Subaru Pinch Bolt - Tips in Advance?

On some vehicles, there is a slot in the knuckle, and if you clean out the slot, you gain access to the approximate halfway point of the bolt. Apply the rust penetrant there, and leave it there at least 24 hours ahead of wrenching on the bolt. On my Taurus, there are only threads on the first half of the knuckle from the tip of the bolt to the mid point. The second half of the knuckle does not have threads but can be packed with rust.

This is how the Subaru setup is, open slot on the knuckle and pinch bolt is only threaded half way up the bolt.
 
I like the thermal shock idea, but am a little worried about the cast knuckle not liking that very much...
Any updates?

I get it the bolt isn’t the same, but another thing that the MB FSM has you do is pack the pinch with some grease.

See my situation here:


You would be well suited to get some in the pinch, also at the base where the bolt head touches the knuckle, and also the nut. Anti seize, especially the marine type on the threads.
 
Just to make sure I checked the photo from Project Farm and compared it to my current can of Liquid Wrench. Looks pretty close. Gibbs turned out to be very good as well. Both were better than Sea Foam Deep Creep.
 
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Any updates?

I get it the bolt isn’t the same, but another thing that the MB FSM has you do is pack the pinch with some grease.

See my situation here:


You would be well suited to get some in the pinch, also at the base where the bolt head touches the knuckle, and also the nut. Anti seize, especially the marine type on the threads.

So I do have an update!

Went out and decided I wouldn't try to do the whole project, just was gonna work on that one bolt on each side. If it came out, great, I would lube it up and put it back in for next weekend. First thing, and probably should have done this before, used a pick and got all of the gunk out of the slot that was in the pinch bolt (the one that @JHZR2 shows gets packed with grease). Did that and used some Kroil that I had and doused things pretty well. Used the induction heater which I was able to sorta smush a coil around one side of the pinch and then the other. Got it hot enough that the oil was smoking off of it, but might not have been hot enough to really break it loose. Rattled it with a small impact driver (more for fasteners, not bolts), then stepped up to a little bit of back and forth with a Milwaukee stubby impact, and also a 3/8" breaker bar handle so I could work back and forth without having to have it ratchet.

Nothing.

Tried more heat, saw Kroil bubbling out of the threaded end, tried to turn it again, nothing. Tried to use my imitation Shake and Break, and got a lot of loose flaky rust off the bottom of the vehicle, but no movement at all. (see my other thread for that fiasco).

Repeated on the other side to get the stuff out and oil it up, but didn't rattle it the same way.

Maybe next weekend with having some time to soak some I can get more heat on it and see if it will come out. Right now my backup plan is that the ball joint boots don't seem bad, and Im not aware of them being too lose, so I may just do the LCAs and leave the old ball joints and kick that can down the road. Need to really figure out how much heating I should do with the induction heater before I crank on it I guess...
 
As much as there are a lot of fans of Kroil, it pales in comparison with Liquid Wrench. Flame suit on.


Do you have a longer 1/2”breaker bar? Time will help with the penetrating oil but you might want to buy a can of Liquid Wrench, but not the deodorized type as there is no data on it. It's cheap, much less than Kroil.
 
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As much as there are a lot of fans of Kroil, it pales in comparison with Liquid Wrench. Flame suit on.
I’ve always had good luck with liquid wrench in liquid form. I prefer that to aerosol.

That said, if this is seized and corroded so tight, I have my doubts that much will wick in ever.

Time is a hope, but I find that doubtful if there isn’t a crevice to try. That bolt buster that goes on an air hammer, if the whole getup can fit under there, is a good bet. It will let a lot of axial impact occur, not just rotational. I’d probably try that next.
 
The reduction in torque due to the use of a penetrating oil is actually quite small yet we all use them. Here is something from Project Farm on the topic. Kroil did quite poorly but most were quite poor.

 
I used what I had handy that wasn't gonna make a huge mess. I also have some PB Blaster, some ATF/Acetone, and maybe liquid wrench somewhere. I know its more of a feel good thing than possibly working, but if anything actually works its way in there at all, Ill take it.

I do have a longer breaker bar, and a bigger impact gun, but that's when I start actually breaking things. For now Ill just let it soak some, then will try more heat and a little more of the back and forth with the impact to see if that helps, along with seeing if hand pressure works.

I did try the bolt buster, and it did fit in there, but it didn't work for me. Maybe next week it will, or I just need to really heat the knuckle more first. I didn't try to see what temp it actually got up to, just enough smoke was rolling off the metal that I figured it was pretty toasty.

Since I don't know that my ball joints are for sure an issue, Im tempted to let the sleeping dog lie for now.
 
I think we all know what to do to ramp up your efforts but it may be stymied by a fear of breaking the bolt. Here is a photo of a Consumer grade set of Cobalt drill bits available on Amazon. Beside it, is a bolt I removed from one side that fortunately came free with propane heat, then Liquid Wrench. My mechanic, Andre drilled out the broken bolt. The bolt on this car is 2-1/2 inches long. Keep in mind only one side of the "pinch" is threaded. We were unlucky enough that the bolt broke at the first thread and Andre had to drill 1-1/4 inches just to get to the threaded section. The other alternative would have been to drill from the other end of the bolt but it was tapered and would be almost impossible to center the drill. I think Andre had some special bits that were a step up from Cobalt but I know the Cobalt bits are pretty good. If you felt comfortable enough you could try get a hold of a compact impact wrench that can do 400 ft lbs. That Milwaukee stubby was probably doing 250 ft lbs. Also, although its good to start with a few blips leaning on it and running for over 10 seconds builds the torque big time, but the risk of snapping it gets high as well. Then the drilling starts.

