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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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 Posted: Tue Mar 03, 2015 8:47 pm Post subject: |
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| Brian wrote: |
| Is there enough room for a bolt between the flanges? I can barely stick a finger back in there. |
You mean a normal hex head bolt head like 13mm right?.....which is what I was referring to.
Im trying to remember....but I believe on my type 4 I have done that at one point many years ago when I was missing a bolt on kne of my cars. It will take a thin wall socket. It may actually take a wrench.
To torque it properly you would need a crows foot for your torque wrench.
Dang....now you got me wondering. I will have to dig through the log book or go out and measure my CVs in the morning. Ray |
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cdennisg
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Joined: November 02, 2004
Posts: 20278
Location: Sandpoint, ID
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| Posted: Tue Mar 03, 2015 9:33 pm Post subject: |
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Interesting read. I just tighten the shit out of them with a drop of Loctite on clean threads. Never fails.
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed Mar 04, 2015 10:39 am Post subject: |
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| cdennisg wrote: |
| Interesting read. I just tighten the shit out of them with a drop of Loctite on clean threads. Never fails. |
I just start with clean lightly oiled threads and a new Schoor washer each time....and make sure the plates and cap are not swimming in grease in the stack up and I have never had a problem with that method.
This is not to say I have never had problems. I learned the above lessons early on. When you leave the threads and plates packed up with grease from a boot job or grease job....you end up with the bolts being a constant check item. If you dont use new lock washers each time.....you will occasionally have a bolt or two work loose.
If you are the type that never checks anything until you hear noises....you can occasionaly lose a bolt this way.
Once I started doing things carefully.....right about the end of high school.....I never have had problems with these bolts. Ray |
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cdennisg
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Joined: November 02, 2004
Posts: 20278
Location: Sandpoint, ID
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| Posted: Wed Mar 04, 2015 10:48 am Post subject: |
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I have always made sure there was no grease in the way. That just seems like common sense to me.
Curious as to why Loctite is rarely mentioned for this application?
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed Mar 04, 2015 12:13 pm Post subject: |
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| cdennisg wrote: |
I have always made sure there was no grease in the way. That just seems like common sense to me.
Curious as to why Loctite is rarely mentioned for this application? |
I have used loctite once for this and had trouble removing one or two bolts. I will admit that the splines in a couple of bolts were less than perfect. I keep mine squeeky clean and any dirt in the splines gets blown out with carb cleaner and a wire brush.
I would bet that locktite does not get used for the most part because 9 of 10 people I see doing joint work install the bolts before cleaning the joint up after packing....
and just pushing the grease out of the joint hole with the bolt.....insuring its packex upcwith grease....and loctite cant be used under those conditions.
Most people bolt it up this way and then wipe off the excess grease. ....which leaves the threads and joint faces swimming in grease. A recipe for coming loose. Ray |
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PITApan
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Joined: November 09, 2014
Posts: 1058
Location: Northern Colorado
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| Posted: Wed Mar 04, 2015 3:42 pm Post subject: |
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| cdennisg wrote: |
I have always made sure there was no grease in the way. That just seems like common sense to me.
Curious as to why Loctite is rarely mentioned for this application? |
Really getting lock tight to work is not so easy. You need completely clean metal and Locktight (Tm) recommends the use of their primer for best adhesion.
As someone mentioned, how often do you hear of the joints coming apart?
Is every body totally cleaning their threads like Ray says? Or using Fancy special washers? Or the latest torque spec.?
I doubt it. But the legions of failure the OMG types predict don't seem to be happening.
My first though on seeing the OPs pics was that there4 as a torquing failure of some kind. Even theorizing bad bolts is a little farfetched (but not out of the question). If it happened to me the first thing I would check is my torque wrench and my next suspicion would be that I failed to torque them at all---got distracted, whatever.
On my bike every torqued bolt has little dab of green paint next to it. After assembly and torquing, every one was inspected for correct torque and then marked with the paint. Sometimes the dab is next to the bolt, sometimes on the head, but every one has it. If I worked that carefully some of the failures I've had in the past would not have happened. |
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cdennisg
Samba Member
Joined: November 02, 2004
Posts: 20278
Location: Sandpoint, ID
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| Posted: Wed Mar 04, 2015 4:34 pm Post subject: |
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| raygreenwood wrote: |
| cdennisg wrote: |
I have always made sure there was no grease in the way. That just seems like common sense to me.
