Track Suspension...best Coil Over Kits!

[Tektrader69]

From personal experience, with Eibach Springs of course, approximate prices only;

Cheers

Gary

Where do Proflex with external canisters fit amongst all these?

Edited August 27, 2009 by Tektrader69

[sav man]

Proflex = MCA

unless your talking about the real Proflex from Europe

[iplen]

My first Proflex/MCA experience was hitting a hole that I thought was going to rip a front wheel off a corolla rally car, and i barely even felt it (was blown away with how well it worked). We then had the struts rebuilt and setup correctly, because they were completely f***ed and the improvement from them being bloody incredible before the rebuild was daylight again. Later ran DMS in a Subaru, and was impressed after the bad reports I had heard, but compared to very basic MCA the DMS still struggled, and yes they did eventually crack, and they Springbound quite consitently

[mosoto]

Bilstein PSS9, single adjuster, revalved and with spring rate changes for our roads/tracks, $4.5K

Then daylight

Yamahas (Japanese Ohlins), single adjuster, revalved and spring rate changes for our roads/tracks, $4K (with some knowledge they can be made to work OK, not great, but OK)

That is somewhat different to the opinion given on the G35driver forums by someone of similar background as yourself. My understanding of his views in various posts are the Ohlins (the jap ones) are a superior unit than the bilstein.

Ohlins PVC coilovers Monotube, adjustable damping (listed on many web sites as rebound only, this in not correct) Full height adjustablity on the fronts

Spring rates 560/392

Side note: PVC vavling system operates on compression side to improve control and still offer ride comfort. IMO a top 5 coilover system. Excellent valving, built with the rare ablity to adjust to true ride quality settings and yet reach true performance settings in the stiffer settings. (I did run them on a shock dyno).

Standard ride height on 350Z -.8"/-8"

Min drop amount on 350Z Front: -2" Rear:-.2"

Max drop amount on 350Z Front:-1.4" Rear -1.4"

http://www.carrozzeriajapan.co.jp/ohlins/4w/pcv.html

^use this to translate http://babelfish.yahoo.com

Bilstein PSS coil over (Monotube construction, non adjustable dampners)

Spring rates 370/240-420 (rear progressive)

Note: A superior choice for ride quality vs Tein basic, Eibach Pro-S and Kw Variant 1, better valving and monotube vs twin tube. Likely a better choice vs Tein CS too. You can also have them revalved to use stiffer springs, you can even have them converted to have adjustable damping.

Bilstein PSS9 coilover (Monotube construction, adjustable dampners)

Special Note: If you keep the damper adjustment at or below 5, this setup delivers a ride and drive quality that is beyond reproach. Settings above 5 are not advised, ride and performance is compromised. I own these, but had the valving reworked and have installed stiffer springs.

Spring rates 370/240-420 (rear progressive)

I'm not trying to find fault just curious as to the differing opinions. Surely our roads aren't so different that it changes the requirements and setup of the coilover.

Edited September 12, 2009 by mosoto

[shoei]

pick a suspension tuner, heasman, East coast, MCA, DMS etc and follow their advice. I use Zenodampers he only does bikes though

Otherwise you will end up spending more on suspension that you have buget for, dont buy anything before talking to the experts and save money in the long run

you will find that off the self stuff is for the masses, your suspension tuner will revalve the shock according to your needs, dont pay more the $250 a corner for a revalve and dont pay more then $50 for a spring exchange

ohh and pick someone local to you and have patience, perfection does not happen overnight

[Snowman]

Ok there seem to be plenty of eggsperts out there so here's a quick question (which seems to regularly have a long answer).

Shock types aside - there seems to be 2 quite different trains of thoughts on spring rates out there.

Now my understanding is as a rule of thumb spring rates should ideally follow the weight split of a car.

AKA - if a cars weight split is 50f/50r then the spring rates should be pretty close to identical front and rear. Skylines (well GTR's at least - I have NFI what the weight split in a GTS is) are a lot front heavier and I've always run much higher weighted front springs as a consequence. But a lot of people seem to run a much higher rear rate than I do, as well as a softer front. I can't fathom the logic as to why this would be, so I'd love to hear the reason for it - if there is one!?

I'm looking at changing my shocks over currently and the suggested spring rates by the builder were significantly different to what I'm running - hence the question.

