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glenspeed
Wed, Oct-13-2004, 07:46:30 PM
Anyone know or done a comparison of Eibach, H&R sport springs and say Koni SA sport shocks with the spring rates and shocks on H&R, Bilstein or GC coilovers?

Ride height adjustability aside, I am trying to determine how different the handling would be between the two setups assuming you set the ride height exactly the same.

jonam
Thu, Oct-14-2004, 05:32:55 AM
Anyone know or done a comparison of Eibach, H&R sport springs and say Koni SA sport shocks with the spring rates and shocks on H&R, Bilstein or GC coilovers?

Ride height adjustability aside, I am trying to determine how different the handling would be between the two setups assuming you set the ride height exactly the same.
I would say go with a coilover system. It depends on what spring rates you go with those coilovers. and furthermore, the coilovers you mentioned all have different characteristics which alone will make the comparison valid.
If it's for street use, matched springs with sport shocks would be OK and probably can't tell much difference from full coilover kit. but for track applicaiton, there's no question that you need full dedicated coilover system. If someone knows what he is doing, one can get a quality shocks with good matching springs. but for regular people, it's safe to get a coilover kit. I would highly recommend GC over other two if track performance is your main concern (and street). Bilstein wouldn't be bad for street...but I heard many complaints as to H&R (too harsh w/o good balancing the car).
Talk to Dan Law(moderator) if you want GC kit at good price and service.

glenspeed
Thu, Oct-14-2004, 03:25:14 PM
I've got the H&R coilovers now and they are ok for the street, bit harsh but not terrible. I am thinking of going to a fixed height system because I want more simplicity. So something like the TC Kline sport system is looking good, but I wanted to know if the spring rates on the H&R coilovers would be different from their sport springs and also what the Koni sport shocks would be compared to the H&R coilover shocks. From what I have driven, Koni's (in a Dinan system) seem to have a nicer dampening than the H&R so that would be a plus.

I track the car and instruct several times a year but this car is my daily driver so I really don't need the coilovers. IMO coilovers are overkill for daily street driving. I don't like the slammed look and once you adjust the height you pretty much leave it alone, so that's why I am thinking of the sport spring/Koni route.

Dan Law
Thu, Oct-14-2004, 03:51:29 PM
Glenspeed:

May I suggest that your desire to change suspension is motivated more by the inherent deficiencies of the H&R system than by a desire for simplicity. I have worked with many different suspension systems. As expected, there is a bell curve distribution of quality amongst the various brands grouped by price. In the H&R Kit price point distribution, various brands such as Bilstein's PSS9 and KW fill the middle of the curve, TCK and GC are at the high end of the curve, and (unfortunately) placed absolutely by it's lonely on the low end is H&R.

The H&Rs are by far the worst I have encountered for a number of reasons:
1. The dampers are basic Bilstein yellows - not so bad but not PSS9 quality

2. The springs are cheap H&R units which are cut mid wind and not taperred so as to sit well in the spring perches

3. The rear ride height adjusters - both old and new designs - are very prone to cracking along the adjustment axis

4. H&R's customer AND dealer support is the worst I have encountered

5. Knowing of the issues with cracked rear ride height adjusters, H&R regularly runs out. This usually entails a 3 month backorder.

May I suggest, especially for an accomplished driver like you, that going to a ride height adjustable system is a recommended thing to do. While you are correct that you just want to set and forget the heights, I would assume you would want the system balanced. A fixed height system can NOT be balanced unless it is either custom fitted prior to fixing the ride height or shimmed to result in an equal cross distribution of weight. There is nothing wrong with purchasing a ride height adjustable system and setting the cross weights once for the life of the vehicle - assuming no hits, sagging &c.

My suggestion would be for you to purchase a Ground Control or TCK ride height adjustable kit. You will be very satisfied with the ride of either as they are well integrated kits. Further I would suggest getting the Rear Upper Shock Mounts either offers - the stock mounts have failed even with stock suspension which can be quite expensive to repair. Be sure to specify a good spring rate - dependent on where you live and road conditions (TCK and Ground Control both allow spring rates to be speced AND use quality springs). Finally, DO get the rear top adjustable option as it makes changes to damping a clean 30 second job.

