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Bent Strut And Knuckle
Published by bmw6953
08-23-2010
Bent Strut And Knuckle

Does any one have a DIY for this? how had is it to replace?
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  #1  
By dcorn on 09-14-2010, 11:00 PM
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Bump, I have the exact same problem. Hit a huge pothole on the highway and bent the strut, knuckle and put a bubble in the tire.

I'll be getting the BMW performance shocks and struts that are on clearance for super cheap.
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  #2  
By bmw6953 on 09-15-2010, 11:40 PM
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Nice, What dealer is this? are you doing it your self or having a dealer or shop do it? if you do it your self shoot me the DIY
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  #3  
By dcorn on 09-20-2010, 08:06 AM
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www.getbmwparts.com

Look in the BMW performance section and you see the kit for sale for only $133. I just ordered that and a knuckle for about $300. I'm guessing with a bit of help, I can do this install on my own. Ball joints should be the toughest part. The dealer quoted me $1300 to replace the strut and knuckle...
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  #4  
By bmw6953 on 09-20-2010, 11:54 PM
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Yup I got quoted the same thing they said i would get alot of tire wear because after my aligment the front right side is still off by a degree but i have not noticed anything. the only thing that bothers me is the vibration when I brake. Since its that cheep im just going to replace it as well. I was looking 325i suspension and it does not seem to be that hard. I will look it up TIS. You and I will both need a aligment after the instilation.
Last edited by bmw6953; 10-04-2010 at 11:52 PM.
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  #5  
By dcorn on 09-30-2010, 09:00 AM
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Yeah, after I told them I heard a humming while driving and a slight pull, they aligned the car for me (of course not covered under warranty). The dude then told me the knuckle and strut were bent and they couldn't get the alignment in spec. Said the caster was out 1* on that side and that it would screw up my tire on that side (complete BS). Then he told me they'd fix it for $1700 or whatever. I just told em no way, I'll do it myself and get coilovers for that price lol.

So yeah, got my performance shocks/struts and H&R springs, in addition to a new knuckle. I'll see how bad the knuckle is (if at all) and then replace as necessary. So far, the parts have cost me about $450, even with shipping, for used springs and new shocks/struts and knuckle. Oh, and about $200 for a new tire to replace the one with the bubble. So I'm saving myself over a grand. Just don't see where the $1000 worth of labor comes in.
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  #6  
By bmw6953 on 10-04-2010, 11:50 PM
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Let me know how the instalation gose. Take some pics if you can. I want to replace it my self but I want to make sure I do it right. As far as that $1000 of labor its just the amount of hours the repair should take acording to BMW repair standards, even thought the tech can probably do it in half of the time they charge you for.
Last edited by bmw6953; 10-04-2010 at 11:55 PM.
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  #7  
By dcorn on 10-06-2010, 12:10 AM
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Sheesh, just got the front suspension done and starting on the back. This job would have gone so much faster if I had some air tools. The wheel bearing bolts are insanely tight and I just got them loose before my 1/2" ratchet broke. Went over to a friend's house to borrow one and swapped the wheel bearing in 2 seconds to the new knuckle with the help of an impact gun.

The knuckle swap really isn't too much more work than a spring/strut swap. The only extra work consists of removing the caliper and rotor (2 18mm bolts and a small hex screw), heat shield (4 10mm bolts), removing 2 control arm nuts and 1 tie rod nut (all 21mm), and taking the wheel bearing off (4 18mm bolts I believe). Reassembly of the knuckle setup took about 5 minutes. No special tools are needed except maybe an impact to make your life 1000x easier. I have a few pics I'll post up later.


Oh, and I can definitely see where the strut was slightly bent because there was a dent where it went into the knuckle. However, I have no freakin clue how the tech could tell me the knuckle itself is bent. A friend and I both stared at it for a few minutes to see even the slightest difference between the old/new knuckle and we saw no change. Pretty sure I could have just left it alone and been fine forever, but what's done is done.


