Ironhead Custom Neck Cups

[oldkarkid]

Here is a little project I am working on for a member here. The Ironhead I am building has had a Honda CB 750 front end fitted to it. In order to make the conversion, special neck cups need to be made. 3" round bar is turned down in the lathe .001" at a time and must be precise in almost every area of the piece. Timkin tapered bearings are used and races are pressed in. They take nearly 5 hours per cup to produce.

[jjw]

That looks like a 'before' pic? Where's the after (cup) pic?

[oldkarkid]

The cup sitting on top of the round bar is the cup I made. In a way this is both a before and after picture.

[fergerburger]

is that mild steel? I thought neck cups were hardened.

[rivethog]

Neck cups arent' hardened (at least none of them I've ever seen are). Only the race is.

[rivethog]

Unless your lathe is underpowered, there's no reason to take .001" cuts to remove large amounts of "waste" material. A single .125" cut will save 124 .001" cuts. That's a LOT of time saved. If your lahet is underpowered, then kudos for having the patience to make do with what you have.

[oldkarkid]

Originally Posted by rivethog

Unless your lathe is underpowered, there's no reason to take .001" cuts to remove large amounts of "waste" material. A single .125" cut will save 124 .001" cuts. That's a LOT of time saved. If your lahet is underpowered, then kudos for having the patience to make do with what you have.

Neither one of our lathes is underpowered.I do make bigger cuts, but only to rough cut. I dont like beating up bits, thats all. I enjoy it so thats all I really care about.

If I wrote down all the cuts I made, this post would have been way over the top for most people to enjoy. I dont like to get all technical and try to be above everyone else.

[alank]

I'm with rivethog, don't see 5 hrs for that neck cup. Take large metal removing cuts until you get down to .010 of the size you want, then shave it down to perfrction. My machinest friend at the machine shop says he never takes less than .040 cut (.080 total diameter) to remove unwanted metal. Thats on a large lathe, I have a small lathe and usually cut .015 to .020 off for waste material.
Work looks good, I assume the cup you made will be welded to the neck, or is it placed in the original neck cups?

[oldkarkid]

Alan, they are made to slip fit into the frame just like big twin neck cups. That way it can be reversed if ever needed.

[Geeto67]

They are looking great.

The cups are being made for my "secret project" 74 IH. When I have the bike knocked up into a roller I'll give everyone a look.


here is what I started with:


a semi running 1974 that I traded a running and reliable 1973 cb750 for straight across. It belonged to a friend and when the wiring harness burned up on him on his way home one night he traded it to me in a fit or rage.

This bike so far has proven to be the epitome of how an IH gets a bad reputation when a bunch of ham fist-ed previous owners who don't know what they are doing work on a perfectly good IH. My buddy paid $2K for this bike by they way and if I were there to stop him I would totally have, there were glaring problems with it.

The biggest problem was the wiring. The previous owner before my buddy had wired the bike with....no shit...lamp cord from home depot and left over 60's Chevy small block charging components (voltage regulator, rectifier, coil). He mounted these on plastic mounts he made from what looks like cut up plastic drawers kids usually use in college dorms (that you see on the streets of NYC all the time come garbage day in may). Half the oil tank mounts were missing and the other half were broken. There were about two places where a nut-sert was needed to mount an original battery box and oil tank mounts I had laying around. There is at least one bolt broken off in the engine cases - it isn't leaking so far but it soon will. The forwards were junk, so much play in them that you had to reach down and fiddle with the shift lever to get the bike to shift into neutral when the bike was off.