Heat88

I bought replacement pedal arms because the teeth on the biggest chain ring on the existing crank set have been sharpened to a point because the chain kept slipping off. On the new arms, inside the area where you screw in the arm puller, there are 4 balls of grease. Where do I put that grease? I found a video on YouTube that shows(on a different make and model bicycle than mine and using his own grease) grease being put on the end of the axle and on the threads of the bolt that holds the arm on. Is that what I'm supposed to do with the grease? Also, I guess the manufacturer expected only a bike shop repairman to replace the pedal arms and not an end user. I can't find any instructions anywhere about what to do with the grease balls. The manual on Shimano's website isn't very good. How does the manufacturer expect me to get the grease balls out of the puller mounting area? I ask not because I don't know how(I guess I'll use a flat blade screwdriver), but because I'm wondering what the manufacturer had in mind. Maybe they expect you to use a grease brush? I have one of those too somewhere.

Since I'm new, I can't post links yet. Go to YouTube and search for "Bike Maintence videos: how to remove pedal arm" to find the video I was referring to. Go to Amazon and search for SHIMANO M361 Hybrid Crank set (Black) to find my crank set.

One more thing. In the picture of the crank set on Amazon.com, there's a piece of metal above the two bolts. What is that for? I hope its not important because the crank set I bought on E-Bay(the same one that's on that page) didn't come with it.

Bill Kapaun

Do you mean bearing balls?
This is a good resource for repair and for you to learn the terminology.
https://www.parktool.com/en-us/blog/repair-help
Crank Service & Bottom Brackets are your likely subjects.

Kontact 

No, he means that the manufacturer has put globs of grease in the extrator threads.

I would assume that the grease is there to lube the threads on the crank bolts. You could also put a minimal amount on the spindle tapers, but wipe it off to next to nothing.

choddo

By the way, chainrings sharpening to a point isn’t because of the chain slipping off. The chain was slipping off because the teeth were sharpened to a point

and that was probably accelerated by a worn chain so I hope you’re also replacing that? It’s important to replace the chain before it gets to +1% extension to maximise the life of the cassette and rings.

Heat88

That's exactly what the guy in the video did, but it wasn't the video I mentioned above. It was actually in another one.
A few questions from that other video:

1. How come he needed a puller to get the arms off but they slid right back on?
2. He tightened the bolts with a torque wrench. Is that necessary?
3. He said the acceptable torque range is 35 to 45 Newton meters. How does he know?
4. When he was tightening the bolts with the torque wrench, the only resistance was his other arm holding the other crank arm. Can you properly torque that way? I've never used a torque wrench myself, but I have seen them used and the person using it was always torquing a bolt that was on a large immovable machine.

If you wanna see the video where the guy is torquing the bolts, search for: Square Taper or Octalink Crank Removal & Installation (Practical Guide)

Heat88

Yeah, I'll check that.

Trakhak

1. It's in the name: square taper. Because the four mating surfaces of the crank and spindle are tapered, they don't fully seat together until the crank is pushed all the way onto the spindle. If you don't torque the bolt fully to spec, the taper allows the arm to wiggle its way off under your pedaling force.

2. Torque wrenches aren't absolutely necessary unless you're inexperienced. But the consequences of guessing wrong on the torque can be substantial: too little torque, and the crank wiggles around enough for its soft aluminum mating surfaces to deform, necessitating replacement of the crank; too much torque, and again, the mating surfaces deform and/or the crank develops a crack(s).

3. He knows the torque spec because he read the spec provided by the manufacturer of the crank.

4. Of course you can properly torque that way. You watched the guy in the video doing it. Not sure why you would ask that question.

That said, my technique is to use two socket wrenches at once (i.e., one torque wrench and one conventional socket wrench). That way, I torque the two crank bolts to spec at the same time. (Tightening both sides at once that way, the torque wrench doesn't click until both crank bolts are torqued to spec.)

