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335 OEM Strut Bar-DIY
Published by uberschnell
12-09-2007
335 OEM Strut Bar-DIY

So I bought the OEM strut bar before I was told that it wont fit, so I decided to make it work anyways.

1, You will need to shim the strut bar about 2mm to clear the stock air box. I machined a set of spacers, but decided to go to Ace Hardware and try out Stainless Washers instead for this DIY.
You will need to shim the two mounting points on each side (as seen in photo below). I used washers that closely matched the diameter of the bolt shanks. Each washer is 1mm thick. As you can see in the photo, there is still plenty of grip left on the studs.

2, When installed there is a 1 to 2 mm gap between the bar and the air box. Once the car is running you will hear a taping sound coming form the air box tapping against the bar due to the engine vibration. It makes contact in three places. I cut up pieces of high temp hose (about 2mm thick) and used some 3m adhesive to mount in the three areas contact is made.

3, Tighten up and no tappng sound at all. + The rubber protects the airbox lid from scuffs but can't be seen from above.

4, Bar makes some contact with the hood insulation, but nothing major.
__________________
- 08 135i - Wavetrac LSD, AST 4100, Swift springs, Brembo GT brakes, M3 front sway, Meyle HD links, Dinan Camber plates, Whiteline subframe bushings, M3 rear guide and upper link, M3 front control arms, HP custom M3 front Strut brace, Megan rear control arms, F30 brake shields -
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  #1  
By AM335 on 12-09-2007, 08:16 PM
Magna3, did you notice any performance difference? Thanks for the write-up btw. It appears that 1 strut mount bolt is loosened, does anyone think an alignment is in order after this install? Thanks.
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  #2  
By AM335 on 12-09-2007, 08:18 PM
Magna3, do you think there will be any long term damage from the STB / hood insulation contact? Thanks.
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  #3  
By baggerben on 12-09-2007, 08:22 PM
i doubt an alignment would be needed. but you never know.
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  #4  
By canucklion on 12-09-2007, 08:39 PM
If I had a 335i, I'd wait for BMW to come out with one specifically made to fit a 335i
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  #5  
By uberschnell on 12-09-2007, 09:35 PM
No alignment is not needed, there is another bolt that needs to be removed + an alignment pin to free the strut.

As for performance, I've taken it off and driven around then re-installed it and drove the same route. You can feel it tighten up the front end when making slalom-like turns, where the car is thrown from one side to the other. Not huge by any means, but it never hurts to tighten a car up.

I'd say 60% engine bling, 40% performance upgrade.

As for the liner, it looks worse in the photo. I've had it for 4000 miles and no fraying or damage is apparent.
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  #6  
By TheLegacy on 12-09-2007, 09:43 PM
thanks for getting this up for us
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  #7  
By rwalker on 01-06-2008, 01:16 AM
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This weekend I decided to duplicate Magna3's feat. I have a 2007 335i sedan, on which the OEM strut tower brace is not supposed to fit.

I wasn't happy with having the bar touch the airbox at all, so I decided to be a little bit more aggressive with the spacers. I used the same 1mm washers (in stainless steel) as Magna3, but used a different placement to achieve a slight arch of the bar over the airbox.

Instead of 2mm under each strut tower mount point, I went with 2mm under each inner strut tower mount point, and 1mm under each inner joint point.

Here's a line diagram of Magna3's washer placement vs. mine:


Mounting the bar this way requires a little bit of force, as the bar is somewhat pre-loaded in this non-straight mounting configuration. But the generously-sized sliding joints of the bar give plenty of wiggle room to get it all together.

The resulting airbox clearance is abundant:



On the passenger side mount, you can see a slight ramping in the joint:


Here's a picture of the driver's side mount, with a closeup on the 2 1mm spacers under the inner mount point:


The finished product:


The hood closes just fine, and the hood liner shows no ill effects. I'll post again in a couple of months to show any long-term impact.

Hope this helps you.

