crank hardware

htown16 · Mar 9, 2012

I am getting ready to put my crank back together. I have a new set of hardware, all studs and nuts. The old was 4 bolts and two studs. In the new set two of the studs are longer than the other four. Also four of the nuts are longer. With the thick part of the flywheel down I assume the longer studs and bolts go in the top holes and the lock plates go on the bottom two, correct? I have Mick Hemmings DVD and he doesn't use any thread locker, but I was thinking about using blue.
Also he doesn't use a torque wrench, but I would prefer to though, what would be a suitable torque? I may have to get a crows foot extension to get on the bottom nuts.

Hobot · Mar 9, 2012

Correct fastener arrangement with lock plate at bottom, which don't lock the nuts just retains dowel. Factory didn't use t-wrenches on crank, you just nip up as TtighT as hand tools allow and use red stud loctite not the lesser strength blue.

303 fmj · Mar 10, 2012

htown16 said:
I am getting ready to put my crank back together. I have a new set of hardware, all studs and nuts. The old was 4 bolts and two studs. In the new set two of the studs are longer than the other four. Also four of the nuts are longer. With the thick part of the flywheel down I assume the longer studs and bolts go in the top holes and the lock plates go on the bottom two, correct? I have Mick Hemmings DVD and he doesn't use any thread locker, but I was thinking about using blue.
Also he doesn't use a torque wrench, but I would prefer to though, what would be a suitable torque? I may have to get a crows foot extension to get on the bottom nuts.

per the Old Britts web site---the 12 nuts are 30 ft lbs.---no mention of thread locker---but as Hobot mentioned---I too use red loktite---as well as new hardware.
Clean all surfaces well----really well. torque evenly as possible criss-cross pattern---several stages.

As one final note here---for me----I only use the "Loktite" brand of thread lockers----there are others--you can even get at 7-11 stores most likely----much more reasonable cost and i'm sure some people will get these trying to save a few bucks---then if something fails--here goes the rap crap "well, I used loktite on the bolts and it didn't hold"----well bud---it wasn't "Loktite" you used so please don't call it that.

Hobot · Mar 10, 2012

Best wishes both measuring and applying 30 lb ft and then expecting that low amount to stay tight in the long run with locite at or above its softened take off state. The soft steel 'locker' is a sight of crush down for clamp force loss in the heat cycling.

rpatton · Mar 10, 2012

The plate that retains the dowel is very soft. Some people delete it for hardened washers. Are the dowels a press fit into the flywheel?

Dances with Shrapnel · Mar 10, 2012

If you don't have proper crows feet or jigs to use a toque wrench then you will do ok by calibrating your wrench hand with a torque wrench. Get a feel for what 30 ft-lbs feels like and go from there.

Don't go overboard with trying to get as tight as hand tools will allow as you can go too far; there's only so much of the elastic range of the bolt you want to/need to use up.

The steel tab plate is a "no never mind" and will be fine in retaining the dowel; heat cycles will do nothing detrimental here. Red loctite on clean threads is the way to go.

If you are planning to rev it at and around redline and beyond a lot a steel flywheel is a must - my standard caution statement here. DAMHIK.

cjandme · Mar 10, 2012

I've been following this thread and this is super good "gouge" to me. I love this forum. Cj

rvich · Mar 10, 2012

It is pretty easy to use a spring scale and an end wrench to torque those nuts. My end wrench just happens to be 6 inches, so going by the manual of 300 inch pounts or 25 foot pounds, I pulled with the spring scale to 50 lbs of pressure.

And yes the long studs on top with long nuts. The plate holds the dowel. My dowel was a slip fit so of course I put some loctite on it. I will probably never get the damn thing apart again!
Russ

AussieCombat · Mar 10, 2012

Please use loctite on those nuts.
If you'r not sure... Search... "Compound fracture of the Crankcase"
AC.

htown16 · Mar 10, 2012

Got it snugged up today. 25 ft/lbs per the manual on the upper four nuts that I could get my torque wrench on, tried to tighten the lower two to approximately the same titeness by feel. Used the plates on the bottom two along with red loctite on all of them. I prefer not to use the red, but I doubt if I would ever open the crank up again. The bike shows at least 12 k miles and the amount of sludge in the trap was minimal. With regular oil and filter changes I don't think it is something I will have to address again.