Crankycrank

Found this. Apparently, it comes from the factory with 4 balls of grease at the square taper hole for installation. Magnify to see the grease.

Iride01 

Is this a bike made in the last 25 years? The sharp teeth on your chain rings might very likely be intentional. The chain falling off is probably for some other reason. However changing cranks you might unknowingly correct the cause of the chain drop and toss out a perfectly good crank.

ScottCommutes

I agree with all of the above.

I understand OP's concern about trying to get an accurate torque on a part that is free to rotate as you torque it vs. a part that is solidly attached to a machine. It is a little tricky to torque - do the best you can. Not an absolutely critical value. I have a torque wrench, but don't use it for these.

Any place on a bicycle where metal touches metal gets lubed. Places with no relative movement get grease. I usually just use a grease gun with a small tip and spread it with my finger. Any grease will do. The manufacturer automated that particular step as a convenience for you.

The square taper is an ingenious mechanism (also found on certain machine tools). You push it into place via a bolt and likely will need a special extractor tool to get it off. Threads are provided for the specific purpose of installing the extractor tool. Extracting a crank with the tool is very easy but a little bit ingenious/elegant.

I have in my life replaced a few parts that, looking back, didn't need to be replaced. Not the end of the world, especially when you believe yours has seen many miles and much wear.

Trakhak

Yes, it's not an absolutely critical value, but someone who has never installed cranks before can easily underestimate or overestimate the correct torque. Using a torque wrench eliminates the guesswork (assuming the wrench isn't wildly out of adjustment).

Using a torque wrench on one side and a socket wrench on the other sets both bolts to the correct torque at the same time, eliminating the trickiness of the job.

wheelreason

How do we know that each bolt will share the torque equally? and are you using the same length wrench?...

Trakhak

You're joking, of course, but for those to whom the answers aren't obvious:

The length of the socket wrench is irrelevant. Otherwise, for example, you'd have to worry about the fact that the crank arm you hold to resist the turning force is shorter than the torque wrench.

Amplifying: the torque set of the two (finger-tight) bolts can only be brought to three possible states:

1. Both are below the correct torque setting. No click.

2. One has tightened to the correct torque setting but not the other. No click.

3. Both are at the correct torque setting. Click.

I've explained and demonstrated this simple technique to a few mechanics. Some get it immediately, some have to think it through. But they all quickly stopped using the single-torque-wrench technique, once they realized that the two-wrench technique was both easier and faster and guaranteed equal torque for both bolts.

Editing to add:

If only one bolt needs to be torqued to spec (i.e., when the other is at or even above the correct torque), it still makes sense to use the socket wrench plus torque wrench.

When the looser bolt is brought up to the correct torque spec, the torque wrench will click. The result is the same as using only one (torque) wrench, but it's easier and less awkward to use two wrenches.

In my experience, all the objections raised to the two-wrench technique can be rebutted by saying "That would be true of the one-wrench technique, too."

Kontact 

While this is very thoughtful, it is completely unnecessary and requires twice the number of tools. There is nothing inaccurate about using one or the other crank arms.

ScottCommutes

The best way to do it would be however the manufacturer specifies. I expect either method would get similar results, but I suspect the two wrench method would be slightly less accurate because there are twice as many threads (with friction) in the equation.

Trakhak

Oh dear. Picking up two wrenches instead of one.

Seriously:

Of course there's nothing inaccurate about using one crank arm or the other. I didn't suggest otherwise.

And: sure. Few bike enthusiasts have a shop-quality torque wrench capable of being used to set crank bolt torque lying around. But if you do, try using the two-wrench technique sometime.

In any event, as I said, it's faster and eliminates the need to grasp the (annoyingly short) off-side crank arm and is thus easier (especially now that I'm an elderly weakling). People who work in bike shops generally like discovering ways to make a task both faster and easier, with no downside.

I admit to feeling a bit proprietary about this discovery. It's a shame that so few people seem aware of it. And now it's the twilight of the two-bolt crankset era, so it's effectively obsolete anyway.

