Vincent, are you going to harden the flywheels? If you do then you will not need the hardened washers at each side and the interference fit will remain good if you have ever to press out and refit the crankpin.
ET: Engine (Twin) Big end lubrication article by Phil Irving
- Thread starter Cyborg
- Start date
No need for hardened flywheels, no washers, just high tensile steel. BUT crankpin and conrod bores have to be lapped dead parallel - standard with roller/needle bearings. Also take care for 0.01mm play in the bearings. I check this with a feeler blade when doing a test assembly conrod-crankpin-needles. Certainly conrods have dremeled oil grooves at side faces where the oil is flung out for lubricating cylinder and piston .
Vincent, what is the idea with the bigger hole between the small ones , two each for the conrod bearings ? I do a big bore ~16mm down the center of the pin which gets plugged after finishing the rest. From there the two drillings for each rod get the oil supply , evenly fed when the drillings are positioned at 9 or 15 o`clock. The plug can be seen at the left pin in the photo, supply hole corresponds to the drilling in the flywheel.
At the time I could get the INA type crank bearings from stock - no more since many years - unless BSAF got some deal with them. So really the crowded long needle version would be my plan today, you cannot kill them or better them with anything else. As was shown in many decades crank speeds were never a matter of concern , was it Tony Rose, who did 100 000 miles in two years with standard bigend bearings - which were basically crowded albeit with 3 rows and spacers in there. I´d love to know why they did that . . .
Vic
Vincent, what is the idea with the bigger hole between the small ones , two each for the conrod bearings ? I do a big bore ~16mm down the center of the pin which gets plugged after finishing the rest. From there the two drillings for each rod get the oil supply , evenly fed when the drillings are positioned at 9 or 15 o`clock. The plug can be seen at the left pin in the photo, supply hole corresponds to the drilling in the flywheel.
At the time I could get the INA type crank bearings from stock - no more since many years - unless BSAF got some deal with them. So really the crowded long needle version would be my plan today, you cannot kill them or better them with anything else. As was shown in many decades crank speeds were never a matter of concern , was it Tony Rose, who did 100 000 miles in two years with standard bigend bearings - which were basically crowded albeit with 3 rows and spacers in there. I´d love to know why they did that . . .
Vic
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Hi Norman, i thought long about it, and I turned to EN36C or B. Set in by 1.5 mm to some 58-60HrC. ( from my memory)... so more pressing up lenght. Than after hardening we milled the bores. Now its up for pressing. (Peter Feulner calculed for a 20 ton press.... i go only to 15...bugger...).
Vic: the middle bore is to be closed up with M4 set screw. Under the middle distance ring. (So to do the oil equal to each conrod).
Cheers
From Spain
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If you get totally stuck then I can get up to 25 tonnes in my hydraulic press.