[Sydneykid]

That is somewhat different to the opinion given on the G35driver forums by someone of similar background as yourself. My understanding of his views in various posts are the Ohlins (the jap ones) are a superior unit than the bilstein.

I'm not trying to find fault just curious as to the differing opinions. Surely our roads aren't so different that it changes the requirements and setup of the coilover.

There arer three reasons I don't rate them as high as the Bilstein PSS9

Spring rates 560/392

Ohlins PVC coilovers Monotube, adjustable damping (listed on many web sites as rebound only, this in not correct) Full height adjustablity on the fronts

Spring rates 560/392

Side note: PVC vavling system operates on compression side to improve control and still offer ride comfort. IMO a top 5 coilover system. Excellent valving, built with the rare ablity to adjust to true ride quality settings and yet reach true performance settings in the stiffer settings. (I did run them on a shock dyno).

Firstly the front spring rates ie; 560 lbs/inch, is simply rediculous, it's a higher rate than we ran in the circuit racing 350Z. Perhaps more importantly, the balance of the effective spring rates is not in line with the weight distribution. With 55% of the total weight on the front it makes no sense to have 70% of the total effective spring rate there. The rear effective spring rate at 200 lbs/inch is not too bad, it's the front spring rate that is way out of line.

Secondly this leads me to the conclusion that, if the spring rates are so out of balance, the damper rates must be equally so. If we attempt to fix the excessive front spring rate by fitting springs with more appropriate rates ie; 33% softer, then we will almost certainly run into valving issues. If we use the external adjuster to reduce the rebound damping to more closely match the softer springs, at the same time we will be reducing the bump damping. Which is undesirable when using a softer spring, where it would in fact be more appropriate to increase the bump damping to supplement the spring rate.

Lastly the fact that they are marketed almost soley for JDM consumption means high frequency valving tuned for fine gravel and tarmac style road construction with high quality maintenance. In Australia we use course gravel road construction, as well as jointed concrete and we have what would be considered very poor quality maintenance.

So let's compare that with the Bilstein PSS9's, a far more sensible effective front spring rate, one that is also more in tune with the weight distribution. In fact an almost perfect 56/44 match. No change in spring rate required and hence no chance of the damper adjustment being counter productive. Engineered in Europe where course gravel, concrete and even cobblestone roads are not uncommon.

In conclusion, the Bilsteins are serviceable, have readlily spare parts and alternative valving and very experienced local technicians and the Yamahas don't have any of those.

I believe I have good reasons for my rankings, but in the end it's just my opinion and I'm not right all of the time.

Cheers

Gary

[Sydneykid]

Ok there seem to be plenty of eggsperts out there so here's a quick question (which seems to regularly have a long answer).

Shock types aside - there seems to be 2 quite different trains of thoughts on spring rates out there.

Now my understanding is as a rule of thumb spring rates should ideally follow the weight split of a car.

AKA - if a cars weight split is 50f/50r then the spring rates should be pretty close to identical front and rear. Skylines (well GTR's at least - I have NFI what the weight split in a GTS is) are a lot front heavier and I've always run much higher weighted front springs as a consequence. But a lot of people seem to run a much higher rear rate than I do, as well as a softer front. I can't fathom the logic as to why this would be, so I'd love to hear the reason for it - if there is one!?

I'm looking at changing my shocks over currently and the suggested spring rates by the builder were significantly different to what I'm running - hence the question.

The way I do it;

1. I ask the tyre engineer what effective spring rates the tyres like, after all maximising the tyre's performance is what it's all about.

2. I measure/calculate the effective spring rate versus actual spring rate noting leverage and movement ratios

3. I weigh the car with the driver in place and enough fuel to do the race distance

4. In a front engined rear wheel drive car the front spring rate is the one that more closely matches the highest effective spring rate the tyres like to operate in.

5. In a front engined rear wheel drive car the rear spring rate is the one that more closely matches the lowest effective spring rate the tyres like to operate in.

