Subaru Pinch Bolt - Tips in Advance?

C

Clarkbug

Joined
May 5, 2012
Messages
176
Location
NY
Hello everyone.

Need to swap the lower control arms on my 2014 Forester. I purchased new ones from Subaru, and they come with new ball joints. I have about 105k on the vehicle now, so was thinking I'll just swap them. I bought the Astro Pneumatic ball joint puller, since I know that part can be a bear.

But there are also lots of horror stories about the pinch bolts snapping in the knuckle, and it's honestly been keeping me up at night thinking about it. I have sprayed them with some ATF/Acetone already, and have other various penetrants ready when I get in there. I am planning to try and use an induction heater to heat the area some, but not sure how well that will "fit". (You have to get the area inside the coil for the heater to work).

Any tips on getting those bolts out? Hand tools only? Smaller impact and just rattle it back and forth? Really want to avoid a broken bolt, or worse having to swap the whole knuckle out.
 
Sounds like you've prepared as well as you can, I might only add that just hitting the bolt head and knuckle with a suitably sized hammer, sometimes helps free up stuck stuff, especially after you've heated it and let it cool. I've never used and induction heater, but heating and dumping water on it to get some thermal contraction going might help too.
 
I think I do happen to have a knock-off version of one of those in my toolbox. That might work out OK for me as an option to rattle on that bolt after heating and see if it will loosen up.

I wasn't sure if impact guns were a better play, or using hand tools for better feel would give a higher chance of success...
 
IndyIan said:
Sounds like you've prepared as well as you can, I might only add that just hitting the bolt head and knuckle with a suitably sized hammer, sometimes helps free up stuck stuff, especially after you've heated it and let it cool. I've never used and induction heater, but heating and dumping water on it to get some thermal contraction going might help too.
Click to expand...
I like the thermal shock idea, but am a little worried about the cast knuckle not liking that very much...
 
CRC Knock'er loose or some other penetrating oil, and perhaps maybe some Freeze-Off when you actually do remove the pinch bolt (a few seconds before you undo the bolt, spray the Freeze-Off)

Also, when you finally do it, remove it SLOWLY, with hand tools only. use the minimum amount of force for it to loosen. DO NOT use any impact tools on that pinch bolt!

When you install the new ball joint, slather anti-seize on the base of the ball joint and on the pinch bolt.
 
Clarkbug said:
I like the thermal shock idea, but am a little worried about the cast knuckle not liking that very much...
Click to expand...

I wouldn’t worry much about thermal shock unless you’re heating it red hot. Nor about beating on them. Bearing ball joints out of cast knuckles is standard practice for my old MB cars.

Can’t you spread the gap to open it? Sometimes hammering can loosen stuff too.

Is there enough threads to beat on the bolt in and out?

IMG_5031.webp



I didn’t have issues with my 30yo pinch bolts on my 300D. They get packed with grease but it was long gone. Hammering it each way helped get it out easy.
 
Number_35

Thread '2011 Subaru Impreza - Drive Axle Replacement'

A friend, great person and neighbour, heard a bad noise coming from the front end of his 2011 Subaru Impreza. He looked underneath, and found a split open boot on the passenger-side outer CV joint.

He bought a TrakMotive unit locally, and brought it over this evening. We installed it without too much hassle - the splined end of the axle came out of the hub no problem at all.

We went for a test drive, and there was a bad intermittent clunk. He said it was the same noise as before (which was not at all like the clicking of a failing CV joint I had assumed he had heard).

So I checked...
  • Wow
  • Like

I went through this with my friend's Subie earlier this year. The bolt was pre-broken for me. ☹️

I hope yours comes out intact.
 
JHZR2 said:
I wouldn’t worry much about thermal shock unless you’re heating it red hot. Nor about beating on them. Bearing ball joints out of cast knuckles is standard practice for my old MB cars.

Can’t you spread the gap to open it? Sometimes hammering can loosen stuff too.

Is there enough threads to beat on the bolt in and out?

View attachment 303189


I didn’t have issues with my 30yo pinch bolts on my 300D. They get packed with grease but it was long gone. Hammering it each way helped get it out easy.
Click to expand...
With the Subaru it's a threaded bolt, not a through one like yours. So beating back and forth won't help me just yet.

Number_35 said:
Number_35

Thread '2011 Subaru Impreza - Drive Axle Replacement'

A friend, great person and neighbour, heard a bad noise coming from the front end of his 2011 Subaru Impreza. He looked underneath, and found a split open boot on the passenger-side outer CV joint.

He bought a TrakMotive unit locally, and brought it over this evening. We installed it without too much hassle - the splined end of the axle came out of the hub no problem at all.

We went for a test drive, and there was a bad intermittent clunk. He said it was the same noise as before (which was not at all like the clicking of a failing CV joint I had assumed he had heard).

So I checked...
  • Wow
  • Like

I went through this with my friend's Subie earlier this year. The bolt was pre-broken for me. ☹️

I hope yours comes out intact.
Click to expand...
Well that doesn't sound like a fun time. I hope mine comes out easier than your ordeal!
 
I snapped a pinch bolt on a Ford Taurus and a mechanic friend drilled it out using his top quality drill bits. For the most part he stayed in the center.

The same mechanic liked to use an air hammer to shake the knuckle when applying penetrant. He also would work the bolt back and forth if it would move.

When using heat, acetylene is your friend. Propane heat is puny compared to acetylene. Mapp is hardly any better. A Mapp oxygen kit is hotter than just propane or Mapp by itself. Acetylene is best.

Let’s see if anyone suggests an impact wrench. A compact impact wrench with a 250 ft lb break out torque might be best but let’s see what the pros say. I’m thinking a series of quick blips might be best rather than full on ugga duggas. Time and vibration is your friend with rust penetrants.
 
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On my 2015, I heated them up with a propane torch and sprayed with PB plaster while hot. It seems to draw the blaster into the threads. Did this a couple times and they came out without issue. Concentrate on the threaded side the knuckle.

The hard part was getting the ball joint to come out of the knuckle because it rusts and binds up. It was loose in the pocket but wouldn't fall out. Clamping a vice grip to the stud and hitting it with a hammer pulled it out.
 
JHZR2 said:
Oh that’s interesting… is the notched part of the ball joint shaft also threaded?
Click to expand...

No, the notch on the ball joint itself is smooth.

The OEM design is just bad. The one side of the pinch part is closed, the pinch bolt threads into it but through it. If there isn’t/wasn't anti-seize applied from the factory, the bolt is seized in there.

If the bolt snaps while trying to remove, in order to not have to then replace the entire knuckle, some will drill out the bolt and drill through the tab so that a regular nut and bolt can be used to squeeze it. Seems to work fine. If the pinch bolt can be removed successfully, plenty of anti-seize on the new one will hopefully make removing it the next time much simpler.
 
CarbonToast said:
The hard part was getting the ball joint to come out of the knuckle because it rusts and binds up. It was loose in the pocket but wouldn't fall out. Clamping a vice grip to the stud and hitting it with a hammer pulled it out.
Click to expand...

Thankfully you were able to get it out fairly easily. Just a FYI to anyone else, there is a tool for pulling them out easily as well. Often needed for the more stubborn ones.
 
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.
 
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