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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > "Guide Support" question



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      11-27-2011, 09:59 AM   #1
hdrewh
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"Guide Support" question

Found a set of ZSP springs for my non-ZSP E90 328. (not easy in this 335-dominated forum )

Aside from the bump stomp which I knew about, realoem shows a different part number for the "guide support" for sport/performance vs non-ZSP...

http://www.realoem.com/bmw/showparts...16&hg=31&fg=10

Its also double the price. Anyone know what/why the difference for this part between sport/non-sport, and what horrible things may happen if I skip it?

Thanks.
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Last edited by hdrewh; 11-27-2011 at 10:32 AM..
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      11-27-2011, 12:42 PM   #2
luckyu
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Quote:
Originally Posted by hdrewh View Post
Found a set of ZSP springs for my non-ZSP E90 328. (not easy in this 335-dominated forum )

Aside from the bump stomp which I knew about, realoem shows a different part number for the "guide support" for sport/performance vs non-ZSP...

http://www.realoem.com/bmw/showparts...16&hg=31&fg=10

Its also double the price. Anyone know what/why the difference for this part between sport/non-sport, and what horrible things may happen if I skip it?

Thanks.
The sport guide support (... 098) is 0.18" shorter. It affects front ride height, so if you keep your current part, your ride height will be 0.18" higher than stock.

EDIT: Also, the sport guide support is made of steel and not aluminum, and is much heavier and probably much stronger.

I have a pair of sport guide supports that came off my car with about 14K on them, if you decide you want to change.

I think the ZSP suspension will work a little better if you use slightly shorter bump stops. In front, use the one from E36 M3. In rear, from E85 Z4, p/n 33 53 6 770 350 (includes dust tube). The potential risk from using shorter stops is additional understeer, and the benefit is the car body will remain flatter over bumps.
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2007 328i ZSP. M3 suspension: custom valved Bilstein shocks, Hyperco race springs, M3 lower control arms front and rear, M3 sway bars, and M3 subframe bushings. E46 front guide supports. Euro tail lights.

Last edited by luckyu; 11-27-2011 at 12:49 PM..
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      11-27-2011, 05:22 PM   #3
hdrewh
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Thanks, great info. Ya know, I got a good deal on barely-used ZSP springs, with the intention of pairing them with Koni FSD's, and hoping to get a decent deal on a ZSP front sway as well, essentially correcting my non-ZSP purchase decision.

But the Koni's, if I can't find 'em used, round up or down to $700 depending on where I order from. Add it all up and I'm within BMW Performance Suspension territory, give or take a couple hundred. So I might go that route instead. Remaining concern is the tighter Performance Springs, I hesitate based on the roads where I live.
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mods: Koni FSDs, Eibach Pro's, Sport/Heated Seats, BMW Perf. short shifter, M-tech shift knob/e-brake handle/steering wheel, split armrest, black grilles, 50% tint, 3M clear bra.
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      11-27-2011, 05:52 PM   #4
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Quote:
Originally Posted by hdrewh View Post
Thanks, great info. Ya know, I got a good deal on barely-used ZSP springs, with the intention of pairing them with Koni FSD's, and hoping to get a decent deal on a ZSP front sway as well, essentially correcting my non-ZSP purchase decision.

But the Koni's, if I can't find 'em used, round up or down to $700 depending on where I order from. Add it all up and I'm within BMW Performance Suspension territory, give or take a couple hundred. So I might go that route instead. Remaining concern is the tighter Performance Springs, I hesitate based on the roads where I live.
Bilstein HD's or Koni Yellows are also good choices that you can find used. I think the Bilsteins are fantastic (you can click on my sig to see what I did). Really great feel, and the comfort level remains high.

I don't know if you're in the City or not. Lowering the car can make a big negative difference on how your car feels on really rough roads. Also, I have a suspicion based on several "335 in NYC, Oh God the pain" threads, that stiffer shocks and more suspension travel can actually be more comfortable. Porsches are said to handle NYC potholes better than 335, and M3 is also better.
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      11-27-2011, 06:00 PM   #5
hdrewh
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Makes sense. I don't live in the City but work there, and often drive in.

Which shocks and bump stops (shorter=more travel?) would yield more suspension travel in my upgrade quest, and any idea how they would compare with the out-of-the-box Performance Suspension?

Still coming up the learning curve here....
Thanks again.

Last edited by hdrewh; 11-27-2011 at 06:39 PM..
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      11-27-2011, 06:46 PM   #6
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Quote:
Originally Posted by hdrewh View Post
Makes sense. Which shocks/bump stops (anything else?) would yield more suspension travel in my upgrade quest, and how would they compare with the Performance Suspension? Still coming up the learning curve here....

Thanks again.
No problem, I will try to give you the benefit of my woefully incomplete experience. I think stiff shocks help with "suspension travel issues" because they reduce wheel movement compared to weak shocks. I think Bilstein's are valved more stiffly, esp. in bump, compared to Koni FSD, Koni Yellow, and BMW Perf. With my setup I notice less suspension movement.

EDIT: Also I think Bilstein monotubes and Koni Yellows are a much higher quality shock than whatever is in BMW's kit. In particular I have a lot more faith that Bilstein's tuning is really good now that I've tried it; but also B's are more rugged, they last longer, response is better, theyit don't fade, and they're rebuildable and revalvable. I guess you could say I'm a convert...

Bump stops, I gave the parts I would use. I haven't used them to increase total travel, but I chose to use shorter ones so they don't engage as much, because that caused the car to wallow and float a lot.

EDIT: I did a lot of measurements to ensure I had enough room in the wheel well, and to ensure no coil bind in the rear.

Performance suspension is going to lower your car more than ZSP springs. BMW says 10 mm lower, which if we believe them that would be as low as 13.6". I would ride no lower than 14.25" in front, but probably your current height is even better.

It's lowering the car that causes problems with ride quality and suspension travel. The problems can be alleviated with any or all of: stiffer springs, stiffer shocks, different bump stops, and shorter strut/shock bodies. Companies who make coilovers make shorter bodies, but the alternatives you're considering use standard length, so space under there is limited.

I don't have a formula for how much travel or ride height is really necessary in various circumstances. I chose to address everything: higher ride height, shorter bump stops, stiffer shocks, and... actually springs were basically the same as before. I wanted to be sure, so I threw everything at the problem!

If you read my "M3 on 328i" thread and find it confusing because I don't explain the basics, let me know and I'll make a new thread to try to explain things better.
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2007 328i ZSP. M3 suspension: custom valved Bilstein shocks, Hyperco race springs, M3 lower control arms front and rear, M3 sway bars, and M3 subframe bushings. E46 front guide supports. Euro tail lights.

Last edited by luckyu; 11-27-2011 at 08:16 PM.. Reason: clarification + Bilstein plugging
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      11-27-2011, 09:40 PM   #7
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You could keep your existing guides and add SP lowering perches to give correct ride height. Would be less expensive.
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