6. In a front engined 4wd car the front and rear effective spring rates are closer together than in a a front engined rear wheel drive car

7. In a front engined fwd car the front and rear effective spring rates are even closer together

The starting formula is then pretty simple

Front spring rate = what the tyre likes / the front leverage ratio / the front movement ratio

Rear spring rate = the front spring rate X weight distribution / the rear leverage ratio / the rear movement ratio

This give me a good starting point for the spring rates. Personally I then prefer to tune out any handling imbalance with antiroll (ie; swaybars sizes and adjustment). Some people do the same via spring rates.

A simple example, in an understeering chassis I would use more rear antiroll and/or les front antiroll to overcome it. Some people would use a higher rear spring rate (than the above formula would indicate) to overcome it. A combination of the two (more rear spring + more rear bar) is not uncommon. The problem with the higher rear spring rate is that its always there, even when the car is not understeering (ie; accelerating and/or braking). Whereas more antiroll is only there when needed, ie; when cornering. Plus its damn site easier to adjust a swaybar than it is to change the rear springs.

There are further complications in the form of anti dive and anti squat geometry that have an effect on the spring rates. For example it is beneficial to dial out excessive nose dive under brakes with anti dive geometry than by using higher front spring rates. Once again the problem with the higher front spring rate is that its always there, even when the car is not braking ie; when accelerating.

Another item that affects the spring rate choice is the availability of adjustment. For example if there isn't enough negative camber available to maintain the optimum tyre contact patch, then there may be no choice other than to increase the spring rate above that which would otherwise be ideal.

It is always worth keeping in mind that shock absorbers with separate adjustment for bump and rebound mean we are less reliant on springs, to optimise the chassis control. That shock absorbers change the timing of events, slow them down or speed them up. Which doesn't necessarily mean change the amplitude of the event, just how long it takes to have an effect.

Add it up and it's easy to see why there are multiple answers to the "what spring rate do I run question?" Personally I always prefer to run the softest spring rate possible and use the other weapons like anti roll bars, anti dive/squat geometry, damper adjustment, correct camber and caster to achieve a superior result. For some people that's all too hard and they reach for the only gun they know, higher spring rates.

Cheers

Gary

[shoei]

The starting formula is then pretty simple

Front spring rate = what the tyre likes / the front leverage ratio / the front movement ratio

Rear spring rate = the front spring rate X weight distribution / the rear leverage ratio / the rear movement ratio

hey SK just wondering where does the weight of the car plus driver and fuel fit into this formula? is it factored into "what the tyres likes"

so if a car has a leverage ratio of 1:1 and movement ratio of 1:1 then spring rate = what the tyre likes

how do you figure out what the tyre likes? is there another formula that factors in weight and tyre pressure

[mosoto]

Thanks Gaz. I understand what your saying about the spring rate bias being heavy on the front, that did concern me a bit, but does it matter if the damper is correctly matched to the spring?

Would it be more beneficial to revalve & respring the rear up to about 500 for track use, given the rear is not a coilover but separate spring & damper (as in OEM)?

Also the Bilstein are progressive rear spring. How is that comparable to the Ohlins linear springs?

I'm also not keen on the bilstein "helper" springs on the front, When installed they become useless and remain under max compression. I thought that a bit of a crap design to be honest

Even though I won't be lowering the ride more than 30mm I'm not keen on coilovers where height adjustment effects spring & damper travel as is with the Bilsteins.

Gsedan35 had this answer to one of my ? on g35driver adverbatim. He runs PSS9 revalved with 560F/500R spring rates, albeit his is a sedan.

I would never run a truecoilover rear setup, so all my suggested products run their rear springs in the oem location.

The Ohlins DFV is a excellent option. To me, it was not appropirate to list anything beyond $1900 in my list given the price point what was mentioned sell's for.

The Ohlins DFV and the original PCV are bulit in Japan by Carrozzeria. That product is imported into the U.S. by Ohlins USA. They aren't valved like the typical JDM product. In fact they are brought here unchanged and were run on Ohlins 7 post shaker suspension testing system before they were offered by them in this country. I have run the PCV version on a shock dyno, the DFV is valved the same and differ's only in that the PCV valving system is also on the rebound side and it has aluminum cases vs the PCV's steel cases. Without revealing too much from the dyno's I ran, at their lowest settings they mirror the Bilstein Pss9 set to full soft. The stiffer settings mirror the valving of the Truechoice Phase 4 coiilover set to full stiff. So, the DFV is a excellent option, for a price. To be honest, I have not really looked into weight savings enough to know which suspension products are lighter then others. I just know the DFV does have aluminum cases.

