Managed to break the keyed washer and the flywheel has spun.

Yet to get it off and see the damage. Hope I can salvage both.

Weird seeing as i spent about 10 hours lapping the bloody thing and making sure the keyed washer was not putting the torque load on the crank instead of the flywheel. Also had made sure that the bolt was not bottoming in the thread.

Clearly I got something wrong because the ends of the key washer that have broken off show no evidence of fatigue failure, just ductile and bruising from being thrown around inside the diaphragm spring area.

But it means that the engine has to come out now, which I was hoping it would not.

Bugger.

Ideas on what to look for and measure as it comes apart so I can make sure I don't stuff it up again?

cheers
michael

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

bloody hell

could only mean the flywheel isn't seating on the crank - IE the taper has worn off the inside of the flywheel to the point where the tapers don't meet and the keyed washer bottomed out on the crank

doesn't it?

I can't tell you what the Taper is (as in ratio)...

If you have a lathe I can tell you how to measure your taper to within... well... what ever your dial gauge is graduated?

If you don't really care that much but just want to sort it so it doesn't happen again... I too usually spend ages lapping mine in... but then I check them with a light smear of bearing blue... obviously 100% contact is ideal,, but I'll settle for as low as 75-80%.... If you check it like this, you can physically see how much contact it has, so there is no guess work involved, and you can be assured that if there is a problem again, it wasn't due to the taper..

If you're not getting enough pre-loading out of your nut and washers.... well.. you can fix it properly by assembling it, checking with a feeler gauge and facing of the appropriate amount.... or... theres the "good enough for the bush" method that will work fine, but it might sound a little dodgy..... colour in the last 10mm of the tail with a texter..., put the flywheel on as far as it will go... using a scribe mark out where the edge of the flywheel is.... remove flywheel and use an angle grinder to grind (not cut) the excess off... go to the line and then another 1mm past.....

Sounds dodgy, kinda is,, but it will get you out of trouble and It works on industrial machines when they break down so I don't see why it won't here

<edit> I don't see why I should have to point it out.. but if you're going to do it with an angle grinder, don't let the tail change colours, don't let it get too hot,,,, so don't push to hard and take light bits off at a time and allow it to air cool

Bummer!

Lapping the flywheel / crank too much can produce a step inside the taper of the flywheel, so when it's torqued down, instead of seating on the taper, it seats on the step. Check for that, note it will only be very fine.

_________________

Got my shaft polished on friday

Spiro at St George cranks did the job when I dropped in. What a gentleman.

All I need to do now is get a new flywheel centre and put it in the lightened flywheel, get that rebalanced, check the assembly etc etc.

I think it was bottoming out on the C-washer and torquing up on that instead of the taper. Although it may have wobbled when it span on the shaft to cause the damage. GR reckons he has seen this before.

Now I know to check that and have the centre of the flywheel relieved if it is too close.

cheers
michael

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

yes , flywheels are tending to move further & further onto the cranks now-days,,, they`ve been on & off a few hundred times & go further & further on each time

machining the inside of the flywheel is becomming more & more common because of that

easy check (once the flywheel has been fitted) is to make sure the clutch plate actually spins free... stick a long thin screw driver in-between the flywheel & the backing plate & you will be able to "Jab" the edge of the clutch plate,,, then try to turn it

obviously you can`t have the tin-hat tightened up to do this , but it`s a simple test to make sure before bolting it all together & wondering why the clutch doesn`t diss-engage... then of course having to rip it all apart again to effect repairs

every engine should have this check done,,, whether you think you`re good or not,,, if you don`t do this simple check then you`re bonkers

so,,, if your clutch was diss-engaging,,, then i doubt that your flywheel was button-ing on the C-lock,,, more likely you had a lip from lapping as GT said,,, OR you just didn`t have it tight enough... Or maybe the key-washer was already cracked,,, or maybe your flywheel center was crap to start with,,,or,,,or,,,or ,,, but hey i`m not looking at your engine so i can`t really tell what your particular problem is,,, so go with what you can find/see/sort & try again

_________________
No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Good tip there Matt. I trial fit the Flywheel on it's own before I fit the Transfer Housing.

I fit up the Flywheel - no clutch plate, no backing plate - with the Primary Gear Thrust Washer, C Clip and C Clip Thrust that I am going to use in the final assembly. You can actually look up in to the back of the Flywheel and see how much clearance you have. With something like plasticene, you can even measure the clearance. I do the Bolt up tight, but usually no need to go 'all the way' with it as once it's 'tight' it will - at best - only come down another 1 to 1.5 thou. when tightened 'all the way'. You can also check that the Primary Gear is still happy to spin.

_________________

yeah they can be a pain these days,,, 20 years ago this problem was a very rare thing, but now they`re all "Worn-in"

you should try the big stroke cranks (91mm stroke) with no C-lock groove,,, no C-lock,,,

the flywheel & primary gear washer both needs to be "set" at a certain tension/distance,,, any tighter & have to trim the back of the flywheel , or the washer some more,,, next time it comes off & goes back on, it needs another trim

pain in the Ar$3

_________________
No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Michael I have a very good spare flywheel hub, PM sent.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Ah the benefits of so many engine build experiences.

I think I have read every possible thing about rebuilding these engines here and other sites and books, and I never came accross this before.

Oh well, live and learn.

Or can I just come and do an apprenticeship with my long service leave (i.e. you won't have to pay me) I am a fast learner on the job

cheers
michael

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

Matt, this is what you can see;-

_________________

yeah but i couldn`t be bothered to fit, tighten & remove the flywheel twice if i don`t have to,,, checking that the clutch plate spins easy (with a long thin screw driver between the backing plate & the flywheel) is easy as & good enough for me

we have to plasticine the "non C-locked" cranks/flywheels, because there is no datum to start from, so we simply have to do them twice, bugga-it

& even then, if you tighten the flywheel up more than you did the last time , it can still grab-up on the dam primary gear,,, they really are a pain in the butt

Butt... generally the std issue mini flywheels & cranks are easy enough, once you have done 400 million of the damn things & yet you can still get caught out

_________________
No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.