Topic: '74 Fork vs. '77 Fork

[EastSidinA4]

Ok, I have a 1974 CB750K and when I installed the brake calipers back on, I stripped the inside of the lower aluminum fork. I've tried to tap it with a bigger hole but with no luck.

My question is, I have a spare set of 1977 fork lowers, are these interchangeable within these years? Can I use the 1977 fork lowers (the aluminum part that holds my caliper and wheel) on my 1974 wheel/fork/brake set up without any issues? They look identical from just looking at them and the internal's look the same. Im just not 100% if they have the exact geometry.

[SOHC Digger]

Can you heli-coil the old lower?

[EastSidinA4]

Do you think that would be safe since its the bolt that holds on the brakes? I dont know much about helicoils...do I just drill out a bigger hole and drop them in there and screw them back on?

The fork swap wont be a big deal since I have an extra set of fork seals. I just wanna know if I'm wasting my time trying to install fork lowers that wont even work.

[SOHC Digger]

Heli-coil is a safe option. There is not a lot of metal removed to drill and tap for the helicoil, and after a few drops of locktite on the helicoil prior to installation, it will be just as strong as before.  As far as whether they are compatible, I am not sure.

[Honda?]

Aww damn. Well if you decide against the helicoil would you sell me a fork tube without chrome pitting?

[754]

If you already drilled bigger, then a helicoil may not fit..

 But in that case I would tap to next closest size and make a stud..
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 77 legs will fit but swap both as legs are longer.. better yet just install complete 77 fork assemblies (not trees), they can be run without covers and not rust.. may have to use a 77 fender..

[EastSidinA4]

If you already drilled bigger, then a helicoil may not fit..

 But in that case I would tap to next closest size and make a stud..
....................................................................................

 77 legs will fit but swap both as legs are longer.. better yet just install complete 77 fork assemblies (not trees), they can be run without covers and not rust.. may have to use a 77 fender..

Fortunately I drilled to the next size up which is M7 and that happens to be the size that the M6 (which is the one i stripped) helicoil. It seems like a good fit when I tightened it, this time making sure not to over tighten (hopefully tight enough).

The 77 legs seem identical with just looking at them, they dont look longer at all. I used the internals of the 77, hopefully that wont be a problem?