who needs a sludge trap

[mikeb]

i'm back to the crankshaft reassembly with newly delivered flywheel bolts, as per this thread: https://www.a7a10.net/forum/index.php?topic=16477.0

the problem remains that the thread in the crankshaft is damaged so when even testing a new bolt it quickly damages the outer of the male thread (see pic). to clean the thread, so far I've attempted to burn out old loctite with a torch, clean with a tiny dremmel brush, clean the thread with a bolt with a groove cut (as per the pic) and try other 26tpi softer bolts - similarly damaged. (to recap, a tap won't go in through the flywheel hole and anyway would remove metal).  the crank is on -10 so hopefully some life in it yet.

i figure the easiest path is to use a new bolt with some bearing retainer loctite (stronger than red?) and if it achieves 35 ft-lbs then call it done. but i don't rate my chances of ever getting that flywheel bolt out again without doing further damage. its the one that retains the sludge trap.

so maybe I could:
1. use a shorter flywheel bolt (not the longer one) that won't locate the sludge trap. the plugs should hold the trap in place so do I care if it possibly rotates? then i could in future remove the trap without removing that bolt.

2. I have an external oil filter on the return so how about leaving out the sludge trap altogether, so i never need to get the bolt out? just rely on the filter?

3. maybe file a notch on the inside of that bolt's washer so on future removals, some acetone could eventually dribble down and soften the loctite. but i've never done that- i assume it works on green.

even with the filter, I did notice a bit of cr*p in the sludge trap on disassembly, so maybe the external filter does not catch it all.


any thoughts, votes, or other ideas?

thanks
Mike

[Greybeard]

Did you remove the flywheel from the crank?

[mikeb]

Did you remove the flywheel from the crank?

no GB, i'm trying to avoid that - would be significant work and more delays amidst our lockdown.

[Greybeard]

Did you remove the flywheel from the crank?

no GB, i'm trying to avoid that - would be significant work and more delays amidst our lockdown.

I'm writing from observation and logic as I have never removed a flywheel.
I wrote a post where I suggested that the hole in the fywheel, (which surely should have no thread) and the thread in the crank might be slightly out of line and the bolt may have been forced in. Have you discounted that idea? Anyway, having the crank thread exposed must help you deal with cleaning it.

[mikeb]

GB yes i read your post and checked the flywheel hole and crank thread are aligned. I think the thread damage is probably from past superstrength loctite or PO violence. its hard to see down there. removing the flywheel is beyond me so trying to work around it, else, yes, if i did i could then see the thread and maybe repair. hence my questions

[KiwiGF]

The “retaining grade” of loctite (used for bearings loose in their housing) softens quite easily when heat is applied, which is great if you know it was used......if you are worried the loctite is what will prevent the bolt being removed then I don’t think it should be a worry.

Maybe try an experiment with heating the loctite to check you can soften it and loosen a bolt of that size?

[Black Sheep]

Removing the flywheel isn't so difficult. Heat, oil and careful use of a suitable mallet and off it comes. Worth marking alignment before doing it to ensure it goes back on accurately.
It will make your task so much easier.

[JulianS]

Have just removed an A65 flywheel with careful use of a heavy copper mallet then threading it off the crankshaft.

On reassembly the bolt holes in flywheel and crank need careful alignment.

I am very cautious with flywheel bolts having had one sheer with fatigue and wreck a crankcase.

[muskrat]

G'day Mike
As BS mentioned, it's not hard to knock off the flywheel. Done a few LJ's with no problems.
cheers

[RDfella]

The tap won't pass through the flywheel because a it has to be slightly bigger than the bolt it's cutting for, otherwise the bolt would bind. My first approach would be to carefully grind a couple of thou off the OD of the tap so that it passes through the flywheel. Should still be enough tap to be able to resurrect the crankshaft threads.

[mikeb]

hmm... so if i was to remove the flywheel, could someone give me some tips on that? how to hold the crank, how to heat the flywheel, where to hit with what. and especially getting it back on and aligned? Blacksheep - you say use  oil?

i have only mapp-pro gas and an electric heat gun, or at a stretch the kitchen oven (but in lockdown my better half won't be going out, so there could be trouble ). the crank is large journal, newly ground, bearing and shims fitted.

RD - if i took a bit off the outside of the tap then i guess the cutting edge of the lands would be blunt - given the bolt thread is losing its outer edge, I wonder if a blunt tap would remedy the female thread's damage? and accurately starting the tap in the damaged thread could be tricky

thanks

EDIT: found a vid of a guy removing an A7 flywheel. the LJ is obviously different, but i guess that's a clue: https://www.youtube.com/watch?v=CMBu3V8-k6o

[chaterlea25]

Hi Mike,
If removing the flywheel is not achievable
Rather than grinding the tap, are you or a friend able to make a homemade slightly undersize tap from silver steel (drill rod) and harden and temper it?
There are lots of guidance videos on YouTube and such media on tap making

John

[berger]

Mikeb my girlfriend says get your wife to make some buns and cakes and she can bake them at the same time    i use the oven and gas rings a lot she's a good en

[Greybeard]

Mikeb my girlfriend says get your wife to make some buns and cakes and she can bake them at the same time    i use the oven and gas rings a lot she's a good en

Does she have any say?

[mikeb]

ok i've got the flywheel off another LJ crank for a practice. crank web held in vice, heated flywheel with mapp-pro and hit flywheel with a copper hammer. it did require a fair beating which makes me anxious.

i note it came off the crank on a bit of an angle, appears to be coz a wider section at the journal end of the crank (around the sludge trap bolt) prevents much movement sideways of the fylwheel, whereas 180 deg. from that can move further to the side. was I supposed to rotate it first for easier parallel sideways removal?

and now to get it back on. i'll heat the whole flywheel to 200 deg C and maybe freeze the crank. should it be started offset for more a parallel initial fit and then rotated for alignment? if so how? this won't be easy, especially to get it aligned.
tips and tricks please!

thanks

(GB - does here - less such strife = happy life)