BCNR33 ride height?

[Laurence]

Just the usual questions about ride height with coilovers.

I notice that Tein talk about the ride height in terms of reduction from stock Ft:-51mm Rr:-36mm with their HA dampers which have 9kg/mm fronts and 8kg/mm rears

http://www.tein.co.jp/hadamp2ne.html

Then Ft:-46mm Rr:-16mm on their RA which have 12kg/mm springs all round

http://www.tein.co.jp/radamp2ne.html

Mines go with f:-40 and r:-20 with 10kg/mm springs front and rear

Unfortunately the JIC site does not have heigh specifications but from what I can work out the springs should be 12kg/mm f and 10kg/mm rear.

This combined with the fact the car is a non-V-Spec which is higher than a V-Spec means... well I dunno really. The guard to wheel centre measurements (with a 30cm ruler ) are approx 365mm front and rear.

Tyres are Yokohama A03R and it is hopefully going to Sandown soon so any suggestions would be helpful as I want to be able to go in and tell the people installing them what to set them at.

I notice that they seem to drop the front more than the rear. Stock the car seems to have a nose up attitude and it pitches under braking and acceleration quite a lot. Does anyone know what the stock spring rates are?

I guess the other question, how hard is it to install them yourself?

[Laurence]

Just FYI, they look a hell of a lot like these ones...

[Beer Baron]

It's not as simple as that, because those coil-overs (at least the teins anyway) are height adjustable so I don't know where that measurement comes from, it could be with the cuff wound up at the highest ride height setting, or the lowest, or halfway. The HAs (I know cause I have them) have a 'helper spring' too to keep the main spring captive at full droop. One suggestion I'll make is don't get the RAs. RAs don't have damper adjustment (HAs do - 16 levels), and 12kg/mm springs are very, very, very firm!!

Richard

[ferni]

Standard GTR's are setup like a grasshopper, lower in the front than the rear(looking at them anyway)

I was advised to level out the height of my car looking at the chasis, not to bother with measuerments center wheel to guard...

[Laurence]

It's not as simple as that, because those coil-overs (at least the teins anyway) are height adjustable so I don't know where that measurement comes from, it could be with the cuff wound up at the highest ride height setting, or the lowest, or halfway.

If you have a look at the link it is a recommended height, they also give the full hieghest/lowest range. If someone knows the standard V-Spec guard to wheel centre measurements then I can simple use that minus the lowering spec to come up with the ride height to set these too.

I rechecked the ride heights with a proper ruler and they were 37cm rear and 39cm front so it is definitely nose up stock. Also if that is how bad I do it with a ruler then imagine how bad it would be by dead reckoning!

Then there are other things like setting the spring preload. Very bad, because there is no point setting the ride height correctly if there are different prelaods.

Goodness, me. I thought this would be not that hard.

[Sydneykid]

If you have a look at the link it is a recommended height, they also give the full hieghest/lowest range. If someone knows the standard V-Spec guard to wheel centre measurements then I can simple use that minus the lowering spec to come up with the ride height to set these too.

I rechecked the ride heights with a proper ruler and they were 37cm rear and 39cm front so it is definitely nose up stock. Also if that is how bad I do it with a ruler then imagine how bad it would be by dead reckoning!

Then there are other things like setting the spring preload. Very bad, because there is no point setting the ride height correctly if there are different prelaods.

Goodness, me. I thought this would be not that hard.

It's not.

Preload is irrelevant, a 100 lbs per inch spring always takes 100 lbs to move it 1 inch.

Ride height is usually centre of wheel to guard, vertically.

I prefer R33 GTR's no lower than 350/355 mm front and rear

The sill to ground measurement should be close to parallel, never nose down

Std spring rate (from memory) is 175/125 lbs front /rear. That's 3 kg/mm and 2 kg/mm

12 kg/mm is 670 lbs per inch, even on the race GTR's I have never used a spring rate that high for R tyres (slicks are a different matter).

On the race GTR's we would usually run 400 to 450 lbs front and 200 to 250 lbs rear. That's 7/8 and 2.5/3.5 kg/mm.

Hope that helps :wavey:

[Laurence]

As always extremely helpful... Thankyou.

So what is the point of preload then?

As I understand it (which I clearly don't) if we use a 100lb/in spring and we stick in and inch of preload it takes 100lb of force on the spring before it moves at all... Just looking at the numbers I can see that all of the preload would be taken up just by having the car sitting on the ground.

As for the sping rates... hmm. Well the springs have nothing written on them. Might have to take them somewhere to find out what they actually are.

[skyline]

Sydneykid and all,

Do you corner weight the car when setting up coil overs?Ie set ride height first very close to what you desire then do fine adj to heights using scales(incl drivers weight) to try and achieve equal or near equal weights in all 4 cnrs?

Regards,

SKYLINE(Kym).....