Edit: And as far as the cost of the tech doing all the work. This took me a very long time to finish because it's the first time I've even taken the wheels off my car so I wasn't familiar with the suspension at all. If I had to do this again, it would probably take me a third of the time, especially if I had the right tools. I feel like a tech could do all this work in 3-4 hours at the most, even with the knuckle swap.
Last edited by dcorn; 10-06-2010 at 01:43 PM.
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  #8  
By bmw6953 on 10-10-2010, 06:04 PM
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GOOD Work! However now I am double thinking if I should replace the steering knuckle. since they recomended it maybe I will I dont know yet. I have air tools so thats good to know.Did you crompresse the spring and if you did what did you use? Some pics would be great! I have'nt done it yet but I will very soon. How does your car feel? does it feel like it needs to be re aligned?
Last edited by bmw6953; 10-10-2010 at 06:19 PM.
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  #9  
By dcorn on 10-11-2010, 06:01 PM
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First, here are a few pics (Sorry they kinda suck, forgot my camera and these were taken with my Droid in a dark garage)

So you've all see the writeup on taking the suspension apart. What a pain to use the spring compressors when they are all the way up in the wheel well. I recommend a ratcheting wrench Took me forever to get the bent strut out of the knuckle, but with the help of a small sledge, it's out. Next step is to remove the caliper, rotor and dust shield.



You are left with the two control arms and tie rod to take off, which are simply 21mm nuts. The tough part is the stud of each one spins, so you need a hex key or something to hold it in place. What I did was put the hex key in a ratchet and spin that, but hold the nut in place with an adjustable wrench. Works fine as long as the ball joint isn't at a weird angle.




The ball joints slip right out after the nuts are off and the knuckle is free. Oh, don't forget the ABS sensor, which you need a torx socket (not bit). Now you have to deal with the 4 bolts holding on the wheel bearing. Like I said before, I put the knuckle in a vice and went at it with a 1/2" ratchet and it ended up stripping. Gotta take that back to Sears for a new one lol. Went to a friend's house and he had the bolts out and the wheel bearing attached to the new knuckle in all of 5 minutes. A good impact gun works wonders. It would have taken me at least an hour with a breaker bar to get those out.

Not sure why the numbers on the back are different. You can see the old knuckle was made by Alcoa, which is awesome, but the new one isn't I guess. On a side note, it's amazing how light the knuckle is. I'd guess only 2-3 lbs at the most. The wheel bearing probably weighs 3 times that much.





And here is what you are left with in the wheel housing.



Once the wheel bearing is on the new knuckle, reinstall everything reverse of how it came out.

ABS sensor
Control arms and tie rod
Dust shield
Brake rotor and caliper
Put strut assembly together and compress spring a lot
strut assembly back into knuckle and strut tower
sway bar and any wiring that was displaced

Oh, and the BMW performance strut/shock kit came with all new bumpstops, spring isolators, dust covers, nuts, bolts, all kinds of stuff. I used a bunch of it where I saw fit.

Quote:
Originally Posted by bmw6953 View Post
GOOD Work! However now I am double thinking if I should replace the steering knuckle. since they recomended it maybe I will I dont know yet. I have air tools so thats good to know.Did you crompresse the spring and if you did what did you use? Some pics would be great! I have'nt done it yet but I will very soon. How does your car feel? does it feel like it needs to be re aligned?
I'm not sure what to say about replacing the knuckle. I guess I feel better that I did it, but I still call BS on them being able to tell it was bent just from looking at it on the car.

I used the normal strut type spring compressor that has a bar with hooks on each side of the spring. I guess it's necessary to get the top of the strut out from under the fender because you really can't push the control arm down far enough.

The car feels good, about the same as before except body roll has diminished with the H&R springs. Big bumps are much harder on the car now, but I'm sure that's partially because of the runflats still. Wish I could have gotten all new non-RFT's. Not sure if the car needs an alignment, but I'm definitely going to get one. Taking that much apart and introducing that many new parts surely threw off something.
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  #10  
By bmw6953 on 10-11-2010, 11:00 PM
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Good work! good Write up!I also feel better about replacing the knuckle. I will be doing all of this soon. Thanks for all your info!
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  #11  
By dcorn on 10-12-2010, 09:22 AM
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Sure thing man. I've had a ton of suspension experience on Mustangs and Jeeps, so I guess it really wasn't too bad. I was just worried about screwing up something on a $45k car that I've had for 4 months.
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