I'm posting a repair/upgrade method for the NB steering axle (model: 61000 & 61002) drive-cup/hex-shaft ("U-Joint that attaches the wheel to the toy."). This repair has successfully held up under some nasty abuse. It appears that this is one of those parts that commonly break, especially after the rig has fallen off a cliff, or just dropped. I'm aware the company sells the replacement part fairly cheep. Even with it being cheep to order, I was too impatient one evening and started a repair/upgrade quest. I wanted to eliminate this weak part!



A long series of picture links showing the basic steps involved, including descriptions will be posted in this message (providing the links work correctly). The pictures are not great quality (sorry), but should show enough information to get the basics. I have a camera stand now, so future pictures will be better quality. There will be approximately 14 pics, so I figured hyper-links should be used to reduce the load time for slower connections versus having them all try to load at once.

The following repair method can easily be modified to meet your needs. It would be fairly easy to substitute the plastic parts with metal ones if desired.

I did not find this type of repair posted at the time of repair. I'm not sure if this method repair type has been posted since then, sorry if it already has/was, if not...then here goes....


Step 1. The original part 1/4" hex shaft broke, leaving the 'cup' portion intact (forgot to take photo of broken piece). I used a hack saw blade to cleanly cut the remaining 1/4" hex shaft from the 'cup'. Then I drilled a small hole in the center of the cup followed by a larger 15/64" drill bit. This bit was one size smaller than my 1/4" drill bit, to avoid taking off too much material. I used a solid plastic 1/4" hex handle (originally an electronic tuning tool), any strong 1/4" hex shaft should work well (plastic or metal). Then I scribed an outline of the hex shaft (centered) onto the back side of the 'cup'.
http://i119.photobucket.com/albums/o158/godshour/IMG_0631.jpg

Step 2. Used some inexpensive needle files to start shaping the hole into a tight 1/4" hexagon.
http://i119.photobucket.com/albums/o158/godshour/IMG_0634crop.jpg

Step 3. Completed filing the plastic hex, plastic hex shaft fit snug.
http://i119.photobucket.com/albums/o158/godshour/IMG_0633.jpg

Step 4. I took my larger soldering iron (a small one will work too) and carefully melted the end of the plastic hex shaft, working it into a flat 'nail head' shape. The rough looking 'nail head' axle shaft "melt" will stay firmly bonded. Use only the minimal amount of heat needed to melt/form the nail shape. Excessive heat will turn the plastic brittle, minimal heat will keep it very strong.
http://i119.photobucket.com/albums/o158/godshour/IMG_0634.jpg

Step 5. Using a cordless drill for my lathe, I used a file to smooth the underside and top of the melted 'nail head'. Use minimal lathing for the underside of the 'nail head', do as much by hand as possible! This is to avoid filing off the edges of the hex shaft. The underside of the 'nail head' shaft will mate with the 'cup' hex hole. Then I carefully "lathed" the radius of the 'nail head' just enough for it to bottom-out inside the 'cup', nice and snug.
http://i119.photobucket.com/albums/o158/godshour/IMG_0636.jpg
http://i119.photobucket.com/albums/o158/godshour/IMG_0637.jpg

Step 6. Additional cordless-drill lathing was required to create a small bowl shape dip on the 'nail head' to allow the rounded 'dog bone' head to fit its normal depth into the 'cup'. I just used a sharp corner of my file to eat out the bowl shape with the drill running. I noticed the 'cup' and 'dog bone' normally meet and operate half-way in, by checking the other "unbroken" side for comparison. This is how I was able to determine how much bowl to cut.
http://i119.photobucket.com/albums/o158/godshour/IMG_0638.jpg
http://i119.photobucket.com/albums/o158/godshour/IMG_0642.jpg
http://i119.photobucket.com/albums/o158/godshour/IMG_0644.jpg

