Rear alignment bolt fused to trailing arm.
 

This is the rear-refresh from hell.
Started with a shock replacement (Koni), which raised the height on my 912E. Makes sense - the original shocks had 121,000 miles on them. (Prior owner had an alignment done 8,000 miles ago so the ride height was acceptable when I bought the car last March.)
Okay, might as well put in Neatrix bushings. When unbolting the spring plate bolts I found that the adjustment bolt (closest to the hub) is fused to the spring plate.
I tried MAP gas and ended up bending my wrench. I heated the aluminum trailing arm almost past the point where I was worried that I was going to change the metal's properties.

Here's some pics - both sides are fused solid.
How would you proceed?
I can see me getting the system re-assembled with the new ride height, but no way to adjust toe? (Or is this the camber bolt?)

(Not my first rodeo - I've done this on my three 911s.)

Thanks in advance.

Bill K

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Got an air chisel?

wow thats alot of corosion! east coast car I would think you need to address that first before even tring to get it out.

Get yourself some PB Blaster penetrant and try that. Spray daily for a few days. It is more effective than WD40. You might be surprised how well it works.

Scott

I just did this. Same problem.

1) Put a nut on the end, two is even better. Make sure the nut(s) extend past the bolt so the threads won't get damage.
2) Brace teh arm the best you can in a vice. Try to make sure the brace is as close to the bolt as possible.
3) Heat
4) Get a hammer
5) Got to town on the nutted end. It should knock out.

BTDT for since last Sunday, also using Kroil.

No air chisel either. Wouldn't that make toast of the aluminum trailing arm?
Bill K

Tried that with the arm still in the car. With all the MAP gas, the cherry-red bolt started to deform.
Bill K

Probably too much flex with it still on the car. It needs to be against a backing if you know what i mean. You want to heat around the bolt, not the bolt.

Heat/cool cycles work as well to break up the corrosion.

heat the plate around the bolt with map and then touch an old candle to the bolt. the wax will drip between the parts, unlike penetrating oil that will just evaporate.

^^^ This. The energy hitting it will be absorbed by the arm. Needs to be solid.
What about using a big C clamp as a press. Use a large impact socket on the back to straddle the bolt and a nut on the threads set down flush. Tighten the heck out of the clamp as you heat the aluminum. It should pop

To confirm, this eccentric bolt has no thread contact with the al. trailing arm. Correct? The bolt head has thus corroded onto the al. material, most likely stuck in the ID of the trailing arm hole. Heating both steel bolt and al arm should have created different expansion rates, thus creating room for penetrating oil to .... penetrate the joint. Since al. expands at a greater rate, try heating just the aluminum.

One option is to drill through. Start with a small drill as close to the center as possible.

Once through, gradually increase the drill size. With each drill-through, the bolt should become weaker, and at some point, can be driven out. place a large socket on the opposite side and back it up with block of wood for support as you urge out what's left.

Sherwood

Sherwood, I think that's where I'm headed.
I might finish the bushing and index job as is, just to get it out of the garage, and come back to it when the temps get spring-like and there's not 11 inches of snow outside.

Thanks all.

I'll post the resolution when it happens.

Bill K

If you’re heating the bolt, it gets bigger. You want the bolt to stay cold while heating the plate. As the plate is aluminum and the bolt steel, the plate will heat much faster than the bolt, but definitely you want to put heat around the bolt and not on it directly. Everything gets bigger theory heat, even holes.

As stated in the original post, I heated the aluminum trailing arm.
No way to heat the trailing arm to the point of expansion and not affect the thru bolt, which is what happened in my situation.

Here's gratuitous pics of the car - despite the rust issue with the fasteners under the car, the car is still very presentable.
The problem arose, I presume, when the prior owner only drove the car occasionally, went through the car wash, and came back to his dirt floor garage and parked it for another month or two. I am gradually replacing all the hardware in the chassis.
Bill K

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Use 50/50 ATF/acetone mix. Alternate that and Corrosion X (amazon or wherever) once every hour or so over 8-10 hours. Let sit over night. Following day it should come out by simply tapping with a hammer. Have done this exact thing on very rusty cars.

I am thinking you have a torch oxy acetelyene. Heat bolt cherry red quench with cold water. Shock should release it. C clamp idea proposed with deep socket over threaded end and pushing from ball joint end while heating around the fitting. Failing all cut with torch. The heat will cut thru bolt but heat will not transfer because the seperation between bolt and arm. The remainder will be able to drive out but I believe one of the first two ways will work. Good Luck Thanks Rob.

Sorry, missed that! Like you said...not your first rodeo. Lots of good advice here...Good luck!

Have you tried yelling at the bolt? Haha
Just kidding, I grew up in the Midwest/Rust-West. I can tell you patience and the heating and penetrating oil will do miracles after a few attempts. I never knew you didn't need an impact to remove 1/4" or smaller bolts until I moved to California ;)

Careful with that A/C torch. Cherry red is close enough to the melting point of Al alloy (~800-1200F). Applied heat will transfer quickly to the aluminum, and overzealous/excessive heat might modify the shape of your control arm. There will be no warning of impending parts distortion or liqufaction.

Color/temp. chart for most metals (except for aluminum):
https://www.hearth.com/talk/wiki/know-temperature-when-metal-glows-red/

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Sherwood

TA-DAH.

Thanks all. Combination of soaking - 5 days, turning with a wrench with BFH, and turning while tapping the nut.

Anyone recognize the bolt/nut on the right?
The head is 7/8 inch, and the nut is 11/16th. Notice how much more surface/contact area there is in the shoulder that fits into the swing arm.

New hardware will be here on the 28th from our host. ($62.50 each, for the eccentrics - ouch)
Bill K

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