1B8727B8-4252-4BE1-961F-23C814741508.webp
 
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This was the type of Liquid Wrench used. Canadian label shown. There’s also a low odour version but it was not tested.

View attachment 303630
I think it has a little something in it to "cut the rust". Maybe just acetic acid? I used it with some wire brushing on an old cast iron table saw for the mitre gauge slots and it worked quite well to allow easy sliding, where as before it was almost impossible to move. The MSDS doesn't show any acid at all though so it might be just the smell that makes me think it does something....
 
For the time and effort it takes to do this job I would just buy another knuckle. It's not worth the car sitting for a week+ while I try different solvents, drill bits, torches, etc.
 
I think we all know what to do to ramp up your efforts but it may be stymied by a fear of breaking the bolt. Here is a photo of a Consumer grade set of Cobalt drill bits available on Amazon. Beside it, is a bolt I removed from one side that fortunately came free with propane heat, then Liquid Wrench. My mechanic, Andre drilled out the broken bolt. The bolt on this car is 2-1/2 inches long. Keep in mind only one side of the "pinch" is threaded. We were unlucky enough that the bolt broke at the first thread and Andre had to drill 1-1/4 inches just to get to the threaded section. The other alternative would have been to drill from the other end of the bolt but it was tapered and would be almost impossible to center the drill. I think Andre had some special bits that were a step up from Cobalt but I know the Cobalt bits are pretty good. If you felt comfortable enough you could try get a hold of a compact impact wrench that can do 400 ft lbs. That Milwaukee stubby was probably doing 250 ft lbs. Also, although its good to start with a few blips leaning on it and running for over 10 seconds builds the torque big time, but the risk of snapping it gets high as well. Then the drilling starts.

View attachment 303667
Use a hinge centering bit to get the bit centered then use a L/hand cobalt drill bit. Something like one of these will do the trick.

https://www.amazon.com/dp/B0DXKVPPT...b033b74695&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw
 
For the time and effort it takes to do this job I would just buy another knuckle. It's not worth the car sitting for a week+ while I try different solvents, drill bits, torches, etc.
I thought about that too. But then its also a hub/bearing (which may not be a bad thing anyway), and probably a new dust shield, and the ABS sensor that Ill snap on the way out of the old one. I know time is money and all, but the vehicle can sit and let me be patient since its still working just fine (until I go to hard at something and actually break it)

I do have that same set of cobalt bits, and it looks like the end of my pinch bolts are dimpled in the center already as a good spot to drill them out if I did snap them. I also have a bigger impact that Im sure will twist that head right off the bolt if it doesn't loosen it up. I figure this is an instance where torque or brute force wont help me unless it was a "break it out and move on" scenario. Im not to that point yet, so still trying to be patient.
 
I thought about that too. But then its also a hub/bearing (which may not be a bad thing anyway), and probably a new dust shield, and the ABS sensor that Ill snap on the way out of the old one. I know time is money and all, but the vehicle can sit and let me be patient since its still working just fine (until I go to hard at something and actually break it)

I do have that same set of cobalt bits, and it looks like the end of my pinch bolts are dimpled in the center already as a good spot to drill them out if I did snap them. I also have a bigger impact that Im sure will twist that head right off the bolt if it doesn't loosen it up. I figure this is an instance where torque or brute force wont help me unless it was a "break it out and move on" scenario. Im not to that point yet, so still trying to be patient.
the bolts being so long makes running an impact almost always require the drill.

most of the time people are touching that bolt it's to replace the wheel bearings (at least on the forester) so it's pretty easy to justify.
 
the bolts being so long makes running an impact almost always require the drill.

most of the time people are touching that bolt it's to replace the wheel bearings (at least on the forester) so it's pretty easy to justify.

Nope! Most of the time people are touching that bolt on the SJ Forester it's to replace the control arms :sneaky:
 
I thought about that too. But then its also a hub/bearing (which may not be a bad thing anyway), and probably a new dust shield, and the ABS sensor that Ill snap on the way out of the old one. I know time is money and all, but the vehicle can sit and let me be patient since its still working just fine (until I go to hard at something and actually break it)

I do have that same set of cobalt bits, and it looks like the end of my pinch bolts are dimpled in the center already as a good spot to drill them out if I did snap them. I also have a bigger impact that Im sure will twist that head right off the bolt if it doesn't loosen it up. I figure this is an instance where torque or brute force wont help me unless it was a "break it out and move on" scenario. Im not to that point yet, so still trying to be patient.
If you were able to drill into the bolt on the dimpled end, using a conventional right hand rotation bit would impart a left hand turn into the bolt and if you got really lucky it could back out. The other advantage is that you would be drilling the bolt where it’s engaged to the threaded part of the knuckle and once it reaches the middle point of the bolt, you might be able to pound the bolt past the unthreaded section.
 
Straight acetone, wait a minute, then PB Blaster. Wait. Hand impact and hammer if you have it each direction half a dozen times. PB Blaster again wait. Put the half inch bar on it and try to get a quarter turn spray again. Work back and forth if you got it moving then spray and wait. Try to remove. You’ve done all the prep and soak, time to commit!
 
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