I decided to babbitt the bearings myself and my efforts worked out really well, I'm happy to say.
Removing the flywheel with screw hydraulic puller. This type of puller only has a short travel so you have to keep backing it off and screwing the main body forward or packing under the ram.
Wear on the crank where the seal runs.
Crank set between centres jig for welding.
I electric welded it using low Hydrogen welding rods.
Crank set up in lathe for a bit of peening on the weld on the negative side of run out. The crank only bent about three thou of an inch(total indicator run-out) due to welding. Well purists might say the crank actually only bent one and a half thou if the indicator shows three thou TIR.
The support jack is on the positive side of run out so that the negative side can be peened. This causes the negative side to lengthen (stretch) which causes the crank to pull (bend) towards the negative side thus correcting the run out. Due to the amount of imbalance my little lathe wouldn't machine the weld so I took the crank to work and machined it there. I then had the crank ground at an engine reconditioning workshop.
Three Kilograms of Tin based babbitt metal. There is no lead in this alloy, well if there is any it is a very small percentage as an impurity.
Home made melting pot
Some of the ingot melting down. It must not be overheated. The pouring temperature for this alloy is recommended to be 415 to 440 Celcius. (779 to 824 Fahrenheit)
1/4 inch base plate up on a brick at each end, Bronze bearing bush clamped to base plate, clay washed(coated) tapered mandrel in place and a sheet metal dam wired in place. The inside surface of the dam is also clay coated. The spring is to keep tension on as the centre bolt lengthens from the heat. The base plate, mandrel and bearing shell all have to be heated. Generally the mandrel should be the hottest the bearing shell a bit less and the base to be cooler than both of them.
As soon as the whitemetal is poured I used a warmed up piece of 1.5 mm(1/16") wire to go up and down in the molten metal to help remove any air bubbles. I did that fairly quickly then used a water spray bottle to start cooling the underside of the base plate then the outside of the bearing shell. The cooling should be directional from the base plate upwards and from the outside of the bush towards the mandrel. The large gap I have between the mandrel and mandril clamp is to facillitate getting the gas torch to the inside of the mandrel to ensure that the mandrel is the slowest to cool. Overall though the metal should be solidified within about 5 minutes to prevent any seperation of the constituant metals in the babbitt alloy.
This should be a new window, minimise or close it to return to Home Page or press