Curious as to why Loctite is rarely mentioned for this application? |
I have used loctite once for this and had trouble removing one or two bolts. I will admit that the splines in a couple of bolts were less than perfect. I keep mine squeeky clean and any dirt in the splines gets blown out with carb cleaner and a wire brush.
I would bet that locktite does not get used for the most part because 9 of 10 people I see doing joint work install the bolts before cleaning the joint up after packing....
and just pushing the grease out of the joint hole with the bolt.....insuring its packex upcwith grease....and loctite cant be used under those conditions.
Most people bolt it up this way and then wipe off the excess grease. ....which leaves the threads and joint faces swimming in grease. A recipe for coming loose. Ray |
I used purple Loctite, if it matters. It is easier to remove for a fastener this size. It is low strength designed for 1/4" size fasteners. Cleaned the threads with brake Cleaner and compressed air.
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Brian
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Joined: May 28, 2012
Posts: 8340
Location: Oceanside
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| Posted: Wed Mar 04, 2015 4:49 pm Post subject: |
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True, loctite only works if it's the only thing on the threads.
My rule for loctite is: Blue if it comes out every now and then, and red if it should never move.
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Randy in Maine
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Joined: August 03, 2003
Posts: 34890
Location: The Beach
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| Posted: Wed Mar 04, 2015 5:31 pm Post subject: |
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| Actually "locktite green" would be better after the screws are correctly torqued. |
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cdennisg
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Joined: November 02, 2004
Posts: 20278
Location: Sandpoint, ID
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| Posted: Wed Mar 04, 2015 5:45 pm Post subject: |
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| Randy in Maine wrote: |
| Actually "locktite green" would be better after the screws are correctly torqued. |
Isn't green the sleeve retainer? I have used it for a crank pulley sand seal in the past. If you are talking about the Loctite that is intended to weep into the threads after assembly, how do you plan to get to the end of the bolt where the threads are exposed to get the Loctite in there? Both ends of my axle are well buried from that kind of access.
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PITApan
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Joined: November 09, 2014
Posts: 1058
Location: Northern Colorado
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| Posted: Wed Mar 04, 2015 5:55 pm Post subject: |
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| cdennisg wrote: |
| Randy in Maine wrote: |
| Actually "locktite green" would be better after the screws are correctly torqued. |
Isn't green the sleeve retainer? I have used it for a crank pulley sand seal in the past. If you are talking about the Loctite that is intended to weep into the threads after assembly, how do you plan to get to the end of the bolt where the threads are exposed to get the Loctite in there? Both ends of my axle are well buried from that kind of access. |
There is green retaining compound (stud and sleeve locker) and green wicking grade for post assembly work. |
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carlvon
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Joined: January 09, 2015
Posts: 93
Location: San Antonio, TX
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| Posted: Wed Mar 04, 2015 7:46 pm Post subject: |
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| SGKent wrote: |
There are millions of buses that traveled hundreds of millions of miles without a CV coming loose. The culprit may be buying other then Lobro CV joints, that or a bad batch of bolts. Were they allen head or star head?
BAP Geon used to be a good line, however I don't know where they get their current inventory from. |
I agree, but the contributing factors are too numerous to calculate.
The bolts that were included in the kit were hex, but when I reinstalled, I bought 12 new 3 square bolts.
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Carl
1978 Champagne Edition II 2L FI |
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carlvon
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Joined: January 09, 2015
Posts: 93
Location: San Antonio, TX
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| Posted: Wed Mar 04, 2015 7:47 pm Post subject: |
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| Brian wrote: |
| I've been told many times; torque the bolts, check after a few hundred and if none are loose, forget they exist. |
And that probably works 99.9% of the time. However, and engineer will tell you that temperature changes, fatigue, and dynamic loads would negatively affect the bolted join over time.
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Carl
1978 Champagne Edition II 2L FI |
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carlvon
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Joined: January 09, 2015
Posts: 93
Location: San Antonio, TX
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| Posted: Wed Mar 04, 2015 7:54 pm Post subject: |
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| raygreenwood wrote: |
The Norlock washers are no different than Schnoor. They are both hardened, serrated both sides and are bellville washers using a combination of "tension" and metal bite to lock instead of thread friction alone.
