Topic: Help with suspension options

[2kwk4u]

Since I have more time than disposable income, I've been milling over my suspension "way ahead" for quite some time now.  Here's where I'm at now, along with my reasoning.  Please check my reasoning and let me know where my logic is flawed.  (I'm looking at you, SOB and BenL)

- My car is an '08 GXP (non Z0K)
- I already have the race backbone and DDM ProBeam. 
- The car is my daily driver.  I do occasionally autocross it, but that's NOT my priority.  I don't race often enough or drive well enough to *really* be competitive.

So here's what I'm thinking, step by step:

1) Z0K bars, front and rear
- It seems commonly accepted that the rear bar only is optimum for autoX, leaving the FE3 front bar in place to reign in some understeer.  But it also seems I've read that for street driving (or track days) where higher speeds are seen that both bars are better for stability.

2) Koni SA shocks
- Bob, where did you get yours?  Did they send you a shock dyno printout for each one?  From what I've read, they're great shocks, but there are inconsistencies from one to the next as far as what the adjusters are really doing at a given setting.

3) Z0K springs
- Has anyone ever seen the spring rates for these?
- I know they'll drop the car some, and that's fine.  I'm not looking to go super low, though.  This is a daily driver.  That's why I'm considering...

4) Convert to adjustable coilover setup
- This is where I start running into questions.  I'm not talking about buying KW's, BC's, B&G's...  or God forbid Penske or Ohlins (not that I wouldn't take them at BC prices )
- Are the DIY conversions worth a damn?
- If I go DIY conversion, what will be the adjustment range of my ride height?  i.e. will it be stock (Z0K) and higher?  stock and lower? 
- Once set, can I be reasonably certain that they're "set it and forget it"?  i.e. will the adjustments creep over time, even after everything settles in?
- The biggest reason I'm considering adjustable coilover is for corner weighting, not ride height adjustment. 

5) Polyurethane bushings
- I've read mixed reviews as to whether they're worth it.  Opinions?

Obviously alignment will be a consideration as well.  I can sort that out on my own, once I start buying and installing all of this. 

Is there anything else I'm missing?

[2kwk4u]

One bit of reasoning I didn't mention... you'll notice that this looks like the Z0K parts list.  The logic behind that is that Z0K was engineered to work together.  It seems to me this route would give more predictable results than hodge-podge/piecemeal (like Eibach springs, someone else's bars, company 3's shocks, etc).  

I know that I already have the backbone in there, which is obviously non Z0K.  To me, though, the backbone only stiffens the whole platform and allows the suspension to do its job better.  Is that the correct reasoning?  Would it make any sense to swap the Z0K crossmember for the ProBeam (again, autoX class is NOT a big consideration for me).

[snaponbob]

Since I have more time than disposable income, I've been milling over my suspension "way ahead" for quite some time now.  Here's where I'm at now, along with my reasoning.  Please check my reasoning and let me know where my logic is flawed.  (I'm looking at you, SOB and BenL)

- My car is an '08 GXP (non Z0K)
- I already have the race backbone and DDM ProBeam. 
- The car is my daily driver.  I do occasionally autocross it, but that's NOT my priority.  I don't race often enough or drive well enough to *really* be competitive.

So here's what I'm thinking, step by step:

1) Z0K bars, front and rear
- It seems commonly accepted that the rear bar only is optimum for autoX, leaving the FE3 front bar in place to reign in some understeer.  But it also seems I've read that for street driving (or track days) where higher speeds are seen that both bars are better for stability.

2) Koni SA shocks
- Bob, where did you get yours?  Did they send you a shock dyno printout for each one?  From what I've read, they're great shocks, but there are inconsistencies from one to the next as far as what the adjusters are really doing at a given setting.

3) Z0K springs
- Has anyone ever seen the spring rates for these?
- I know they'll drop the car some, and that's fine.  I'm not looking to go super low, though.  This is a daily driver.  That's why I'm considering...

4) Convert to adjustable coilover setup
- This is where I start running into questions.  I'm not talking about buying KW's, BC's, B&G's...  or God forbid Penske or Ohlins (not that I wouldn't take them at BC prices )
- Are the DIY conversions worth a damn?
- If I go DIY conversion, what will be the adjustment range of my ride height?  i.e. will it be stock (Z0K) and higher?  stock and lower? 
- Once set, can I be reasonably certain that they're "set it and forget it"?  i.e. will the adjustments creep over time, even after everything settles in?
- The biggest reason I'm considering adjustable coilover is for corner weighting, not ride height adjustment. 

