Arrma Kraton 6s driveshaft pins

[Starfox2005]

Hi all I am new to the forum and I have a Kraton 6s. Recently the truck broke a rear driveshaft pin and I am currently looking for a way to just replace the pin. I have already read the other post on how to remove it but am wondering if anyone has used a 1/8in pin. The size is 3mm but here in the U.S. the hardware stores don't sell pins in millimeters. Just trying to fix it ASAP. Thanks!

 

[PaPa Thorn]

They might not sell metric pins but they sell metric drillbits. Cut the end off.

 

[Starfox2005]

They might not sell metric pins but they sell metric drillbits. Cut the end off.

I thought about this but I would like to replace multiple with the least amount of money spent. Because I think you can only get about one pin per drill bit. I'm wondering if a 1/8in rod will work in place of the 3mm pin. I just don't know if it is not possible to squeeze the little extra diameter into the shaft pin hole. Thanks for the advice though!

 

[Jimbobjr]

You wont be able to force the pin into 3mm hole. .007" does not sound like much but it will not work. either get the mugen drive pins or dowel pins from amazon and cut them to length.
https://www.amazon.com/s?k=3mm+dowe...649011&tag=googhydr-20&ref=pd_sl_4l8abhbdtb_e

 

[pstill9302]

I just went through this exercise as the pins my pins were a little "flattened" where they ride in the drive cups, but my dogbone was fine. You have to be very precise about the diameter of the pin that you are using. Drill bits sound like a bad idea to me as they are extremely hard, not sure about the diameter specs, and are not cost effective as mentioned. Typical dowel pins that you will pick up from anywhere are going to be "oversized" pins (this is on purpose, as they are meant to press into the nominal size hole, 3mm in our case.) So the pins are about .002-.008mm [.0001"-.0003"] oversize (DIN 6325.) This is too tight/too much press into the dogbone hole (I know from experience, I tried and ended up bending a couple about 2/3 the way thruogh the hole and having to pull back out.) SO I took my standard dowel pins and chucked up in the drill will some 400 grit and polished them down to an undersized pin spec (-.014mm [-.0005."]) These pressed in equivalent to the existing pins. Best to have a good pair of calipers or better yet micrometers to size properly if you do this, measure the existing pins and polish your new ones to spec. I kind of "winged it" with my crappy calipers and having previous experience with this sort of thing at work. You can get undersized pins from Misumi or elsewhere (h7, g6, or ISO 2338-h8.) But unless they are specifically noted as undersized you will most like have to take them down. You could also ream out the hole to use standard pins but you need a good reamer (not just a 3mm drill bit.) Amain hobby has these that look like they would work:

 

[Starfox2005]

You wont be able to force the pin into 3mm hole. .007" does not sound like much but it will not work. either get the mugen drive pins or dowel pins from amazon and cut them to length.
https://www.amazon.com/s?k=3mm+dowe...649011&tag=googhydr-20&ref=pd_sl_4l8abhbdtb_e

Thanks for the information!

 

[Starfox2005]

I just went through this exercise as the pins my pins were a little "flattened" where they ride in the drive cups, but my dogbone was fine. You have to be very precise about the diameter of the pin that you are using. Drill bits sound like a bad idea to me as they are extremely hard, not sure about the diameter specs, and are not cost effective as mentioned. Typical dowel pins that you will pick up from anywhere are going to be "oversized" pins (this is on purpose, as they are meant to press into the nominal size hole, 3mm in our case.) So the pins are about .002-.008mm [.0001"-.0003"] oversize (DIN 6325.) This is too tight/too much press into the dogbone hole (I know from experience, I tried and ended up bending a couple about 2/3 the way thruogh the hole and having to pull back out.) SO I took my standard dowel pins and chucked up in the drill will some 400 grit and polished them down to an undersized pin spec (-.014mm [-.0005."]) These pressed in equivalent to the existing pins. Best to have a good pair of calipers or better yet micrometers to size properly if you do this, measure the existing pins and polish your new ones to spec. I kind of "winged it" with my crappy calipers and having previous experience with this sort of thing at work. You can get undersized pins from Misumi or elsewhere (h7, g6, or ISO 2338-h8.) But unless they are specifically noted as undersized you will most like have to take them down. You could also ream out the hole to use standard pins but you need a good reamer (not just a 3mm drill bit.) Amain hobby has these that look like they would work:
View attachment 140058

Ok thanks I am going to take a look online. If you undersize the pin then do you need some kind of adhesive?