[Sydneykid]

Sydneykid and all,

                          Do you corner weight the car when setting up coil overs?Ie set ride height first very close to what you desire then do fine adj to heights using scales(incl drivers weight) to try and achieve equal or near equal weights in all 4 cnrs?

                         Regards,

                                      SKYLINE(Kym).....

I set approximate ride heights first, with a Skyline (and most road cars) you can never get equal weights on all 4 wheels. The front is heavier than the rear, you can't change that with spring heights. On a GTR the right hand side is heavier than the left hand side. Then when you put the driver in, the right hand side is heavier again.

A car is kinda like a table with 4 legs, if you have one leg shorter then the others the table rocks. This is unstable, every time you turn the steering wheel the chassis rocks easily to that unloaded wheel and then goes firm. Just like the table you get diagonal pitching and a sudden stop. The higher the spring rate the more sudden the stop.

Since you can't change the front to rear weight spread, or the right to left, what you are trying to achieve is to get the diagonals equal. Generally when you get a Skyline perfect on the diagonals, the fronts are prety close to the same, wit hthe left hand side a bit lighter. But the right rear (where most of the drivers weight goes) is always heavier than the passengers rear.

Hope that helps

[Sydneykid]

As always extremely helpful... Thankyou.

So what is the point of preload then?

As I understand it (which I clearly don't) if we use a 100lb/in spring and we stick in and inch of preload it takes 100lb of force on the spring before it moves at all... Just looking at the numbers I can see that all of the preload would be taken up just by having the car sitting on the ground.

As for the sping rates... hmm. Well the springs have nothing written on them. Might have to take them somewhere to find out what they actually are.

The job of a spring is to hold the car up, the amount of preload is determined by the spring rate and the weight of the car tha teach spring has to hold up.

An example might help....

If you have say a 1,300 kg skyline with 3 kg/ mm springs in the front and 2.25 kg/mm spring in the rear. The front weight distribution is ~60%, so that's 780 kgs divided by 2 = 390 kgs per front spring. That means to hold the Skyline up, the front springs need to compress 130mm (390 / 3). The rears would be 520/2/2.25=115 mm.

Note that this difference front to rear (130 vs 115) is quite normal as all the variable weight is in the rear, stuff like fuel in the tank, passengers in the rear seat, luggage in the boot etc .

Just in case it helps some more, a standard Skyline springs is ~350mm free height (out of the car). There is around 25mm of preload to hold the spring in the seats on the shock.

Hope that makes sense

[David Kemps]

Sydneykid: how do u get ur racecars to handle with so low springrates? does it not roll or are the swaybars the key?

cause japanese coilovers always come with really hard springrates, say for r33 gts25t tein HE's are 10kg and 8kg.

if i have good wheels and tyres on the car, the TEIN HE suspension, whats the next biggest thing i can do to increase the car's handling? swaybars? pineapples to stop movement?

also do u know what other bars the r33 gtr came with different from the gts25t to stiffen up the chassis like rear strutbrace, under the car bars etc?

thanks

Dave

Dave

[Sydneykid]

Sydneykid: how do u get ur racecars to handle with so low springrates? does it not roll or are the swaybars the key?

cause japanese coilovers always come with really hard springrates, say for r33 gts25t tein HE's are 10kg and 8kg.

if i have good wheels and tyres on the car, the  TEIN HE suspension, whats the next biggest thing i can do to increase the car's handling? swaybars? pineapples to stop movement?

also do u know what other bars the r33 gtr came with different from the gts25t to stiffen up the chassis like rear strutbrace, under the car bars etc?

thanks

Dave

Hi Dave, let's start off with a race car is the sum of all of its parts, not just the springs. Secondly Australian racing circuits are not smooth, they have bumps and ripples, joins and large ripple strips. The fastest way around a circuit can not be compromised by dodging the bumps or not riding the ripple strips.

So we need springs that can absorb bumps without throwing the car off line, not 1 mm. To control roll we use stabiliser bars, to control the dive under brakes we have anti dive geometry in the front suspension and to control the squat on acceleration we have some anti squat geometry built into the rear suspension.

The stabiliser bars are of course adjustable, this enables us to tune the handling very quickly and in long distance races allow for the rear weight reduction due to fuel usage. You can't do that with springs, they take time to remove and replace and can not be "adjusted" on the move.

The most important part of the suspension on a modern saloon race car is shock absorbers. These days, not only do we have separately adjustable bump and rebound damping, we can independently adjust the high frequency and low frequency damping for both bump and rebound. Plus we can change the gross compression valving so we can ride the ripple strips, the we have 5 way adjustable dampers.

So the concept of a modern race car is to have the softest spring rate that will still hold the car up and then use bars, dampers and geometry to achieve the ultimate result.

