Front towing D-rings. Cab11/12? Bolts securing bumper

[Mike K]

Alex

On my C8 the bolt is 2" overall length and the thread is 7/16" UNC

Paul , the C8 is a Chevy not a Morris in this case

[rob love]

I'll second Grant's suggestion of welding on a nut one or two sizes larger than the broken bolt/stud. I use MIG myself for this purpose, but the materials techs I talked to about it were surprised this works as they prefer the arc welder for that purpose.

The risk in this case of buggering it is low since the broken bolts are in a cast steel. The mig will not weld the cast without suitable prep. Clean the exposed broken stud until shiny, then situate a nut over the stud. Set the heat of the mig to the highest possible. Fill the hole of the nut, trying to get as much weld as possible onto the stud before the hole starts to fill up. As the whole thing cools, the weld will shrink, making the welded portion of the stud shrink with it. Between the heat and the shrinkage, the broken bit will likely work free. Work it back and forth a bit until either starts to move, or you break the nut off. If you break the nut off, clean the area a little and do it again.

I have not met the bolt yet that will not come out this way, and when you are talking smaller bolts, it is often amazing how small the amount of weld that hits the broken bolt will still bring it out. Sometimes I have had to do it a second time after the nut shears off, but never had to do a third.

The drilling through method will work too, but will take longer, and if you are not on exactly at 90°, you risk drilling through the threads.

[cletrac (RIP)]

To remove a broken bolt in cast iron I use a cutting torch. The bolt blows out without melting the cast then run a tap through to touch up the threads.

[Alex van de Wetering]

Grant, Rob, Dave, thanks for your suggestions to get the remains of the bolts out. I did try the weld method before the chassis went to the blasters, but I wasn't having much luck. I guess I tried 5 or 6 times, but every time the nut sheared of (or the angle iron I welded on at one time)...maybe I didn't get enough heat in the weld, I don't know...but after failing I cleaned up the remaining material and added a centrepoint in preparation for drilling the studs out.

Mike, that's exactly what I was after. I am surprised the bolts are just plain bolts as the parts book didn't mention a size, only a part number and description. Did you really remove one bolt just to answer my question?

Thanks for the imput guys. I hope to have ago at removing the studs this weekend.

Paul...Mike is right; I should have mentioned "Chevrolet".

Alex

[Mike K]

I had the same problem, a couple of those bolts on my C8 were broken off . I drilled them out carefully .

BTW the early production C8 used a folded bumper bar , but later they were fitted with a channel iron section bar , the corners are sharper . The folded bumpers have rounded corners Mike

[pauldavies]

Hi guy's let me just say a broken bolt in whatever vehicle is a problem, we all have different ways to remove the bolt and if our combined knowledge helps that is the reason the forum is here. Well done to all who replied, did the bugger come out?