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Old 11-21-2012, 02:57 AM   #1
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Default Tip: How to reduce the friction in LCC and LNC.

(Extracted from an older thread.)

When I first ran my at the time brand new LCC it was sluggish, weak (as in low torque), and in three minutes the motor overheated.
Obviously something was wrong!
It took me half a year to identify (and handle) all the sources of uneccessary friction in the rig. Now it's only the inherent sources (mostly the worm drives) that are left.

Here's what I've found, and how to handle it:

Lubricants
The LCC (excluding the motor) can do with only two(*) lubes:
1. A spray-on dry film lubricant (DFL) based on either PTFE (Teflon), which is great but expensive, or Silicone, which is good and cheaper.
2. A water resistant grease that can handle high pressure and beatings. "Marine grease" or something Molybdene Sulfide based will do nicely.

What to check
(Going from the motor out towards the wheels.)

1. Pinion.
The pinion should mesh nicely with the idler gear. With the pinion in place you should be able to rotate the idler a little (like 0.2mm or 0.01") without it touching the pinion.
Lubrication of the pinion, as well as all other cog wheels in the LCC, isn't necessary. If you want to do it use DFL. (Grease will attract dust and dirt, therefore dry lubrication is the way to go.)

2. Gearbox center plate. (LCC only)
The three screws holding this plate to the housing are typically drawn too tight, which cause an axial strain on the main bearings and thereby friction. The screws should be drawn all the way in, and then losened ~1/4 rotation.

3. Dig forks. (LCC only)
If you actually use the dig apply DFL (or a thin oil) on the dig plates where the forks run.
If you don't use the dig, remove the dig forks!

4. Drive shafts.
The joints do wear a bit. Dissemble and apply DFL (or just apply some thin oil without dissembling, risking dirt to stick and make the situation worse).
While you're at it, apply DFL to the entire exterior of both shaft halves to make them slide easier over obstacles.

5. Worm drives.
Make sure the spools are properly seated by pushing them side to side. There should be a hint of room to wiggle the spool between the bearings. Adjust by adding/removing shims if necessary.
Apply a liberal amount of grease. The task of the grease is not only to reduce the heat generated, but also to transfer the generated heat from the gears to the casing.
(It gets even better if you also replace the front drive with HD parts, since they have a different gearing causeing the front wheels to spin slightly faster than the rear. The difference in speed decrease friction while turning, which is what you do most of the time.)

6. Rear axle.
The long screws holding the rear hubs are often overtightened, making the spacer press against the bearings causing axial pressure and friction.
The proper way to mount the rear hubs, axle and bearings is to
a) place the rear axle (shaft) into position (inserted in the worm spool).
b) place a bearing at the inner edge of the hub.
c) thread the bearing and hub onto the axle and push it into position.
d) add the long spacer and the outer bearing to the axle.
e) mount the hub end by turning the screws all the way in and then back them out ~1/4 turn.
f) add the short spacer.

7. Wheel hexes.
In their standard shape the ring like "shim" on the inside of the hex will press against the bearings if you draw the weel nuts tight, causing friction and gradually wearing down the bearings.
The easy fix is to not tighten the wheel nuts.
A better fix is to grind off the rings from the hexes, like this:

That way you can tighten the wheel nuts as much as you like.

Results
I've done all of the above, including removing the dig forks, and there's a huge difference compared to the original state!

(*) You will probably want a third, O-ring grease, to keep the shock absorbers fit as well. That's not so much about driving friction though and therefore out of scope for this article.

Last edited by Olle P; 09-27-2013 at 02:13 PM. Reason: Minor changes for extra clarification.
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friction, lubrication



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