Topic: 400F Parts List Question - triple bridge difference -

[Zane]

Does anyone know what the difference is between the two triple bridges listed in the CB400F Parts List?

What I can see is that: 

Honda Part # 53230-377-305,  BRIDGE, FORK TOP - spans frames CB400F-10000001 to CB400F-1023114

and that:

Honda Part # 53231-377-010,  BRIDGE, FORK TOP - spans frames CB400F-1023115 and up.


Unless I'm missing something obvious (something which happens far more than I would like it to happen) those numbers tell me that the clamp was changed somehow after the first 23,114 of the bikes were made.  Maybe the "somehow" is unimportant (like paint), but then again maybe it's enough of a change so that the two are not interchangable.  I do not know.

I'm interested in a particular triple clamp, but the fellow selling it doesn't know the year or serial number of the bike the clamp is from.  It would have been only the first 24 thousand or so of the bikes sold in the US which have the former clamp, so odds are this fellow is selling the latter clamp - but I don't like rolling the dice when I'm buying integral parts.

I know it's a fine point, but do any of you afficiandos out there have an answer?

Cheers,

Bill Z.

 

[SWEETPEAUK]

Fork clamp bolts on the early models were 8 x 54mm later changed to 7 x 54mm. should be easy to tell difference the bore will 7mm on the later model.

[Zane]

I'm impressed.

Thank you.

Can I ask how you gleaned that info?  Was it in some parts list somewhere?  Or did you learn from experience?

Regardless, thanks again.

(Does it seem funny to you that they "advanced" the design by making those bolts smaller?  It seems to me that those forks are pretty light weight to begin with and that the 8 mm bore would have had an advantage over the 7mm modification ...)


Cheers,

Bill

[SWEETPEAUK]

The difference is something I came across when making some bolts. If you look at the "Service Honda" fiche programme it shows frame number difference when you select the bolt. 

My old 750f2 also had 7mm bolts and so has my 75 400/4. Wasn't there a problem with top Yoke (tree) cracking with the 8mm ones?.

[Zane]

The difference is something I came across when making some bolts. If you look at the "Service Honda" fiche programme it shows frame number difference when you select the bolt. 

My old 750f2 also had 7mm bolts and so has my 75 400/4. Wasn't there a problem with top Yoke (tree) cracking with the 8mm ones?.

Yikes!  I don't think I'd want my top bridge to crack if I was sitting stopped on the bike, much less moving.  It makes sense when you think about it though - minus 2 mm of metal.  I mean there's not much to the clamp at 7mm - 8mm would be that much worse.  So yeah, I can see where the chances of developing a crack would be increased with the larger bore. 

You might think though (even back in 1975) that if the issue were a safety issue, they would have recalled or updated the thing somehow.

Anyway, thanks again.  And thanks for telling me how you figured it out.  I'll remember it.

Cheers,

Bill