Hobot · Mar 10, 2012

Ok ok if ya gonna play that way, being all mechanical correct, then best to do as I do, if not going by grunt/groans, measure the elastic bolt stretch set, which is on same order-amount as for similar sized and grade as rod bolts, as way better method than torque wrench mis-leading. In the crank fasteners I like to go 0.0005" over indicated stretch. Cast iron flywheels have about 130 yr half life if not rev'd beyond redline, though some let go sitting at idle.

beng · Mar 11, 2012

A lot of old Norton engines I have taken apart have the pre-Locktite method, staking the nuts, bolts and studs with a centerpunch to lock them up. I do not know if they ever did this at the factory or not.

But that effectively ruins them and their threads when they are taken apart over the stakes, unless you go to the trouble to grind or drill them. Which also pretty much makes them unattractive for re-use.

Not that anyone should stake fasteners in place of using Loctite these days, just reminiscing about the old ways.......

rvich · Mar 11, 2012

I notice the Mick Hemmings stakes his on his rebuild video. When I tore my '74 crank down I was on alert for this potential but I did not find any punch marks, but there did seem to be some kind of "loctite" on the threads, most noticable where the nut had been seated against the flange. I have every reason to believe that I was the first one back inside that motor.

Russ

Hobot · Mar 11, 2012

I've taken apart 4 cranks so far, 2 factroy, 2 my own assembled and found the factory nipped fasteners still very tight but on my own 'over torqued' red loctited nuts, to point of breaking jaws off spanners, I found my crank nuts rather on the lose side to remove again. ugh. One should not re-use rod or crank fasteners so stake em and get new ones, ugh, next time in there.

Bolt stretch method should measure .006-.007" longer than at rest. This way avoids the torque relieving lube of un-set loctite or slight mis machined thread match resistance. At running temps the red loctite is almost as soft as comes out the tube, ugh. I've yet to hear a single success story of any thread or bearing locker holding tight inside Cdo engine or tranny. I use loctite same as my dead white tail deer key fob for better fastener luck hopes.

DogT · Mar 11, 2012

Mine were punched from original. I did the same like Hemmings video after tightening as much as I could with a box end.

It's amazing how fast locktite comes off with a bit of heat. I had to do that on my GB mainshaft nut the other day and it came right off kind of gummy with blue locktite and the heat gun. That's actually the recommended way to remove locktited nuts, heat.

Dave
69S

Hegel · Mar 12, 2012

Someone tried welding the nuts to the bolts on my Fleabay crank. :roll:

htown16 · Mar 12, 2012

Blue loctite doesn't require any heat to remove, just ordinary hand tools. Red loctite requires the heat. I have had to heat parts that had red loctite to the point they were glowing red to get it to break loose.

Hobot · Mar 12, 2012

Regardless of which loctite used inside engine it will not stay crusty-hard at operating temps so back to grunt/groan torque and hope that's enough or stake em too if too timid to torque too much. Btw its common upgrade to bore 750 cranks to take 850 size studs as interference fit.

Dances with Shrapnel · Mar 12, 2012

hobot said:
Regardless of which loctite used inside engine it will not stay crusty-hard at operating temps so back to grunt/groan torque and hope that's enough or stake em too if too timid to torque too much. Btw its common upgrade to bore 750 cranks to take 850 size studs as interference fit.

The crankshaft does not get hot enough to adversley affect the red locktite in this application. As mentioned in an earlier post you really need to heat up the fastener (with a torch) to soften up the red locktite.

Hobot · Mar 13, 2012

Well ok Loctite site says 325' F to remove red type, and crank better not get that hot, but I don't have to heat red that hot to get it to work off with just a draging gritty resistance that would resist full backing off but not likely the vibrations and thermal loss of clamp force. Heck I use it too but not as any relief of applying full scary .007" stretch torque too.

When I began Trixies 4th redo she had prior 3rd redo crank inside with scored journal so got to see how easy to remove my prior spanner breaking torque with red locktite in chilly fall conditions no heat. Sorry my only faith in loctite in air cooled engines is to keep nuts from fully falling off not retaining full clamping is all. Taking 2 factory assembled cranks apart was pretty tough to get nuts started off, did they use t-wrenches of glues?

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