Sirio Conrod
08-24-2005 | 01:28 AM
#16
Tech Apprentice
Joined: Nov 2004
Posts: 62
Originally Posted by Toolmannz
Hi I have recently rebuilt a sirio .12 after a conrod failure the bronze big end bush had totally disintergrated.
After measuring everything up I discovered the Big end journal was 0.06mm
out of round,I dont know if this was a factory problem or a result of the conrod failure.After looking around for a replacement conrod I decided to make my own as the originals dont seem able to cut it.
As Im an engineer I remachined the crankpin and made a new conrod with a steeper knifedge profile to give it more strength and also machined 1mm radius around the pin ends to reduce fatigue at that point.The new conrod is made from alloy tooling plate Light and strong.
So far its run great .
After measuring everything up I discovered the Big end journal was 0.06mm
out of round,I dont know if this was a factory problem or a result of the conrod failure.After looking around for a replacement conrod I decided to make my own as the originals dont seem able to cut it.
As Im an engineer I remachined the crankpin and made a new conrod with a steeper knifedge profile to give it more strength and also machined 1mm radius around the pin ends to reduce fatigue at that point.The new conrod is made from alloy tooling plate Light and strong.
So far its run great .
08-24-2005 | 04:19 PM
#17
Tech Rookie
Joined: Aug 2005
Posts: 4
Hi NeRacer
Making the conrods isn't a problem but knowing what size exactly the journal
on your motor would be .As i stated the journal on my crankshaft was oval by .06mm so it needed remachined before i could make the bush for the conrod the correct fit.I used the specs from this forum and ran 0.04 clearance.
If you can provide me with all the relevant sizes of your bigend and conrod diameters I may be interested.
If you can tell me how to post a photo on here I will show you a picture of the new rod i made for my engine.
Making the conrods isn't a problem but knowing what size exactly the journal
on your motor would be .As i stated the journal on my crankshaft was oval by .06mm so it needed remachined before i could make the bush for the conrod the correct fit.I used the specs from this forum and ran 0.04 clearance.
If you can provide me with all the relevant sizes of your bigend and conrod diameters I may be interested.
If you can tell me how to post a photo on here I will show you a picture of the new rod i made for my engine.
09-04-2005 | 12:13 AM
#18
Tech Rookie
Joined: Aug 2005
Posts: 4
Sirio Conrod Fix
Well the first conrod I made has blown the bottom end out same as the original.So being stubborn I remade a new conrod out of Titanium with Aluminium Bronze Bushs.Have since raced this and did a complete stripdown
to check for wear the new rod and bushs are holding up well with no sign of elongation of the conrod bigend.Finally I may have fixed it
to check for wear the new rod and bushs are holding up well with no sign of elongation of the conrod bigend.Finally I may have fixed it
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