Topic: Machining new 350f upper triple tree

[camelman]

Hi all, it’s been a few years since I’ve been here. I bought a 350f recently which has the dreaded cracked upper triple. A friend is going to machine a replacement upper for me, but I don’t have the d-washer or know where to buy one. Can someone send me thickness dimensions for a d-washer? Also, is anyone else interested in buying a350f upper triple if he makes extras? They won’t be cheap, but will get more cost effective with volume.

Thanks,
Canelman

[seanbarney41]

I would assume that your machinist is not going to make triples from cast aluminum like Honda did.  I assume he is going to machine from billet.  That right there will make it much stronger and it will not require D washers.  No other manufacturer uses D washers.  Not even all Honda's use d washers.  I am not even convinced the d washers that Honda used actually serve any purpose other than to warn you not to over-torque.

If you want d-washers just for the simple true reproduction value, understood.

[camelman]

You nailed it. I like keeping as stock as possible, hence the d washers, but doubtful we’ll keep all the pockets on the underside of the triple. Good to know possible reason for the washers!

[Kevin]

Welcome back, Camelman!

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[carnivorous chicken]

350Fs didn't have D washers. Doesn't mean you can't use something like it with a machined replacement...

[camelman]

CC, thanks for the reality check. I looked up the fiche on cmsnl and none are listed.

So, if it wasn’t a d-washer issue, then are the OG top bridges just a consumable unit? It seems almost all I see are broken.

[newday777]

CC, thanks for the reality check. I looked up the fiche on cmsnl and none are listed.

So, if it wasn’t a d-washer issue, then are the OG top bridges just a consumable unit? It seems almost all I see are broken.

Maybe a torque wrench wasn't used and just plain old over tightened on the bolt(s)

[grcamna2]

A problem I noticed on many vintage Honda's that have the OEM cast top triple clamp with the 2 pinch bolts is:it seems they sit for a long time and then when someone goes to remove the top triple,it's kind of 'stuck in place',even though the steering stem top nut and both pinch bolts are removed;could be because of corrosion from water sitting in there and dis-similar metals between the cast alloy and steel parts.
I've seen workmen then take a hammer and repeatedly hit both sides of the cast top triple clamp,right where the pinch bolts are located;they're in a hurry to bang the part off there,plus those cast parts are hard and brittle & it doesn't take much to fracture them. A great way to remove them is spray some Liquid Wrench spray all around the points of contact,then slowly and carefully use a dull screwdriver and begin to carefully pry the cast piece between the steering stem adj. nut and the bottom of the top triple,a little at a time;slowly and No Hammer please.   

[Kevin]

TTR400 (Kevin Bidgood) machined this one for me many years ago. He said it took over 8 hours of milling to do it.

[calj737]

TTR400 (Kevin Bidgood) machined this one for me many years ago. He said it took over 8 hours of milling to do it.

No doubt! Plus, if he did mahine the risers as a single part with the top clamp, he had a huge amount of waste material to remove. Given the lack of contouring on the riser portion, it would be far better and cheaper to machine the risers as bolt-ons from below. Simply install studs into the bottom of the riser, pass through machined holes in the top clamp, then bolt from below. Would also allow slightly different height risers to be used/made as needed.

[MauiK3]

Wow, very nice looking!

[camelman]

Kevin, is that for a 400f? I think I have the same part from TTR400. I bought a bunch of stuff from him years ago when I was is South Africa for work. He’s a fun guy to hang out with.

A friend of mine has hundreds of hours available on multi-axis mills. He’s exploring how to do it best, and is considering the multi-piece approach Calj mentioned.

[carnivorous chicken]

CC, thanks for the reality check. I looked up the fiche on cmsnl and none are listed.

So, if it wasn’t a d-washer issue, then are the OG top bridges just a consumable unit? It seems almost all I see are broken.

Maybe a torque wrench wasn't used and just plain old over tightened on the bolt(s)

Yep... I think people crank on them, overtighten, and then they just crack. They're still out there, and for less than the cost of machining one I imagine. Some folks use 400F ones as well but they are slightly different. I bought a 350F "project"/parts lot and the the triple tree was one of the first things I verified on it (as well as my recent purchase of a complete bike that I got running).

[camelman]

Glad you found a good one. Any chance you have a spare seat pan available in that purchase?

[carnivorous chicken]

Glad you found a good one. Any chance you have a spare seat pan available in that purchase?

Unfortunately not...

[Kevin]

Kevin, is that for a 400f? I think I have the same part from TTR400. I bought a bunch of stuff from him years ago when I was is South Africa for work. He’s a fun guy to hang out with.

A friend of mine has hundreds of hours available on multi-axis mills. He’s exploring how to do it best, and is considering the multi-piece approach Calj mentioned.

Yes, for a CB400F, but it would work on a CB350F.
This is the only one of these that TTR400 made. He made a few other styles, but I think they are all for clip on bars.
You should look through your stash...you might already have something that will work.

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[rfndzc]

Hi all, it’s been a few years since I’ve been here. I bought a 350f recently which has the dreaded cracked upper triple. A friend is going to machine a replacement upper for me, but I don’t have the d-washer or know where to buy one. Can someone send me thickness dimensions for a d-washer? Also, is anyone else interested in buying a350f upper triple if he makes extras? They won’t be cheap, but will get more cost effective with volume.

Thanks,
Canelman

I’d be interested to learn more.  Did you get it fabricated? I’ve been modeling mine and was going to bring it to a machinist, looking for a result like the one posted above. 

[grcamna2]

TTR400 (Kevin Bidgood) machined this one for me many years ago. He said it took over 8 hours of milling to do it.

Yeah ! !