28 replies to this topic

[BaronVonchesto]

certainly sounds like changing the crank will be the safer and easier option... though perhaps not cheaper. If the cost of the crank is similar to what the machine shop is asking to fix the taper I'll just change the crank.

[BaronVonchesto]

changing the crank could very well mean different main and bigend bearings too.

[DeadSquare]

Warning,  Bodge.

 

When you have drained the oil, take the engine out, remove the rad and hoses and fan.

 

Plug the water pump and thermostat orifices and plant the engine, water pump down, in a shallow hole in sand or soft earth.

 

Rub the crank and flywheel with sandpaper to remove any detachable metal and apply a good smear of coarse valve grinding paste.

 

Gently put the flywheel on and rotate it like a gramophone 10 times, then remove the flywheel and wipe both surfaces carefully.

 

Repeat, once or twice until you can feel no "raised bits";  5 times would be the max as it is surprising how much metal the paste is removing, and on a 10 degree taper that is going to move the flywheel so far up the crank that it engages the C washer.

 

To see how close you are getting to the C washer, assemble it and wrap a "worm" of plasticine round the crank before fitting the flywheel and giving it a thump with a lump hammer.  Lift the flywheel off carefully the squashed plasticine is the clearance.

 

Change to fine paste and repeat a few times before changing to wet tooth paste, which will take a lot of rotating to produce something near a shine on the parts of the crank the are touching, and then you can asses the contact area.  If it looks promising, you might get away with saving the crank.

 

Check with the plasticine that there is at least 1mm for the flywheel to tighten on the taper before, using plasticine,  have a dummy run torquing the flywheel onto the crank and (if you can get it off) finally checking the plasticine for clearance.

[GraemeC]

I would be trying the various methods described to at least start to clean up the taper and see what it looks like, however I'd do it in situ - if it will clean up then with care and time it is quite possible you could get it fully cleaned up and useable without pulling the engine

[BaronVonchesto]

i think i'll go ahead and take out the engine. as troublesome as it is, the thought of doing it in situ just doesnt seem feasible, especially since it's unconfirmed if the effort will pay off...

[Magneto]

I'm surprised some of you guys think 50% or less engagement of the surface area is sufficient....

[Dr s]

Dead square has it. It’s worth an hours work or so.

[Steinwhine]

The precision location of the flywheel to crankshaft is critical for both concentric location for balance capabilities and minimising engine vibration plus the capability of transmitting the engine torque without micro fretting between the two tapered surfaces. One must also consider the safety aspect because if these flywheels do become detached from the engine the consequences can be bad ! . So my strong advice to you given the photographic condition of your crankshaft is throw it away and get another one. Any thoughts on welding should be binned as the metalurgical properties of the crankshaft will be changed directly affecting its mechanical properties .

[BaronVonchesto]

for those who are wondering what the update on this is, the local machine shop said he could fix it, but I found a decent crank going for cheap. late A+ 998 kind. So i decided I'd just fork out the cash for that and to have it balanced rather than risk a fix. Better to be safe I figured. Also changed main and bigend bearings.

 

Ho hum, 1 worn flywheel key set me back about 1k pounds and several months... but my mini is FINALLY back on the road as of yesterday!

Edited by BaronVonchesto, 22 November 2019 - 08:30 AM.

[DeadSquare]

Why is it that children seem to delight in taking their toys to pieces ?

 

Let that be a lesson to you.  Don't do it again !

[Spider]

Nice work, I know it's been an expensive and unfortunate exercise for you, but hopefully, happy Mini Days ahead now.

 

Thanks for keeping us in the loop.

[dotmatrix]

You can change the centre hub part of your verto flywheel. Buy a new centre and lap the two together

Edited by dotmatrix, 22 November 2019 - 07:29 PM.

[BaronVonchesto]

You can change the centre hub part of your verto flywheel. Buy a new centre and lap the two together

 

already did that. bought a new flywheel boss and mated it to the replacement crank

[daenesh]

just send it to a decent mechanic.. we have plenty here in KL/PJ/Seremban as well that are recognized members of our local groups. You won't get conned or over charged.