Replacing Driveshaft (Dog Bone) Pins On Arrma 6s Vehicles

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Mr.Duke

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I've seen quite a few people over the years asking if it was possible to replace worn pins in the driveshafts on Arrma 6s vehicles and if so, how to go about doing it.

IMG_1308.JPG


Since I've got a few sets of driveshafts laying around with the pins worn down, I figured I'd find the time to rebuild them with new pins and put them back into service again on a couple of new builds I've been gathering parts for.

After a bit of searching around the web for a quality pin, and a tool that would accomplish the job, it's surprisingly easy.....
* as long as you have the right tool * for the job.

Arrma uses two different length pins that are press fit into their driveshafts.
3mm x 12.75mm pins at each end of the center shafts and inner shaft on the front and rear driveshafts.
IMG_1220.PNG

The 2 odd balls are 3mm x 14.5mm pins on the large end of the outside rear dog bones
IMG_1311.PNG


Luckily, Mugen sells high quality pins and are a perfect replacements for both of those stock 3mm Arrma pins.
3 x 12.8 pins Part# MUGC0270 for the 8 smalls
IMG_1312.jpg

and 3 x 13.8 Part # MUGC20271 for the big ends at the rear
IMG_1313.jpg


The longer of the two Arrma pins actually measures out at 3mm x 14.5mm, but the difference of 0.7mm between the the two isn't enough of a variation to make a difference in its function.

to press the pins in and out:

You've basically got 2 options here, and this may or may not be the breaking point of this exercise when it comes to the expense of rebuilding your dog bones with new pins.

Option 1: buy a tool that is specific to the job at hand.
IMG_1316.PNG


Since I'm a fabricator at heart and I don't feel the need to spend $60 on a tool that I can easily make myself, I chose option 2.
The tool I made is an old standing seam roofing clamp used for solar panels that can be purchased online for about $6 and repurposed as a pin press very easily.

How it functions is a bit difficult to describe so here's a quick video to get a better understanding of the premise behind making your own pin press.


Pressing the worn pin out
IMG_1195.JPG

IMG_1213.PNG

Press the new pin in behind the old one
IMG_1305.JPG

The end result.
IMG_1306.JPG

Good as new and ready for more abuse ?

- Edit to add a couple quick videos to show how to make a simple inexpensive pin press tool and how I press new pins into the ends of the driveshafts

Link to aluminum standing seam roof clamp that I repurposed into a pin press
https://www.rapidmaterials.com/S-5-...MIkvbfgaeo5AIVCo7ICh3F4AkjEAQYAiABEgIAR_D_BwE

 
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Wondering why you didn’t just use a bolt for the left one with a dimple? You could get a socket on it easier than risking stripping the Allen head. You also wouldn’t risk drilling thru the grub. Bolt head would also give more leverage too.

And just so I understand the right side, you just snug that side up to hold the shaft and new pin in place, then press it in with the left side?

I’ve replaced u-joints in my work van before and use a similar process to press those out and back in. Obviously this is a much smaller scale, but same principle. ??
 
IMG_1321.JPG

I use a 3/8-24 grade 8 bolt to get it started and finish with the grub screw. There's not enough force being exerted for me to worry about stripping out a hex.
It was late last night when I made the post and left out a few specifics, while also misstated in the video the depth of the pilot hole I drilled to hold the pin. Instead of 7mm it's 2.5mm
 
I went back and edited the OP to include more details on how to make your own pin press for less than $10 and how I press them in.
Are the pins hardened dowel pins? Great press, far better then using a punch, nice work.

They're replacement driveshaft pins for 1/8th scale MBX7R and MBX5 Mugen buggies. Probably tool steel group if I had to guess
 
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“They're replacement driveshaft pins for 1/8th scale MBX7R and MBX5 Mugen buggies.”
I thought maybe they were just standard dowel pins, like from grainger. $7 isn’t bad though, I’m too Pennsylvania Dutch sometimes...
 
You know your stuff.
Thank you. I try to pass on any helpful information to you guys whenever I can. It's what "The Arrma Forum" is all about ?
 
It would be great if we could replace the diffcups just as easy as on the x-maxx. The cups wear pretty fast also.

I wonder if boots and grease would have much impact on wear of the pins and cups
 
I wish we had a way to easily donate money to the guys like this, bickety, liberty, and all the others who contribute to the hobby.

Off to buy some pins- not because mine are worn- but just because. :)

I have no tool- but have a vice, a torch, a punch, and a hammer. I probably can still make it work. Ah-ha-ha-ha....
 
I wish we had a way to easily donate money to the guys like this, bickety, liberty, and all the others who contribute to the hobby.

Off to buy some pins- not because mine are worn- but just because. :)

I have no tool- but have a vice, a torch, a punch, and a hammer. I probably can still make it work. Ah-ha-ha-ha....
Comments like this are worth more to me than money.
Thank you ?
 
It would be great if we could replace the diffcups just as easy as on the x-maxx. The cups wear pretty fast also.

I wonder if boots and grease would have much impact on wear of the pins and cups
Try using wax based lube. I find that really helps my cups last longer on all my trucks. I use white lightning clean ride.
 
Thank you. I try to pass on any helpful information to you guys whenever I can. It's what "The Arrma Forum" is all about ?
Yep? I saw vids on the Mugen tool before, I even asked my LHS if they did that service. He said no because for the cost of the service guys either get their own tool, or just get new driveshafts. ?‍♂️

What I want to know is if anyone has sucessfully used a pair of 12" Visegrips (my fav?) to rotate the pins to get more mileage out of them?
 
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