OzVMX Forum
Clubroom => Tech Talk => Topic started by: 090 on October 22, 2009, 06:29:01 am
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Who does such a thing?
Also, who would then make a pin and supply a bearing and washers to suit .
I'm thinking of getting a batch made but i don't want a heap of rods made that i then cant buy pins, washers and bearings to suit.
To suit the cr480's.
Cheers, Brad.
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Brad, Give me the dimensions and I'll see what comes close
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Hi Gents
I am also looking for a 1983 cr 480 Honda rod kit, I would be prepared to buy three rod kits at the right price/ fair price.
Thanks
Gavin Williams ala Crabman
South Africa
Help Help
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Your biting off a bit here, I would first measure the rod and look for an alternative rod(maybe from a jet ski or snow mobile) because that is the easiest solution. BTW a rod goes up and down at one end and round and round at the other so YES it will work.
If you want to go the remanufactured route then be prepared to buy 100 min and perferably 500 because your unit cost on less than 100 will be very high. There are companies in Taiwan that will manufacture anything to a very high standard for a very cheap price but they require a volume order. There is also a company in Spain that will remanufacture rods on low volumes.You will also need to supply a drawing or pay for the drawing to be made.
Bearings et won't be a problem because if you get a custom rod made you will make it to fit commonly available bearings etc ;)
Have you got a bare rod to measure?
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There is a company in NZ that makes forged rods, well i think they were forged, maybe billet I cant remember exactly. They advertise in that NZ Motorcycle/tractor marketplace/trader magazine at the newsagent.
First i would try here. They claim to have the worlds larges supply of rods. They can send you a con rod dimension sheet which you can sent to them by fax with dimensions of your rod. They will then try and match it up to another rod as they have a huge list of rod dimensions
www.bbimporters.com.au
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Argo Marine on the NSW central/north coast makes one-off and small production run billet (rather than forged) rods. Seem to have a good reputation among the historic car guys.
Prices for car rods were expensive, but not outragous by bike standards (cheaper than when the "NLA NOS hysteria" takes hold...) - and I assumed that car rods are dearer due to the split big end requiring a lot more machining to make.
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Had a long conversation with head bloke at Argo and what he said about making a 2T rod didn't fill me with any confidence whatsoever
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Finding replacement rods is a problem that many of us face in keeping our old bikes running. Obviously the best way is to have NOS but as time goes on this seems almost an impossibility. Like others have mentioned alternative rods from other sources i.e. different brands, go carts, jet skis, outboards etc are a possibility but its still very hit and miss and its a lucky dip really.
I guess if access to a well equipped workshop is available things such as different pin diameters or the ability to modify rod widths at either or both ends are a possibilty. I'm not so sure about billet rods though. With CNC machinery this would be an easy way to make a one off from billet and suitably heat treated and ground, but without the grain flow that is inherent in forged rods I'd say the risk of rod failure in a highly stressed engine would be highly probable. Would be good to try it but who would be willing to suffer the catastophic damage of failure.
I have been able reclaim one rod (elsinore 125) that had a small amounts of wear by having the big end bore ground to clean it up and then make a matching stepped crank pin to restore the correct running clearance and using the standard needle bearing. The case hardening in this area is usually deep enough to allow such a mod provided the material removed is no more than 0.2-0.3mm on diameter.
Wish there was an easy solution to this.
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Nothing is hit and miss about using another rod, they go up and down and round and round in jet ski's and snow mobiles as well. I have a big chart on rod widths, lengths and centre to centre distance, so it's measure and match up. Outboards use a split rod and bearing therefore not suitable.
For instance there is 2 options for a replacement for a CR 125 depending on if it has a 20 or 22mm crank pin. No grinding etc etc, it's not out of a CR but who cares?
Good point about the grain flow in a forging that's why they are so strong and rarely fail . Also ONLY the bearing bores are heat treated the rest is untreated.
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Having spent the best part of 18 months tracking down rod manufactures - getting quotes - buying rods that are supposed to do the job but are know where near the ball park ::)
Lozza- is on the mark with jet ski & snow mobile rods :)
Brad , first up you need an old rod in hand , next write down all the necessary dimensions ... big end pin Dia - small end pin dia - centre to centre's
A PE 400 rod replacement ended up being a Seadoo 650 ( jet ski )
I'll fill you in on Sunday
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if the rod is a little longer you can put a spacer under the barrell.and away you go
ie later cr rods fit just need 4mm spacer under barrell
jim
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My claim to fame is not my technical knowledge of bikes, mine is riding anything with a throttle relatively slowly.
Can anybody confirm the feasability of using a CR 500 rod kit with a 4 mill spacer?
What material would be recommended for the spacer?
As I am building a race bike, I would prefer to remove any potential problems. What type of problems couls/ would I pick up?
