I'm rounding bolts! How do I get these suckers off?!?

[Tommy Z]

I'm trying to replace the CAT on my 79' SC and as expected the nuts and bolts are as frozen as can be. Hit them all with BP Blaster yesterday and the day before and so far I've only been able to loosen 1 without it starting to strip. I've hit them with a little flame but I'm reluctant to go too crazy for fear of setting the damn thing on fire. What is the best method to get these off? Some of them are really hard to access as it is but my only choice maybe a dremel tool with a metal cut off wheel. Is that a stupid idea? Any other methods I should consider?

[kevingross]

Either heat, and a fair bit of it, or cut them off. Or break them off, trying to wrench them. You are going to replace them.

[Harpo]

Map gas or a cutting torch will be required and yes there is a very significant risk of fire. Personally I used a Sawzall and replaced with headers.

[911obgyn]

Those will need to be cut off. I use a solvesall with a metal blade. A dremmel will work too. To keep the flanges cut the cat side. If you can get bolt cutters in there thosewill work to.

[Shaun @ Tru6]

I've both cut off with a die grinder and used an oxy-mapp set-up. I prefer the playing with fire method but both work.

[Tommy Z]

OK! It's demo time! Not that I was expecting to be able to re-use the bolts and nuts but I figured I could take the ones I was able to remove to the Home depot to find suitable replacements. I'm assuming as long as I have the lengths and the widths reasonably close is there anything else about the nuts and bolts I should use as a criteria for selection? Steel I would assume? Stainless? Should I be looking for the exact bolt sizes specified in the PET? I don't know that I will find M8 x 40's at the depot. Can you get those at the auto parts store? Thanks again boys!

[Joe Bob]

Do yourself a a favor. Cut out the cat first. Then tackle the bolts.

[Tommy Z]

Bob, I was just thinking the same thing!

[Sboxin]

Originally Posted by Tommy Z

I don't know that I will find M8 x 40's at the depot. Can you get those at the auto parts store? Thanks again boys!

I use Ace Hardware for Metric bolts and nuts . . . M8 no problem . . .

Regards,
Roy T

[911pcars]

Some of those fasteners appear to be petrified. However, before any mass destruction attempts, I'd start with a combination of heat (with bolts, around the threaded periphery; on nuts, on the nut itself) and penetrating oil. The heat will tend to expand whatever will expand, perhaps giving penetrating oil a chance to invade and separate the contact surfaces. Remember that the object is not total destruction. Heated metal is more susceptible to deforming - if that's important to preserve function and appearance.

Sherwood

[proporsche]

if you know how to use the gas torch -use it It is very easy tool to remove those bolts and nuts..If not use impact chisel and split the nuts ..that works well too.I would not destroy the cat .If it is ok you can get pretty penny for it form boys where they need it to smog theirs 911.

Ivan

[911pcars]

A small grouping of removed fasteners, all w/o destroying the matching threads. Patience has its rewards.





Sherwood

[proporsche]

Originally Posted by 911pcars

A small grouping of removed fasteners, all w/o destroying the matching threads. Patience has its rewards.





Sherwood

Yup, easy does it.;-)

Ivan

[pmax]

Just destroy them with your favorite BFT.

[911pcars]

BFT? Oh, tool.

[john walker's workshop]

Oxy/Acet torch. Air hammer bit to punch the remains through the holes. Watch where the sparks go.

[pmax]

[HarryD]

As noted above heat is your friend. Get them red hot. Keep a fire extinguisher handy as well.

For replacement hardware go with grade 8.8 bolts and silicon brass nuts. They will be easier to disassemble next time. Be sure to use anti seize as well.

Stainless steel is not good as it tends to gall.

[eastbay]

BTW, 5/16" nuts and bolts work fine for a replacement if that is all that is around.

[Shaun @ Tru6]

Use Belmetric for new hardware. Most of their stuff is German made vs. Chinese at HD