Rear Subframe Bolt Frozen! Ideas?

[Cinnabar325is]

So I'm working to remove my rear subframe for a rebuild. I have everything apart ready to drop it except the driver's side 14mm bolt is completely frozen.

I'm familiar with the trick of driving it up into the passenger compartment from the underside. I've been trying to do that for two days, letting it sitting overnight drenched from the top and bottom in PB Blaster.

At this point, the nut (sitting flush with the end of the bolt) is completely mushroomed, I've been beating it so hard with a 6 lb hammer. I've tried hitting it from the top, just to break it loose. I've also tried putting a hydraulic jack underneath the bolt and working the jack in short, quick motions trying to break it free; it just lifts the whole car every time. Haven't moved it even a millimeter!


The passenger side bolt came free right away. Heat is not an option as the gas tank leaks (being replaced) directly above the bolt.

If you have any clever ideas or solutions, I'm all ears. This has really put me off schedule and I'm out of ideas.

Thanks.

[slippery]

Empty the tank and use heat. I would just heat it up from the inside of the car if it was me.

J

[Cinnabar325is]

Don't think it's that simple. Even if the tank were emptied, there'd still be a lot gas vapor and I can't seal the tank off because of the holes which, of course, are on the top side.

My second thought is that if the bolt is really this stuck, there's a good chance it's corroded almost it's full length. With the rubber bushing around it, I have no chance of getting good heat to it's entire length. Even with oxy-acetylene which will more than likely light the rubber bushing on fire... which brings me back to the gas tank issue.

[SmokeE30]

i has left handed drill bits that work petty good for broken bolts.

[Cinnabar325is]

i has left handed drill bits that work petty good for broken bolts.

It's not broken.

[AndrewBird]

I would grind the head of the bolt off inside the car and get a new one. Like you said, it is likely rusted the whole length of the bolt and will never come out.

[CarsSuck]

I cut out the bushing material and then ground flats into the inner sleeve and removed it with a three jaw puller and a bit of that penetrating oil. I thought it was unwise to screw around with the subframe mounting bolt.

Did it take a little extra time? Yes, but i didnt ruin any heat treating or bend any critical mounting points either.

[noid]

Get a set of bolt extractors in the appropriate size. The more you turn the more it will bite into the bolt, works wonders.

[Cinnabar325is]

I would grind the head of the bolt off inside the car and get a new one. Like you said, it is likely rusted the whole length of the bolt and will never come out.

The bolt head is recessed 2 inches into the chassis. Not getting a grinder or anything else in there.

I cut out the bushing material and then ground flats into the inner sleeve and removed it with a three jaw puller and a bit of that penetrating oil. I thought it was unwise to screw around with the subframe mounting bolt.

Did it take a little extra time? Yes, but i didnt ruin any heat treating or bend any critical mounting points either.

Not quite sure what you mean, could you explain it more? What did you do with the bolt itself?

[cheapthrills]

Can you still lower the subframe? Or is the old subframe bushing still stuck in the body? You can try getting some prybars/hydraulic separators between the subframe and the body.

The first time I dropped my subframe, I had one subframe bushing that was totally stuck in the body, though I was able to pound its bolt through. I basically took everything else off (the other side's bolt and the diff mounting bolt, driveshaft, ABS and speedo wires, brake lines and Ebrake cables), ready to drop the subframe, and rotated the whole bitch around the stuck bushing. This caused the aluminum to snap and the whole subframe assembly to drop. I recommend not being underneath it during this process.

The second time I dropped my subframe, I couldn't get the bolt out, but was able to drop the subframe. Once it's out of the way, wiggling the bolt back and forth and hitting it sideways with a hammer broke it free. It probably isn't rusted, just really dug in.

For other's reference, here's a diagram of what he's talking about. The top of the subframe bolt is knurled, and digs in to the seat. Nut/bolt extractors are not applicable.



Side note: use AKG poly bushings. This is a job you only want to do once, and they add almost no discomfort.

Side note 2: you can drop your fuel tank without dropping your subframe.

[CarsSuck]

If you cut through the rubber, from the bottom of the subframe, you can separate the inner part of the bushing from the outer, then you can yank the subframe down. This will leave you with the inner sleeve and a bunch of rubber sticking to the stud and stuck up into the body. Remove excess rubber from the sleeve with a razor then use a dremel or a small angle grinder to grind in flats so you can use a three jaw puller (I used a caged one for good measure). The stud stays right where it is, because youre pulling the sleeve down off of it. Press the outer part of the bushing out of the subframe, and put it all back together. Its pretty easy to balance the assembled rear end on a jack and then slowly raise it back into place.

If you've mashed the hell out of the bolt threads or bent it at all you need to do what nitro said and grind of the top off and replace them.

[Cinnabar325is]

If you cut through the rubber, from the bottom of the subframe, you can separate the inner part of the bushing from the outer, then you can yank the subframe down. This will leave you with the inner sleeve and a bunch of rubber sticking to the stud and stuck up into the body. Remove excess rubber from the sleeve with a razor then use a dremel or a small angle grinder to grind in flats so you can use a three jaw puller (I used a caged one for good measure). The stud stays right where it is, because youre pulling the sleeve down off of it. Press the outer part of the bushing out of the subframe, and put it all back together. Its pretty easy to balance the assembled rear end on a jack and then slowly raise it back into place.

If you've mashed the hell out of the bolt threads or bent it at all you need to do what nitro said and grind of the top off and replace them.

Got it out, did something similar to this. Cutting the bushing apart and pried the subframe down and off. Then used a cutting wheel to cut through what remained of the bushing in 3 vertical cuts and then chiseled it off the bolt. Then was finally able to hammer the bolt up from the bottom and out.

Culprit for all this trouble: a tremendous amount of corrosion between the steel bolt and aluminum bushing, along the full length of the bushing-bolt contact.