Caliper bolt broke

I overtorqued it on my 95... 2/3 of the threaded portion is stuck in the flange.

1) The bolt says FC 9.8 on the head, and I was using a 13mm socket on it.
Is this a metric bolt, with it's grade somewhere between 8.8 and 10.9 ?
I found that the 5/16 course thread nuts fit it at the hardware store, and
bought 4 bolts that look identical in grade 8. This is to replace all of
them. Haven't tried fitting them in yet.

Will they work? And, is grade 8 recommended in this application?

2) What's the best way to go about removing the stuck portion? There is
some bolt sticking through the back side of the flange.


Any other tips here would be great.

CameronB said:

I overtorqued it on my 95... 2/3 of the threaded portion is stuck in the flange.

1) The bolt says FC 9.8 on the head, and I was using a 13mm socket on it.
Is this a metric bolt, with it's grade somewhere between 8.8 and 10.9 ?
I found that the 5/16 course thread nuts fit it at the hardware store, and
bought 4 bolts that look identical in grade 8. This is to replace all of
them. Haven't tried fitting them in yet.

Will they work? And, is grade 8 recommended in this application?

2) What's the best way to go about removing the stuck portion? There is
some bolt sticking through the back side of the flange.


Any other tips here would be great.

Click to expand...

lotsa PB Blaster, some heat, and a good pair of vice grips

Uh - the nuts from US coarse thread may fit, but they are not the same. I would not recommend doing this if your old bolts are metric. There should be plenty of places to get a proper metric hardened bolt - I would recommend a 10.9, then you'll be sure it's strong enough.

In the case of the caliper mounting pins I would stick with an OEM part. You don't have to worry about size, thread pitch, or grade. Thread pitch is important because you don't want that one backing out on you if it doesn't grab correctly. The wrong size could cause the brakes to bind, and incorrect grade could allow it to bend where it should remain rigid.

after you remove the broken bolt., you need to replace it with a bolt that is designed for the caliper. i would not use a generic bolt. shouldnt cost to much from the dealer or auto parts store.

also use anti seize on the bolt so it wont happen again.

You CANNOT interchange metric and SAE fasteners just because the "threads match up pretty well".

Go buy the CORRECT metric threaded fasteners, in the CORRECT grade.

These are your BRAKES you are working on. It's not the same as finding new screws to hold your ashtray in place :laugh:

Also take it from someone who knows, wrong bolts, torqued incorrectly means the caliper WILL COME OFF when the bolt fail.

Go to the dealer as previously recommended. I bought a set of those bolts and as I recall, they were not at all expensive.

Thanks

I was confused because I haven't found this "9.8" metric bolt anywhere, even the specialty fastener store.
Plus, the Jeep Dealership mechanic said I could find the proper bolt anywhere.

So anyways, I'll take the advice and call the dealership parts counter and Napa for prices on OEM.

I was examining the calipers on my 98 Classic today as the passenger side seemed to grabbed some applying the brake and chirpped a little when releasing the brake. Figured the caliper slides needed greased or something. To my surprise the upper caliper bolt on the passenger side is missing. The lower caliper bolt is a six-sided metric. However, on the driver side both bolts look like 24 point star heads (not sure what these are called). Are the bolts supposed to be a different type on each side?

-Chuck

Nope, both bolts are supposed to be the same. I've had mine out a couple of times but I forget which bit I used. Interesting, I just went out and looked at mine with my sockets n bits and flashlight in hand. When I got it I could swear it had hex bolts holding the caliper on as I pulled the calipers once to check the wear on the pads. I had it in dec of 2001 I think for the rotor recall, had new pads installed then and have not really looked at them since then other than to check thickness thru the top and feel the rotors. When I just looked now they are regular bolts, 1/2 inch to boot, dealer must have replaced them when they did the rotor replacment cause nobody else has touched them. I'm actually getting ready stick new pads in this weekend, I also want to clean up the mounting ledges which can be wear item on jeeps. The bolt length is also very important, no longer than 2.66in [67.6mm] shank length, torque is 11ft/lbs.

I guess I will call the stealership today and see how much they want for a couple of sets. Hope they sell them alone and don't try to make it a whole caliper or nothing deal.

Rich, how do you clean up the mounting ledges, fine sandpaper? FSM mentions using mopar multi-mileage grease on mounting ledges and dow111 silicone on caliper slides. Can I find these at AZ, Napa, PB, etc?

Do you guys recommend mopar pads or will third party pads work ok? Any specific grade (orgainic, semi-metallic, metallic)?

Thanks!

Ditto with using the "right" bolts. Stopping is one of the most important funcitons and you don't want to take short cuts and loose it!

The bolts are not that inexpensive around here. >$9 each! Shucks, CarQuest etc. They often come with the sleave and you should install as a set.

I got Carquest loaded Calipers and needed the bolts, bought the bolts at Carquest and now have extra sleaves!

The stock bolts have 12 point heads. Mine would not come off and became round, PIA to remove.

Hey guys ya gotta remember there are course and fine threads on standard bolts n nuts and with different pitches.on the threads.
The same goes for the meterics.In both,the pitch on the bolt has to be the same pitch as the thread it is screwing into or one or the other will either strip out or once it's in,it ain't comining out without breaking.