1M strut tower brace on a 135i

[JSavela]

Since I just installed coilovers, I've been looking for a reasonably priced option to gain access to the tops of the struts for adjustments. I really wanted an OEM look, but considering I just wanted it for access, I couldn't justify the cost of a full M3 brace kit. I looked at pictures of a 1M and saw that it used a different brace than the M3. Looking through RealOEM confirmed that the 1M used the M3 strut tower rings, but used the same center mounting method as the 135. Once I compiled the PN's, and checked pricing, I found that the 1M brace "kit" (see pic below) could be pieced together for about $205. I ordered it all up hoping that it would fit and when it got here, everything bolted right up without any issues or modifications.

Here is the OEM 135i brace

Here is a comparison of the 135i and 1M braces:

Here is the 1M brace installed:

Here it is all back together:


Here is the complete part list:

QTY / PN / Description

1 / 51618055091 / Strut Tower Mounting Ring - Left (Same as M3 part)

1 / 51618055092 / Strut Tower Mounting Ring - Right (Same as M3 part)

1 / 51618051973 / SPRING DOME STRUT, LEFT (unique to 1M)

1 / 51618051974 / SPRING DOME STRUT, RIGHT (unique to 1M)

6 / 51717895241 / Hex Nut, M8 (These replace the 6 stock nuts that hold the strut in place)

4 / 31316769731 / Self Locking Collar Nut, (same nut as the 6 getting replaced by the PN above. So, if you want, you could use 4 of those 6 instead of buying these 4 new ones)

2 / 51617891281 / Strut Tower Covering Cap

[ilikebmxbikes]

Nice write up and thank you for sharing part numbers. This thread is a good contribution. Previously people have been installing modified M3 braces but this is much easier.

[Derk1127]

Thanks for this, I actually just got the parts from ECS to do this, it took about a month to get though because the bars were special order!

[sour97]

thanks. for the post. feel and difference compare to OEM?

[Eddie135]

That is a really cheap price, compared to getting the modified M3 ones.

[Dackelone]

NICE work!

Thanks for posting the part numbers. I might just have to look into this mod now.

[SalemChiro]

Thanks for posting this.

Would this fit the N54 also?

[JSavela]

Thanks for the kind words guys. The install was about as easy as they come. I never completely removed the large center ext torx bolt, just loosened it enough. I slid the old dome strut out and replaced it with the new one one side at a time. The entire job took me about 30 mins, even with stopping to take pictures along the way.

As far as performance improvement, I'm not in a position to notice if there is. I just took my car out of storage and bolted on a set of coilovers, subframe bushings and M3 arms. As a complete setup, it feels great. I would guess the 1M brace had nothing to do with the transformation. That wasn't the goal of this mod anyways. It was all about gaining access to the strut tops and keeping that OEM look without spending $400 on a full M3 brace.

It also took me about a month to get the parts because the dome struts were special order. The availability of the dome struts is my only concern about this upgrade. Manufacturers typically make a certain number of extras to stock for replacement parts. Since the dome struts are unique to the 1M, I doubt they made a whole lot of extras. I wouldn't be surprised if us 135 owners bought up their stock of extras fairly quickly.

[JSavela]

Originally Posted by SalemChiro

Thanks for posting this.

Would this fit the N54 also?

Yeah, it'll work on the N54 coupe. I'm not sure about the convertible since I don't know if they use the same type of stock bracing.

[vivanapoli806]

Thanks for posting. Will be doing this for sure. Got quoted $186 for all the parts, not bad at all

[JSavela]

For those of you who are pricing things out, it's worth mentioning that the 6 nuts ring up at about $10 each. Since the OEM studs aren't long enough to reach up beyond the thickness of the black mounting rings, these special nuts are required. If someone comes up with a cheaper option (replacing studs or alt. source), let us know what worked for you.

[SalemChiro]

Originally Posted by JSavela

Yeah, it'll work on the N54 coupe. I'm not sure about the convertible since I don't know if they use the same type of stock bracing.

Just checked my convertible...looks the same.

If you've removed the strut alignment pin, do you think this brace would allow you to still slide the strut top in slightly to gain negative camber?

[ULOOKN]

Would you know if this would fit a coupe 125i?

[PeteA]

Not bad...but the HP Autosport one is functionally superior (even though it costs a bit more) as the mount point is a unified piece.

[JSavela]

Originally Posted by SalemChiro

If you've removed the strut alignment pin, do you think this brace would allow you to still slide the strut top in slightly to gain negative camber?

Good question, but I'm not sure. If I had to guess, if all of the nuts/bolts were loose, I bet there'd be enough slop to allow for the small adjustment.

Originally Posted by ULOOKN

Would you know if this would fit a coupe 125i?

If the 125 stock brace looks that same as mine, it should work. Companies like to share parts between cars, so I would think it would work.

Originally Posted by PeteA

Not bad...but the HP Autosport one is functionally superior (even though it costs a bit more) as the mount point is a unified piece.

I agree 100% that the M3 brace is superior to the 1M. If I were looking for a stiffer setup, I'd consider the M3 brace or even something that goes directly between the strut towers. For now, this is perfect for giving me access to the rebound adjustments.

[ULOOKN]

Originally Posted by JSavela

Good question, but I'm not sure. If I had to guess, if all of the nuts/bolts were loose, I bet there'd be enough slop to allow for the small adjustment.

If the 125 stock brace looks that same as mine, it should work. Companies like to share parts between cars, so I would think it would work.

I agree 100% that the M3 brace is superior to the 1M. If I were looking for a stiffer setup, I'd consider the M3 brace or even something that goes directly between the strut towers. For now, this is perfect for giving me access to the rebound adjustments.

Thanks for your reply.
I just ordered a set today

[Sixle]

Does the P/N for the mounting rings include the plastic ///M dust covers?


Edit: found the number for the caps

post the part # for the caps: 51617891281 x2

[3002 tii]

Question, it appears you have a n55? Did you have to modify the heater closing panel (like how HP Autosport requires to do so)?

[3002 tii]

Originally Posted by JSavela

For those of you who are pricing things out, it's worth mentioning that the 6 nuts ring up at about $10 each. Since the OEM studs aren't long enough to reach up beyond the thickness of the black mounting rings, these special nuts are required. If someone comes up with a cheaper option (replacing studs or alt. source), let us know what worked for you.

Do you know size and thread?

[MightyMouseTech]

This, this is fantastic! Thank you very much!

[JSavela]

Originally Posted by Sixle

Does the P/N for the mounting rings include the plastic ///M dust covers?


Edit: found the number for the caps

post the part # for the caps: 51617891281 x2

Not sure how I forgot to include these. Thanks for pointing it out. I've updated the original post. I'm sorry if anyone ordered up everything without the plastic caps.

Originally Posted by 3002 tii

Question, it appears you have a n55? Did you have to modify the heater closing panel (like how HP Autosport requires to do so)?

Nothing had to be modified. It was a direct replacement.

Originally Posted by 3002 tii

Do you know size and thread?

It's an M8, probably 1.25 pitch. You can remove one of your 6 stock strut mount nuts to double check.

[MightyMouseTech]

Hmm, going to be installing the Dinan fixed upper mounts, hope they will work with this.