Best way to torque down cub cylinder

[captainhowdie]

This is my first time building a cub motor and was wondering how you torque the damn thing down. Its impossible to get a socket on the nuts, so how do i torque it to 20lbs without a torque wrench?

[Valin]

I am not sure on a cub motor, since I have never worked on one, but you can either try to use a crows foot, and if that doesn't work, just use a wrench. I have to use a wrench to tighten the base bolts on my 280hp sled motor. Human torque wrench!.......It's no big deal.

[captainhowdie]

You cant put a socket on any of the front four nuts. I may just have to do it by hand ( but would rather somehow torque it to spec.

[captainhowdie]

I am not sure on a cub motor, since I have never worked on one, but you can either try to use a crows foot, and if that doesn't work, just use a wrench. I have to use a wrench to tighten the base bolts on my 280hp sled motor. Human torque wrench!.......It's no big deal.

I will try the crow's foot though and see. Thanks for the idea

[VegasJeff]

I will try the crow's foot though and see. Thanks for the idea

I had to grind the box end of a 12mm wrench just to make it fit. It is basically torqued to "two grunts" with a long box end, hahaha.

[sleeper06]

I have assembled older cubs and needed to grind wrenches to fit,but the last couple didnt need it ,either way do it by hand just dont kill it

[superfastyfz450driver]

just remember if you are going to use a crows foot to tighten it up you need to readjust your torque wrench setting slightly lower sinde you will be farther off center

[racer]

Bear with me through this please:

 

As an avid shooter and part time machinist I make and modify things. Long story short, I wonder if someone could mate a trigger pull gauge, hell for that matter a fisherman's weight gauge would work too, to an adapter and make a crude, yet VERY adjustable torque wrench.

 

The formula for torque is: Tau = ®(F)sin(theta)

 

Where r = length of arm

F = force applied

sin(theta) = the angle at which it is applied.

 

For simplicity we will use T = r*F

 

We can keep things at a right angle and ditch the trig.

 

So slip an open end wrench into a fixture (read - tube with hole drilled across the thing) and measure

the distance between the center of the wrench and center of the hole. Estimate the hole with a nut in it for closer measure.

 

We'll assume it 22.8inches in length, or 1.9ft. That's our r.

 

T = r*F > 20 = 1.9*F > 20/1.9 = F

 

Therefore by exerting 10.53lbf on the assembly you have reached a 20lb-ft torque spec.

 

Keynotes:

 

1) Force gauge must be at right angle to lever to achieve accurate measure

 

2) Lever must be horizontal and supported to remove any errors due to the acceleration of gravity.

 

3) Make sure your force gauge can handle the force you are using. If it won't you need a longer lever.

Edited September 29, 2009 by racer

[rubberneck]

I also use the ground down box end wrench/ 2 grunt method. LOL Racer, im sure you could do that and it would certainly be the most accurately torqued down cub on the road. However, by the time you get done with the math, ill have the head on and be pressure testing the motor.LOL

[racer]

Haha, probably. But it would be to spec!

[captainhowdie]

Haha, probably. But it would be to spec!

Damn racer, you lost me on that shit. If you come up with an easier way let us know. I used the 2 grunt method like everyone said, Not by choice, but ya gotta do what ya gotta do. Thanks all for the replies!