Topic: top fork material

[wolf550]

does anyone know if it was just another type of aluminum used for top triple clamps?
made an aluminum casting for my wifes 350f out of aluminum reinforced with more aluminum at the clamping bolt area to see if it will work.

also would a casting out of copper or brass be better in terms of having more give at those areas where the 350f top triples crack from over tightening?

[Flyin900]

Interesting work you have done. Why reinvent the wheel though? I have never seen a set cracked, yet I realize there are ham fisted PO's out there.
It would be more economical to just find a used one in good shape. The spec for clamping the top triple tree is around 10-12 ft lbs if I recall.

[Don R]

 I'd think proper clearances would solve the problem. I stopped squishing the D washers on my 750K's and now just remove the slack after breaking one.
 I thought the CB top trees like that don't use the D washers weren't prone to cracking. I never owned a 350 though, just 400's. That casting is impressive though. 

[grcamna2]

I think the top triple is a hard cast alloy to make it strong as there's a lot of forces working on that piece.

[Tim2005]

I think the top triple is a hard cast alloy to make it strong as there's a lot of forces working on that piece.

Yes it's very possible that it is made of something special, it's highly stressed. Some years back I remember someone had made a batch for UK classic racing that just weren't strong enough, and they were collapsing on the turn in to fast corners.

[wolf550]

I just came back from the local salvage yard. they had three bikes with the triples and they were all cracked in the same location on the front round clamp area before the bolt. it could have been due to being age, being outside or the owner had cracked it and just did not notice.
I did not see any of the special D washers on any of them. but the area is so thin that maybe the washer was just lost over time.

it seems like a hard part to find and with prices ranging from 150 all the way to 750 on ebay.

I was looking at the aftermarket triples available and I would have to use clip ons, did not have instrument bezel holes for the original tach and speedo or they had mounts for their own instruments.

now owning a 350F, this was just a side project to see if it could be done and within tolerances to be safe.

my wife did say uh uh you are not putting that on my bike to test! LOL

this set once done with the reinforcement to the clamp area I will test out on the other set of forks to see if:
1)after clamping down to what the spec ft/lbs is, if it cracks
2)keep clamping down and up the ante of the ft/lbs until it cracks

dont know how many times it would take but would be interesting to find out.
I did not know if other metals that have a higher melting point might also be stronger for such a purpose.
I could even try this with steel and see how that goes with a 3d printer using pla lost casting process.

figure it would help someone else down the road

[grcamna2]

I just came back from the local salvage yard. they had three bikes with the triples and they were all cracked in the same location on the front round clamp area before the bolt. it could have been due to being age, being outside or the owner had cracked it and just did not notice.
I did not see any of the special D washers on any of them. but the area is so thin that maybe the washer was just lost over time.

it seems like a hard part to find and with prices ranging from 150 all the way to 750 on ebay.

I was looking at the aftermarket triples available and I would have to use clip ons, did not have instrument bezel holes for the original tach and speedo or they had mounts for their own instruments.

now owning a 350F, this was just a side project to see if it could be done and within tolerances to be safe.

my wife did say uh uh you are not putting that on my bike to test! LOL

this set once done with the reinforcement to the clamp area I will test out on the other set of forks to see if:
1)after clamping down to what the spec ft/lbs is, if it cracks
2)keep clamping down and up the ante of the ft/lbs until it cracks

dont know how many times it would take but would be interesting to find out.
I did not know if other metals that have a higher melting point might also be stronger for such a purpose.
I could even try this with steel and see how that goes with a 3d printer using pla lost casting process.

figure it would help someone else down the road

Could you melt-down some broken OEM top triples to recast them ?

[Flyin900]

I have restored many CB350F and CB400F and not seen the so called D washers used on these small bikes. There should be two 8mm flat washers, one on the bolt head and one on the nut on each top clamp to have this assembly correct.
As previously noted I have been fortunate not to have had any cracked at all. I bead blast and repaint both the top and bottom triples, so cracking would be quite evident.

Unfortunate that the local breaker has cracked ones in his yard.

[wolf550]

I just came back from the local salvage yard. they had three bikes with the triples and they were all cracked in the same location on the front round clamp area before the bolt. it could have been due to being age, being outside or the owner had cracked it and just did not notice.
I did not see any of the special D washers on any of them. but the area is so thin that maybe the washer was just lost over time.

it seems like a hard part to find and with prices ranging from 150 all the way to 750 on ebay.

I was looking at the aftermarket triples available and I would have to use clip ons, did not have instrument bezel holes for the original tach and speedo or they had mounts for their own instruments.

now owning a 350F, this was just a side project to see if it could be done and within tolerances to be safe.

my wife did say uh uh you are not putting that on my bike to test! LOL

this set once done with the reinforcement to the clamp area I will test out on the other set of forks to see if:
1)after clamping down to what the spec ft/lbs is, if it cracks
2)keep clamping down and up the ante of the ft/lbs until it cracks

dont know how many times it would take but would be interesting to find out.
I did not know if other metals that have a higher melting point might also be stronger for such a purpose.
I could even try this with steel and see how that goes with a 3d printer using pla lost casting process.

figure it would help someone else down the road

Could you melt-down some broken OEM top triples to recast them ?