-Rob
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  #8  
By AM335 on 01-06-2008, 07:23 AM
Rob, thanks for the post and pictures. Yes, please post again later when you have long-term effects on the hoodliner. Did you feel any difference with the STB? Thanks.
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  #9  
By rwalker on 01-06-2008, 01:11 PM
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Quote:
Originally Posted by AM335 View Post
Rob, thanks for the post and pictures. Yes, please post again later when you have long-term effects on the hoodliner. Did you feel any difference with the STB? Thanks.
I feel a difference: the front end has a higher resonant frequency. It's more drumlike. The car recovers from big bumps under the front wheels better. The car used to have what felt like cowl shake in a convertible. I'm still running the stock runflats, but now the front end finally seems fully up to the task of wheel control (more like my old ZHP).

I haven't pushed the car hard around any corners in this configuration. I didn't do this mod to improve cornering, and don't expect to feel any improvement besides the one listed above. By the way, here's why I did the mod:

http://www.e90post.com/forums/showpo...6&postcount=21

-Rob
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  #10  
By AM335 on 01-06-2008, 02:49 PM
Rob,
Thanks again. From what vendor did you buy your STB?



Quote:
Originally Posted by rwalker View Post
I feel a difference: the front end has a higher resonant frequency. It's more drumlike. The car recovers from big bumps under the front wheels better. The car used to have what felt like cowl shake in a convertible. I'm still running the stock runflats, but now the front end finally seems fully up to the task of wheel control (more like my old ZHP).

I haven't pushed the car hard around any corners in this configuration. I didn't do this mod to improve cornering, and don't expect to feel any improvement besides the one listed above. By the way, here's why I did the mod:

http://www.e90post.com/forums/showpo...6&postcount=21

-Rob
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  #11  
By doba_s on 01-06-2008, 03:31 PM
Quote:
Originally Posted by AM335 View Post
Magna3, did you notice any performance difference? Thanks for the write-up btw. It appears that 1 strut mount bolt is loosened, does anyone think an alignment is in order after this install? Thanks.
haha ... now it is faster ...
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  #12  
By rwalker on 01-06-2008, 05:28 PM
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Quote:
Originally Posted by AM335 View Post
Rob,
Thanks again. From what vendor did you buy your STB?
Here:

http://cgi.ebay.com/BMW-E90-E91-3-Se...sid=p1638.m118

I've tried to catch one on the E90 classifieds (a used OEM STB can typically be found there for ~$150), but I had real trouble closing a sale. Usually, they're snapped up very quickly; they're hard to catch. Finally, I made a deal and then the seller flaked; ug... Eventually I got tired of waiting and went with a new one.

-Rob
Last edited by rwalker; 01-06-2008 at 11:14 PM.
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  #13  
By stressdoc on 01-07-2008, 11:51 AM
IMO this is a good mod, and although the arched tension is not ideal, it probably has little real effect on function. A brace is especially useful if you tighten up the suspension with coilovers, or if you have an xi. I would be curious what your SAs have to say about warranty issues, as this is a non-standard installation.

In addition to this front brace, I want to install a rear shock tower brace -- with a LSD and all the torque of the 335, there is a lot of flex in the rear subframe.
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  #14  
By rwalker on 01-07-2008, 12:28 PM
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Quote:
Originally Posted by stressdoc View Post
In addition to this front brace, I want to install a rear shock tower brace -- with a LSD and all the torque of the 335, there is a lot of flex in the rear subframe.
Do you know of anyone who makes a rear STB for E90s?

-Rob
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  #15  
By rwalker on 01-07-2008, 12:35 PM
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Quote:
Originally Posted by stressdoc View Post
IMO this is a good mod, and although the arched tension is not ideal, it probably has little real effect on function. A brace is especially useful if you tighten up the suspension with coilovers, or if you have an xi. I would be curious what your SAs have to say about warranty issues, as this is a non-standard installation.
What are your thoughts on the arched tension in light of this article?