I can both advise you as to your specific spring rate needs and get you Ground Control products at a good price; I encourage you to contact me offline at: de_law@bellsouth.net

Dan Law
770.631.6779

Dan Law
Thu, Oct-14-2004, 04:03:24 PM
I realize that I didn't fully address your question.

My experience has been that you will find a much smoother ride with the adjustable dampers than the Bilsteins from the H&R kit. I personally would lean towards the Konis but the PSS9 Dampers are pretty good provided you replace the springs with quality units properly speced such as Eibach ERS.

Tastes vary but I like to leave the Konis on full soft for street usage and tighten them up for track days.

Dan Law
de_law@bellsouth.net

glenspeed
Thu, Oct-14-2004, 04:33:46 PM
Thanks Dan. I very much appreciate your input.

I actually didn't mind the stock suspension setup, a bit soft and more body motion than I wanted at the TRACK, but excellent for the street especially in a daily driver. So the objective was not to build a race car or dedicated track car, but to merely enhance the already decent handling without giving up too much comfort. With the Dinan systems I have driven on (stage 3) I found the suspension actually felt softer on bumps than the stock system which I attribute to better shock dampening. This was a plus.

If I could get less body movement, quicker cornering transitions and less squat and dive and only give up a little in daily ride comfort that would be fantastic. (and the slightly lower stance would look good too :beer:)

So I wasn't looking for a night/day difference but a good improvement over stock, which leads me more in the direction of a simple fixed height system with adjustable shocks versus a full coilover with adjustable shocks. I actually went with the H&R because of the non-adjustability of the shocks (to keep things more simple) and I liked a similar setup in another instructors M3. He is actually extremely happy with his H&R suspension! I like the KISS principle and believe sometimes the more choice you have the more complicated things get. I also like the shut-up and drive mantra and don't want to get into constantly adjusting a system to search for better lap times whereas most of the improvement almost always comes from the driver him/herself. I remember a guy I know bought a coilover for his VW and for the whole season spent more time adjusting the shocks, ride height, rake, etc than he did doing laps!

I will take another look at the GC and TCK systems. They were pretty much my next consideration if I wanted to stay with a coilover system. If not, then do you have any opinions on say the TCK non-adjustable system? I would think it is similar to a ACS or Dinan system...

Dan Law
Thu, Oct-14-2004, 04:40:59 PM
Ground Control also has one. Better than stock but I wouldn't pay for the very incremental benefit they provide. Heck I have my virtually new stock M3 suspension (20 miles) I'll sell you for half the price. Just get the Euro Spec ride height springs and you'll be 99% to what you're contemplating.

Dan Law

glenspeed
Thu, Oct-14-2004, 04:56:35 PM
Ground Control also has one. Better than stock but I wouldn't pay for the very incremental benefit they provide. Heck I have my virtually new stock M3 suspension (20 miles) I'll sell you for half the price. Just get the Euro Spec ride height springs and you'll be 99% to what you're contemplating.

Dan Law

Well I have my stock suspension as well (18K miles) and maybe going with sport springs? but my experience tells me sport springs with stock shocks won't be great. that takes me back to a TCK fixed height system??? and I think TCK uses H&R sport springs.

Dan Law
Thu, Oct-14-2004, 05:09:48 PM
I was suggesting True Blue BMW OEM European Spec springs. These should work with the stock dampers.

glenspeed
Mon, Oct-18-2004, 05:28:31 PM
So far, I've found out that the stock spring rates are 180lb front and 320lb rear

Dan Law
Mon, Oct-18-2004, 05:38:30 PM
Just a word of advice.

You will find that the ratings for the stock springs will correspond somewhat to similarly constructed springs - say H&R Sport. Which is to say, barrel shaped, nontapered, nonchamphered, progressively wound.