We are lucky down under, we have a long history of inexpensive, good quality, aftermarket stabiliser bars (courtesy of KMAC and SELBYS) that other countries simply don't have. Plus we have a lot of European influences in sophisticated shock absorber valving (courtesy of Koni and Bilstein). The Japanese are deficient in those areas, so they rely excessively on springs to do everything. As everyone knows you can't do everything properly with only one tool.

So to improve the handling of cars equipped with Japanese coil over kits, the first thing I do is check the spring rates. Most times they are way too stiff, quite often you can get a good improvement by changing the rear springs to the front and buying some more appropriately rated rear springs. A cheap fix for under $200 inc fitting. Then I add appropriately rated stabiliser bars, adjustable if you want to fiddle, fixed if you want to fit and forget. The most important thing is then to get the suspension geometry (camber, caster, toe, anti squat and anti dive) right so that the maximum contact patch of the tyre is maintained.

Moving onto bracing. Front strut brace is always good idea on a Skyline, rear strut brace not so important. Rear subframe o'rings (pineapples) are good for adjusting the anti squat and also for removing the mush in the rear suspension caused by the soft cradle bushes.

Lastly HICAS removal, HICAS is not your friend, I always remove/disable it. There are plenty of posts on how and why.

Hope that helps

[Bleck]

Sydneykid, thanks for the info re: suspension setup. I have had a problem for a while of little to no traction on my R33 gts-t with 210rwkw. It has Tein height and damper adj coilovers. Camber kit and pineapples fitted. I have read that you recommend to get 200lbs springs made up for the rear and swap the rears to the front. As I know little to nothing about suspension:

Do whiteline make a 200lbs spring for the r33 or is it a custom order??

Do I need to order a specific type/size of spring to compensate for the fact that the Teins are adjustable?

Why swap the rear springs to the front?

Cheers,

Bleck

[Sydneykid]

Sydneykid, thanks for the info re: suspension setup.  I have had a problem for a while of little to no traction on my R33 gts-t with 210rwkw. It has Tein height and damper adj coilovers. Camber kit and pineapples fitted. I have read that you recommend to get 200lbs springs made up for the rear and swap the rears to the front.  As I know little to nothing about suspension:

1.Do whiteline make a 200lbs spring for the r33 or is it a custom order??

2.Do I need to order a specific type/size of spring to compensate for the fact that the Teins are adjustable?

3.Why swap the rear springs to the front?

Cheers,

Bleck

Hi Bleck, suggestion follow;

1. Yes, but it would pay to check with them

2. No, exactly the reverse, because the Teins are adjustable you can adjust them to suite the spring rates.

3. The rear spring rate is ~30% too hard for the rear, but just about right right for the front. Skyline springs are the same physical dimensions, so the rear and the front springs are interchangeable. The reason you do it is cost, why buy 2 sets of springs when swapping one set will do the job and save you 50%. I don't sell springs so I don't need to tell you that you need to spend your money with me and buy 4 springs when you really only need 2.

I have told a large number of people this system, about 80% of them are happy, some want a more compliant ride and end up buying even softer front springs. But if you can save some money why not?

Hope that helps

[Bleck]

Great info,

Few more questions:

1. Putting the rears into the fron would make the front stiffer than the rear. Is that a problem??

2. I want to keep the same ride height (eyebrow height). With the softer springs they will compress further than the standard Tein springs, which will require me to wind up and further compress the coil. Do I need longer springs to compensate for this?

I'm running the top model Hankook tyres 265/35-18's with camber setup as you've previously stated. Do you think that using the softer 200lbs spring on the rear will greatly improve the traction?? At the moment it's drifting all over the place and killing the rear tyres.

Cheers

[Sydneykid]

Great info,

Few more questions:

1. Putting the rears into the fron would make the front stiffer than the rear. Is that a problem??

2. I want to keep the same ride height (eyebrow height). With the softer springs they will compress further than the standard Tein springs, which will require me to wind up and further compress the coil. Do I need longer springs to compensate for this?

3. I'm running the top model Hankook tyres 265/35-18's with camber setup as you've previously stated. Do you think that using the softer 200lbs spring on the rear will greatly improve the traction?? At the moment it's drifting all over the place and killing the rear tyres.

Cheers

Suggestions follow;

1. The springs are different rates now, otherwise why bother changing over front to rear? The front of a Skyline carries 60% of its total weight and the rear 40%. So the front spring rate needs to be around 50% stronger than the rear. With a new pair of 200 lb springs in the rear, the Tein rears will be just about right for the front.

2. That's what adjustable lower spring platforms are for.

3. The lower rear spring rate will help this, but you do have to keep it balanced, refer #1. The rear springs rates are so high now that the tyres are skipping from one little ripple on the road to the next, the softer rate will enable the tyre to follow the road surface. More contact = more traction.

Hope that clarifies:cheers: