlip grooves to use.

i do not want these springs to offer better handling etc.

Depending on how much you lower it you may have to make some camber correction otherwise it will wear out tyres.

This is what is usually needed for each height increment, note that all measurements are centre of wheel to guard;

Standard (new) height is 380 mm front and 370 mm rear

360/350 mm needs only the standard rear camber adjusters

350/340 mm needs 1 front camber kit and 1 rear camber kit

340/330 mm needs I front camber kit and 2 rear camber kits

So on that note i want the spring rates to be friendly to my car as i've had rough stiff spring cars and i certainly don't want that.

You don't have to

i seen that Hsd HS series are f8 r7. unsure if this would be to hard or not?

Since 3 is standard what do you think more than double that is goingh to be like?

i noticed that tein super streets are at about 5kg, but i am not a fan of the old school design of the super streets as the length of the stroke gets shorter the lower you go, so when i lower the car it will inturn get rougher.

Not necessarily, it depends on the choice and dimensions of the bump stops and how low you want to go.

Regardless of the shock/spring construction, the suspension geometry turns to crap if you go below 350/340.

ISC's are about the only company that offer's any spring rates you want. However unsure to what rate i would want.

Standard seems like it should suite your purposes.

Cheers

Gary

[2lord]

thanks for that nice big messag for me mate.

Yer i dont have coil overs in my car as standard as they are just struts, perhaps it was an option or something.

i have 19's on my car at the moment and i like the really low look so i'm prob looking at lowering my car about 5inches i would sugest. I am getting my guards rolled+lipped to suit before i lower it.

i am going down the coil overs route as i have had them before on many occasions and really liked the fact that u can constantly change the setup. camber/hardness/rebound/height etc.

i figure if i decent set of spring in my car will cost me about 500 installed. for double that i could nearly buy coil overs and change the setting all the time.

the main drama i think i'll have is i'll spend 500 on some springs and i either won't like them or the height won't be wat i want.

hmnn

[Sydneykid]

thanks for that nice big messag for me mate.

Yer i dont have coil overs in my car as standard as they are just struts, perhaps it was an option or something.

i have 19's on my car at the moment and i like the really low look so i'm prob looking at lowering my car about 5inches i would sugest. I am getting my guards rolled+lipped to suit before i lower it.

i am going down the coil overs route as i have had them before on many occasions and really liked the fact that u can constantly change the setup. camber/hardness/rebound/height etc.

i figure if i decent set of spring in my car will cost me about 500 installed. for double that i could nearly buy coil overs and change the setting all the time.

the main drama i think i'll have is i'll spend 500 on some springs and i either won't like them or the height won't be wat i want.

hmnn

Oh my, you have some serious understanding to learn.

1. R32/33/34's have double wishbone suspension so you can't change the camber with adjustable strut tops

2. They only have ~3.75" of travel standard, so lowering them 5" is not possible without major surgery

3. The term "coil over" means that the spring goes around the the shock, and yes they do have that standard

4. Because they are double wishbone, they don't have "struts", they have spring/shock units.

5. Obviously 5" lowering is illegal, on two counts actually, one being the lack of ground clearance and the other being retained travel, nowhere near 2/3rds of standard.

6. The more you lower a car the higher the spring rate has to be to aborb the impact in the shorter distance available. For 5" lowering I'd say 4 pieces of 4 x 2 instead of springs would be about right.

Perhaps some more research is required.

Cheers

Gary

[2lord]

ok fair enough.

however i have 19's so my car is pretty much 2inches higher off the ground than standard allready.

i have seen some low r34's before using only coil overs as the method and it seems to be ok. In terms of legallity of the ride height, i am not to worried at his point as i can lower my car a lot before i'd even come near 100mm off the ground. My car is sitting unusually high.

In terms of the spring rate needing to be harder due to the fact that the travel of the suspension is less. If you use the right type of suspension you will find that however the car gets lower the spring it self is moving and the length of stroke of the suspension is'nt reduced therefore the spring/strut aren't compacting like some cheaper suspension setups. The thing that makes most cars ride like shit is the use of lowered springs alone, that reduce the length the shock aborber has to travel. If you set things up right. you can have a harder spring rate with longer suspension stroke will ride alot better than a softer spring combined with a shorter suspension stoke.

well thats my understanding anyways.

I am used to the nissan s type platform so i'm still learning as to the dynamics of the r34 skylines etc.

feel free to shread my down if my concept is lacking. :-)

Edited May 20, 2008 by 2lord

[Sydneykid]

ok fair enough.

however i have 19's so my car is pretty much 2inches higher off the ground than standard allready.

i have seen some low r34's before using only coil overs as the method and it seems to be ok. In terms of legallity of the ride height, i am not to worried at his point as i can lower my car a lot before i'd even come near 100mm off the ground. My car is sitting unusually high.

In terms of the spring rate needing to be harder due to the fact that the travel of the suspension is less. If you use the right type of suspension you will find that however the car gets lower the spring it self is moving and the length of stroke of the suspension is'nt reduced therefore the spring/strut aren't compacting like some cheaper suspension setups. The thing that makes most cars ride like shit is the use of lowered springs alone, that reduce the length the shock aborber has to travel. If you set things up right. you can have a harder spring rate with longer suspension stroke will ride alot better than a softer spring combined with a shorter suspension stoke.

well thats my understanding anyways.