To explain about the Pss9/10 adjuster's. Normally, I will let everyone know to not run the setup on settings past 5. At full soft they deliver a ride and drive experience that is excellent, beyond reproach. As you turn them up, things start to decline and once you go past 5. basically taking you into deminishing returns.

When someone mention's track use as you did, it's a different story, picking another product makes more sense because of what is happening valving wise when you set them to settings past 5. Mid speed damping ballon's far too much along with the high speed damping. Yes this is a rebroad minded person of the adjuster going from fully closed to fully open in only 1/2 a turn (as seen from inside the damper, not talking about the adjustment dial).

It's still a great product, provided your not going to track the car.

I'm waiting to hear back from Gsedan35 as to the reason for those spring rates but going by his shock dynos thats probably not an issue if they are so similar to the PSS9 on the comfort settings.

So all that jargon aside, In your opinion what would have been a better setup for the V35, coilover or not?

Edited September 15, 2009 by mosoto

[Beer Baron]

well i run these in my 32 GTR. they are excellent shocks for the money. some may claim they are not as good as the sweedish made ohlins and that may or may not be the case. but they performed well when tested on a shock dyno and more to the point perform well in my compromised road/track car. they can be rebuilt if needed without too much problem for me and for their cost they are as good as anything else near them in price. all alloy shock body, remote canisters all round, decent size pistons and separate bump and rebound adjustment, they are nice and light and have height adjustable at the lower mount and the lower spring seat so you can adjust height without affecting stroke.

http://www.carrozzeriajapan.co.jp/ohlins/4w/flag-r.html

[mosoto]

Thanks for chiming in BB. What are the spring rates on your set and who have you approached to service them?

[Sydneykid]

Thanks Gaz. I understand what your saying about the spring rate bias being heavy on the front, that did concern me a bit, but does it matter if the damper is correctly matched to the spring?

Too high a pring rate sacrifices traction, nothing you with the shocks will change that fact.

Would it be more beneficial to revalve & respring the rear up to about 500 for track use, given the rear is not a coilover but separate spring & damper (as in OEM)?

Sure it would balance up the rates, but in doing that you would end up with is too high a rear spring rate. Hence compromise the rear traction.

Also the Bilstein are progressive rear spring. How is that comparable to the Ohlins linear springs?

The rear progressive (soft) spring rate is almost completely sacrificial. The progressive winding is used much like the helper spring on the front. It will have a slight effect on ride comfort when the fuel tank level is low and only the drover on board. Handling wise it's a straight comparison as you would expect with only ~10% variation in the (high) spring rate.

I'm also not keen on the bilstein "helper" springs on the front, When installed they become useless and remain under max compression. I thought that a bit of a crap design to be honest

Trying not to pick on you, but from this observation it is obvious that you have very little understanding of what helper springs are actually there for. The idea of a helper spring is to facilitate as much droop travel as possible, so the shock has sufficient extension to keep the wheels on the ground. As the rate of the main spring increases the amount it is compressed by the weight of the car lessens. Add to that the requirement to keep the spring trapped at all times and its easy to see that without helper springs there would be very little droop travel possible

An example, ignoring movement and leverage ratios for a moment. Let's say you have a 3600 lb car (~1650 kgs) with 500 lbs/inch front springs and 400 lbs/inch rear springs. That means 1800 lbs/inch of total spring rate (500 + 500 + 400 + 400 = 1800). When you put the weight of the car (3600 lbs) with 55/45 weight distribution onto 1800 lbs of spring rate you get 2” of suspension compression at each spring (corner). Keeping in mind the need to keep the springs trapped, that means as soon as you lift the chassis 2” the wheels come off the ground.

Now add helper springs at the front and progressive (sacrificial) coils at the rear. That adds substantially to the amount of droop travel helping to keep the wheels on the ground.

The reason why helper springs are not used is simple cost, they can keep the cost down by leaving out the additional components.

Even though I won't be lowering the ride more than 30mm I'm not keen on coilovers where height adjustment effects spring & damper travel as is with the Bilsteins.

