# M3 strut brace install questions



## alee (Dec 19, 2001)

Since the group buy for the M3 strut brace is well underway and it looks like people will be phoning in their orders soon enough, it's time to ask a few quick questions about the installation, as I'm sure they'll crop up eventually.

I read Ack's post which mentioned that only a 13mm wrench is needed.

Questions:

1. What is the BMW specified torque requirements when you mount the brace?

2. What are the risk(s) (if any) if you don't torque it enough or overtorque it by hand without a torque wrench?

3. What could go wrong with this install (i.e. what's the HACK factor here -- what are the chances I'll end up with a car I can't drive)?

4. I don't own any tools... if I were to buy the correct tool(s) for this install, what would you recommend (assuming I were to make a trip to Sears and wanted to spend under $100)?

Thanks!


----------



## Nick325xiT 5spd (Dec 24, 2001)

You can get the tools for a couple bucks. All you need is a 13mm box wrench. I recommend springing for the ratcheting variety for a couple more bucks. 

I torqued to tight, using a six inch or so long socket wrench. It's worked for me. About the only way you'd screw something up so badly that you wouldn't have a car to drive is if you left the bolts off... 

I'll look up the torque specs sometime when I'm not feeling so lazy.


----------



## Kaz (Dec 21, 2001)

The nuts that go in that location if you don't have a strut bar are either 24 or 34Nm depending on whether the flange on the nut is small (18mm) or large (21mm). Seems pretty loose to me, but that's out of the book. I really can't see too much harm in overtorquing it (at least from the amount of reasonable torque you could get into a 13mm combination wrench). Any looser than specified, and your front strut could come loose, but probably not fall out very easily.

As for tools, IMO a good general starting point for little money is a 3/8" socket set, preferably all-metric, so you don't spend money on SAE sockets you may not use unless you work on stuff around the house. Sears has a nice set with their new polished, low-profile ratchet and laser-etched sockets that will do nicely.


----------



## The HACK (Dec 19, 2001)

It's a pretty HACK proof project. All you need is make sure the top strut hat does not move (or if you're in the mood for negative camber, move it). If your car is sitting under load (i.e. not on a lift or jackstands) then you'll be fine.

The nuts, from what I understand, is very sensitive to UNDERTORQUING. And Kaz is right, it's the 24Nm (or 18ft-lbs) torque setting. If you want to do the job right, get the torque wrench. If you just want to wing it (since the strut brace is, afterall, mostly cosmetic) just hand tighten it and go over it with a racheting wrench. Do be careful, the reason why BMW specs a torque rating for these nuts is that overtightening it WILL stretch the threads, or worse yet, break off the bolt.


----------



## RichP (Apr 23, 2002)

they come with lock-tite on them, so even at the 18 setting, they should be fine; someone on fanatics already overtorqued one and broke the bolt though, so be careful!


----------



## Mr. The Edge (Dec 19, 2001)

yes, the torque spec is LOW (18-20 ft-lbs)

When I installed mine that seemed awfully loose, but I've had no problems in the year or so that I've had it on.


----------



## The HACK (Dec 19, 2001)

RichP said:


> *they come with lock-tite on them, so even at the 18 setting, they should be fine; someone on fanatics already overtorqued one and broke the bolt though, so be careful! *


They're ONE USE nuts, meaning they've either got some sort of plastic inner lining that gets crushed as the nut is being tightened, or the threads are made in a way that it'll deform a certain degree when the desired torque is reached and prevent the nut from backing out.

Another reason why they're so damn expensive.

EDIT: Meaning once you tighten it, do not loosen it back up or you'll need to get a new set of nuts. Hence having a torque wrench is VITAL for the install.


----------



## Mr. The Edge (Dec 19, 2001)

The HACK said:


> *They're ONE USE nuts, meaning they've either got some sort of plastic inner lining that gets crushed as the nut is being tightened, or the threads are made in a way that it'll deform a certain degree when the desired torque is reached and prevent the nut from backing out.
> 
> Another reason why they're so damn expensive.
> 
> EDIT: Meaning once you tighten it, do not loosen it back up or you'll need to get a new set of nuts. Hence having a torque wrench is VITAL for the install. *




not sure about that. I bought a used one and the nuts were fine


----------



## AB (Jan 11, 2002)

atyclb said:


> *
> not sure about that. I bought a used one and the nuts were fine *


that's what she said


----------



## The HACK (Dec 19, 2001)

atyclb said:


> *
> 
> not sure about that. I bought a used one and the nuts were fine *


All strut nuts are one use only. Using used nuts will compromise a) the torque rating and b) compromise the nuts ability to stay on the thread. I would NEVER reuse the one use only strut nuts and shock mount nuts. Don't be surprised if they back out of the thread sometime in the future.:dunno:

It's your call.


