CCT Spring Steel
- Johnny Wishbone
- Posts: 124
- Joined: Tue Aug 10, 2004 3:21 pm
- Location: Dublin, Ireland
CCT Spring Steel
Sorry for creating yet another post for this topic, but just thought of a different angle for this. It's pretty much common knowledge that failure of the spring leads to the CCT problems - does anyone know what grade steel the spring is made from, ie, chrome-vanadium, high carbon, etc??
The reason I ask is that I find it hard to believe that a manufacturer such as Honda would design a spring which fails at the rate it does I have a feeling that the mechanical design of the spring itself is probably sound enough, but the post-production heat treat may not. For those of you who mightn't know, heat treating steel or pretty much any other metal or alloy will give the material different mechanical properties (strength, hardness, elongation etc etc) depending on the heat treat. The heat treatment is usually done after manufacture or machining so as not to introduce any residual stresses back into the part. If we knew the exact make-up of the spring it would be simple to create a heat treatment profile suitable for the spring which might improve it's elastic limits and stop it from failing.
The reason I ask is that I find it hard to believe that a manufacturer such as Honda would design a spring which fails at the rate it does I have a feeling that the mechanical design of the spring itself is probably sound enough, but the post-production heat treat may not. For those of you who mightn't know, heat treating steel or pretty much any other metal or alloy will give the material different mechanical properties (strength, hardness, elongation etc etc) depending on the heat treat. The heat treatment is usually done after manufacture or machining so as not to introduce any residual stresses back into the part. If we knew the exact make-up of the spring it would be simple to create a heat treatment profile suitable for the spring which might improve it's elastic limits and stop it from failing.
Out of my way or I'll eat the lot of ye!!
I think
I think before looking for answer to this question it make sense to have people with failed CCT to check where exactly spring broke - is it actually somewhere in the middle, or it is "ends" that normally slots into CCT parts that breaking down.
I agree with you (being graduated on that area ) that thermochemical treatment might be crucial to spring reliability, but if it is ends of spring that got broken - then it means spring should have localised treatment, rather than constant through all spring.
Spring seems to be high-carbon steel, just regular so-called "spring steel" ("constructional spring steel" is kind of term from my home country, probably not correct for UK).
I would expect that it is steel 65G, 15LM or 20C (I do not now European steel identification standard) - it actually 0,65-1% of carbon and 0,45-0,75% of Mn, also can have 0,20-0,25 % of Si.
If I'd be back in Kiev I'd get analysis of it for nice talk and 30 minutes, but here..
Anyway - I think this is a bit too much to pull for us, it is a Honda job, and I suspect that effort of making Honda do smething might be well equal to efforts on creating treatement profile
I agree with you (being graduated on that area ) that thermochemical treatment might be crucial to spring reliability, but if it is ends of spring that got broken - then it means spring should have localised treatment, rather than constant through all spring.
Spring seems to be high-carbon steel, just regular so-called "spring steel" ("constructional spring steel" is kind of term from my home country, probably not correct for UK).
I would expect that it is steel 65G, 15LM or 20C (I do not now European steel identification standard) - it actually 0,65-1% of carbon and 0,45-0,75% of Mn, also can have 0,20-0,25 % of Si.
If I'd be back in Kiev I'd get analysis of it for nice talk and 30 minutes, but here..
Anyway - I think this is a bit too much to pull for us, it is a Honda job, and I suspect that effort of making Honda do smething might be well equal to efforts on creating treatement profile
4 wheels moving body, 2 wheels moving soul
- Johnny Wishbone
- Posts: 124
- Joined: Tue Aug 10, 2004 3:21 pm
- Location: Dublin, Ireland
ha bleedin ha!
That's a good point though Bluesman, the location of failure of the spring is important. For all we know Honda's supplier for these springs is forming them after receiving bulk treated product thus introducing stresses into the spring. As far as a heat treatment goes a simple heat treat & quench cycle would do - not sure of the advantages of doing a local, the spring is pretty small already! Best just to drop the whole thing into a furnace. I'll see if I can come up with a cycle for HCS then. Might try a few different cycles on a few springs to get the best result.