Dont fall for the " Nordlock uses a double bellville method"...line of sales BS. The amount of tension for bolt type and diameter is specified.....and is what decides what thickness of bellville washer you use.....and how much tension it has.
So unless Nordlock washer pairs have excessive tension....which I know they dont.....that means each half provides 50% of the required tension. |
In basic function of applying tension in addition to friction, yes, they are the same. The difference is the Schnoor uses a spring that is susceptible to fatigue, whereas the nordlock uses a hardened cam. The nordlock can be reused, but the Schnoor can't.
I'm not falling for marketing, I'm looking at the mechanics and physics of it. If you watch the video of the junker testing, you'll notice something interesting when they tested the nordlock. After the test, they kept the graph running when they loosened the bolt. As they loosened the bolt, the clamping force increased. This is a direct indication of what happens as the bolt tries to vibrate loose - tension increases. I wish the video included a junker test of a Schnoor, and it's subsequent loosing clamping force.
The washer pairs themselves do not provide the tension the way a schnoor does - the tension is provided by the cam, not a spring.
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Carl
1978 Champagne Edition II 2L FI |
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carlvon
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Joined: January 09, 2015
Posts: 93
Location: San Antonio, TX
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| Posted: Wed Mar 04, 2015 8:34 pm Post subject: |
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| PITApan wrote: |
| Carl, Your knowledge of some simple (I think) engineering leaves you at the mercy of the marketers. I cannot help. I'm sorry. |
I love physics, and I enjoy figuring out how things work. If you think that physics is simple, we could have some great discussions. I'm not falling for marketing, I'm following the mechanics and physics of the device.
| PITApan wrote: |
| I do suggest you check your torque wrenches and techniques. Your failure might have been nothing more than you thought you got correct torque on them but in reality it was too little. There are a number of causes of this. Wouldn't be the first time it's happened. |
The cause may never be known, but my guess is on the bolts slackening first, then bolted joint failure due to excess dynamic loads attributed to by the loss of clamping force. I'll need to find someone with a good torque wrench to compare to, but I'm working under the assumption that my wrenches are within +/- 4%.
| PITApan wrote: |
| The reason I suggest this, aside from the fact it does happen, is your comment about always lubricating the threads of fasteners. Nothing could be farther from the truth and a great many threads are specified to be assembled bone dry. It is a specification that is usually called out. That you do not know this reveals something about the depth of your mechanical experience. So I say, without any intent to insult or belittle you, and I think it might sting some, but double check your tools and methods. If there is an error there you will get bitten again and again. I'd rather risk some hurt feelings than abandon you to that fate. |
Some specs say to lube, some say to dry - it's up to the engineer to determine how the friction coefficient and other factors work together to acquire the proper clamping force required to secure the joint. The problem is, most don't care. They don't consider the application, or environment the joint will be in when it's being serviced. What they are trying to accomplish is getting the the proper amount of stretch on the bolt (typically 75% of yield strength) to apply the proper amount of clamping force required to secure the joint considering all external forces including dynamic loads.
Case-in-point, the CV bolt being installed after being packed (greased and not cleaned), and not as the materials were when it was designed and tested in the lab. Or reusing bolts and washers that have already been stretched or fatigued.
It would be nice if torque specs specified the actual clamping load required instead of the torque required; however, this would require a force gauge in the joint. Some of the best torque specs are the ones where the engineer specifies how many degrees past finger tight. This procedure puts the proper amount of tension (axial load) on the engineered joint.
I'm not insulted, and my manhood is still intact. My skin is very thick (has to be for my day job). You can question my physics/ME all you want (or have a technical conversation with me), but the bottom line still exists - a dry application of torque does not equal the same amount of clamping force that a lubed one will. The amount of axial load generated when you torque a bolt is dependent on the friction coefficients of the materials and many more contributing factors. Those other factors are hard to determine, even if all of the materials are new. The lube removes much of the materials' friction coefficients, and allows for more clamping force. Yes, a lubed bolt won't have the same amount of static friction as an unlubed bolt, but with the proper tension washer (be it schnoor or nordlock), will keep 90% of it's clamping force and will be unaffected by dynamic loads for the life of the fastener. This is why they recommend a 15% increase is torque when installing in a lubed joint using a schnoor or nordlock washer.
