Gary, Eibach Pro-Kit vs. H&R Sport

Suspension shopping for my E30, and I have heard a lot of personal opinions on the slight differences between the 2 springs, but I'd love to hear a true comparison from you.

I know your E30 knowledge may be lacking, but in general, I'm sure the companies produce very similar spring rates across the applications.

Well I'm an idiot, I just found the E46 comparison on the Tirerack website. Meh, at least it only took me about 15 mins.

Still, if you have any thoughts, please feel free to reply.

I think you guessed it. The only direct comparison we have is on the E46 cars. From what I've heard of other applications,(this is very generalized...) the Eibach had slightly better ride, while the H&R has been a tiny bit more firm and controlled. In most cases we found the two to be very, very close to each other, but I'm sure this could vary from application to application.

http://www.tirerack.com/a.jsp?a=AB2&...sion/index.jsp

Well, it's always good to confirm with a solid unbiased source.

I think I will go with the H&R's, if not for the higher stiffness then the slightly higher ride height, there seems to be a significant difference between the ride height of the 2 brands on E30's.

Why oh why don't you guys sell Bilstein shocks?

Originally Posted by Mystikal

Why oh why don't you guys sell Bilstein shocks?

I know some people swear by these Bilsteins, but why not Koni? Lifetime warranty, great reputation, and they're adjustable.

To repeat more clearly : I'm definitely not bashing Bilstein, I'm sure they make a great product. I get asked about these a few times a week. Are they less expensive than Koni? Since we don't carry them I have no idea...

Actually yes, they are about $75-100 less for the set, depending on the vendor. The more I read about Koni's the more tempted I am, but it's still a tossup.

If I keep my sanity, I'll probably wait until spring to mount my new parts.

Originally Posted by Mystikal

Actually yes, they are about $75-100 less for the set, depending on the vendor.

Ah, I understand now. Thanks for letting me know on that.

Get Konis.

I have the H&R Sport. They are VERY firm and controlled.

Koni now makes both twin tube as well as Monotube shocks (gas), and chooses the most appropriate design based on the vehicle. All the BMW shocks are twin tube from what I understand. Looking at the two, it makes sense that the Monotube might be more 'heavy duty'

Originally Posted by Gary@Tirerack

Koni now makes both twin tube as well as Monotube shocks (gas), and chooses the most appropriate design based on the vehicle. All the BMW shocks are twin tube from what I understand. Looking at the two, it makes sense that the Monotube might be more 'heavy duty'

Wow, interesting info fellas! I wonder if Monotubes are also a bit lighter?

Gary, what do you think of the Bridgestone's Air suspension? How is it in real life?

thx

The Bridgestone Praxis supsension is awesome. I do hope they decide to release a BMW application soon.

More info for the curious here :

http://www.praxissystems.com/index.asp

Originally Posted by The HACK

Even the adjustible units? I thought the monotube design made the adjustment virtually impossible...Would be very cool if it is, I'd put Koni's on my wife's car.

hack, did you pick up a Z4? I was away for a while, so I may have missed the new addition. How do you like it?

Originally Posted by Gary@Tirerack

The Bridgestone Praxis supsension is awesome. I do hope they decide to release a BMW application soon.

More info for the curious here :

http://www.praxissystems.com/index.asp

Thanks Gary. Yeah, I was reading up on the systems and liked what I read. just wanted to see how it differed from the adjustabe Coil-overs in terms of performance.

Hack, whats the wifes car? I'll see what design they use!

Akakubi, The 'race' setup felt firm like coilovers and handled like them on the autocross course. I think the main advantage is being able to change modes on the fly to the touring or sport mode for someone who has a car they they drive both on the street and track often.

Of course these were WRX's so it was hard to guage how the ride on the different modes on a much more civilized car like the E46 would feel.

Originally Posted by Gary@Tirerack

Hack, whats the wifes car? I'll see what design they use!

Akakubi, The 'race' setup felt firm like coilovers and handled like them on the autocross course. I think the main advantage is being able to change modes on the fly to the touring or sport mode for someone who has a car they they drive both on the street and track often.

Of course these were WRX's so it was hard to guage how the ride on the different modes on a much more civilized car like the E46 would feel.

I see. Thanks for the input!

FWIW, from what some friends and I have experienced over the years, Bilsteins tend to blow when something happens and/or they get old, whereas Konis just get softer. Good thing you can adjust the Konis stiffer. But because Bilsteins pretty obviously blow out, it's a pretty trivial matter to get them replaced under their warranty.

Originally Posted by The HACK

There's a long discussion here...

http://www.bimmerevolution.com/phpbb...opic.php?t=232

http://www.bimmerevolution.com/phpbb...opic.php?t=172

I think I may have posted something in the general forum too. I can't remember if I posted pictures in the showroom forum or not...

Nice and congrats! I really enjoyed driving the Z4 also. Is that a new forum you started?

