Impossible bolt

[428Marauder]

1965 full sized Merc. There are 4 bolts holding the rear bumper bracket to the frame. 2 are out, one on each side. The difficult ones go through the frame and there’s a nut there that is difficult to reach. There is a decent sized access hole but it’s at a weird angle. I am able to get a flex extender on my impact driver and get that on the bolt head on the outside but there’s no way to hold the nut inside the frame. I offered a local mobile welder $100 to do the job and he declined. If it was clean metal I would weld the nut in place but it is rusty and hard to get to in order to clean. It’s even hard to get a picture but I tried. Any ideas? There’s very little room to move so any ideas of cutting or grinding the bolt head are out.


https://ibb.co/wR7v0FD

ETA: I can get a small air hammer to the bolt head but trying that will scratch my exhaust tips. Not a big deal if I was sure that would work, but I’m not.

[mike7570]

Cut the head off the bolt and push it through, buy new bolts (oops just saw that “very little room”)
Can you wedge a crow’s foot or a screw driver between the nut and the frame and keep it from turning?
It also looks like a distributor type wrench would fit the opening. A good excuse to buy more tools.

One more: will it tighten? Just crank down on it with a breaker bar and snap the bolt. I couldn’t tell you how many rusted bolts I snapped off taking apart my mustang.

[428Marauder]

The problem with getting any kind of wrench on either the bolt head or the nut is that there’s a lip (like an I beam) so you have to go in at an angle. This pretty much rules out any type of wrench staying in place. I’ve been able to get a small pair of vice grips on the inner nut but then when I turn the bolt head the vice grips just spin. Tightening does the same thing, the rusted on nut just turns when you turn the bolt head. I was also able to get a socket with an angle attachment on the inner nut but when I crank the bolt head it spins and falls off. What I just described is the closest I’ve been able to come and probably what I will continue to try.

ETA: it is much easier to turn the bolt head outside the frame then to turn the nut inside the frame, but there’s not much room either way, even with my trunk floor currently cut out.

[1964Fastback]

Would an offset box wrench

https://www.harborfreight.com/hand-tools/tool-sets/wrench-sets/offset-box/8-piece-sae-offset-box-wrench-set-32041.html

fit on the nut?  Or a deep socket on a 3/8" ratchet?

Pat

[428Marauder]

Can’t get a deep socket in that hole, but those offset wrenches might do the trick. I’ll go get some tomorrow.

[cleandan]

If you can get a socket on the difficult to reach nut then you may have a couple options.
1) Purchase a socket that fits the nut but with a hex head also. insert socket, install wrench over hex head, turn other nut against wrench on hex head of socket.

2) drill a hole through the socket to fit a rod. Insert socket on nut, put rod through hole in socket via the small oval access hole in the frame, turn other nut against the rod that now binds against the hole in the frame.

3) Same socket, but maybe you don't have enough socket length to drill a through hole.
cut a groove in the top of the socket and weld a rod on there to bind against the frame.

4) Grind socket with two flats, leaving as much material as possible. Grind flats to fit an open end wrench, vice grip, adjustable wrench. Insert socket, install wrench, turn other nut against the wrench.

[Heo]

can you reach it if you first remove the bumper from the bumper bracket?

[machoneman]

Offset wrenches may work. We used to modify tools for our race cars to ease nut/bolt removal or tightening. Bend a wrench, cut one up, re-weld if needed, grind the snot out of offending wrench metal. Just don't use your Snap-On tools! Harbor Freight is your friend.

[428Marauder]

In the end, none of it worked (although I didn’t get to try the drilled socket method) I was able to use a pry bar and get enough room where I could get in there with a small cut off wheel. Cutting the bolt head at various angles and then hammering on it with the pry bar and I was able to break them loose. Now I have to go throw these in a volcano or something.

https://ibb.co/Hq05n4T

[machoneman]

Good you got it out. The pic tells a real story of how tough the removal was!

[badcatt]

Some time ago I did this on a 1966 S55 parts car. I let penetrating oil soak on it for several days. And thanks to Dad I have a old set of off set wrenches. It came off fairly easily. But it can't be tight when it's liquid.