broken brake caliper bolt

[Warpdrv]

One reason I don't always like torque wrenches..... As stated if you use some never seize or grease to prevent corrosion it will change torque parameters, thus I just do everything by feel.... Not hard to realize when a bolt is tight enough to keep from backing out...

I'm a wire wheel junkie, when its time to reinstall bolts / nuts I like to clean the threads and apply some never seize when needed.

 

[Twigg]

It's a developed skill, knowing where you can play "fast and loose" with recommended torque settings, and what they mean in the first place.

Caliper bolts, while they are a safety critical item, actually do not usually need to be very tight. A bit of Locktite Blue is better than a "too tight" bolt. All they have to do is hold the caliper in place along the length of the bolt, and not fall out. They don't hold anything down with a clamping force in the way, say, cylinder head bolts do. So snug them up nice and tight with a standard 3/8th ratchet handle, and lock the threads. If you are paranoid, drill a small hole through the heads and wire them in place.

Develop a "feel" for what you are doing. The Service manual will give you the spec, but work out what it is the bolt is doing too, that gives you an idea of what is required and why. Use a calibrated torque wrench to develop an idea of what various torques feel like, and remember that your ratchet handle is shorter, so the tightening force needs to feel greater than you feel with a TW.

ps ... Never, ever, ever use Locktite Red unless you don't intend removing the bolt later. It requires high heat to break the bond, and smaller bolts will shear before they come loose. Only use if if specified.

 

[mcatrophy]

One reason I don't always like torque wrenches..... As stated if you use some never seize or grease to prevent corrosion it will change torque parameters, thus I just do everything by feel.... Not hard to realize when a bolt is tight enough to keep from backing out...
I'm a wire wheel junkie, when its time to reinstall bolts / nuts I like to clean the threads and apply some never seize when needed.

I've never liked torque wrenches. About the only time when I would use one is on stretch bolts such as for a cylinder head. Other than that, I do it by feel.

 

[Donal]

Like most things in life it all depends on what you are trying to achieve.

(Very) Basically there are two types of bolting arrangement, Shear & Tensile.

For Tensile visualise a cylinder head, where the forces to be contained are parallel to the bolt.

For Shear visualise two plates which can slide together. This (I believe) is what we have in the brake calliper arrangement. To contain the shear forces you can simply rely on the shear strength of the bolt, think of the bolt as a shear pin.

The most effective method is to rely on the friction generated between the faces of the plates by applying a clamping force. To achieve the required friction the clamping force needs to be applied properly, which means pre-loading the bolts so they clamp the plates with the designed load.

The hollow bolts could possibly be to allow the bolts to 'stretch' (think of a spring) and maintain a constant clamping force under varying conditions.

Some bolts don't really matter and just snugging them up will be fine, others need to be treated with the respect they deserve. If the calliper bolts are not tight enough all of the shear loads will be held by the (hollow) bolts.

I'm sure Mama Yamma's little boys spent several hours of their lives pondering over this and came up with the specified torque. The only problem with the torque figure is how it is converted into bolt pre-load as discussed above......

 

[Jerambelu]

I just had one of the caliper bolts break on my '05. It felt a little "soft" as it was being tightened up to the recommended torque. Fortunately, I was able to back the broken piece out by hand. I fixed it temporarily with a hardened hardware store bolt while I wait for a new set to arrive. I ordered new ones from Partzilla.com for 2.62 each plus 5.95 shipping.

As Donal mentioned, I assume the bolts are designed to stretch, therefore theoretically, they can be over-streched, I figured if one broke, the others could too, cheap insurance.

 

[Klubis]

Good thread!

One of the most interesting things was the hollow bolt? Sounds like a question for Kevin Cameron".

Some things I always torque, like lug nuts, heads, valve covers, anything with important machined surfaces. I feel like for most situations I can rely on my mechanic's "feel", due to my longevity and the sheer number of sheared bolts I've been responsible for. Whenever possible, I finish the installation with a torque wrench, though.

One thing I have learned, is that if my torque wrench says it still needs to be tighter but my "feel" says its tight enough, always trust the "feel". Something is wrong and I need to stop and re-assess the situation. This is analogous to not trusting my GPS when it insists that I make a right turn and go down the boat ramp. Always defer to the course of action that is less likely to add problems I don't need says I, unless it is a moral issue which is a completely different subject.

Good info on adding grease or whatever to the threads and definitely worth passing on.

Easy Outs! Yikes! I love them, but I hate it when I get in a situation where I need to use one. It means something has gone wrong. As one of you already said, if you do the first part right, they work well. Unfortunately, that was the part I was least good at. So due to the longevity etc. mentioned above, I've learned to really take my time, slow down, measure 2 or 3 times, make sure I punch exactly where I want that point of the drill bit to be exactly and not do anything that adds to the unintended problems list.

There is a wealth of good information on this forum, and I just wanted to add my 2 cents!

 

[Bokerfork]

Why are the bolts hollow?

Easy, they're predrilled for the eventual use of an easy out.

But seriously, the only other place I know of where hollow bolts are used is in light poles and other traffic structures. If I remember correctly it was so they would shear off when struck by a motor vehicle and therefore cause less death and property damage. Seems odd that a bolt designed to shear off would be used in a caliper given the lateral forces it will receive.

Well, whatever. My $.02

 

[Hotboot]

The aircraft mechanics opinion on hollow bolts: they are meant to stretch during installation, dissipate heat in use and better handle dis-similar metals in use . They should be replaced after a few tire changes and lubed with blue locktite for the lubrication value.

I would never use a torque wrench on soft hardware like that, even the rear axle spec from Yamaha is crazy tight and blamed (in my garage) for bearing failure. Touchy feely common sense applied at all service points here since 1974, nothing has fallen off in a gazillion miles.

 

[Chuck35]

In automotive applications I have seen hollow bolts used to shear off when over torqued in order to save damage to a more expensive part.

If you want a solid bolt, the gen 3 and R1 etc uses Yamaha pn 90105-10638

 

[roger dodger]

In a related question, should this bolt have a washer or not?

- would that change the torque setting?

-my '03 has washers, my buddies '03 does not ... which is correct?

 

[ionbeam]

In a related question, should this bolt have a washer or not?
- would that change the torque setting?

-my '03 has washers, my buddies '03 does not ... which is correct?

The OEM brake bolt is a flange head bolt so it does not and should not have a washer. The flange is to distribute the clamping force over a larger area.

 

[Fred W]

I do torque certain mission critical fasteners, such as caliper bolts and axle nuts. But I do not use oil, grease, anti-seize, or lock-tite any place that the torque spec doesn't call for it. I've never snapped off a bolt when using a torque wrench. Coincidence?