5) Polyurethane bushings
- I've read mixed reviews as to whether they're worth it.  Opinions?

Obviously alignment will be a consideration as well.  I can sort that out on my own, once I start buying and installing all of this. 

Is there anything else I'm missing?

In order;

1) Correct on the bars. With matched FE3 or Z0K bars the factory handling tendencies (basic understeer) will be maintained. But, with the BackBone and ProBeam, Kappas tend to become more neutral. That said, with the matched set of Z0K bars the way your car NOW feels will be maintained, but flatter. (Hopefully I explained that well enough.) After you install the pair of stiffer bars, you will have the FE3 bars left over to play with, so you can experiment if you like. Keep things simple and use the correct factory bushings to keep things quiet under the car.

2) PM or e-mail about the shocks. (Same on the bars - I can save you some money through friends.) This business of dyno charting the Konis is way overblown. They are great value for the money. Get them, install them, enjoy them.

3) The Z0K springs are 20% firmer than FE3. The FE3 springs are 175f/220r. The drop is about an inch or so.

4) As I have repeatedly shared with Kenny, K.I.S.S. Get the Konis, get the Z0K springs, drive the car. Smile. If you eventually want to go adjustable, PM me. You'll need a modest list of parts. But for doing what you have described, the Konis with the Z0K bars and springs with transform the car. The Z0K bits will put the car at a very nice lowered stance. Going lower will start to create compromises (for daily driving) that you may not want to put up with.

Corner weighting? Forget it. With the factory pieces, the car will be so close that doing anything else to the balance would be a pure waste. Besides, cornering weighting a stock car is almost impossible because the only way to fully do it would mean ADDING ballast to the right side of the car.

5) Minor improvement, big pain in the a$$. Spend the money on better tires !!!!!!! Seriously.

Kenny and I have shared a bunch of e-mails covering ALL of this. If he still has all my responses, maybe he will forward them to you.

[kennysabarese]

I have a lot of email between Bob and I saved to refer to, but I think this summarizes everything we've been talking about the last month really well.

I am ordering Z0K springs soon, maybe even today. And my SA Konis are arriving tomorrow.

I decided to go with the Z0K because the gain with going with harder springs is not enough to justify the loss in comfort. My car is already pretty rough just with just the z0k swaybars and I am about to put solid aluminum seats which do not have any springs in them like stock seats so it's gunna be a rough ride.

The only reason to convert the Konis to use standard springs would be if you want to change the spring rates to make the front and back even, or the front harder than the rear. (current setup is rear is harder than front) I currently have no desire to do this. My reason is because, as much as everyone likes to bash GM for having too much understeer, for street driving, understeer is safer. I don't want the car to freak out on the highway at 90MPH when I make a mistake and have 20 cars around me.

I also don't really wanna spin on the track at 100 either and crash into a wall. With just front and rear z0k swaybars the car felt pretty damn good and it didn't understeer too much, and I lost the back a few times.

I haven't even done a performance alignment yet and that is going to make a big difference.

Anyway. I 98% agree with Bob. But for fun I think I'm going to take my shocks and springs to Joe Stimola so he can dyno and adjust them since I don't trust myself for adjusting them properly to match the springs and each other. For a small amount of money why not have one of the most renowned shock guys in the country set up something for you

[kennysabarese]

BTW Here are the spring rates

Stock GXP
F: 3800N - 30.5 N/mm - 174.16 lbs/in
R: 3900N - 40.0 N/mm - 228.41 lbs/in

Z0K GXP or GMPP
F: 3100N - 37.0 N/mm - 211.28 lbs/in 
R: 3200N - 50.0 N/mm - 285.51 lbs/in

[lil goat]

By no means an expert on any of this stuff but I will throw in my 2 cents, the Z0K springs lower the car but not near as much as coilovers, Bryan has Z0K and I have the HKS coilovers his car is much higher than mine by at least an inch, I think even more. I would not spend the time and money on poly bushings except for the sway bars, will you notice a huge difference, most likely no. They are only about $15 a set and add the ability to grease them without removing them, if you have rubber up front in winter they will squeak if it's not lubed every year, I don't know if the poly will even squeak they have grease channels inside instead of being flat so they don't push the grease out as fast, mine don't squeak but they were lubed in September. So for a daily driver the Z0K's might be the best choice, I would not do them with stock shocks as mine blew with the stock springs, had three replaced, with the Koni's should be great. Once upon a time Rhys Millen Racing had a bunch of left over Koni's from the TV show Setup they were going to sell cheap, I will see if they are still around they were brand new.