I don't see why not. if the material for all the top triples are the same over all the 3,4,5,6 and 750s I could melt each one down, see how long it takes to melt and just see if it casts like the other CB aluminum I have been using from these bikes (forks, jugs, cam covers oil pans, clutch covers, even the whole 500/550 casings).

[wolf550]

also I had used some broken 750 carb parts awhile ago to make some covers, after casting and starting to drill them I had a hard ass time trying to get the drill to bore through. it was very difficult and quite the opposite of all the other aluminum I have drilled. I did not know if maybe they were melted with some other material being carbs had fuel going through them.

[wolf550]

I have restored many CB350F and CB400F and not seen the so called D washers used on these small bikes. There should be two 8mm flat washers, one on the bolt head and one on the nut on each top clamp to have this assembly correct.
As previously noted I have been fortunate not to have had any cracked at all. I bead blast and repaint both the top and bottom triples, so cracking would be quite evident.

Unfortunate that the local breaker has cracked ones in his yard.

along with these 350 triples, there were broken unicorn 750 triples also.

[grcamna2]

I just came back from the local salvage yard. they had three bikes with the triples and they were all cracked in the same location on the front round clamp area before the bolt. it could have been due to being age, being outside or the owner had cracked it and just did not notice.
I did not see any of the special D washers on any of them. but the area is so thin that maybe the washer was just lost over time.

it seems like a hard part to find and with prices ranging from 150 all the way to 750 on ebay.

I was looking at the aftermarket triples available and I would have to use clip ons, did not have instrument bezel holes for the original tach and speedo or they had mounts for their own instruments.

now owning a 350F, this was just a side project to see if it could be done and within tolerances to be safe.

my wife did say uh uh you are not putting that on my bike to test! LOL

this set once done with the reinforcement to the clamp area I will test out on the other set of forks to see if:
1)after clamping down to what the spec ft/lbs is, if it cracks
2)keep clamping down and up the ante of the ft/lbs until it cracks

dont know how many times it would take but would be interesting to find out.
I did not know if other metals that have a higher melting point might also be stronger for such a purpose.
I could even try this with steel and see how that goes with a 3d printer using pla lost casting process.

figure it would help someone else down the road

Could you melt-down some broken OEM top triples to recast them ?

I don't see why not. if the material for all the top triples are the same over all the 3,4,5,6 and 750s I could melt each one down, see how long it takes to melt and just see if it casts like the other CB aluminum I have been using from these bikes (forks, jugs, cam covers oil pans, clutch covers, even the whole 500/550 casings).

Would your salvage yard give those cracked Honda top triples to you? they might be useful to melt down?

[wolf550]

let me go down and see how easy it is to drill a hole through the broken 350 triple.

[wolf550]

if the top triple material is different I think he might. he seems like a cool guy.

[grcamna2]

if the top triple material is different I think he might. he seems like a cool guy.

I'm wondering if Honda used a similar hardness cast alloy to all their top triples ?

[WideAWAKE]

My 350 is in storage at the moment and I’m not gonna dig it out, but some old pics show a D washer in the clamp.

Bike is 100% Original, minus tires and exhaust tips.

[wolf550]

so yeah the top 350 triple is some hard a@$ stuff!
it did the same thing as the material that the carbs are made out of!
were gonna need a bigger boat i mean stronger drill bit

[wolf550]

this material is alot heavier than the other cb aluminum

[wolf550]

if he would give me those triples for free I would be thrilled!
now I have to go back to making the mold with the holes filled with casting sand or add those in later before closing the mold to cast because this stuff is tough to drill.

[wolf550]

so Ill make another mold to cast with this stuff.
I think if I fill the holes beforehand on the triple and leave to dry I can make the mold and then remove these from the triple and insert in the void areas.
just dont want to be drilling these parts out.

[Deltarider]

When you study the various parts lists of the CB500/550s, you will see, that on the later CB500/550 models Honda has changed the 8mm bolts into 7mm and abandoned the D washers. In addition the prescribed torque value was lowered. Mine has that, the CB550K2 also. Never had a problem there.

[wolf550]

yeah I never had a problem with my 550's with the triples and that was using torque specs and this was before I knew there were D washers that went inbetween that clamp spot.
I don't know how much they tightened these down to give and break.

[wolf550]

started with morning with another test on seeing if other cb top triples would be a substitute for the 350 material.
I put on my extra 550 triple into the bench drill.
it did give to the drill like regular aluminum so I stopped.
when I gave the 550 triple a tap it had a lower ting sound than the 350 triple has.
the 350 has a high ting unlike this 550 top.
Im guessing the size and difference in the clamping area along with the D washer made it okay to use the standard Aluminium.

[wolf550]

cut the material into manageable chunks. even that took forever with the grinder.

[wolf550]

gutted the fork holes and stem hole and handlebar grooves. redid to half 1/16 because what I had in there to start with was too much.