Originally Posted by The HACK

I don't want to pimp someone else's forum here. I didn't start it, but it just happens to be the only place where I can still find references to the new Z4 quickly...Traffic goes by so fast here I couldn't find my post on the Z4 anymore.

I split time between the two forums.

Gotcha!

Wow, looks like the TS guys grabbed this thread and ran with it...

Thanks for the input guys, it's really helping. However I have truly lost my mind and will likely be buying Ground Control coilovers with externally adjustble Konis.

Do it once, do it right. I figure if I'm worried about what stiffness/height to get, why not just be able to adjust everything?

Koni gas shocks are typiclaly LOW pressure gas shocks. This means a twin tube shock with a few nudred psi of gas in teh outer tube. This helps control foaming of the fluid when over heated.


Bilsteins are HIGH pressure gas in a monotube design.

Monotube shocks offer better control of very small movements since they employ a large diamater piston rod

Monotube shocks can be adjustable, but Bilsteins are not available from the factory that way.

Knoi adjustablity can be nice, if you know what are doing, and actually take the time to adjust them. And for the rears, that is not easy (take shock out, remove bmp stop and adjust, then reinstall).

Both shocks are rebuildable later in life.

Bilsteins add spring rae due to their gas pressure. They may raise the ride height slightly.Both are great shocks and so much better than stock, that unless you do a side by side comparison of the two, the differenes are not that uch.

I have run both shocks. For a mainly street car, I prefer the Bilsteins. Bilsteins will go on our Roaster, Knois on the M3.

Hack, I might be misled by my work with motorcycle suspensions but I think there are few things that are off track.

Originally Posted by The HACK

Hijack: On the difference between Bilstein and Koni...

Basically, Bilstein shocks is a simple tube with a piston in it that pushes and compresses air, with oil on the bottom. There are valves in the piston that controls the amount of air that escapes from one chamber into another to control the dampening rate. That high pressure N2 holds the piston on the oil to prevent foaming. The compression (bump) damping on most modern shocks is from forcing oil through a flat faced ring with holes parallel to the shock axis. These holes are covered by a precise stack of metal shims that flex to allow more oil through as the shock piston speed increases. That's why BSteins are cool, the flexible shims don't let much oil through at low shock piston speeds (braking, turning, accel) for good control, but then flex to allow a lot of oil through at high piston speeds (hitting a big bump). AFIK ALL single tube signs use shims to meter the oil flow.

Since these valves are machined into the piston monotube designs ARE NOT ADJUSTIBLE. Any shock design can be made externally adjustable, its just more expensive. The racing shocks I work on (a Penske 8900) are high pressure single tube and have three damping adjusters. Koni and other multi-tube design dampeners employ multiple chambers filled with oil of different viscosity, with a valve controlling the opening between the chambers so as the piston move up and down, the oil evacuates from the inner tube to the outer tube, and the valving on the tube controls the dampening rate. The valve on the tube can be adjusted. Like you write, the valving in a low pressure or emulsion (no pressure) damper controls the rate. Although different viscosities are used when rebuilding, I think inside the shock all of the oil is the same weight normally and the valving is altered to produce different reboud and compression



[disclaimer: This is stuff I wish Jay is here to clarify...Most of what follows is from MY understanding extrapolated from his seminar] Major technical difference, is that multi-tube design dampeners are designed to STOP MOVING past a certain rate of compression. The key here is not multi or single tube, its how the compression damping is controlled. If shims are used then you get the delayed onset of hydraulic lock and a wide operating range, if the shock uses a fixed sized hole then you get the narrow operating range of older designs. The shock will either be stiff all of the time and lock over bumps or it will offer very little damping but be compliant. So if your wheel go over a gigantic pothole the size of Grand Canyon and the springs are moving at XXX meters per second, the dampener can not react fast enough to slow down the movement and the oil does not compress. BMW OEM shocks are Boge duo-tube dampeners. Monotube shocks are filled with air and use the compressibility of air to control dampening rate, and will accomodate much higher rate of compression than multi-tube design.

That said, most multi-tube dampeners are designed to accomodate pretty extreme rate of movement from the spring and wheels. There are very little difference in performance between monotube shocks and multi-tube shocks now a days. If you need a shock with adjustibility, go with Koni. If you want a monotube shock with a more graduated rate of compression vs. spring rate, the only game in town is Bilstein (they hold the patent to monotube design). There are several brands of monotubes including most of the yellow bodied Koni sport shocks. The patent was originally held by DeDion. So you will sometimes hear a single tube high pressure shock referred to as a DeDion type. That is one of several patented technologies Bilstein uses. I will try to start a string to get Dynosor and RS2 to chime in they seem like some of the sharpest guys on this stuff. All of the stuff pinecone said also jibes with my experience exactly.

Ironically, Bilstein's PSS system uses monotube but the PSS-9s uses double tube design.

I hope this didn't come out as me busting on you. This stuff is fairly involved, and you didn't present yourself as being all knowing. I just thought I'd try to keep this (hijack) discussion rolling with some of my own fuzzy knowledge.