 

[pstill9302]

No, the hole in the dogbone must be undersize. I can't accurately measure w/o a set of good gage pins, etc. All I know is a standard oversize pin was too tight of a press. I had to make the pins undersize to press in properly. I just did it on my bench vise with some small 1/4 drive sockets and a 3mm screw (which is typically .002" or more undersize and slips right thru the hole when pressing old ones out.) There is press fit adhesive (loctite 609 for instance) that you can use for slip fit situations but was not required for this. Of course I could have got the one off dogbone that had weird holes in it and standard pins wouldn't go. But I would assume these are made using the same tooling and should be consistent such that they don't have issues with this while producing 1000's of them....I am also assuming the pins you would get from amr, hudy, etc. are sized properly as they are sold for this purpose. Worst case you just buy a new dogbone. Then you can mess with the pin situation on your spare w/o it keeeping you from running.

 

[Jimbobjr]

I push standard dowel pins in no problem with my home made pin press.

 

[PaPa Thorn]

I just went through this exercise as the pins my pins were a little "flattened" where they ride in the drive cups, but my dogbone was fine. You have to be very precise about the diameter of the pin that you are using. Drill bits sound like a bad idea to me as they are extremely hard, not sure about the diameter specs, and are not cost effective as mentioned. Typical dowel pins that you will pick up from anywhere are going to be "oversized" pins (this is on purpose, as they are meant to press into the nominal size hole, 3mm in our case.) So the pins are about .002-.008mm [.0001"-.0003"] oversize (DIN 6325.) This is too tight/too much press into the dogbone hole (I know from experience, I tried and ended up bending a couple about 2/3 the way thruogh the hole and having to pull back out.) SO I took my standard dowel pins and chucked up in the drill will some 400 grit and polished them down to an undersized pin spec (-.014mm [-.0005."]) These pressed in equivalent to the existing pins. Best to have a good pair of calipers or better yet micrometers to size properly if you do this, measure the existing pins and polish your new ones to spec. I kind of "winged it" with my crappy calipers and having previous experience with this sort of thing at work. You can get undersized pins from Misumi or elsewhere (h7, g6, or ISO 2338-h8.) But unless they are specifically noted as undersized you will most like have to take them down. You could also ream out the hole to use standard pins but you need a good reamer (not just a 3mm drill bit.) Amain hobby has these that look like they would work:
View attachment 140058

Not cost effective? WTF are you buying drillbits?

 

[HPI Challenge OG]

Papa, you just took the words right out of my mouth... Or out of my head... Or maybe my thoughts but either way I was thinking "drill bits not being cost effective"??? While reading this entire thread.
My go to pin replacement is Bosch titanium coated cobalt drillbits. I can't remember the exact size I use off hand and I'm at work at the moment. But I keep the little package the drillbits came in inside the top of my toolbox so I can just grab it when I'm going to hardware. They come 2 bits per pack for about 5 bucks along with other varying amounts I think up to like 20 drillbits but I swear by them... If you're mechanically inclined and confident with the tools you have to do it the right way, I swear by this method. I've replaced 7 or so broke pins from my 6s Kraton and my 8s exb and have never had to replace those again
We have established that most driveshaft pins are just every so slightly larger than the hole so the pins stay put after they are pressed in. One major thing people forget is heat. Lots and lots of heat before pressing a larger pin in the driveshaft. So as to make the steel expand as much as possible, press your pin and drop that mother in a bucket of room temp water. Leave it for just a few minutes or so and wam bam thank ya mamn you got a dogbone pin you will never have to replace again