I am used to the nissan s type platform so i'm still learning as to the dynamics of the r34 skylines etc.

feel free to shread my down if my concept is lacking. :-)

So you didn't use lower profile tyres on the 19 "rims? You must have some serious speedo error.

There are 2 issues in regard to the legality of lowering. The first is the ground clearance minimum of 100 mm, at 350/340 (30 mm lower than standard) a 3" exhaust sits just above 100 mm from the ground as it goes under the rear subframe. I strongly suggest that you measure yours. The second legality issue is the requirement to maintain 2/3rds of the suspension travel. R32/33/34's have around 3.75" of compression travel standard, so if you lower it 5" it can't possibly have 2/3rds of 3.75". Hence it's illegal.

Let's get to the ride comfort question. If you increase the spring rate then the car will ride harsher. The only time your example has merit is with larger impacts where all of the travel is used. Then the longer travel/higher spring rate MAY be better than the softer spring rate/shorter travel. But with the the more normal sized impacts, the longer travel does nothing for the ride comfort and the higher spring rate still increases the harshness. In simple terms, 10% of the time you MIGHT be better off (big bumps) but 90% of the time (normal bumps) you DEFINITELY won't.

The length of stroke has absolutely nothing to do with cost, so the genralisation "some cheaper suspension setups" is very misleading. You can pay $20K for long travel suspension and you can pay $400 for short travel, the cost tells you nothing. It's about chosing the right style of system for your requirements, whilst understanding the limitations of the model of car you are dealing with.

Cheers

Gary

[2lord]

hmn quite the epic we have going here.

thanks for the input mate.

I think i'll have to sit down and work out exactly what i want.

My car does however have low profile tyres, but i still recon its higher.

My car is a Non Turbo model so as far as 3"exhuast goes, i don't have any of that sorta gear (no point)

Finding the right suspension for the right price is where my main dilema is. I am thinking that Isc's are probably the best considering i can choose any spring rate, i am unhappy with majority of companies offering a set spring rate and most are way to high.

Some ppl might like 14kg springs but not me.

[adam87]

i think from what your saying is you want the car low regardless of legalities and you want a base height adjustable coil over. eg. like ISC's where you use the bottom mount of the coilover to lower shorten the length of the coilover without touching the spring

i have ISC's, my car is used only for drifting on a track (ie - better conditions than roads) and iv had no troubles at all. mines an s13 tho not a 34.

so from what your saying just look for a coilover that is base height adjustable in the same sprinrates as the teins as you wont be able to go as low as you want with standard spring rates

[2lord]

yer thats exactly what i'm looking for.

[V28VX37]

Sorry to resurrect an old thread but I couldn't find a specific answer - like the original poster I'm looking for recommendations on suitable coilover spring rates for an R34 GT-T sedan. The car is street only, so I'm after good quality ride and comfort rather than outright handling (see my related thread here). I specifically want to avoid harsh/crashy ride.

I'm currently considering BC Racing BR series coilovers that come with 8kg front and 6kg rear by default. To me that seems a bit high, especially as I will be upgrading the swaybars at the same time – F:28mm / R:25mm compared to stock F:22mm / R:18.5mm – so a fair bit thicker. These should control body roll pretty well so I should be able to go a bit softer on the springs, right?

So back to the coilovers, I'm thinking something like F:6kg / R:5kg - is anyone running these rates on a sedan? What's the ride like? Thanks!

[Willis]

The way i estimate how harsh it's going to be is just based of personal experience. For example.. i had 12kg F and 10kg R in my R32 GTR.. and it was track spec stiff.... not good.

The approx weight of the car would have been ~1480-1550kg with me in it.. my old coilovers were 8kg front and 6kg rear and they rode very nice.

So how i estimate it is, weight of the car compared to the spring stiffness. So if your car is ~1600kg then 6kg front and 5kg rear will be rather comfortable.. and handling should be good caus of the swaybars. If my car was ~1600kg and i wanted a nice street ride i wouldn't go any higher then 8/6.

Take what ive mentioned as a grain of salt as i'm only speaking from my limited personal experience.

If you can.. find a member with the same car as yourself (with coilovers obviously) and ask him to take you for a ride. That will give you an idea

[V28VX37]

If you can.. find a member with the same car as yourself (with coilovers obviously) and ask him to take you for a ride. That will give you an idea

Thanks Willis, that's a good tip. Any volunteers with a sedan on coilovers in Melbourne?

[Willis]

As long as it's not above 8kg front and 6kg rear, i think you'll be happy! Unless your 30+ ? Haha.

[V28VX37]

Well I've now ordered a set of BR series in F:6kg / R:5kg, will let you know how they go...

[V28VX37]

Well I've now ordered a set of BR series in F:6kg / R:5kg, will let you know how they go...

Finally got around installing these on the weekend. Based on some initial driving it seems like a good choice, not too stiff and more compliant + less crashy than the OEM shock & King Spring combo.

I set the front halfway between hard and soft and the rear to 10 clicks from full soft (1/3 of the way). At this stage I'm definitely glad I didn't go with the standard F:8 / R:6.

This said, I reckon spring rates aren't directly comparable between different setups. Shock travel and the size of the spring must also play a role - in other words typical coilovers will need stiffer springs to compensate for the lack of travel. Just compare the OEM front shock + King Spring on the left to the BC Racing on the right: