About primary locking tools

[Karl H.]

In several posts I read warnings from Max Headflow and FSG not to use the wedge type locking tool. They recommend the locking bar instead. It made me sit down and do some calculations about the forces that might occur (using engineering mechanics). Please excuse for metric units and German words: replace "N" by "lb" and "Nm" by "ft-lb" in the final equation and you have at least an acceptable approximation. "Keil" is "wedge"

Result: Bending forces (FS) at tranny shaft (and crank) are more then ten times (!) higher using the wedge. Simply spoken the wedge method results in a gun tackle effect.

Example: Torquing down the comp nut to spec with 165 ft-lb (TC88) results in a bending force on tranny shaft of about 16,500 lb using the wedge. But breaking the nut (red loctite!) with lets say three times the spec. torque results in a force on tranny shaft of about 50,000 lb

Thanks to Max and FSG for the advice!

By the way: A buddy of mine removed the inner primary and had to use a huge breaker bar to get the comp nut loose. At assembly he recogniced a bent tranny main shaft an wondered about. Don't ask me what locking tool he used ;-)

[road-dawgs1]

Way above my little cop mind.

[rbabos]

Nothing like seeing it with the force angles in play. Personally I aways thought was a barbaric form of abuse on the chain.
Ron

[moscooter]

 

What the hell does this mean....................."gun tackle effect."

[rbabos]

What the hell does this mean....................."gun tackle effect."

Block and tackle stuff. I think it refers to running through one pulley for leverage rather than two.
Ron

[truck]

Wasn't the reason for switching from the wedge to the bar to prevent the primary case from cracking? I don't understand how it could crack but that's what I remember reading.

[Admiral Akbar]

Karl,

Thanks for working the numbers.. I was too lazy to work the calculations.. Imaging what the numbers are if a rag or screw driver handle is used instead..

Looking at the calcs I may have some questions later but I think that it's a good first order set of calcs..

Max

[Admiral Akbar]

Wasn't the reason for switching from the wedge to the bar to prevent the primary case from cracking? I don't understand how it could crack but that's what I remember reading.

I think it was to keep the case from shifting and damaging the inner primary bearing  but I could see where on the early cases you could crack the O ring boss on the motor as a result..

Max

[stglidesrule]

I used an air impact wrench to loosen the comp nut on the OEM comp and used the wedge and a 1/2" torque wrench to tighten down the bolt on the SE comp. No issues.

[Coyote]

Air impact off, locking bar and a TQ wrench on.

[Rusty Steel]

Just got to be careful not to loosen up them magnets on the rotor.. I've taken off about a dozen comp sprockets with an air impact and haven't had a problem YET. 

[Ohio HD]

Just got to be careful not to loosen up them magnets on the rotor.. I've taken off about a dozen comp sprockets with an air impact and haven't had a problem YET. 

I've always heard that there is a possibility that you can loosen the magnets too. I think the key is a lot of air pressure, and heavy duty air impact. You know, just rip the nut off, rather than clanking away at it. I haven't loosened any magnets yet either.

[Coyote]

The key is not using a cheap ass impact and beating the hell out of everything. A good impact will pull the comp quickly and you can't even feel the impact on the rotor.

[Karl H.]

Imaging what the numbers are if a rag or screw driver handle is used instead..

Max

Good finding, Max! The forces depend on how far the chain is pushed away from the pulley. The smaller the wedge the higher the forces. If using a wedge on a TC88 than the big (and stepped) one which is recommended by the factory.

[Karl H.]

What the hell does this mean....................."gun tackle effect."

I you use a simple block and tuckle (gun tuckle) the force which brings the two pulleys together is twice the force you apply on the loose end of the rope. Same effect with wedge locking: The force on the pulley shafts (gear and crank) is twice the force in the chain.

[barny7655]

I use 3/4 snap on impact with a impact socket,one ,hit its off,and 3/4 torque wrench, just makes it safer for user and the bike , the old saying bigger the better, only for this though, cheers Barny

[Admiral Akbar]

I use 3/4 snap on impact with a impact socket,one ,hit its off,and 3/4 torque wrench, just makes it safer for user and the bike , the old saying bigger the better, only for this though, cheers Barny

Why?? are you worried about breaking a 1/2 in drive??

Max

[barny7655]

I do a lot of harmonic balancers on cars , remove and replace , the bolt that holds them on , one would think a 1/2 impact would remove them ,not, so 3/4 the go ,its just the undo, that needs that shock to start it ,most up market double hammer 1/2 guns range from 750,to 900 ft lbs  in reverse,we have 16 mechanics with all types of air impact guns,so when  a new model comes out i try it on some of these bolts,some do ,some dont,but when your gun over rattles trying to undo , those hammers wear, just replaced both on my gun as one snapped,as another post has said dont want those magnets to dislodge ,we run our compressor at 7 bar,as we say here every one to there own ,cheers barny

[truck]

we run our compressor at 7 bar,as we say here every one to there own ,cheers barny

You made me look it up. 7bar = 101.xxx psi.

[Karl H.]

I found another reason why the primary of the TC96 (up) must not be locked with the wedge type tool of the TC88:
Using the wedge you might bend or brake the auto adjuster (at least the early versions) by the resulting chain force.

Karl

[barny7655]

i forgot to add , its the volumme of air that undoes the nut , not only  psi of the air compressor ,3/4 does the job but requires a larger air flow that a 1/2 inch ,the electric one also does well on these nuts,  cheers 

[rbabos]

I think they went to the locking bar due to not enough clearance for the chain to deflect when using the block. Broken inner primary could result.
Ron

[xlfan]

Is it possible to use the bar on the inners with inspection cover stand-offs?

xlfan

[rbabos]

Is it possible to use the bar on the inners with inspection cover stand-offs?

xlfan

Yes but it requires a custom bent flat bar with a job in it to clear the stand offs. Bend up a 1/8 welding rod as a template for clearance both ways with flipping and tooth contact angles, then bend a flatbar to match.
Ron

[doubletrouble]

My ingersoll rand 2131 max hasent failed me yet @ 175 psi - busts them loose no sweat . But it has failed me - honda crank bolt .