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Discussion Starter · #1 ·
Can anyone confirm the correct torque to use in tightening the rear caliper mounting bolts for Avid BB7 brakes? I have two sets of instructions that I've printed from the Avid web site. One set says to torque the rear mounting bolts to 80-90 inch-pounds. The other set says to torque only to 40-60 inch pounds. That's a pretty big discrepancy. Which of the two torque specifications is correct?
 

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Derailleurless
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JonathanGennick said:
Can anyone confirm the correct torque to use in tightening the rear caliper mounting bolts for Avid BB7 brakes? I have two sets of instructions that I've printed from the Avid web site. One set says to torque the rear mounting bolts to 80-90 inch-pounds. The other set says to torque only to 40-60 inch pounds. That's a pretty big discrepancy. Which of the two torque specifications is correct?
Yeah, I agree with the others... throw away your perfectly good torque wrench and just feel it out - NOT!

Com'on, Dave & V., the guy's got a torque wrench, he should use it! It's not like torque values represent "the establishment" or something evil. It's good sense to use it.

JG, the 40-60 value you have is likely the cable fixing bolt. Are you sure you're reading the correct value? The mounting bolts and CPS bolts should be in the 70-90 in-lb range, and that's what they've been listed at in every installation sheet I've got in my file going back to the orginal BB7s.

The current sheet (which I'm guessing you have already) is here: http://www.sram.com/_media/techdocs/bbdb-mtn-160-install.pdf
 

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Discussion Starter · #5 ·
Thanks Nate. Yes, I have two perfectly good torque wrenches that cover high and low ranges of torque values. I'm very picky, and I pretty much torque every bolt that is important (which is most all of them!). I do make an exception for water-bottle bolts; I don't torque those. :D And I don't have a wrench that will let me torque the pedals onto the cranks, so I have to go by feel there too. But otherwise, I use those torque wrenches a lot. (And especially for brakes!)

So Nate, here is a link to a PDF of the 2006 instructions on Sram's website:

http://www.sram.com/_media/techdocs/2006_BB5and7_English.pdf

Look at the top of page 6, at step 3 showing the mounting of the rear caliper. The diagram clearly specifies 40-60 inch pounds of torque. I'm thinking that must be a typo.

The link you sent me, btw, means that I now have two sets of instructions giving the higher numbers, and one set with the lower range.
 

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I'll go so far as to correct Avid's sheet. I haven't seen that version of the installation instructions previously.

Note that on the prior page, the correct value is shown for the front installation, and all of these adapters can be treated the same.



Going back a few years, I was amazed at the cost of low-range torque wrenches, and I especially despise "clicker type" torque wrenches at the low end of the scale. So I searched eBay far and wide, and found a nice dial indicator torque wrench for around $25. Suspicious of the ridiculous price, I took it to a local calibration outfit, and it checked out pretty much perfectly.

Once again, the crappy eBay photo and questionable auction text netted me another incredible deal!

 

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vmajor said:
Eh, I indeed missed the pasr of the post where Jonathan clearly states that he HAS a torque wrench.
Ahh, ok, you got me there... but I'm allowed to read into the deeper meaning of his post, aren't I?

Hey, if you've got an "in" with SRAM, how about asking them why nobody is answering Avid emails? And then send 'em a copy of that typo in the install instructions?
 

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Discussion Starter · #9 ·
Guys, guys, no need to read anything into my original post. I never mentioned wrenches -- no need to. All I asked for was confirmation on the torque specifications.

I'm sticking with the 80-90 inch-pound numbers for now. I'm also going to email Sram and ask for some clarification. If there's a typo in their instructions, they might want to correct it.
 

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Discussion Starter · #10 ·
Maybe I won't contact them. They don't give an email address on their website. That's unfortunate. Companies should be more open to hearing from their customers. (Ironically, they do ask for my email address).
 

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The plough
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Lol :D

PM me the email address you were sending to for reference. (it may be in the posts somewhere, but I am tired...)

I'll direct them to this thread and email them the typo image.

Oh and its not hard to have an "in" with pretty much any bike company once you are in Taiwan and ride and attend events. Company people all like to ride too...shocking eh?:eek:

...it also helps that our business is to know people ;)

V.

EDIT: definitively tired, look at all them smileys... totally out of character...
 

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Eeek, it was August of '07 (just looked), but I emailed a couple of specific BB7 questions to [email protected] (lacking a better addy), and never got a reply.

I used to have a good relationship with a couple of the guys at Avid when they were their own company in Colorado, but I've had a difficult time with SRAM with the exception of the hub gear guy. My local shop even had a few choice words, but that was a few years back, and I hear SRAM has worked to correct their dealer line of communication.
 

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The plough
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SRAM service rocks.

Here is the reply:

"It’s my pleasure to answer it.

According the latest user manual in my hand, the torque is 9-10 Nm.

To be honest, I never measure my torque on this position."

So here we have the real values, and the recommendation. Thus two finger tightening in this position at least seems to be a good way to do things. This way, you can spend more time and devote more attention to locations where over-tightening can indeed cause failure.

...and no I am not quoting names in SRAM just in case some ham fisted freak of nature manages to strip the IS mounts :D

V.
 
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