Are there any other suggestions ?
All advice is greatly appreciated
Gavin / cRABMAN
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I am going to go to some length to get a suitable cr480 rod kit sourced. I took a crank to George Mackensie who has all sorts of charts and he looks at a lot of different possibilities including Seadoos etc. I will find the rod and measure it up.
George sorted a ktm125 '84 model with an Aprilia rod and an rm125 '01 piston so he has some idea.
Can anybody confirm the feasability of using a CR 500 rod kit with a 4 mill spacer?
Crabman,are you talking about a cr500 rod for your 480? If you are they are too different. An '88 type rod can be used on the earlier 500's and use a spacer.
Talk to you on the weekend Stew.
Thanks everyone so far. I will post some measurements and see if anyone can find something similar.
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Good point about the grain flow in a forging that's why they are so strong and rarely fail . Also ONLY the bearing bores are heat treated the rest is untreated.
I recall reading an old thing from the 70's that cast jet turbine blades were stronger in tension than the forged items. So much trivia. So little time!
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I have tried fitting a '84 500 rod to a '82 480....but it was more than 4 mill difference I'm sure.
Had a base plate spacer made up to lift cylinder to suit extra rod length, only to find exhaust manifold wouldn't line up (as well as carb)
If I remember correctly (and usually I don't) raising the cylinder caused the main frame downtube to foul the exhaust manifold outlet.
Put the old rod back in and sold it.
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evo has nailed the catch with using a longer rod, you need a corresponding decrease in compression height of the piston IF you want to package the engine as it was before. Space on even an old mx bike with an up pipe is at a premium
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Brad
How many rod types and what quantity of each type are you looking at getting manufactured. Also as a guide, what sort of dollars would you think is a fair price per rod.
I'll have a talk with a few of my machine shop contacts to see if its viable. We could look at a few of the common CR and RM styles perhaps.
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Just the one type for now which is the 480. Ten or maybe a few more to try and make it worth the while for the manufacturer. I have no idea about price.
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Albeit that I am a long way away.i would take two and maybe more.
Thanks
Gavin ala Crabman
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If I remember correctly it's not the manufacture of the rod that's the problem most machine shops can do that, it's the creation of the bearing surface in the rod that's the issue.
If you can find someone to do that then it would just be a case of getting the old rod "resurfaced" instead of getting a whole new rod made.
The big and little end pins can be bought in any length as rod and cut to size or a volkswagon big end pin suits the 480, but needs to be shortened about 1mm.
The problem is getting the surface on the rod done, if that can be solved your home and hosed.
Good luck guys.
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http://www.euro-rods.com/ (http://www.euro-rods.com/)
These guys make conrods (although I suspect that they get Carrillo to manufacture them) for Euro bikes , but I think I remember reading that they do custom orders . I have been waiting for the Aussie dollar to improve before buying some Husky 390 rod kits off them (& the time is almost right).
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I don't think anyone really knows how exactly a 2T rod is made.
This is from a fellow who runs Falicon cranks in the US and was kind enough to explain the process to me.
A forging die is machined in 2 halves split longditudly along the rod.
A steel blank is forged from the dies in a industrial 200T press in one go.
Any flashing removed.
Now the interesting bit,( bores are not to hard evo)
The rod it's self is only about 32-35HRc in hardness which is quite ductile.
The rod bores are machined to size, oiling slots, reliefs and holes added
A copper coating is sprayed onto the rod everywhere EXCEPT the bores(the copper colouring on a rod)
The rod is heat treated and brought up to min 60HRc the same or better than the rolling elements of the bearing.
The bores are honed/ground to final size.
The parts of the rod that are copper coated remain UNAFFECTED by the heat treatment
So the centre of the rod is ductile and the bores as hard as the rolling elements in the bearing , perfect.
I think you will have trouble getting someone to make 10 rods properly Brad.No use going to all this trouble if they are not up to scratch.
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What about billet CNC rods from steel or alloy? If you got a mate you does CAD that’s the hard part out the way. Triumph twins have big chunky alloy rods, and i know guys put them in hotted up 850 Nortons too. They are split end cap type with shell bearings i know, but an enclosed circular big end with a pressed in hardened outer bearing ring could fitted and done that way. Same thing for the small end. Is there a grade of billet steel or alloy that could be machine and up to the task?
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have used these people before to rebuild rods and cranks on V8 motors. Not sure if they do small bike rod rebuilding?
Crankshaft EngineeringUnit 2, 20 Tradelink Road, BROWNS PLAINS, QLD 4118
p: (07) 3806 7488
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Forged aluminum rods are approx half the tensile strength of steel(less for machined), hence they are twice the size.Which runs into packaging issues,then you have to get the insert to stay in there with 2 vastly different expansion rates.Plain bearings don't work in 2T engines, they need lots of oil.