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Bike: Honda 69-72 cb350

Hey all spoke to my mechanic today about getting a torque wrench onto my camshaft sprocket bolts. He told me I don't need to torque the bolts and I should use loctite on them and call it a day. What do you guys think? They have a lot of experience on vintage bikes so I trust them, but this seems a little odd. The manual says I should torque the bolts to 15ft-lbs my issue is I can't get the torque wrench onto the bolt with or without adaptors for the wrench.
 

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bk69cb350 said:
Bike: Honda 69-72 cb350

Hey all spoke to my mechanic today about getting a torque wrench onto my camshaft sprocket bolts. He told me I don't need to torque the bolts and I should use loctite on them and call it a day. What do you guys think? They have a lot of experience on vintage bikes so I trust them, but this seems a little odd. The manual says I should torque the bolts to 15ft-lbs my issue is I can't get the torque wrench onto the bolt with or without adaptors for the wrench.
Are you sure it's 15 ft lbs? If I recall those are 6mm bolts and you'll snap them in a second with 15 ft. lbs. 15 inch lbs might be more like it. Locktite along with proper torque is the way to go.

You should be able to use a universal swivel adapter on a long 1/4" drive extension to tighten them.
 

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Camshaft sprocket bolts are 7mm and the spec I show is 12 to 15 Ft/lbs (per Chilton's)
That's roughly a good healthy snug on an 8" wrench .......And, YES, locktite 'em...
For comparison, the 6mm Phillips crancase cover screws are spec'd at 5 to 8 Ft/lbs... (about half as tight, so a gentle or "just" snug ....) ;)

Anyone show/find a different spec for these?.....
 

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Discussion Starter · #4 ·
Yea it says 15 ft lbs in the manual I have which is a chiltons. I am using 3/8 inch sockets. I tried the swivel adapter or universal joint adapter and it doesn't get on there quite right. I tried using several extensions and they are all too long. I don't have 1/4 inch, but will look for it. Maybe I can borrow one or work something out.

Anyone else know what might work to get my torque wrench in there. I am definitely gonna torque and loctite em since I trust Sprint's opinion.

Thx
 

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I was looking at the factory Honda 250/350 manual and it doesn't spell out the torque for the cam gear bolts but it does say they are 6mm. Right below that it says to use 15 ft lb's of torque for the head bolts which are 8mm hence my comments.
 

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Here is a picture of that pages I was referencing.
 

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No arguement Mike.....Just examples of how "different" manuals can confuse...

bk69cb350 : read below before you "torque" them down hard......

I just use locktite and give them a " good healthy snug " which is probably closer to, and/or at just below the LOWER end of the spec (as the replacement bolts one is supposed to use each time are NLA)....... I wonder if these bolts are specially hardened as well as being "special purpose" positionally?

Chilton's......................... Says they're 7mm and get 13 to 14.5 ft/lbs
Clymer's......................... Says they get 13 to 15 ft/lbs (size not mentioned)
Honda factory manual....... Says they're 6mm (and thus about 9 ft/lbs max)

All three spec the head cover stud nuts at about the same 13-15 ft/lbs and they ARE 8mm...

NO WONDER the noobies get confused.......I'm confused! .... :shock:
 

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In the end, regardless of what the manual says, the mechanic needs to know what size bolt they are tightening. Given the discrepancy in the manuals, obviously, measuring the bolt would be the answer here.
 

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Whatever the book may say, Mike is right - 15 ft/lbs is way too much on those bolts.
They'll break, and then you'll really be screwed, as the bolts are special, and NLA.......
 

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Bill and Mike.... That's why I told bk69cb350 to hold off (it does sound a bit high, but you never know)...and why I'm trying to ascertain what the correct spec should actually be.....Now I'm so curious as to go to the yard with a torque wrench and see what they actually "break loose" at.....
 

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I was thinking of finding a 6mm and 8mm bolt and doing the same thing myself. However, I'm guessing the cam bolts are better quality spec than the other bolts on the frame and that's all I have.
 

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I have no idea why they're "special", other than the shoulder on one of them.
The early Honda manual does specify 13 ft/lbs.......the later 350 manual says 13-14.5 ft/lbs .

LokTite is pretty much always acceptable to me......
 

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tbpmusic said:
I have no idea why they're "special", other than the shoulder on one of them.
The early Honda manual does specify 13 ft/lbs.......the later 350 manual says 13-14.5 ft/lbs .

LokTite is pretty much always acceptable to me......
What page did you find the torque spec on the older factory Honda manual. I've got my own manual and the one on your CD and don't see it anywhere.

I took a 6mm x 25mm bolt and put it in a vice about half way up bolt and applied some "torque", it handled 15 ft. lbs ok but broke at 20. I then put two 8mm spacer nuts in place then installed a 6mm nut. I held the 6mm in the vice and applied more torque. It was ok at 15 ft. lbs but striped the nut at 17 ft. lbs.

Not scientific but showed the nuts are probably weaker than the bolts. :) A hardened steel (or are they cast iron) cam would probably not strip like that.
 

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Results of "break-loose" tests..... It took 15 ft/lbs to break the shouldered bolt, the "allthreads" one broke just above 14...... (loosened in that order)
 

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Did you verify that it was 7mm?
 

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Didn't take them all the way out...(afraid they would get "misplaced" )....LOL.....
I'll see if I can get a measurement today..... ;)
 

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The cam bolts will be made from a higher tensile strength material than other "general use" bolts. These bolts will need to withstand high stress loads and are generally used where two parts bolted together are subject to severe load reversals and vibration, for example cam sprockets. If the book states 13-15 ft/lbs then that's what you should use.

Using loctite is a very good idea if you are not replacing these bolts with new Honda parts, as these bolts are a one use only, made so, (in several different ways, most likely just a closer tolerance) so that they bind in the camshaft, this acts as locking force (friction) and is most likely why the hight torque value is required. :D :D The higher torque (force) is to overcome the resistance when finall seating of the bolt ;)

Oh just a note for those who don't know, don't ever lubricate a bolt that will be locked using a torque value, as this can cause a higher torque value to be applied or create a short term hydraulic lock (very unusual).

Just a quick edit....if the required torque to turn the bolt is 2 ft/lb then this is added to the standard value to give the required seating value. So the resistance (torque) may be in this case 2 ft/lb then the actual torque applied is only 11-13 ft/lb's ;) ;)
 

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Strange :| the parts numbers which usually give the game away for size and length, don't :(
These numbers are for the CB350 K2 US model
90081312000 which is 6x14
90085312000 6 X ?
 
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