Idiotic Jeep fastener

[SteveH - CO]

1990 Jeep Cherokee. Front disk brake caliper bolts. I can find zero info on the internet. About 7-8mm, shallow 12 point. No known socket I have will even begin to work.

I plan to replaced with the readily-available common fasteners after I get this miserable thing off. Not my truck - helping a buddy.

Is there a special service tool, or just Vise-grips and prayer?

Thank you - Steve

 

[mrb1]

https://www.harborfreight.com/7-pie...e=180&gad_source=1&gad_campaignid=21901739207...metric

https://www.harborfreight.com/7-pie...e=180&gad_source=1&gad_campaignid=21901739207...standard

.

 

[Honch]

Its hard to tell from your picture, but that does not look like a 12 point, it looks like a spline head.

 

[Herzog]

For that year (1990) it's not metric. It's just a standard 12 point socket. Probably close to 7/16 or 3/8... but hard tell from the photo (or remember)
Also, this is assuming that's an OEM bolt... been a while but I swear I remember my 1989 having that same bolt head on the calipers.

 

[SteveH - CO]

I tried every 12 point SAE and metric I own, and they have very little grip and spun easily. I own (of course) 12 point spline SAE, but not metric. I will buy the metric set and see if that's it.

Thanks all!

 

[Herzog]

I tried every 12 point SAE and metric I own, and they have very little grip and spun easily. I own (of course) 12 point spline SAE, but not metric. I will buy the metric set and see if that's it.

Thanks all!

That's interesting. My gut tells me that's not an oem bolt for that year then. Best of luck!

 

[Firebrick43]

It’s 35 YEARS OLD. Rust has reduced the size of the corners and probably you tried the wrong size first and deformed what was left.

Either wire brush and weld on a nut over the original to get a purchase or use vice grips. It’s already ^*#+#+. Move on and get a new one.

 

[NakeDiesel]

you will need a spline socket for it, a regular 12pt won't work.

 

[rlitman]

It looks to me like someone rounded it by hammering the wrong socket on. Shouldn't be difficult to loosen with a rounded nut socket, or a spline socket if you've got one, or even vise grips. Then spend the $2 and replace it.

Can't speak to your model year, but my TJ has 12 point bolts on the wheel bearings. The only 12 point socket I own is dedicated to those, and in all fairness, I kind of like them. So long as you have 12 point sockets, 12 point fasteners are pretty foolproof, until some fool hammers a 6 point socket on them.

 

[SteveH - CO]

but my TJ has 12 point bolts on the wheel bearings.

This has 12 pt. wheel bearing bolts, as well, but they are 13mm (far larger), and have a much deeper spline engagement - a 12 point socket fits easily and securely.

These tiny brake bolts are very shallow, so there's very little engagement with the socket.

I'm not against welding a nut onto it, and/or using Vise grips. They will be coming off.

 

[cvairwerks]

A number of places say the correct bolt is M12x1.25x35 10.8 and they are unobtanium from the dealers.

 

[stockerwithalocker]

Own a few cherokees. That is not the stock caliper bolt, stock they are 6pt hex head. Fyi be aware the threads in the knuckle tend to strip when you re-install that bolt. Check if there is a helicoil there already which may or may not be the stock threads.

 

[NUTTSGT]

Almost looks like someone put an 12 pt ARP fastener in there.

 

[NUTTSGT]

A number of places say the correct bolt is M12x1.25x35 10.8 and they are unobtanium from the dealers.

Is that a special thread pitch ?

Shouldn't M12 be either 1.75 or 1.50 ?


oops, ahh I see it now. It's "extra" fine.

JIS Flange Bolt 10.9 Extra Fine M12X1.25 / 17mm Wrench

Bel-Metric sells metric hardware & specialty automotive supplies worldwide. Visit our website to purchase metric fasteners, nuts, bolts, screws, washers & more.

belmetric.com

 

[cvairwerks]

oops, ahh I see it now. It's "extra" fine.

One of the reasons that I despise metric.

 

[Firebrick43]

Almost looks like someone put an 12 pt ARP fastener in there.

Probably put this cheap one in there.

https://www.amazon.com/Omix-Ada-16749-09-Brake-Caliper-Pin/dp/B000FQ0HRU?tag=atomicindus08-20

A number of places say the correct bolt is M12x1.25x35 10.8 and they are unobtanium from the dealers.

What would you expect for a 35 year old vehicle? Plenty of aftermarket parts houses have them and you could always get them from mcmaster carr as they carry that size

 

[RalphInCA]

The work of a “helluva salesman”.