----------



## Mr. The Edge (Dec 19, 2001)

The HACK said:


> *All strut nuts are one use only. Using used nuts will compromise a) the torque rating and b) compromise the nuts ability to stay on the thread. I would NEVER reuse the one use only strut nuts and shock mount nuts. Don't be surprised if they back out of the thread sometime in the future.:dunno:
> 
> It's your call. *


we're talking about these right?


----------



## RKT BMR (Sep 7, 2002)

atyclb said:


> *we're talking about these right?
> 
> 
> 
> ...


OMG... _$7.60 EACH?!?!?!?!?_
:jawdrop:


----------



## alee (Dec 19, 2001)

The HACK said:


> *Hence having a torque wrench is VITAL for the install. *


So what's a cheap but good one that I can pick up?


----------



## The HACK (Dec 19, 2001)

atyclb said:


> *we're talking about these right?
> 
> 
> 
> ...


Yeah. They're all one use only. Again, you may not think you're having any problems with them right now, but I'll bet it's probably no longer at 18-20ft-lbs right now. It probably doesn't take more than 10 ft-lbs to hold the strut brace down, and that's why you haven't experience any problem with it. I'd suggest you check them with your torque wrench and see if they're still within spec.

If you've seen these nuts NEW, you'll see the very last thread tapers to make these nuts "self-locking". Once used the last thread deforms to conform to the shape of the thread and locks itself down. The second you remove and re-use them, that last thread will no longer lock down and you're basically taking a chance that 18ft-lbs spread through the thread will hold the nut together. :thumbdwn:

Like I said, it's your call. I'd suggest you replace them with new one use, self locking nuts.


----------



## Mr. The Edge (Dec 19, 2001)

The HACK said:


> *Yeah. They're all one use only. Again, you may not think you're having any problems with them right now, but I'll bet it's probably no longer at 18-20ft-lbs right now. It probably doesn't take more than 10 ft-lbs to hold the strut brace down, and that's why you haven't experience any problem with it. I'd suggest you check them with your torque wrench and see if they're still within spec.
> 
> *


just checked, they're all still at 20


----------



## Mr. The Edge (Dec 19, 2001)

alee said:


> *So what's a cheap but good one that I can pick up? *


Home Depot sells a Husky TW that is good from 10-100ft lbs for about $50


----------



## Kaz (Dec 21, 2001)

You are not assembling the Space Shuttle. Hell, you're not even assembling the lower control arm of the car.

Ausgang will probably disagree, but I've seen how these particular nuts work, and backing them out and retightening them a couple of times for this use will NOT do any harm. Especially at the torques these are used at and the material out of which it's made, the threads aren't going to deform to the point where they are going to lose their effectiveness at those loads.


----------



## Mr. The Edge (Dec 19, 2001)

Kaz said:


> *You are not assembling the Space Shuttle. Hell, you're not even assembling the lower control arm of the car.
> 
> Ausgang will probably disagree, but I've seen how these particular nuts work, and backing them out and retightening them a couple of times for this use will NOT do any harm. Especially at the torques these are used at and the material out of which it's made, the threads aren't going to deform to the point where they are going to lose their effectiveness at those loads. *


I will also add the ChuckD at roadfly notes that those with adjustable camber plates retighten and tighten those nuts every time they make an adjustment


----------



## The HACK (Dec 19, 2001)

atyclb said:


> *I will also add the ChuckD at roadfly notes that those with adjustable camber plates retighten and tighten those nuts every time they make an adjustment *


I'll say that there's probably divergent opinion regarding this issue.

I've had my rear self locking nut come loose once because I re-used them when I installed my RSMs. I even torqued them to spec too. Took about 6 month for it to work itself loose.

Those with adjustible camber plates also adjust them often enough to not ever have to worry about the negative effects.

If it works for you...Great. I'd suggest you check them periodically to see if they're still true to torque.


----------



## alee (Dec 19, 2001)

atyclb said:


> *Home Depot sells a Husky TW that is good from 10-100ft lbs for about $50 *


I was thinking something smaller? I already have a Craftsman 1/2" drive one that probably goes that low, but I was thinking of picking up something smaller for jobs like this.


----------

