I was driving down the highway when I heard a pop, the when I went to brake, there was a terrible vibration. Turns out, it was the left front caliper hitting the wheel. The lower mounting bolt came off. Anyone know what size it is? It's kinda urgent.

Its a 17 MM head on EA81's, can't seem to find the thread size in my Hayes. Maybe pull the bolt and take the remaining one into a hardware store and match it up!

Edited March 14, 201214 yr by BendSuby

IMO, these are an OEM-only (dealer, or junkyard) part. They have to be exactly the correct length and strength.

 

If you're really in a pinch, and have no choice but to make do. It'll be a 1.25 thread pitch, probably 12mm diameter. A hardware store bolt will almost certainly have a 19mm head.

Got it fixed for now, until I can get the right bolt. The pitch is 1.25, dia 12mm, as numbchux suggested. The one I found was about 1/8th of an inch shorter, but it'll work for now. Grade 11, so it should hold for the time being. To get it to the school, I used a tie-down (non ratcheting, unfortunately) wraapped around the caliper and knuckle. Held it for light braking, just had to use engine braking as much as possible.

 

Definaately getting a ratcheting tie-down to keep i n case of emergency.

Ive recently noticed my 81 EA81 Subaru has a calliper different bolt then my 85 EA81 Brat. I thought it would be the same all EA81

i'm surprised it caused any issues - i've driven with one bolt instead of two in the caliper before, it doesn't move at all if the remaining bolt is tight. i drove hundreds of miles from Charlotte, NC to Atlanta, GA like that at normal highway speeds with no issue.

Which one?

I suppose it would be worse to loose the bottom bolt.

With the bottom bolt out, the caliper will want to pivot up and into the wheel.

With the top one missing, the force of braking will just twist it tighter into the knuckle.

Which one?

i don't recall, i only know that i've done it before, twice actually. i assume i would have looked at it from a rotational/force stand point and made an educated guess which would be best, like you said, but i never heard any noises and i have always assumed from then and repairing it properly afterwards that it never moved.

 

here is how i stumbled on this: all but one lug nut sheared off at 2am 250 miles from Atlanta, where I was living at the time. i always carried tools back then. i knocked out the sheared off studs. then i borrowed one caliper bolt from each side and one lug nut from each rear wheel (same thread) giving me two bolt/nut combos to replace the sheared off lugs - for a total of three including the one remaining lug that didn't shear off. they "barely" fit since they're shorter than the studs but they crabbed enough threads to work. worked fine, no braking issues at all. i recall tightening the one remaining caliper a bit to "compensate" - whatever that means. LOL

Edited March 14, 201214 yr by grossgary

i don't recall, i only know that i've done it before, twice actually. i assume i would have looked at it from a rotational/force stand point and made an educated guess which would be best, like you said, but i never heard any noises and i have always assumed from then and repairing it properly afterwards that it never moved.

 

here is how i stumbled on this: all but one lug nut sheared off at 2am 250 miles from Atlanta, where I was living at the time. i always carried tools back then. i knocked out the sheared off studs. then i borrowed one caliper bolt from each side and one lug nut from each rear wheel (same thread) giving me two bolt/nut combos to replace the sheared off lugs - for a total of three including the one remaining lug that didn't shear off. they "barely" fit since they're shorter than the studs but they crabbed enough threads to work. worked fine, no braking issues at all. i recall tightening the one remaining caliper a bit to "compensate" - whatever that means. LOL

How the hell do all your lug studs sheer off at once!? Yikes!

That's an awesome fix though

How the hell do all your lug studs sheer off at once!? Yikes!

no clue. it's not the first time i've seen multiple studs shearing - but never seen/heard of 4 shearing off at once though (5 lug XT6).

 

That's an awesome fix though

i was euporic that i wasn't stranded and had to deal with that debacle at 2a!

Hello,

I just purchased four bolts for my 1995 Subaru Legacy Wagon Calipers. Metric bolt size is M12- 1.25 X 25 HHC fine thread.

Toronto, Ont. CAN.

I've been using some 10.9 bolts from fastenal for like 2 years. No issues. Getting some 12.9 bolts with socket cap heads, because it will make getting them out soo much easier, and i'll actually be able to torque the top one properly.   Believe they're 40mm.. but don't quote me..  replacing the bracket on one side due to a seized slide that really messed up the OEM bracket.  I'll find out actual length this evening.  

there are three kinds of threads fine thread, coarse thread, and cross thread.