However, real competition style springs will require significantly higher rates to achieve the same feel. Such springs as Eibach ERS which are straight wound, taper ended, champhered, linearly wound.

Dan Law
DERMotorsports@gmail.com

glenspeed
Wed, Oct-20-2004, 06:29:13 AM
yes, thanks for the explanation.

I also got this from Pete at TC Kline:

The rear is always softer than the front when corrected because of the motion (leverage) ratio. 400lb rear= 264. 500 rear= 330. These #'s are approximate but very close. As you can see 400 front 500 rear is still softer in the rear by 70lbs/in. 3" of wheel travel= approx 2" spring compression.

Dan Law
Wed, Oct-20-2004, 05:27:00 PM
Yeah, Pete is right about that - what he is doing is converting raw spring rates to what is termed "Wheel Rate".

Didn't want to confuse you anymore than I already had....

Pete/TC are good people - BUT buy from ME!!!!!!!:^)

Seriously, I am convinced your H&R will never be perfect. However, cornerwieghting and proper sway installation will pay HUGE dividends. You can well and truely take that to the bank, after all I have no skin in this game....

Dan Law
DERMotorSports@gmail.com

glenspeed
Wed, Oct-20-2004, 10:39:28 PM
Thanks Dan for all the info. I should have done more research before I bought the H&R's, but I was strictly going on a setup that I had felt on the track and pretty much was sold on that basis...
I will probably mess with the H&R over the winter and wait until spring to do anything as it won't make much of a difference in the snow...
It's basically between the GC and the TC Kline S/A kit now...

STALKER
Thu, Oct-21-2004, 12:21:59 AM
Dan,
Would 450 fronts and 500 rears (GC kit) be good for street and track. I don't want something to harsh, GC sways will be on the list too. What size should the springs be, 7" or 6", Im not looking to drop the car more than 1.25". This would be the kit with the bump stops and the camber plates, I think its the $1699 kit. Also, I want the car to be very neutral, how should the sways be set up. Thanks in advance.

STALKER
Fri, Oct-22-2004, 10:02:35 PM
any thoughts Dan?

Dan Law
Fri, Oct-22-2004, 11:15:52 PM
I would think the spring rates you reference are in line for the vast majority of street/track drivers, especially if NVH (Noise, Vibration & Harshness) is a consideration. HOWEVER, one of the many benefits of Ground Control's kits is the ability to specify the spring rate of one's choosing. Frankly, without going into detail of how the auto is used both on street and track, I couldn't state with any degree of certainty if that's right for you.

As to swaybar adjustment, ideally sways should be used to finetune the edges off a suspension setup. Unfortunately for street driving in particular and track driving under changing conditions that just isn't possible. In those situations sways are called upon to do a lot more - what I term masking inherent setup issues. I would suggest a nice starting point for street usage given the suspension setup you've cited is about 3,5" of the end of the front swaybar showing and the next to lightest setting of the medium bar at the rear.

Finally, if asking how to set the sways so as to not have preload the procedure is thus:

Adjust ride heights/cornerweight &c

Loosen the jam nuts on the sway droplinks

Place the auto level on ramps such that the wheels are fully weighted

Adjust the endlinks until they are easily turned by hand between the extremes of length. The droplink adjusters will at first be difficult to turn - requiring a wrench - but will reach a point where the adjusters spin freely somewhere in the middle of their adjustment range - this is the sweetspot where no preload is present.

Tighten down the jam nuts.


Dan Law
DERMotorSports@gmail.com
de_law@bellsouth.net

STALKER
Sat, Oct-23-2004, 09:58:56 PM
Thanks Dan.
Its my daily driver and I will be tracking the car roughly 3 times a year.

heeltoe
Mon, Feb-27-2006, 02:01:15 AM
does anyone know what the spring rates are on a 98' M3 w/a dinan stage 3 suspension? thanks in advance.

Dan Law
Tue, Feb-28-2006, 02:21:41 PM
Seriously, ask DINAN, they will tell you.