Again this shows limited understanding of suspension travel. Or perhaps another victim of junk publicity put out by parts desk jockeys with zero knowledge of suspension. Obviously chasing a sale they are going to tell you what they know, which is usually limited to some positive points about the particular set up they are trying to sell you. Most likely they know nothing about the negatives and even if they did they wouldn’t tell you.

By shortening the shock body you are reducing the droop travel of the suspension. A simple example of the effect of that, go over a bump of sufficient amplitude and the reduced travel means the wheel lifts off the ground after the bump. Obviously not an ideal situation on the road, but equally so on the track where I often see cars with too little droop actually lift both of the rear wheels off the track under brakes. Not a nice situation if you are trail braking on turn in, usually a spin is the result.

Gsedan35 had this answer to one of my ? on g35driver adverbatim. He runs PSS9 revalved with 560F/500R spring rates, albeit his is a sedan. I'm waiting to hear back from Gsedan35 as to the reason for those spring rates but going by his shock dynos thats probably not an issue if they are so similar to the PSS9 on the comfort settings.

Not to diminish the importance of a shock dyno, but unless he has a shock dyno control program to input the mapping of roads/tracks he drives on, it won't reveal anything about ride comfort or tyre contact patch improvements. All it will show is the shock being able to control the spring rate, within the testing parameters. The skill in operating a shock dyno is knowing the specific conditions that the shock is going to be subjected to.

So all that jargon aside, In your opinion what would have been a better setup for the V35, coilover or not?

Firstly you can only have coil overs on the front of a V35 because the springs and shocks are separate on the rear. So without additional hardware the rear ride height won’t be adjustable. The question then is what use to you is front only height adjustment? On a RWD car adjusting the rear ride height to tune the handling is quite common. Personally, once the front ride height is stable (ie; the springs have settled) I would hardly ever adjust it. Plus adjustable ride height is illegal, not that many people worry too much about that, until they get busted one day and have to seek out some standard suspension to borrow to clear the defect. Lesson, don’t throw away your standard springs and shocks.

Therefore the only reason for front ride height adjustment is appearance, you can fiddle with the height until you like the look. Whether that look is good for handling or not is another question. It’s your money, so only you know whether the extra cost (and legality risk) is justified.

Cheers

Gary

[Sydneykid]

well i run these in my 32 GTR. they are excellent shocks for the money. some may claim they are not as good as the sweedish made ohlins and that may or may not be the case. but they performed well when tested on a shock dyno and more to the point perform well in my compromised road/track car. they can be rebuilt if needed without too much problem for me and for their cost they are as good as anything else near them in price. all alloy shock body, remote canisters all round, decent size pistons and separate bump and rebound adjustment, they are nice and light and have height adjustable at the lower mount and the lower spring seat so you can adjust height without affecting stroke.

Cost, is that $6.5K + freight + 10% duty + 10% GST = let's say $8.5K ? If so, are we not talking chalk and cheese with the V35 set.

Who services them in Australia?

What spring rates did you select ?

They have no helper/tender springs, doesn't that concern you regarding limited droop travel?

Cheers

Gary

[Beer Baron]

they do have helper springs (mine do anyway). you're right, they are much more expensive than the others compared though, mine did cost less than $6.5K (but I agree that's not really relevant), but that price is Japanese retail which is often infalted to allow some wiggle room. they accept a normal coil over spring, I think 60mm or something, so choice of spring is whoever you want, eibach, tein, cusco, ohlins, swift, whoever. haven't needed them serviced in aus yet, but 7 years ago I had a set of teins rebuilt here in aus when no one said it was possible. everyone said "you have to send them to japan, throw them out, can't get the seals etc" well a local suspension shop specialising in motorbike suspension quickly made a tool to get them apart, measured the oil viscosity, bought the appropriate shock oil, added valve for re-gassing, went to a rubber o-ring and seal place and matched up the seals and bingo, rebuilt teins that were as good as new. if it came down to it and I really couldn't get them rebuilt here it's not hard for me to have them sent to japan and repaired and in fact ohlins japan pricing on shock rebuilding is pretty reasonable, I've had one set done in japan. but I would bet a local motorbike shop that deals with a lot of japanese motorbike ohlins could do a basic rebuild on them easily.

mine are nismo branded, but they are ohlins flag R. just different colour and nismo sticker set.