[LatinVenom]

I am now will put my 2 cents also.
My car is setup as fallows Probeam and BackBone and Z0k bars front and rear with the Z0K bushings and clamp at the rear bar.
Standard GXP shocks and springs. \
GoodYears Eagles F1 GS-D3's to complement the above.
I do not autocross but do occasionally will go to a road coarse and with what I have the car performs well enough.
This is also my weekend fun car so I feel the above is a good compromise and the car still handles steamily well.

[wspohn]

By no means an expert on any of this stuff but I will throw in my 2 cents, the Z0K springs lower the car but not near as much as coilovers

I wouldn't change springs or shocks without having control over ride height.  Seen too many people find they couldn't get out of their own driveway etc.

I agree that the order of modification should be:

Probeam/Backbone

Bars (I use the ZOK GXP bars)

Shocks/springs

I wouldn't bother with bushes for street use.

I use BCR shocks with 450 springs both ends, set to stock ride height.

[Treeman]

I wouldn't change springs or shocks without having control over ride height.  Seen too many people find they couldn't get out of their own driveway etc.

I agree that the order of modification should be:

Probeam/Backbone

Bars (I use the ZOK GXP bars)

Shocks/springs

I wouldn't bother with bushes for street use.

I use BCR shocks with 450 springs both ends, set to stock ride height.

Man!!  You've been busy!! You just got that car!

[lil goat]

There are lots of options, my HKS coilovers are set at MAX height and are still way lower than the Z0K's. I think the front sway bar bushings are pretty stout and work fine BUT THEY SQUEAK, I did notice a slight difference with poly but it wasn't huge, the car just feels a bit less vague is the best way to put it, for a whopping $15 and a few minutes and no squeak well worth it. The rear sway bushing is soft, not very thick I could feel the difference there, just less roll before the back breaks and a bit more predictable (ie more feedback through the car) I really like the feel with the stock front bar and Z0K rear, I have the front coilovers set fairly soft the car is very neutral with the B0K alignment (Ben's suggestion) I run the rear stiff in summer because I like to break the back loose, it is pretty easy to change from sticky to loose with the coilovers, but the car is low and I have to be careful. At this car point the car handles well enough I can not take full advantage of it, I don't have the skills yet. Think about reducing unsprung weight to improve handling and braking as well, pretty easy to drop 10lbs at each corner.

[Ben L]

I think you are moving in a sound direction with a "matched" ZOK setup (including springs and shocks, with "fixed" heights).  SOB is the sensei on homecooked adjustable coilovers, so I will defer to him, but I think that if you want to go the adjustable coilover route, you really should not exclude pre-engineered solutions like BC and HKS, etc.  After retro-ftting good Koni SAs, and acquiring ZOK springs for them, I am not sure that there will be huge per-corner savings going the DIY route.  But I don't know what Bob can get you SA Konis for, either.

Anyway, the prepack coilovers are purpose-designed and built, and have many details that I do not think you are likely to find going the DIY route unless you build them in.  The valving is matched to the application and spring rates, and my BCs, at least, were dynoed and matched to one another.  Spring rates and ride heights are nearly infinitely adjustable, and the bushings and mounts were nice poly and spherical bearings.  The inherent adjustability of factory coilovers provides another dimension of fine tuning to really dial in the car to address any lingering imbalance issues that anti-sway bar choices may be too blunt of an instrument to deal with. Plus, they permit corner weighting, which may not seem necessary for spirited street and ocassional autox use, but which I found on both race cars made a huge difference in predictable and consistent weight transfers out at the limit, but those were both relatively light FFRs.

I hear what Kenny is saying about understeer, but geez, you've been out autocrossing, and I think anyone would have to admit that our porky cars plow like a beeatch even when not pressed that hard, especially on street tires.  To suit your stated purposes, something must be done, and I am not sure that swapping to the ZOK bars addresses it, although I only got the rear bar. 

Yes I run spring rates nearly double the stock FE3 rates, and have the car slammed, so that the front plastic air dam is an inch and a half off the deck at rest, and being ground to shavings anytime the weight is forward.  But I also played with the front vs. rear rates to address factory understeer.  The ride is harsh on rough roads but I still daily drive the car and love it.  You get used to it.  Even my wife has.  The grip is worth it.  Even after all that, if turned in too hot or pressed too hard and early out of a corner, it will push.  But I have not really had a big problem with tailhappiness (I do have 275s out back) even with a stiff rear end.  She is very stable and neutral, even at high speed.

