Upper A arm bolts C5 - breaking???

Hey guys,

Dang if it is not always something.....

I removed the upper a-arm bolts to put the adjusting bolts back into the spring. When I put the a-arm bolts back in, hit them with my impact on the medium setting, two of them broke ( at the bolt transition point).

Now I would assume that these bolts being a 10.9 strength, they would be quite hard to break? I picked up a couple of grade 8 bolts, they too snapped like a tooth pick.

What the heck is so special that is making these bolts break? I have now found info on a torque spec showing 48 lb/ft. Is this correct? Do these bolts inhibit some stretch for this application? Why would these bolts not be torqued to a greater limit?

Just curious if anyone else ever runs into stuff like this?

tt

Actually, the higher the number the more brittle the bolt. Your impact killed them off.

it's not uncommon to use grade 5s on places where the bolt sees a lot of dynamic loading.

Twin_Turbo said:

Actually, the higher the number the more brittle the bolt. Your impact killed them off.

it's not uncommon to use grade 5s on places where the bolt sees a lot of dynamic loading.

Click to expand...

Now that makes better sense. Thanks TT.

Makes you wonder about the engineering, I am sure they had a reason for their choice....

tt

I feel I see SO much money spent on penny pinching Bullshit, the overall affect is the car is almost unworkable, and for NO good reason.....

FWD is a classic overall example, and over use of electronics is another.....

modern car/truck even has something called a 'body control computer'.....as if anything BUT the engine needs a freeking computer.....

nitwits......

:fishing::fishing::thumbs:

I agree.

I still would like to meet the person who decided to put the fuse box on a C3 where they did. :cussing:

I think that bolt is about 10mm on a C5? Your choices should be a gr10.9 or gr8.8 (in metric sizes). I agree, the impact wrench must be the issue.