[mosoto]

Thanks Gaz. There is absolutely no doubt you know exactly what you are talking about and I'm starting to feel the victim of misinformation, I'm concerned I've made a poor choice.

Unfortunately I don't think I can reneg on the coilovers as they've been ordered & shipped from one supplier to another. Admitedly they've only cost me $2600AUD as a "special" from Performanceshock Inc, but it doesn't take away the fact that they may not be suitable for our roads, as you've stated. I'll try and see if I can get the order switched to the Bilstein PSS9 or the newer PSS10.

[sav man]

they do have helper springs (mine do anyway). you're right, they are much more expensive than the others compared though, mine did cost less than $6.5K (but I agree that's not really relevant), but that price is Japanese retail which is often infalted to allow some wiggle room. they accept a normal coil over spring, I think 60mm or something, so choice of spring is whoever you want, eibach, tein, cusco, ohlins, swift, whoever. haven't needed them serviced in aus yet, but 7 years ago I had a set of teins rebuilt here in aus when no one said it was possible. everyone said "you have to send them to japan, throw them out, can't get the seals etc" well a local suspension shop specialising in motorbike suspension quickly made a tool to get them apart, measured the oil viscosity, bought the appropriate shock oil, added valve for re-gassing, went to a rubber o-ring and seal place and matched up the seals and bingo, rebuilt teins that were as good as new. if it came down to it and I really couldn't get them rebuilt here it's not hard for me to have them sent to japan and repaired and in fact ohlins japan pricing on shock rebuilding is pretty reasonable, I've had one set done in japan. but I would bet a local motorbike shop that deals with a lot of japanese motorbike ohlins could do a basic rebuild on them easily.

mine are nismo branded, but they are ohlins flag R. just different colour and nismo sticker set.

how do you go about adjusting them at the track, when you will inevitible have stinking hot rotors? just a case of being careful?

[Sydneykid]

they do have helper springs (mine do anyway). you're right, they are much more expensive than the others compared though, mine did cost less than $6.5K (but I agree that's not really relevant), but that price is Japanese retail which is often infalted to allow some wiggle room. they accept a normal coil over spring, I think 60mm or something, so choice of spring is whoever you want, eibach, tein, cusco, ohlins, swift, whoever. haven't needed them serviced in aus yet, but 7 years ago I had a set of teins rebuilt here in aus when no one said it was possible. everyone said "you have to send them to japan, throw them out, can't get the seals etc" well a local suspension shop specialising in motorbike suspension quickly made a tool to get them apart, measured the oil viscosity, bought the appropriate shock oil, added valve for re-gassing, went to a rubber o-ring and seal place and matched up the seals and bingo, rebuilt teins that were as good as new. if it came down to it and I really couldn't get them rebuilt here it's not hard for me to have them sent to japan and repaired and in fact ohlins japan pricing on shock rebuilding is pretty reasonable, I've had one set done in japan. but I would bet a local motorbike shop that deals with a lot of japanese motorbike ohlins could do a basic rebuild on them easily.

mine are nismo branded, but they are ohlins flag R. just different colour and nismo sticker set.

At the real Australian price, MCA's would be a much better choice technically, especialy with remote rather than attached cannisters. Then add in local track knowledge, faster turn around, readily available spares and track side support at major meetings. In fact for not much more you could have 2 way adjustable Swedish Ohlins or Sach/Boge, both of which are superior solutions.

That’s the problem with comparing $2K shocks with $7K shocks, the name might in fact be the only similarity. They sure as hell aren’t going to be comparable technically.

Cheers

Gary

[Roy]

When lookng at the pricing of stuff out of Japan, its no longer the black art it was 10 years ago. There are enough agents over there now who can help you out with trade prices or at least allow you to hunt down some decent prices on gear.

And technically, very few forum ppl are willing to buy shocks and spend thousands on labour for re-valving, different springs and wheel alignments, getting something to work a fraction better when you can spend 1/3 - 1/4 of the price for a good solution off the shelf.

Not sayng any of this is wasted info or wrong. Far from it. But i woudl say 60-75% of cars at the tracks would handle better just with a better-proper alignment...so really

[Roy]

I will go as far as saying that for the sort of track work that most of us do, you wll end up with a faster car if you spend 3k on shocks, and 5k on gearbox then if you were to spend 8-10k on shocks alone.