98 and up Caliper bolt inspection. WARNING!

Over at the CBRXX.com a question came up about caliper bolts. The FSM states to replace the bolts with new. Everybody's thinking was because of the LocTite stuff that is on them. Well that is NOT the reason. It's because the bolts are designed to take the load, instead of fork threads, and stretch. I know it may sound wacky to some but there is proof.



As you can see how the bolts have stretch and will break sometime if still used. The VFR and Blackbird is very much a like. Using some of the same parts. I looked in the FSM's I have and it looks like Honda started using ALOT bolts for the caliper mounting in 98.

The first thread is how all this got started. The second thread got start by the resident engineer. This photo is of his bikes and he has found them to be stretching. The last bolt is new.
These threads explain why/how it happens.
http://Lubed threads and torque settings

http://www.cbrxx.com/suspension-tir...per-mounting-bolts-possible-safety-issue.html

So this a word to wise to check your bolts next time you have the front wheel off or if it's been off a lot then check them now. It just may save you a big problem on the road and your life.

 

I can see the concern, and possible problem. However, in reality has anyone ever had a caliper bolt fail? Or even heard of it happening AFATG? I'm not saying it's not an issue, I'm just saying that all those bikes out there with thousands and thousands of miles, this would be a common problem. But this is the first I've ever read about it.

According to the thread on the forum, a poster maintains that the bolts stretch due to usage/stress. If that were true, then they would be a replacement item after X number of miles. The only thing I've ever heard is that you should replace them if you remove them. That makes no sense at all.

 

Ironically, there's this post...

 

Okay, I'm missing the irony in that post? Or are you referring to the guy wondering why the bolt is stronger than the housing? Which, in itself, is a pretty silly question.

 

Because in Grey's post he writes "It's because the bolts are designed to take the load, instead of fork threads, and stretch.". At least I find that ironic, shouldn't the bolt have stretched and not damaged the threads?








Probably should add, I'm just being snarky...

 

Actually that was the wrong second post. This is the one I wanted:http://www.cbrxx.com/suspension-tir...per-mounting-bolts-possible-safety-issue.html Post #24 shows these stretched bolts top/mid and bottom is new. These are bolts from normal wear. Yes I realize the guy over torqued the bolts in the first topic. That's what started this whole thing. Then someone else said they had lost a bolt from their front caliper. Those bolts are not hardened like a grade eight, more like a grade five and are designed to take the side loads and stretch.

That's why you are supposed to replace them when you take the calipers off to replace brake pads or rebuilds. So there is the mile/time frame you're looking for.

How many guys over torque bolts. Remember "torque hammer guy"? Your right when was the last time you heard of a problem. May be cause bikes are newer and are not taken apart much or have many miles on them. As they get older and more work is done on them things like this will start to show up. Like they have on a few bikes over there, now that people are checking. Whens the last time anybody here has ever looked/measured them. If your the type that use their brakes hard a lot you may find this happening. Same bolts on both bikes. So if it's starting to happen with one type of bike would it not happen to the other? It's just a saftey check, that's all. It's not an epidemic thing, just a caution to check.

 

caliper and axle pinch bolts are routinely over torqued because of the lack of torque wrench , a lot of tire shops are guilty of the same thing , one setting on the air gun tightens everything

 

Air gun-heaven forbid!! I use grease on my pinch bolts and caliper bolts and some other stuff I am surely forgetting. I trust my hand tightening routine stuff like that, but would not have a problem nraking out one of my torque wrenches. This story reminds me when the little Suzuki GS 500 was still being raced. It had a one caliper set up and under race conditions would break the boss on the actual fork leg. Anywho, happy two wheeling

 

Has anyone checked their bolts on a new bike (first tire change)? I would assume that the stretched bolts were from over torquing (should be tighten to 33 lb-ft) from multiple removals, however, manual does say to replace with new. I will inspect mine this weekend when I remove wheel and report.

 

33 ft.lbs! I think you'd be better off using the infamous torque hammer! It's 23 ft.lbs, however it would be 31 N-m, so you were sort of close. Not sure if the 2014 has different values, but here's a common values chart that might come in handy.

 

From my 2014 factory manual

 

Yep, definitely different. The 5/6 Gen use the lower torque values from my post. That being said, it pays to read the manuals!

 

Like this one

 

Yes, the 6th gen has the 23 ft/lbs values. Does the 8th gen also recommend replaceing the bolts?

 

Close enough for government work!

 

This thread got me wondering so I pulled the caliper bolts on my '99VFR with 40,000 miles, and checked them. I didn't pull the rear bolts, too much hassle.

I pulled the 4 front caliper bolts and measured them with a set of dial calipers. They measure out perfect, and the threads are perfect compared to a known good bolt. No stretching, and no thinning. So I put them back in. :smile-new: Torqued to 23 lbft. as per the HSM.

 

Good to know about your bolts. Every time I pull the caliper(s) off I check these, so far no issues or concerns, but I think at some point I might change them out, just for peace of mind.

 

I agree with all the above !


Cost and convenience factors mean i've never replaced those bolts on any of my ('86s or '97 or Yamahas) but would if i saw any damage. Shops seldom replace them.Never had one loosen yet. A dab of blue Locktite maybe.

Since the bolt is steel and threads into a softer alloy fitting, woodnya expect the most stretch in there ???!%

Or maybe it's just over-torquin that stretches dem bolts ?

 

Just changed my front tire Saturday. 8th Gen bolts are totally different, twice as long, hollow, and appear to have finer threads. No stretching on my bolts, but will pick up a spare set for the next time, if required. Yes, the manual still says to use new.