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

Guys, does anyone have a picture of the bolt that secures the D-rings and bumper to the cast front spring hanger on a C8?
Even though the cast piece in the front differs from C15, C60 etc., the parts catalogue seems to suggest the bolts used to secure the D-rings are the same throughout the series. The partnumber is "1799028" "Bolt, front towing clevis bracket".

All 8 bolts on my chassis were cut a long time ago. I am trying to determine what thread size and measurements the proper bolts have. As the hex head is quite large and the holes in the casting rather small, I presume the bolt could have a slightly larger diameter boss to fit the larger holes in the bumper???


Alex

The bolts on my C15A were also missing so I can't answer directly.
In the picture on the left, it looks as if the bolts may be threaded into the casting and have either sheared or been neatly cut at the face of the casting. You may be able to soak them with penetrating oil for a while (days, not minutes) and then weld a nut to what remains and get the stubs of the bolts to back out. The heat of the welding seems to act to help release the rust in the threads. With the stubs out, you should be able to measure the threads.
This part is only a suggestion, I have no proof it is correct. If the holes in the bumper look to be in good shape and round, perhaps they were made a bit oversize to allow some adjustment of the bumper positioning?

bolt size
 

Being new to Morris C8's I hope it's the right bolt, D-ring assembly below the Bumper Bar is bolted by a 7/16 BSF bolt. Try drilling the old bolt out in stages working up near the Tapping-Drill size then tap the BSF thru, depending how central you get with your drilling this should be good. If your not so central then try an "EASY-OUT" a bit below the size say 1/4 or 3/8, welding a bolt to the old bolt can be risky if skill level isn't good (sorry) but trying a bit of heat is always good when trying to get a broken bolt out. Best of luck
Paul D
QLD Australia

Bolt
 

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

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.

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.

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? :cheers:

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

drill
 

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

broken bolt
 

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?