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Carl
1978 Champagne Edition II 2L FI |
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carlvon
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Joined: January 09, 2015
Posts: 93
Location: San Antonio, TX
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| Posted: Wed Mar 04, 2015 8:35 pm Post subject: |
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| boothead wrote: |
An interesting PowerPoint presentation from Schnorr:
http://www.schnorr.com/downloads/technical-informa...al-en.html
According to Schnorr, Nord Lock and Schnorr serrated lock washers perform about the same (Schnorr says theirs are slightly better than Nord Lock--would you expect them to say anything else?). Both Schnorr and Nord Lock WAY out-perform other types of lock washers. Take a look at the wave washer results on the graph, maybe we would be better off with flat washers vs wave washers?
Or maybe no washer (vs spring washers):
http://www.boltscience.com/pages/helicalspringwashers.htm
In any case, even Schnorr acknowledges that Nord Lock washers are a viable alternative for lock washers. More expensive perhaps, but to each his own. |
I never said Schnoor washers weren't good - I was just concerned by the fatigue of the spring. Nordlock washers rely on a cam, not spring, so they are not subject to the same fatigue as a Schnoor washer is, and they can be reused.
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1978 Champagne Edition II 2L FI |
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raygreenwood
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Joined: November 24, 2008
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Location: Oklahoma City
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| Posted: Wed Mar 04, 2015 9:13 pm Post subject: |
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I agree about the differences....but its worth it to bear in mind that the schnoor washer ....if you are using the properly speced one has enough over tolerance on the spring load of the bellville to have few if any issues over time with loss of spring force. Add that to the bite of the hardened spiral (and note sprial) serrations. The nordlock teeth are straight....less surface area.
There is also some metal deformation. All of these make for excellent anti-loosening grip.
While the norlock will not fatigue because it is a cam....it is also NOT a spring like a bellville...which is capable of taking up slack as expansion or contraction changes tension.
Advantages to both parts.....but for me...reusability is not a useful factor on bolts this small. If they were 1/2" or Larger and were removed for inspection or service all the time....the much higher cost of large schoors vs the hugher of the Nordlock would start to count In the Nordlock favor.
For these 8mm bolts at just a few cents each for Schnoor washers.....which I can throw away each time without blinking an eye.....I cant, see the advantages of the nordlock. I have used them in numerous places.
Great product.....just not enough advantage for the cost on small bolts. Like I noted...I can buy a bag of 8mm Schnoor 100 count for about $12. Ray |
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Tcash
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Posts: 12844
Location: San Jose, California, USA
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed Mar 04, 2015 10:56 pm Post subject: |
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| Now that version I have not seen. Very nice. Wonder what they cost? I will have to watch and see if they are reusable like the others. If its sprung it may not be. Ray |
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boothead
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Joined: January 12, 2015
Posts: 5
Location: Santa Cruz
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| Posted: Sat Mar 07, 2015 2:29 pm Post subject: |
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| carlvon wrote: |
| boothead wrote: |
An interesting PowerPoint presentation from Schnorr:
http://www.schnorr.com/downloads/technical-informa...al-en.html
According to Schnorr, Nord Lock and Schnorr serrated lock washers perform about the same (Schnorr says theirs are slightly better than Nord Lock--would you expect them to say anything else?). Both Schnorr and Nord Lock WAY out-perform other types of lock washers. Take a look at the wave washer results on the graph, maybe we would be better off with flat washers vs wave washers?
Or maybe no washer (vs spring washers):
http://www.boltscience.com/pages/helicalspringwashers.htm
In any case, even Schnorr acknowledges that Nord Lock washers are a viable alternative for lock washers. More expensive perhaps, but to each his own. |
I never said Schnoor washers weren't good - I was just concerned by the fatigue of the spring. Nordlock washers rely on a cam, not spring, so they are not subject to the same fatigue as a Schnoor washer is, and they can be reused.
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Just received my order of Nord-Lock washers. The fact that they can be re-used is a big plus. Look good, will put them to the test. |
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