The biggest DIY payoff ever will be to get a SmartCamber gauge and turnplates, and learn to do your own alignments.  Its easy as hell on our cars (except rear caster, but factory is fine there).  Follow Bob's advice.  Mark your steering rack tie rod with two lines; stock toe and a smidge of toe out.  The improvement in turn in with a leetle toe out autoxing will amaze you.  Not recommended for road or track, though.

That's all I got.  You are going to notice an improvement whichever route you go, and are on the right path.

[kennysabarese]

I can't really tell if there is less understeer with both Z0K bars compared to both GXP bars. Haven't been under extreme circumstances enough to really tell, and I don't autocross. But I think there is less based on what I've read.

I will probably play with the bars this season on the road courses if I start to experience too much understeer. You can always swap bars if you want to change handling for the track.

The Konis are well known and can be revalved by any Koni dealer. That's why I chose them.

[snaponbob]

Koni SA's can be had for under $600 for a set of 4. Converting them to adjustable height is about $350-$400 plus springs. That said .......

So far I am not fond of ANY of the available under $2K adjustable coil overs and here is why;
1) The KW folks put together a package that makes NO sense. The FRONT springs are stiffer than the rears, and that is just wrong for the Kappa. Add to that the fact that nobody at KW can give ANY definitive answers to ANY questions about revalving and the oddball spring dimensions just does not present any solid reasons to use them for racing. Are they good products? Seems so. But the only thing going for them is being double adjustable.
2) The others are single adjustables. Unlike the Konis, the adjustment for rebound is NOT independent of compression. And THAT is important. As spring rates go UP, adding compression is not what one wants to do. With the coupled adjusters one has NO choice.

The best solutions cost more than $2000. Bummer. The finest (commonly available) solution is Ohlin, but for their double adjustables one is looking north of $5K plus springs. Converting Konis to DAs and adjustable height will run about $2300-$2500 including springs and the purchase of the shocks. Just to fill in the blanks, Penske and ASTs will be expensive as well. (Already checked.) If I was as quick as, or quicker than, Alex Jones I would be converting my Konis or even considering the Ohlins. But, I am not that quick, and the problem is ME, not the shocks. If one has the time, desire, tools, and knowledge to do their own alignments, Ben is very correct about the ease of adjusting the Kappas. And cheap, too. (I can detail that if people want the be bored with more of my input!!) For casual Solo and canyon carving, grab some Konis and GXP/Z0K springs and bars, and add a DDM ProBeam. Have somebody dial in some negative camber and re-establish the per-ma-grin. For some more serious Solo work some more stuff can be thrown at the car for even better results. SA Konis will save a lot of money over DA Ohlins, get your car close to the best setup, and leave thousands of dollars for wheels, tires, and all the other stuff. Should you find yourself scaring the heavy hitters (and so far that is NOT me) then you'll be in a better position do decide more about shocks. Should you start chasing your tails with the inexpensive "adjustable" coilovers, it will better than stock but not as good as more straight forward solutions.

Please don't feel like I am "talking down" to anybody about anything. Just sharing what I have learned (so far) about the Kappas and some of my experience over the past 3 decades making mistakes with other cars. It is just so much cheaper to NOT make some of the mistakes that others have made. For those that want a lower stance and better general handling, ANY of the "coilovers" offer features and benefits. But if one wants to grab their Kappa by the neck and get the most out of a fantastic platform, compromise suspension components will not be the best spent money.

[snaponbob]

I can't really tell if there is less understeer with both Z0K bars compared to both GXP bars. Haven't been under extreme circumstances enough to really tell, and I don't autocross. But I think there is less based on what I've read.

I will probably play with the bars this season on the road courses if I start to experience too much understeer. You can always swap bars if you want to change handling for the track.

The Konis are well known and can be revalved by any Koni dealer. That's why I chose them.

So far, what I (and others) have found is that the paired FE3 bars and paired GXP/Z0K bars will have very similar handling (i.e. basic understeer). I can't wait to read about how the shocks and bars work out for you. It will either be  or I will be just so much dog crap !!!!!!!!!!!!

[kennysabarese]

If you really have it out for the KW's (maybe you like the color purple better than yellow) you should definitely call SRP engineering. They are becoming a dealer, and they are a top notch shock who does racecars shock setup. (they setup the shocks for don knowles T2 car and other cars from Phoenix performance)

[Ben L]

I defer to SOB on this one.  I like my BCs a lot, but the the fact is I am no longer using my GXP in competition.  If I was, I probably would put on it what I had and now have on both FFRs: DA Konis, and damn the expense.  'Nuff said.