Some awesome sales person convinced the engineers working for Jeep at the time that this new fastener system was the best thing ever.

Would save them lots of assembly time/money.

Seemed like a good idea at the time, I guess.

 

[Firebrick43]

The work of a “helluva salesman”.

Some awesome sales person convinced the engineers working for Jeep at the time that this new fastener system was the best thing ever.

Would save them lots of assembly time/money.

Seemed like a good idea at the time, I guess.

Its not the stock fastener, its aftermarket

 

[RalphInCA]

Its not the stock fastener, its aftermarket

Perhaps.

But I’ve seen those fasteners on some other car I’ve owned and I thought it was my Jeep.

I remember because I had to go to HF to buy a set of those gosh darn splined sockets.

Used them once.

 

[RoninB4]

-Because the bolt is somewhat of an unknown I would recommend measuring the OD with calipers and getting the thread pitch correct to determine whether this is metric or inch. Winding the wrong thread pitch in there has a high probability of f*cking up the thread and making the job even worse. Would also closely examine the fastener when it's out to see if it has any material in/on the threads. If it's an aftermarket did they get the correct pitch? If not then it may have been cross threaded if there's material or deformed threads. Good luck

 

[mrvm]

Not the best choice design for a bolt head but 3 of these bolts secure the hub bearing to the knuckle on my JK. I used a hammer to tap on a 12-point 13mm socket & breaker bar to remove these rusty bolts with little effort. The error some make is using the wrong size socket or 6-point to strip the head of the bolt.

 

[stockerwithalocker]

Perhaps.

But I’ve seen those fasteners on some other car I’ve owned and I thought it was my Jeep.

I remember because I had to go to HF to buy a set of those gosh darn splined sockets.

Used them once.

See my post above, that is not the stock bolt. I’m making the distinction to avoid confusing the OP.

You are thinking of the two top bolts that attach the trans to the motor that are external torx bolts.

 

[Beerhippie]

There must be a special place in Hell for every clever engineer who invents new, unnecessary styles of fastener heads.

Locked in a cage over a pool of molten lava with a door held together with nuts and bolts and given a full toolset--except for the one tool that fits those stupid fasteners.....

 

[JeepYJ]

It’s a Jeep thing.

 

[NUTTSGT]

There must be a special place in Hell for every clever engineer who invents new, unnecessary styles of fastener heads.

Locked in a cage over a pool of molten lava, held together with nuts and bolts and given a full toolset--except for the one tool that fits those stupid fasteners.....

Yeah, maybe....but I still take pleasure knowing I got to tell a Chrysler/Dodge engineer what he was planning to do on the Dakatoa wasn't going to work in his own factory about 30 years ago.

The look on his face as I slid out from underneath the front of the truck. .... yeah No .... He was convinced it would work and the Dakota assembly line made the change....2 weeks later, back to the original design..... Ha haha ha ... That 20 something year old kid knew what he was talking about over that Engineer with his degree hanging on the wall.


Sorry for the high jack....

 

[Wrench97]

You need a set of these.
There are a lot of brands out there some better then others I have a set from Mac tool that work really well even on round heads or broken bolts, hammer one on and remove the bolt

 

[Bigblue&Goldie]

My 1984 CJ7 has E-Torx on the Calipers. I think it's the only time I've ever come across E-Torx; for whatever reason my other vehicles don't seem to have them.

 

[lbhsbz]

1990 Jeep Cherokee. Front disk brake caliper bolts. I can find zero info on the internet. About 7-8mm, shallow 12 point. No known socket I have will even begin to work.

I plan to replaced with the readily-available common fasteners after I get this miserable thing off. Not my truck - helping a buddy.

Is there a special service tool, or just Vise-grips and prayer?

Thank you - Steve

That uses an M8x1.25x65mm bolt. 10, 11, or 12mm 12pt should fit. Then get some 6pt bolts somewhere....doesn't need to be anything special, they're under no load whatsoever. I have these in stock but shipping would take a few days.

 

[whateg01]

One of the reasons that I despise metric.

That's as ridiculous as a guy at work who hated metric because the screw heads always strip out.

Guess what! There's a UNEF, too!

 

[SteveH - CO]

Revisiting this. My buddy and I got the old fasteners out with a Vise Grip on the bolt shoulder. This shallow-head bolt is marked '8.8, F-C M8'.

See how shallow the spline area is, compared the hub bearing bolts (which engage easily with a 13mm, 12 point socket). We will be replacing this exotic fasteners with typical 13mm head Jeep caliper bolts and sleeves.