http://e30m3performance.com/myths/St...bar_theory.htm

-Rob
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  #16  
By stressdoc on 01-07-2008, 01:09 PM
I'd have to think about it -- my guess is that the angle change from the staggered washers primarily changes stress only in the bar itself and the attachments on the strut bolts. I don't think the arch exerts any outward pressure pushing the towers apart. The bar just is under tension on the top, and compression on the bottom (which reduces its ability to resist movement between the towers -- the bar can more easily flex upwards because it's already 'bent' in that direction). The nut on the lateral (outside) strut tower bolt is being pushed up -- might want tp periodically check/tighten it. The metal there may deform a bit over time, reducing the stress -- I thought about bending the bar prior to installation to get this effect.
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  #17  
By AM335 on 01-19-2008, 08:37 PM
Rob, do you know the proper torque to tighten all the nuts? Any more input/opinions now that you have had the STB on for approx. two weeks? Thanks.
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  #18  
By rwalker on 01-19-2008, 11:06 PM
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Quote:
Originally Posted by AM335 View Post
Rob, do you know the proper torque to tighten all the nuts? Any more input/opinions now that you have had the STB on for approx. two weeks? Thanks.
Torque specs:
small nuts (6 of 'em): 35 Nm
larger, outer bolts (2 of 'em): 52 Nm

I re-torqued the fasteners today, just to be sure that the washers weren't causing anything to back out or bend. Everything seems to be in ship shape.

Prior to this modification, my driving style was like a tiptoe over lily pads. I swerved around potholes, drifted around bumps, and even dodged the lane-marking reflectors because the front suspension (ZSP) didn't seem up to the task of keeping those heavy, bouncy runflats in check. A "BAM!" from the runflats was usually followed by a "wobba" from the rest of the front end. It was lot like cowl shake in my wife's old E36 M3 convertible.

Now, I still get the "BAM!", but the "wobba" is reduced to something more like a buzz. It's much tighter. I'm a lot more relaxed on the road now. I cautiously venture that I'm "happy".

For true fulfillment on the stock suspension, I think all I have to do is burn the runflats down to the cords so I can upgrade to the Velocity CSL reps and Michelin PS2s.

The hood liner looks to be in pretty good shape so far. There are marks from the connecting studs and a slight indentation from the part of the bar over the motor, but I don't think I'm in any trouble of distorting the hood.

-Rob
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  #19  
By MTL Bimmer on 01-20-2008, 02:25 AM
awsome!! is it the same DIY for e92 328s?
Thanks
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  #20  
By AM335 on 01-20-2008, 08:32 AM
Thanks Rob. Now I hope my brother has a large Torx socket to fit the bolt under the hood.

Take care
- Allan

Quote:
Originally Posted by rwalker View Post
Torque specs:
small nuts (6 of 'em): 35 Nm
larger, outer bolts (2 of 'em): 52 Nm

I re-torqued the fasteners today, just to be sure that the washers weren't causing anything to back out or bend. Everything seems to be in ship shape.

Prior to this modification, my driving style was like a tiptoe over lily pads. I swerved around potholes, drifted around bumps, and even dodged the lane-marking reflectors because the front suspension (ZSP) didn't seem up to the task of keeping those heavy, bouncy runflats in check. A "BAM!" from the runflats was usually followed by a "wobba" from the rest of the front end. It was lot like cowl shake in my wife's old E36 M3 convertible.

Now, I still get the "BAM!", but the "wobba" is reduced to something more like a buzz. It's much tighter. I'm a lot more relaxed on the road now. I cautiously venture that I'm "happy".

For true fulfillment on the stock suspension, I think all I have to do is burn the runflats down to the cords so I can upgrade to the Velocity CSL reps and Michelin PS2s.

The hood liner looks to be in pretty good shape so far. There are marks from the connecting studs and a slight indentation from the part of the bar over the motor, but I don't think I'm in any trouble of distorting the hood.

-Rob
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  #21  
By rwalker on 01-20-2008, 07:10 PM
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Quote:
Originally Posted by MTL Bimmer View Post
awsome!! is it the same DIY for e92 328s?
Thanks
You don't need to shim anything on the E9x 328 or 330 (or 320, etc). The OEM strut bar fits without modification or adaptation. There's another OEM strut bar DIY for non-335s. Try search.

-Rob
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