[boardkat]

if anybody is interested in having their stock bilsteins converted to SA, DA or DA w/ RR, PM me for more info.  i can direct you to the guy on the east coast that will convert them from crimp top to snap ring, and then put you in touch with the west coast builder that is doing the rebuilds/revalves.

[lil goat]

I think the simple answer is what can you afford, the coilovers offer a very nice upgrade for not a ton of money, the boys at Team Falken like the BC's the guys at RMR like the KW's for racing and the HKS for the street on a Solstice, neither are doing autocross which is a very different kettle of fish. I have been happy with the coilovers but what the heck do I know, I don't race my car I just enjoy driving it. I like to be able to kick the back out and have it behave, the coilovers did that very well for me. I am pretty sure I could never take advantage of anything better than what I have on my car now, except maybe some improved brakes, a twisty road some loud music and a nice companion will always trump any form of racing in my book, but that is just me.

I will say that I would never ever spend one time modifying the Bilsteins, they have severe reliability problems, and never really impressed me.

[boardkat]

I will say that I would never ever spend one time modifying the Bilsteins, they have severe reliability problems, and never really impressed me.

the rebuild i'm having done is essentially from the ground up.  the only thing that will remain stock are the shock housings.  all internals are custom parts.  if you've had problems with bilsteins in the past, i'm guessing they were OTS examples.  with the R&D going into this build (suspension modeling, shock/RR build, valving, testing) and with a rough estimate on the price i'll be paying, it was a no-brainer given the 2-3x more expensive Penske/AST setup, which is why i'm encouraging anybody out there to get more info and ask the builder questions.  also, given the choice of a twin-tube vs. monotube setup, and having to actually drive my car on the street, i won't ever go back to a twin-tube shock again.

[snaponbob]

Although converting the Bilstiens is an option, they will be REBUILDABLE, not ADJUSTABLE. And THAT is a big difference.

[2kwk4u]

Thanks for all the input, so far  

I'm definitely up for learning to do my own alignments.  I've read about it, but haven't taken the plunge yet.  Will probably wait until I have all of my parts assembled/installed/settled, and take it to a "pro" for the first alignment.  After that I'll buy the plates and other tools for fun and games in my own garage.

[wspohn]

I'm definitely up for learning to do my own alignments.  I've read about it, but haven't taken the plunge yet.

While I have done this, usually on the race car at 10:00 at night the day before a race when I couldn't get it on a 'rack' anyway, I really prefer to have it done on a modern laser rig. It isn't like you need to do it very often and then you know it will be right.

One thing I've noted from this discussion - several shock/spring combos lower the car and don't have enough adjustment range to allow you to reset ride height to stock or close to stock.  The BCR shocks do have enough to get it back to stock, which for the street is probably low enough. I know that the young kids like to lower them so much they can't drive over a cigarette pack in the road, but for us old farts that gets old real quick.  It also isn't really necessary for good handling (and on some cars is actually antithetical to good handling depending on the bump steer you may be introducing).

[snaponbob]

Thanks for all the input, so far  

I'm definitely up for learning to do my own alignments.  I've read about it, but haven't taken the plunge yet.  Will probably wait until I have all of my parts assembled/installed/settled, and take it to a "pro" for the first alignment.  After that I'll buy the plates and other tools for fun and games in my own garage.

When you get that alignment WATCH what he is doing. Not HOW, but WHAT. Having been a motorcycle mechanic, my own auto mechanic, and a Snap-On dealer for almost two decades where I was able to learn, do, and watch a lot, I was a bit intimidated with the prospect of doing an alignment on my Sky. It actually was not as difficult as I thought it might be. Having air tools sure helps. There is SO much information available for FREE that the task was a matter of putting one foot in front of the other, and double checking all the work. When you are ready, PM me. If you have a compressor and some tools, the "specialty" stuff (including slip plates made from floor tiles and grease) will be under $350.

[boardkat]

Although converting the Bilstiens is an option, they will be REBUILDABLE, not ADJUSTABLE. And THAT is a big difference.

bob, not sure if you were addressing my situation or not but... the OEM bilsteins i'm having rebuilt will have both external rebound and compression adjustments, along with a remote reservoir.

[snaponbob]

bob, not sure if you were addressing my situation or not but... the OEM bilsteins i'm having rebuilt will have both external rebound and compression adjustments, along with a remote reservoir.

Obtusely I was. But, THAT configurations is news. Who is doing it, what are the internals, and HOW MUCH ?????