Topic: Two questions about the rear axle...

[nargent]

My 1976 400f F2 is slowly being rebuilt. After getting new tires, I thought I would try to get the wheels on, and the bike off the Canadian Tire motorcycle stand that I got for Christmas 2 years ago (yes this has been a very slow build, but I'm having fun). Anyway, I hit a snag and would really appreciate some advice. Its probably something simple, but I can't figure it out...

1. The two spacers that fit on the axle: which side is which? I currently have the short one on the brake side and it looks right but I'm not sure.

2. This is the really tricky bit, for me at least: When I try to fit the wheel into the swing arm, there is not enough space to put on both chain adjusters. I've attached a few pictures. I have the chain adjuster in on the brake side, but with this in place, the spacer is hard up against the swing arm on the sprocket side. There appears to be no way I can get the left hand chain adjuster on - I need about 3 mm extra width from the swing arm.

Suggestions please. Feel free to mock me if its obvious, but only if you tell me the answer!

[calj737]

See if these links help you verify your assembly. Your pictures are so small, and the angle is difficult to see the entire configuration.

http://www.cmsnl.com/honda-cb400f-super-sport-400-four-1975-cb400fk0-usa_model444/partslist/F++10.html#results
http://www.cmsnl.com/honda-cb400f-super-sport-400-four-1975-cb400fk0-usa_model444/partslist/F++11.html#results

Click on the link to expand the image for your ease.

[nargent]

Thanks for this. I have pored over the CSML parts assemblies and they don't really help much. I've attached larger pictures.

[754]

On a lot of bikes the sprocket side fits in a seal, then usually there is evidence. Of that. On the spacer. This story of here a small on sprocket side fits hat the spacer can fit into?

[scottly]

The sprocket side spacer looks like it sticks out way too far, and the right side spacer looks to have wear marks from a seal. The spacer on the right may be the left side spacer, but the current sprocket spacer doesn't look like it goes to a 400; maybe it was needed for the old wheel?
The sprocket side spacer is 30mm OD x 33.5mm long, and has a shallow groove near the middle. When seated in the hub, about 14mm is below the bearing retainer surface, leaving about 19mm exposed.
The right side spacer is 30mm OD x 29.5mm long.

[nargent]

Thanks very much Scottly. From the pictures I've been able to find on various threads, I was coming to the same conclusion about the left spacer. The other one is 45 mm and was presumably  put in to fit the non-standard wheel I found myself with. The perplexing thing is that these are the parts I dismantled at the start of this project and I don't remember the fit being especially tight between the swing arm posts. Its possible I wiggled the wheel out without appreciating that it was very tight I suppose. In any event, I can't make these same parts fit back in the swing arm now. I am going to remove 3 mm from the larger spacer and then put it together.

The link you sent me at the end of my last series of posts put me in touch with a really good guy who was looking to sell a pair of 400 four wheels and some other stuff. I was able to drive down and pick the parts up, so now I have an actual 400 four rear wheel and brake plate. It will need a new set of spokes and generally cleaning up, but ultimately I hope to have the correct wheel in the bike with the correct spacers which I've found at 4 into 1. In the meantime I really want to get the bike at least rideable using the wheel that I have. I still haven't been able to identify what bike its from.

Anyway - thanks for the advice and especially the measurements of the spacers!

[scottly]

Put the proper 33.5mm spacer on the sprocket side, and machine the long spacer down to 29.5mm to use on the right side. Otherwise you will be shifting the center of the wheel. BTW, the spacing between the swing arm axle mounting points is 225mm.

[nargent]

Thanks again scottly. I'll put the 33.5 mm spacer on the left as you suggest, so the sprocket and drive chain will be aligned. My hub is thinner than a real 400 four, so machining right down to the 'correct' size for the right hand sprocket will leave it too small. I'm going to go with machining down 3 mm to start, and then test fit and machine more as needed. Incidentally, the distance between fixing points on my swing arm seems to be nearer 229 mm, which also means the right hand spacer will need to be a little wider than expected.

This bike continues to surprise and puzzle me, but at least its starting to come together!

Nick

[scottly]

I'm guessing that with the narrower hub and the combination of the longer spacers the assembly was 7mm wider than the swing arm, and forced into place, spreading the swing arm to 232mm. Then, when the assembly was removed, the arm sprung back 3mm, leaving you with 229mm? In any case, find out what size spacers you need to center the wheel and align the sprockets.

[nargent]

I think that's the answer. As I said I don't remember the rear wheel being particularly difficult to remove, but it seems the most likely explanation.

I machined off 3.1 mm from the longer spacer and now the parts fit together without drama. I have kept the smaller spacer on the left so the sprockets should be aligned. The brake components shouldn't be as important to get perfectly aligned. Given the hub is a bit narrower than the correct size, I think the wheel will be off slightly to the left, but I reckon it should be within a couple of mm. I guess I'll find out when I finally take it out for a spin.

Thanks again.