Forum

[Phil Ashbrook]

I'm a tad worried about fitting the new 612 crank as the shaft on the drive side will be a tight fit , the manual talks of using the crank sprocket with a inner distance piece to pull the crank through the 2 bearings , what does this distance piece look like and can I buy one , how much should it be pulled without binding up on the thrust washer . The timing side is in the manual said to be knocked with a wooden mallet which sounds very crude , I want the crank to be center with the same play on each thrust washer , this crank cost shit loads and I dont want to take crazy risks banging it with hammers , I'm loosing sleep over this , any help would be great .

[Bobw]

HI Phil, Only the the roller bearing centre is tight. I braced the flywheel gap using short 1/2" bolts and nuts to just lightly jack between them. Place the crank flywheel timing side onto a flat surface (workmate or similar) place the thrust washer over the crank, gently heat the roller bearing centre (hot air gun or oven) makings sure it's very clean to reduce the risk of it blueing and place onto the crank and tap it gently down as smoothly and quickly as possible using a tube drift. The bracing bolts will give you confidence that you're not moving the flywheels. Assemble the ball bearing, circlips and spacers into the drive side casing and assemble the crank into the casing, it will go in easily, ensure it turns as some casing castings foul the fly wheels, mine was ok. Assemble the timing side over the crank and again it should go easily. Make sure you take photos to reassure yourself and don't forget the thrust washers. After final assembly tightening the crank sprocket will close any slight clearance without having to drag the crank assembly through the roller bearing. The completed engine is brilliant with no reliability worries so good luck and stop worrying.

[Colin F]

Phil to the best of my knowledge the inner roller races go right up to the thrust washers.
So they are centered,you couldn't have any "play" . As Bob said use a tube over the shaft
to drive them on and you're hitting that with the wood mallet. Crank side play under the
Enfield design is different to most other British bikes and is taken care of by the timing
side roller.
Now the distance piece (140311)they're talking of is between the drive sprocket and the
alt rotor(assuming yours is an alternator fitted model.)So you may have to use the rotor
also to pull it all up.
Finally there are 2 distance pieces or spacers between the drive side roller and ball bearing,
keep us updated Phil
colin

[Phil Ashbrook]

After reading both of your advice letters I'll do the freezer / oven trick with the special tool 140311 distance peice and draw it through the bearings , speed of operation is the important trick with some good oven gloves .

[Mark M]

Phil, the process for building up the 612cc bottom end is actually the same as for every other Bullet model from 1948! The instructions given by H's are an expanded version of those in the Redditch workshop manual. Heat is your friend here as has been described already. A suitable spacer for pulling through the drive side could be the outer race of one of the old main bearings that you replaced. (You did replace them, didn't you?!) If at any point you feel you are using extreme force, stop and check that all is well and that nothing is fouling, delay is better than breaking something. By the way, I've built a few Bullet bottom ends over the years and recently, while doing this job on auto pilot I inadvertently added an extra thrust washer to the t/s crank and then took ages to work out why the cases wouldn't close! Good luck and let us know how you get on. REgards, Mark

[Phil Ashbrook]

All bearings will be the best money can buy , this re-build even gets the big race valves so every uprated part in the catalogue will be in this engine bar the belt drive clutch as I've run out of credit , the engine with regular oil changes should last 20 years or more crank wise , my thinking is getting the engine over engineered and this crank with it's massive Alfa big end will give peace of mind but I must add that the floating bush lasted 15 years before it went , no suprise when looking at high comp ratios 0n the 535 piston , lots of oil passage flushing as I want a super clean perfect re-build .

[Mark M]

Sounds like it will get the best! Good luck, REgards, Mark

[Bobw]

Hi again, there should be no problem pulling the crank through as you prefer. My concern was pulling against the ball bearing inner race and that big crank will chill the heated bearings very quickly and if there is any binding it might be difficult to trace. That said you will have enough force to pull it through cold and perhaps I'm just over thinking. let us know how you get on.

[Phil Ashbrook]

The tight fit was noticed when removing the old std crank with its buggered big end , a fair few blows of a big hammer got it out , I'm sure the roller race bearing can handle a pull through with lots of oil , the manual for the bike is pretty good advice wise so I should put faith into part 140311 to limit the pressure on the thrust washer , bolting up t/s crankcase should be easy but I admit I have not done this for 15 years , this 612 crank was not cheap so I have to get it right .

[Paul]

This sort of work would perhaps be ideal for Hitchcocks new service plans for the future. Send them a half engine and get it repaired/updated and posted back?