The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-55.1 Stripped banjo bolt…helicoil?

dsraven · 09-03-2023, 03:13 PM

for brakes I NEVER rely on a helicoil. helicoil on a caliper would possibly allow shavings into the caliper. sad to toss a new part, but if it were me I would replace it. if doing a thread repair I would dissassemble the caliper, clean it, and drill a larger size hole so threads for a large "bolt" could be tapped into the casting. then install the bolt and drill it for the thread you need for the banjo. I suppose a bolt could be predrilled and threaded and then screwed into the newly cut threads in the caliper. use a thread locker and possibly stake the bolt in place so it never tried to unthread itself. then finish the top end of the bolt where the banjo seal will be so as to be a fresh clean flat surface for the copper washer to seal on. clean the casting inside and out also and then reassemble the caliper. the new copper washers for banjo bolts usually have small ridges machined into them to have a "crush zone" when tightened.
there should have been a new copper washer on each side of the banjo fitting. were they there? if so, check the fitting and the casting to ensure there was no flaw. the copper washer is supposed to crush a little to compensate for slight flaws, thats what the ridges on the copper washer are for, to assist in the crushing and sealing.
new parts could have a flaw in the casting, sealing surface or the threaded part. before you install the new part, or before you repair the old part, check to ensure the bolt hole is perpendicular to the sealing surface for the copper washer and make sure the threads are complete all the way around the drilled hole and also full depth all the way around. try the bolt to ensure it will fit well in a new nut of the same thread. also check it for signs of being stretched since you did torque it down quite a bit by the sounds of it. they tend to stretch where the hole is drilled through the side and, since they are hollow, they tend to stretch when overtorqued or can also twist from the torque applied. it's brakes, best not rely on something that isn't up to par. there are other places to save money.

09-03-2023, 03:13 PM	#2
dsraven Registered User Join Date: Nov 2010 Location: calgary alberta Posts: 7,870	Re: Stripped banjo bolt…helicoil? for brakes I NEVER rely on a helicoil. helicoil on a caliper would possibly allow shavings into the caliper. sad to toss a new part, but if it were me I would replace it. if doing a thread repair I would dissassemble the caliper, clean it, and drill a larger size hole so threads for a large "bolt" could be tapped into the casting. then install the bolt and drill it for the thread you need for the banjo. I suppose a bolt could be predrilled and threaded and then screwed into the newly cut threads in the caliper. use a thread locker and possibly stake the bolt in place so it never tried to unthread itself. then finish the top end of the bolt where the banjo seal will be so as to be a fresh clean flat surface for the copper washer to seal on. clean the casting inside and out also and then reassemble the caliper. the new copper washers for banjo bolts usually have small ridges machined into them to have a "crush zone" when tightened. there should have been a new copper washer on each side of the banjo fitting. were they there? if so, check the fitting and the casting to ensure there was no flaw. the copper washer is supposed to crush a little to compensate for slight flaws, thats what the ridges on the copper washer are for, to assist in the crushing and sealing. new parts could have a flaw in the casting, sealing surface or the threaded part. before you install the new part, or before you repair the old part, check to ensure the bolt hole is perpendicular to the sealing surface for the copper washer and make sure the threads are complete all the way around the drilled hole and also full depth all the way around. try the bolt to ensure it will fit well in a new nut of the same thread. also check it for signs of being stretched since you did torque it down quite a bit by the sounds of it. they tend to stretch where the hole is drilled through the side and, since they are hollow, they tend to stretch when overtorqued or can also twist from the torque applied. it's brakes, best not rely on something that isn't up to par. there are other places to save money.