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Discussion Starter #1
Anyone tell me how to check the taper of the ball joint studs?

Since I have now used all of my 07-13 420 knuckles on other people's projects, I have discovered that OBS 420 knuckles have gone through the roof in price, and thus the used market has dried up on them too. New ones are up to $165 EACH....

So, I'm thinking what about reaming the bottom ball joint hole out a hair to accept the larger Foreman ball joint, allowing me to use the dozen or so Foreman 500 knuckles I have on hand?

I held the two ball joints up side by side today (51355-HP5-601 and 51375-HP5-601) and the latter has a slightly bigger diameter on the barrel. I'm guessin (will check after work) that the stud is also slightly larger, so how do I tell which tapered reamer I would need. It appears most automotive use a 7 degree, but there are other's availabe.

Any machinists here who know?
 

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ahhh...the joy of slapping parts from other makes and models..gotta love it. I would think the threaded part would be the same ?. as for the ball joint hole in knuckle ?, you could always just grind the hole larger ?. myself ?..nope..stock sure saves the headache !!..lol.
 

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Discussion Starter #3
I'm looking at the bottom a-arm hole vs the ball joint stud. The 500 knuckle takes the bigger ball joint, The 420 knuckle takes a smaller ball joint. The nut on both is the same, but I think the stud on the bigger ball joint is bigger where it goes in the hole in the a-arm. That said, if I can find the proper reamer I could ream the hole out a little bigger and use the 500 knuckles.

I could just use a SuperATV or Highlifter conversion, but I like to stick to all Honda parts if possible. Makes the probability of finding parts in the distant future much more likely
 

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I'm looking at the bottom a-arm hole vs the ball joint stud. The 500 knuckle takes the bigger ball joint, The 420 knuckle takes a smaller ball joint. The nut on both is the same, but I think the stud on the bigger ball joint is bigger where it goes in the hole in the a-arm. That said, if I can find the proper reamer I could ream the hole out a little bigger and use the 500 knuckles.

I could just use a SuperATV or Highlifter conversion, but I like to stick to all Honda parts if possible. Makes the probability of finding parts in the distant future much more likely
yeah, if the thread hole is larger ?, you will have to solve that part for sure.
 

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Discussion Starter #5
Shank is not only bigger diameter, but also longer on the bigger ball joint.

Luckily, while digging around looking for Foreman brakes to send to @SamUK I discovered that I did have a set of the OBS 420 brakes after all, so those can go on my kid's 300 (which will require grinding out the upper ball joint hole in the 300 upper a-arm to accept the larger 420 ball joint).

Also, PSN had a 33% off sale this weekend and they happened to list a set of 2013 disc brakes Saturday morning so I snapped those up to use on the other 300 I'm going to get going as soon as I finish with my daughter's.

Just in case anyone is wondering, here are pics of the Foreman ball joint and 300 ball joint side by side.
 

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Discussion Starter #7
PSN was selling the OBS 420 knuckles for $27 and change for a long time. I hoarded several sets, but ended up using them on other people's machines and used them all before I got to my 300's!

The set they had Saturday morning did not show up on the "what we bought" list, but I have my ebay set up to notify me when their ebay store lists 420 knuckles, so I got the notification from ebay, then went to PSN's site and bought them using the discount code.

The knuckles were listed at $60 each, so definitely not cheap like they used to be, but at 33% off they weren't horribly expensive.

Guess that's what I get for using all my cheap parts on other people's stuff!
 

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My answer would be, measure the taper and buy and adjustable reamer. Are 450 or 500 the same as 420? I can measure for you if they are.
 

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My answer would be, measure the taper and buy and adjustable reamer. Are 450 or 500 the same as 420? I can measure for you if they are.
who are you ?, and where have you been ?..hmmm.imposter !?!...lol.
 

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I think the term for that ball joint stud is A-taper , A-taper is used in a lot of pins I deal with with heavy equipment , I have seen bigger sized a-taper reamers , like 1 1/4 and 1 1/2 inch sizes , but never a small size such as a ball joint for a Honda ----if anyone would have one I think it would be a company called MSC

This would be a lot of work , but to repair a-tapers on equipment, they sell weld in inserts , you drill or cut the old taper out and weld the new insert in , that wouldn't be feasible in this situation , just throwing it out there as food for thought
 

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Discussion Starter #11
I think the term for that ball joint stud is A-taper , A-taper is used in a lot of pins I deal with with heavy equipment , I have seen bigger sized a-taper reamers , like 1 1/4 and 1 1/2 inch sizes , but never a small size such as a ball joint for a Honda ----if anyone would have one I think it would be a company called MSC

This would be a lot of work , but to repair a-tapers on equipment, they sell weld in inserts , you drill or cut the old taper out and weld the new insert in , that wouldn't be feasible in this situation , just throwing it out there as food for thought
Those weld in inserts would be good if you wanted to keep the factory upper ball joint in the 300 a-arm. You could weld in an insert to scale the bigger ball joint hole in the 420 knuckle down to the smaller 300 top ball joint shank.


Similar to the torch tip used in this thread to shim the ball joint shank.
https://www.hondaatvforums.net/forums/brakes-suspension/59665-knuckles.html
 

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Like someone said, I personally wouldn't slap it together I'd get the right parts for your model, ball joints can't b taken apart, check I wish replacements either Honda or aftermarket had Grease fittings standard. But they dont
 

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Discussion Starter #13
Zerks would be nice.

Since there is no OEM disc brake conversion that directly fits a 300, and I'm not keen on aftermarket china kits, and now that I've found a set of OBS 420 brakes, I'm going to go ahead and just enlarge the upper ball joint hole in the upper a-arm to accept the 420 ball joint and use the 420 brakes. Lower ball joints are the same so other than enlarging the hole in the upper a-arm everything else is bolt and go.

Here's where I did the swap a while back on my buddy's 300.

https://www.hondaforeman.com/146-honda-rancher-350-400-420/131090-basfnb-s-420-disc-brakes-300-a.html
 

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Have you considered just buying the pads and welding them to the stock arms. Who ever is making the pads obviously knows the taper I'm guessing he's not telling either lol
 

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Discussion Starter #17
I thought about doing it with the upper a-arms, but since all I have to do is slightly enlarge the upper ball joint hole in the a-arm, that's cheaper and easier than buying pads and having to have them welded on.
 

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Have you considered just buying the pads and welding them to the stock arms. Who ever is making the pads obviously knows the taper I'm guessing he's not telling either lol
They do tell if you ask nicely :grin:
@Jeepwm69 I can make and ship pads to you or ship you a drill/reamer. Or of course I can tell you the sizes if you have a hardware store locally that supplies such items.. I’ll PM you :)
 
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