oil pan washers

[bridgepress]

I managed to misplace several of the thin washers that slip onto the M6 bolts holding on the oil pan ('03 LeMans V11). Can I do without them? If not, where can I get them? And what is the torque setting for the bolts?

 

Thanks,

 

Brian

[Greg Field]

You can do without them, or substitute any M6 washers that will fit.

[Guest ratchethack]

Brian, this is a Q that comes up with some regularity, and has actually been known to launch pages of something faintly reminiscent of "debate".

 

Yes, you can do without the washers. Is it a "good idea?" Well, not really, since you've lost the value of spreading the load of the bolt head on the casting, and subjected the casting surface to direct abrasion by the bolt head, among other esoteric engineering considerations. Will it "hurt" anything to leave 'em off? Not enough to get too excited about, unless you over-torque, or lose the bolt by under-torquing it without threadlocking it -- with a lick o' care and common sense, avoiding either development won't be much of a concern.

 

There's a spec somewhere in lbs./in., and one in lbs./ft., but no one I've ever heard of actually uses either one (only very expensive, laboratory-grade torque wrenches work with any degree of accuracy down that low anyway), though I'm certain that there's somebody, somewhere who'll insist on it. I b'lieve that if The Pro's are unanimous on anything a-tall, they're unanimous on recommending "just snug" for the perfect application of torque here.

 

Now this is just me, but I find that a shot of Brakleen or some other handy dandy Wonder Spray Liquor that won't leave a residue in a blind, upside-down vertical threaded hole, followed by a blast o' compressed air to clear the hole, and y'er favorite threadlocker (mine's Loctite 242) on a clean bolt has never failed to satisfy in every possible consideration here -- washer or no washer -- including dissimilar metal galvanic response corrosion resistance and ease of re-cycling the fastener virtually limitless times.

 

I'd button 'er up and ride with the usual big Guzzi smile, pick up some washers when it's convenient, and install them later. But o' course, that's just me, and there are many others with equally effective, perhaps even "better" routines, some o' whom will no doubt take pointed exception to mine as being "way too anal", aka, "too much effort".

 

Hope this helps?

[gstallons]

When the time comes, go to a hardware store, auto parts store or a FASTENAL (they sell fasteners,etc.) store. Buy metric washers for your application.There are metric "wave" washers that I like best. Also Fastenal sell "Shnorr" brand washers that are top notch! Always use some sort of washer with a nut or bolt. Re-read Ratchethach's input....

[Ryland3210]

Hi Brian,

I've sent you a PM. I have loads of the Schnorr M6 washers on hand. I supply them on my foot forward comfort controls and buy them in bulk.

John

[Greg Field]

Shnorr washers should never be used against soft aluminum, in my opinion. I've seen 'em used to replace the wavey washers on Guzzi cilinder heads, and they swaged the aluminum into the hole and tightly onto the stud, such that I nearly had to break the head casting to get the head off. If you do use them, limit the torque and most of all make sure to put the coned side against the fastener.

[Ryland3210]

I managed to misplace several of the thin washers that slip onto the M6 bolts holding on the oil pan ('03 LeMans V11). Can I do without them? If not, where can I get them? And what is the torque setting for the bolts?

 

Thanks,

 

Brian

 

According to Raz: "M6, 10 Nm (7-8 lbft for Americanos)."

 

With the Schnorr washers I will send you tomorrow, you can usually feel the torque build progressively as you compress them. Keep tightening until you feel the sudden increase in torque as they bottom out, then to 7-8 ft lb, or as Raz says, "1/4 turn before stripping." I have to admit, however, that I'm not sure how one knows when stripping is going to occur in advance.

 

Personally, I tighten them by feel when putting screws into aluminum. I learned that the hard way, after stripping the threads out of aluminum castings in my early years. I use the torque methog when into steel when the screws are short, and by the turns method when long enough.

[Greg Field]

Look, no one who is sane puts teeth into hardened, spring steel and intends it for use against soft aluminum. But be my guest, and use these things on the sump of a V11 all you want. Don't even joke about using them on mine, though, or we will be scrapping . . .

