Hi everyone,

I was doing some work on my 2005 MCS this weekend. Attempting to Fix some strut tower mushrooming, install Cravenspeed UTI's and new Strut mounts. When attempting to remove the passenger (right) side strut pinch bolt, the head just twisted off.

After doing some reading, it looks like I have a few options. I could drill it and try to save/re-tap the threads. I drill it and put in a longer bolt with a nut on the end. Or I could put in a new steering knuckle.

I don't think I trust myself to drill it either way, so I would probably take it somewhere for that. I am having trouble finding any guides on doing the steering knuckle. Has anyone done it? How hard is it and what all would it entail?

Here is a dumb question I know. I am not driving it but I may need to at some point. How safe is it to drive? Things seem pretty fused together. the bolt didn't budge. But I know that the head is what held the pinch together.

What do you guys think would be the best/easiest/cheapest option?

Thank you!

 

Cheapest/easiest for me was to mill out the old bolt and retap. Took like 5min on my RF45 mill, ordered a new pinch bolt form FCPeuro. They are a higher grade than the standart 8 grade you can get, I would advise to get the proper bolt if it were me.
https://www.fcpeuro.com/products/bmw...lt-31356778832

 

Don't drive it without the bolt.

 

Ugh, I broke a pinch bolt once too, I ended up taking it to a shop with my hat in my hands and begging them to help me. Which they did for like $800. I tried to drill it out unsuccessful (I kept breaking bits)

I drove it about a mile to the shop, I had 3 corners of the suspension replaced and limped it there, it worked out ok, but I was nervous doing it.

If you can pull the strut and knuckle off the car, I think a shop with a mill or even a drill press ought to be able to sort it out without too much difficulty. I think basically you unhook the ball joints from the knuckle, pull off the brake disc/caliper and wheel bearing/hub, compress the spring and then loosen the top nut, then I think it'll come out.

It's a pain, but doable.

 

Reviving this thread to share how I overcame this problem. Head sheered off the passenger side pinch bolt (my R50 is a rusty car).

I drilled out the shank end of the bolt first... which allowed the pinch gap to open (the shank must have been trapped by rust). Using the gap at the pinch bolt, I took an angle grinder with a cutoff wheel and cut away the small amount of remaining bolt that was keeping the strut from being free.

After the strut was out, I heated and air cooled the knuckle a number of times using a MAP torch. I attempted to use an extractor... with no luck. I then soaked the gap/pinch bolt area in 50% water and 50% muriatic acid.

My plan B was to use a tap drill and tap to install a 1/4th inch bolt in a hole through the center of the threaded end of the bolt. I was able to drill on center... and as I was tapping the threads in the center of the pinch bolt, the bolt began to turn! I was able to remove it without using a bolt to turn it.

My local Fastenal was able to source a grade 10.9 bolt for me. And I'm back on the road.

 

Happened to me, sort of. While doing other repairs, I asked my independent mechanic to loosen the pinch bolt so that I could R&R the struts. He broke the driver's side pinch bolt. He tried but failed to drill it out. I had no hesitation driving it home, put it up on jack stands, but I too was unable to drill it out. Removed the entire strut assembly (planned to do that anyways) and used an angle grinder to cut through the remaining bolt. Found a used knuckle assembly on eBay for about $50. Problem solved.

 

Tried to drill mine this weekend and made a mess of the knuckle. Replacement knuckle on the way. Have spent a lot of time looking here but haven't found a good procedure for doing the knuckle swap. Anyone have a pointer on this, please?

 

The center ball joint on mine was good and stuck. Penetrating oil helped, but still took a 2 pound sledge to get it to let go. Make sure both sides of the front are off the ground. Take off the caliper, caliper carrier, and rotor. Penetrating oil on the rotor bolt - it's a big torx. I would suggest an impact driver for that one. An impact drive will make all of this easier - the ball joint bolts especially, as they will rotate. Axle nut needs to come off and gently tapped out - support the axle on something - I think I tied mine up to something. Both the center and lower ball joints need to be unbolted and then it should come right out. If yours is still attached to the strut, then you'll obviously have to unbolt the strut tower bearing as well. Then take off the wheel bearing and the dust shield.

Not a tough job, but takes a little time. I may have more in my thread somewhere.

 

Thanks very much. That's really helpful and gives me something to consider (i.e. whether I decide to say "uncle" and limp to the shop around the corner to do the knuckle swap or to dig myself in deeper and try to do it myself).

Mine is also a 2003 Indi Blue, but I'm not the original owner - I just got it two months ago.

 

Best color they ever put on the car, as far as I am concerned!

 

Had the same issue on my R60 today.

Fortunately I was able to use my impact to pull the bolt through the hole by simply driving the nut further onto the threads. Once I had pulled the bolt through to the point where it tapers in the middle I was able to remove the nut and clean the bolt enough with a wire brush and use a centre punch to send the bolt back through and out of the holes the way it had come.