As far as Honda goes I didn't intent getting onto them about it, but it would give us all here a piece of mind if it was successful - would just require retro fitting your CCT springs with treated ones.
So anyone know exactly where on the spring they are failing??
That's a good point though Bluesman, the location of failure of the spring is important. For all we know Honda's supplier for these springs is forming them after receiving bulk treated product thus introducing stresses into the spring. As far as a heat treatment goes a simple heat treat & quench cycle would do - not sure of the advantages of doing a local, the spring is pretty small already! Best just to drop the whole thing into a furnace. I'll see if I can come up with a cycle for HCS then. Might try a few different cycles on a few springs to get the best result.
As far as Honda goes I didn't intent getting onto them about it, but it would give us all here a piece of mind if it was successful - would just require retro fitting your CCT springs with treated ones.
So anyone know exactly where on the spring they are failing??
Out of my way or I'll eat the lot of ye!!
I'm straining to remember where it snapped, but I think on the first one the cross piece that goes into the threaded bit... making any sense?? See diagram in gallery to make it a little clearer!!
http://www.abercon.co.uk/vtr1000/gallery/865.jpg
Damned drawing went in sideways!!!!!
http://www.abercon.co.uk/vtr1000/gallery/865.jpg
Damned drawing went in sideways!!!!!
RQ.
The Stig of 2 wheels as well as 4 !
The Stig of 2 wheels as well as 4 !
- Johnny Wishbone
- Posts: 124
- Joined: Tue Aug 10, 2004 3:21 pm
- Location: Dublin, Ireland
Ta RQ! That's kind of what I was getting at in my previous post - if this is where it's failing most or at the other bent end that slots into the CCT housing, then it's pretty clear that the springs are treated prior to forming, rather than after, or that the forming process has simply weakened that area so that mechanically it falls way beneath it's design limits. The 'corner' of that cross section is probably the weakest part of the spring (except for the other bent section at the other end). Anyone else notice the spring failing in this area??
Out of my way or I'll eat the lot of ye!!
Its a (very) long time since I was involved with this sort of thing, but.... has anyone considered that it could be a surge related problem (i.e. the springs in the CCTs hit a natural frequency within their normal operating range). This may also explain why the Vtwin seems to have more of a problem than Honda's other engines???? Also I guess the valves are heavier in the Vtwin.
She's my idea of beauty and thats what I ride.
bluesman
I just got tired of trying to sort out HOnda CCT and has put in ratchet-type (no-go-back) CCT from Kawasaki ZX/ZZR/Z series.
Had to drill holes a bit on side of Kawa CCT, then just slot in an go...
Still have to take it out and make/buy a gasket, cos it leaks....
So, question I have:
a) Kawa CCT has got left about 7 mm of extension to go if chain wears after it has extended into current position.
What do you say guys - that's enough? I hope so, cos it is actually lever system of tensioner and actual movement of chain if CCT extends 7 mm will be quite a lot
b)Is there high pressure of gases/oil round CCT? I mean - there is no much of "overlap" in CCT seat with Kawa CCT cos it is tad smaller surface - will it blow gasket ?
Apart from that- there is no way that Kawa CCT will ever back off, so - sorted.
Had to drill holes a bit on side of Kawa CCT, then just slot in an go...
Still have to take it out and make/buy a gasket, cos it leaks....
So, question I have:
a) Kawa CCT has got left about 7 mm of extension to go if chain wears after it has extended into current position.
What do you say guys - that's enough? I hope so, cos it is actually lever system of tensioner and actual movement of chain if CCT extends 7 mm will be quite a lot
b)Is there high pressure of gases/oil round CCT? I mean - there is no much of "overlap" in CCT seat with Kawa CCT cos it is tad smaller surface - will it blow gasket ?
Apart from that- there is no way that Kawa CCT will ever back off, so - sorted.
4 wheels moving body, 2 wheels moving soul