Trakhak

I admit that it can be a bit hard to get your head around what's happening when you use the two wrenches.

But think it through. Regardless of how much friction in total is in the system represented by the two sets of threads, the torque wrench has to overcome the resistance in each bolt separately. One bolt is almost certainly going to present more friction than the other, so the bolt with lesser friction hits the torque spec first, followed by the one with more friction. Once the bolt with lesser resistance is at spec, the other tightens precisely as if you're hold the crank arm instead of the wrench.

.

base2 

Only because it is germane to the discussion, the effect is similar to balancing a yardstick horizontally on horizontale index fingers. When one side has less friction because the center of gravity is no longer in the central area between the fingers, there is movement until it sets back down to repeat with the other side doing the same. The result is that no matter where you place your fingers on the yard stick, when you bring them together, you will always find the center.

The same thing is going on here. The bolt that is at the higher torque no longer turns, and the force is transferred to the lower torqued bolt by way of rotation of the spindle. So long as there is no other confounding factors like a crank arm zip tied to a chain stay or a spindle that can not rotate both bolts reach the exact same value.

+1 to Trakhak

ScottCommutes

Sorry, Trakhak. Your method will work fine for this application but is not as theoretically accurate as the one wrench method. Torque is a proxy for measuring the stretch in a bolt. Friction is the enemy of good torquing because you have to push harder to overcome the friction and that extra push can't really be quantified. In certain critical applications, part of the procedure is to oil the threads to reduce the friction.

You admit that your method continues to push on a fastener that has already been properly torqued. This is bad. There will be an equal and opposite reaction as it meets more friction. The wrench will click when the second fastener is properly torqued. The first fastener will be slightly over torqued due to that equal and opposite reaction. Again, the effect is negligible.

Kontact 

When you say "picking up", are you referring to buying a second $100+ torque wrench and another 8mm socket? Congratulations, you've discovered the only possible reason to own two identical torque wrenches.

I don't think this would work with only one torque wrench because you would not know what the second bolt is at since your measure of bolt torque is not to the arms or spindle but too each other. One will arrive at torque before the other due to lubrication, burrs, etc.

ScottCommutes

Reductio ad absurdum might explain this better. Put 1,000,000 bolts in a chain with a torque wrench on one end and try to torque them all down equally at the same time. Obviously not accurate, right? Trakhak's method is the least bad case, because it is only doing two at a time instead of many, but it still is a shortcut.

wheelreason

Teaching "mechanics" about torque both scares me and amuses me....

wheelreason

Absorduto Stupido....

Trakhak

Or weld the spindle in place in the bottom bracket, if you're going to go the reductio ad absurdum route. The question is whether there could be a significant difference between the resultant torque setting of the bolts in a bike. The answer, obviously, is "no." (My guess, though it's only that, is that the difference would be well-nigh immeasurably small.)

All that is required is for the bolts to be tightened to the point where they give good service. And, after all, torque specs are given in ranges for crank bolts and in other applications where the exact value is noncritical.

Kontact clearly understood the principle instantly, since his objections have been confined to the need for an expensive torque wrench for the home mechanic.

For another and very clear explanation, see Base2's post above yours.

Finally, please clear something up for me:

Are you suggesting that, even if you had a suitable torque wrench and a suitable socket wrench ready to hand, you would never try the two-wrench technique, for fear of ending up with one or both of the crank bolts at an inappropriate torque setting?

Kontact 

Well, the need for two expensive torque wrenches.

I torque cranks by leaning over the top tube and grabbing the opposite arm and the wrench and using a push/pull motion from directly above the centerline between them. It really doesn't take much strength at all since all you're doing is keeping the crank arm from moving, which is pretty easy considering that arm is locked at the elbow. I think a lot of this kind of discussion comes from a lack of good technique - (for instance) I have never found a crank I couldn't extract, no matter how difficult, by arranging myself so I have a foot on one crank.