I used a grade 8 bolt and nut I had kicking around the shop and all said and done only took a few minutes extra.

Hopefully this helps someone

 

It won’t help anyone here. The R53 knuckle is threaded. There isn’t a nut, and the bolt doesn’t protrude.

 

Ahh, gotcha. Thanks deepgrey.

 

bumping this instead of starting another thread. Does anyone know the part number for these pinch bolts?
Does anyone know if only one side of the knuckle is threaded? I need to take old knuckle off and need to find out if that's going to work


Also, are r56 knuckles common?

Thank you,

 

Should be number six in this diagram, I believe. Pretty sure the knuckle would never tighten if both sides were threaded.

 

thanks; managed to drill it out but still buggered the threads so don't feel comfortable with the thread engagement I do have. Do you know the torque spec for this bolt?

 

So when I tried to replace strut driver side, the pinch bolt snapped on me bolt's head is gone.The rest of the bolt are still there., here are my questions:


1. With the head bolt already gone is this still driveable?" does this mean the assembly is already loose? I can see the pinch bolt is rusted on the non threaded side.
2. How did you cut the remaining bolt? the strut's earlobe is sandwich in between.

I am trying to understand this assembly, so let say pinch bolt is okay -- let's say I removed it, or came out without any problems, say I assembled it back loose not properly torque, it's on the loose side.
If drive down the road will strut slip out of the knuckle assembly?

 

To help you understand....
The pinch bolt only actually threads to one side of the Carrier/Spindle Mount, so rusted in there or not, if the bolt head is gone, there is NO clamping force on the strut.
While it may not pull/fall out right away (because of the tab on the Strut) it will loosen and you can lose some steering control from the wobble/shifting of the strut in the Carrier, and eventually allowing it to pull out by wearing out that tab.

You either have to replace the Carrier, or figure out a way to remove the broken bolt. (Either by drilling it out, or welding a nut onto the broken bolt and hopefully getting it to come out.)
You can try doing either of these things on the car, but quite often it's easier to pop the lower ball joint and and remove the whole assembly (strut and all) to do the job out of the car. Plus if you don't want to tackle the job, with it off the car, you can take the whole assembly to someone who can do the work for you, without having to take the whole car.

That being said, if you're not doing the work yourself, you would most likely have no issues driving it to them as long as it's a short, slow trip, if your mechanic would rather have the whole car.

If you do decide to drill the bolt out, and damage the threads in the Carrier. You can simply drill the threads completely out and use a larger diameter Bolt "and Nut" to pinch the assembly. (Since the threads are already damaged, it would be better to completely remove the threads, in order to use a larger diameter bolt, than a smaller diameter bolt that just fits inside of the remaining threads, and have a looser fit)
And for extra strength, use a grade-8 bolt and Nut combo.
​​​​​​
Hope this helps.
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My son and I went through this a few years ago on his car. The head snapped off the pinch bolts when trying to remove them.

My thoughts:
If the bolt head snapped off then there is no way that bolt is coming loose while driving. Bolt didn't turn because it is rusted/seized to the knuckle. Drive it all you want.

Instead of drilling out the bolt we opted to change out the knuckles. We found both for $50 each at a salvage yard. The salvage yard had removed the bolt - how, I'm not sure. As I recall they left the wheel speed sensors in the knuckles, which was good because our old sensors didn't come out without damage.

We did initially try to take the strut out of the knuckle with the intention of drilling it. After removing the whole assembly from the car, we cut off the strut tab and then cut the bolt in the gap to allow the two halves of the strut mount to separate. We still had to pound a chisel between the tabs to open the gap and remove the strut.

 

Heat. The first time I tried this, I snapped both bolts. I've done a dozen strut replacements since and have never had another bolt fail on me. Apply generous amounts of heat to the threaded side of knuckle and some periodic PB Blaster. Hit it with an impact and it will come right out.

I have spare knuckles that are through-drilled and also some with original intact threads if anyone is in need.

 

Separating the knuckle to install the strut is difficult. You can buy (I did) a socket with a protrusion that fits in the gap and then use a ratchet to turn and expand the opening allowing easy insertion of the strut.

 

https://www.fcpeuro.com/products/aud...xoC_0cQAvD_BwE

 

^^This^^
For anyone doing this, esp to a bolt that has been in for a few years.
If you know you're doing the job, start by using a penetrant on the bolt daIly, for the week before the job. (Simply turn the wheel to either side to get access, no need to lift or pull the wheels to spray)
Also don't forget Anti-sieze when reinstalling.

 

If I am opting for carrier assembly removal, how prone are these screws\bolts into breaking? ( like the pinch bolt )

are these easy to remove?

Please image.

 

The carrier disassembly is this easy? I am afraid I might break head bolts again.