Step 7. Once I was happy with how the 'nail head' axle shaft fit (snug) into the cup, it then was time to cut the plastic hex axle-shaft to length. The length was measured from the stock NB part, this length is measured from the outer bottom side of the 'cup' to the end of the hex shaft. I made sure my new 'nail head' axle shaft was firmly seated into the 'cup' and gently locked the hex shaft portion into my vise-grip. I measure the correct distance from the 'cup' down the axle, plus added the thickness of my hack saw blade. Now I could have a nice flat cut using the vise-grip flat side as a simple guide, while insuring it would stay long enough by adding the hack saw blade thickness.
http://i119.photobucket.com/albums/o158/godshour/IMG_0646.jpg
http://i119.photobucket.com/albums/o158/godshour/IMG_0647.jpg
http://i119.photobucket.com/albums/o158/godshour/IMG_0648.jpg

Step 8. Drill a small hole for the screw lug which holds the wheel to the axle-shaft end. I don't remember the drill size, but it was small enough to make sure the stock NB screw would snuggly make its new threads into the plastic, but not too tight, it could crack. In order to center the hole perfect, I slid the axle-shaft into the wheel. Using a drill of the same size as the NB wheel screw hole, I twisted the drill bit a few times with my finger to make a divot perfectly centered on the axle-shaft end to guide the small drill bit. After removing the plastic hex axle-shaft from the wheel, I drilled the small screw hole slightly longer than the screw. The screw went in snug, and came out snug leaving nice internal threads.
http://i119.photobucket.com/albums/o158/godshour/IMG_0650.jpg
http://i119.photobucket.com/albums/o158/godshour/IMG_0651.jpg

Step 9. At this point you might want to use a medium strength glue or cement to create a semi-strong bond between the new 'nail head' axle shaft and the cup. This would provide a rigid one-piece part similar to the stock NB part. Now that I said that, I have to say that I have not yet glued my part together. I installed it to see how it was going to work, and it has still held up strong as a two-piece drive cup! It is not "perfect", as it has some extra movement causing the wheel camber angle to be off a little. Gluing it will make it right (if I get around to it). I would not recommend using too strong of a glue or cement in case a future repair is needed, but I suppose it could be ground out.

This two-piece method opens up an easy door to make these parts from metal, which would probably not require the use of any glue to keep it rigid. Recreating the two-piece 'cup' or the 'nail head' style axle-shaft will be easy using plastic or metal, and some very basic tools. In fact many 1/4" hex nut-drivers for drills could be modified to make this part. I have many 1/4" socket based tools and bits to make drive axle parts with. I'm glad NB used 1/4" hex, since it will be simple to beef things up without needing hobby store parts.


REAR AXLE UPGRADE/REPAIR:

I was thinking about beefing up the "non-steering" rear axle, as some have posted these breaking too. I will eventually be working on a solid one-piece 1/4" straight axle that would be the whole length from wheel to wheel. The original spur (wheel) gear that's mounted on the small stock NB (approx. 5/32") hex axle shaft will be modified to slide onto a 1/4" shaft. Then modify or replace the axle bearings for the 1/4" shaft. Then drill and tap the ends of the shaft for the wheel lug screw. This will eliminate those plastic axle-shaft end pieces. To prevent the axle from sliding side-to-side, some small screw-down lock collars could be placed inside the housing onto the axle, next to the outer bearings. I'm not sure if you folks have posted this type of upgrade too. If it has not, then I wanted to put it out there now while I was posting this other repair/upgrade to give others an opportunity to try it if interested, since I'm not sure how soon I will get to it (since I'm still working on a gearing mod, and will still take a while).

This message has been edited. Last edited by: Mr Dean,

sweet man... i knew you would be back on soon with somthing crazy for the NB, so are you going to be making any for the rest of us... and how much $$$$$$

where did you get the black part

Mr Dean, thanks for the great post.

Amazing write-up. Very helpful.

I also would like to thank you for taking the time to document your work - "great idea" ! - and now we also know how

wow thats a very descriptive post. sounds like an awsome repair job. also how did you fair on your casting of metal gears.if i remeber correctly.

Ksully,

I am glad to see that this post might help others come up with some repair methods. My repair has still held up well. I used a thin washer on the axle between the wheel shaft and the stationary hub which encases the drive knuckle. After adding this washer I have not had to glue my two piece axle-shaft together to eliminate some looseness it had. The washer makes it nice and snug without binding, of course if it was too thick, it would bind.