[dlaing]

Look, no one who is sane puts teeth into hardened, spring steel and intends it for use against soft aluminum. But be my guest, and use these things on the sump of a V11 all you want. Don't even joke about using them on mine, though, or we will be scrapping . . .

I am happy with a standard washer and a little anti-seize.

 

Loctite is also a fine idea, just be sure to select the right grade, but I prefer anti-seize because the bolts spin out more easily once loosened.

 

As for Schnoors, aren't they a bit brittle and often crack?

Also they seem to rust more than other washers.

That has been my experience.

[Greg Field]

Usually, they are unplated. That's why they rust with gusto.

[Ryland3210]

Greg,

 

By the way, the ones I sent are stainless. You might confusing them with chrome plated split lockwashers offered by some companies for cosmetic reasons.

 

The fact they are hardened does not significantly change the modulus of elasticity of steels. However, it does allow them to deflect more without yielding, and the teeth to stay sharp to do their job. The serrations will get a good grip in the aluminum for sure, and the spring effect will keep the screw under prevailing tension to help prevent loosening.

 

For those who wish to use these Belleville spring lockwashers, for best results install them with the circular contact by the inner diameter towards the screw head as Greg mentioned before.

[macguzzi]

washers what washers

[Ryland3210]

Shnorr washers should never be used against soft aluminum, in my opinion. I've seen 'em used to replace the wavey washers on Guzzi cilinder heads, and they swaged the aluminum into the hole and tightly onto the stud, such that I nearly had to break the head casting to get the head off. If you do use them, limit the torque and most of all make sure to put the coned side against the fastener.

 

It sounds like the washers were installed upside down in the example you gave. Pressure die cast aluminum runs around 42-44,000 psi yield, which would be considered relatively hard, so are you saying the head castings are made with another process?

[Greg Field]

I have no idea how the head castings're made. The washers were installed right side up. The teeth on the washers distorted the aluminum enough to jam the head on the studs. I believe hardened, toothed washers should never be used against bare aluminum. I have never seen them so used by any factory. Maybe someone does it, but I haven't seen it. In the application we're talking about, a flat washer does a perfect job. That's what I'd recommend people use.

[Ryland3210]

I have no idea how the head castings're made. The washers were installed right side up. The teeth on the washers distorted the aluminum enough to jam the head on the studs. I believe hardened, toothed washers should never be used against bare aluminum. I have never seen them so used by any factory. Maybe someone does it, but I haven't seen it. In the application we're talking about, a flat washer does a perfect job. That's what I'd recommend people use.

 

I'm fairly certain they are pressure die cast. I've seen schnorr washers used successfully on numerous die cast aluminum valves. Die cast aluminum is hard, but not very ductile at all, so the high degree of deformation you speak of is surprising to me. I think what happened is that somewhere along the line, the heads got hot enough at some point to anneal the aluminum. That would explain what you're speaking of, especially if the screw had long enough thread engagement to permit a very high tightening torque. Then, once the aluminum was softened, the tension on the screw was enough to peen the aluminum around the screw.

 

OK, so let's look at the basics. The physics and industry practice indicate that screws with, say, several diameters or more of length between the head and tapped part act as preloaded springs in tension, so the prevailing frictional torque of the head can prevent loosening. Conversely, short screws are more prone to unloosening, so some form of thread locking compound or spring type lockwasher is warranted. Flat washers may be OK in the long screw case, but increase the chance of loosening in the second case, unless either a spring type lockwasher or thread locking compound is used as well.

 

An alternative is in the case of high tension screws with short shanks where lockwashers are not used. For example, in bolting a hydraulic cylinder flange of 1" thickness, using 3/4" screws, in some applications we preheat the screws in an oven and get them screwed in quickly before they cool off. The thermal contraction of the screw adds considerable tension to the screw, and they stay fastened even under high vibration conditions.

 

So at the end of the day, in applications where the aluminum is of high yield strength, such the die castings used on the Guzzi's, and is not going to be subjected to annealing temperatures, and where the screw shank is short, in my opinion, Schnorr washers are advantageous. I see no harm in using a flat washer under the Schnorr as well, if space permits. So I guess you and I are both right, depending on the application.