As for the metal-casting gear project, that got put on hold. I think it still has good potential...but I am too limited in my two room apartment, and lack of garage/workshop. I might take it up again this spring/summer when weather is more favorable outside. I live in NW Wisconsin, and this winter has been a bit nippy with daytime temps not making it above zero F, and night temps in the -20 to -30 F. It has finally started warming up (meaning actually above freezing), and now we are seeing a couple feet of snow melting away.

My rig has seen some upgrades this winter though...this includes re-gearing! I made two universal motor brackets that allows extra gears to be mounted on it, while allowing the motor to pivot so the pinion can be adjusted to mesh nicely with the gears. I am using the stock motor, plus some plastic/nylon gears from a tank/track toy that I purchased from Goodwill for a couple of bucks (it also had a good 9.6v battery-pack with plug hanging on it), can't beat that for a couple of bucks. My gearing is now in the 90-100:1 range, I still need to calculate it again, but not by counting the teeth, instead by the gear diameters since it has a change in pitches. It still uses most of the NB gears, with mods. I took some pics that I will post for you folks to check out. It might be a good alternative for some who might try a more complicated approach, it will require the inside of the axle housing to be cut and ground with a Dremel type tool. The gears work great! It has a ton of power with the stock motors, batteries last much longer. It crawls so well and still has enough speed to grunt through tough spots.

I also did a modification to the stock steering! It is roughly 33% stronger & slower turning. It still uses the stock steering servo. I modified the servo output 'pitman arm' by replacing it with a shorter one. Then it connects to some brass rods to each wheel. The old steering linkage is out. The new 'simple' system is cleaner, meaner, and fairly cheap and easy to do. I have not checked this post in a long time, so maybe someone else has made this type of steering mod already, but I will post it too just in case. It looks really cool.

I will need to search the post for names of other folks rigs, but if available I will call my rig Rockcrusher. The new gear system sounds a bit like one of my past GM Muncie M-21 4-speeds, which was quite noisy. But probably not as loud as the famous M-22 "Rock Crusher" which I might use to name my rig with, if available.

As for sources of 1/4" Hex stock, that is not real easy to find and requires a lot of searching and imagination. The plastic like material I used was the center handle portion of an electronics trimmer-pot tuning-pencil. This style tool was most common with the old TV (television) tune-up tool kits, which are still available today. Though it will be hit and miss weather the center handle portion will be a perfect 1/4" hex shape. These tools are fairly inexpensive but very tough since they need to withstand a lot of torque. I will look for some links I have to post showing what I am writing about. I also found a place selling some 1/4" Derlin hex stock, but if I remember correctly their minimum shipment was for many feet. I will post it too, maybe someone else here will find another (newer) source allowing for smaller orders of the material.

Dean.

my yukon already has a metal hex shaft on the inside i think..

it does. I'll have to take the wheel apart.

but its got the ball joint on the drive with another plastic cup. then there is a metal ex shaft that joins the wheel to the axle. there is a Plastic Hex spacer that fits inside the wheel where the bolt goes through. then there is a metal spacer and a nut to tie the whole thing in.

Here are some links to give some ideas as to where some potential sources for 1/4" hex bar:

A couple of links to places that sell similar tools of which I made my replacement "black" hex part with. I don't know if these tools handle portion is like the one I had, but with some research I'm sure some will have a 1/4" hex handle in the center part of the tool. They are typically cheap, and will have two or three inches of handle length. They are tough, providing they are as good as the old ones. The colors will vary.

http://www.minute-man.com/acatalog/TV_and_Radio_Alignment_Tools.html

http://www.unicornelex.com/subcategory.php?cat=E24J00&


Here's a place that sells brass 1/4" hex bar

http://www.farmers-copper.com/brassrods_1.cfm


Another place that sells PTFE 1/4" hex bar (This stuff should be awesome, very tough. I might order some one day.)

http://www.interplastinc.com/temp10.htm

These links are for just reference, I have not made any purchases from them, and cannot verify anything but what is on the web site for reference material.