Triumphrat

lindsayt · 02-06-2008, 01:12 PM

Hi all, so I have a very nice 1/2" drive torque wrench and would really like to use it to check the torque on the rear axle after chain adjustments. I've been looking for 24mm crowfoot wrenches with 1/2" sockets, and have come up completely empty-handed. I don't really want to buy a new 3/8" torque wrench if I don't have to, since they're expensive. I don't want to imagine the math I'd have to do if I used my 1/2" to 3/8" adapter on the torque wrench. Also, it seems really strange that 24mm would be on 3/8" drive considering the forces involved with a bolt that big - mechanically, it seems like 24mm is big enough that 1/2" drive would preferable anyway.

Anybody know where I can find a 24mm 1/2" drive crowfoot? Or should I just not worry with it, and just make sure the axle nuts are "really tight"?

MackDaddy · 02-06-2008, 01:34 PM

Here ya go.

http://tinyurl.com/2oapom

ohiorider · 02-06-2008, 01:36 PM

I've seen a bunch of crows feet at Sears Hardware, but don't know if they have what you want. Re the math conversion ......... as you know, with a crows foot, you need to do a little bit of math to use one with any torque wrench. I'd suggest you double-check my formula (it's from memory). However, putting a 1/2" to 3/8" adaptor on your torque wrench shouldn't make the math any more complicated, since the adaptor doesn't change the LENGTH of the torque wrench + crows foot. It just offsets the crows foot by perhaps 1/2" - 3/4".

Here's the math as I remember it. Lets use a wrench that measures 10" long from the center of the 1/2" drive to the center of the torque wrench handle. Next, install the crows foot and measure the distance from the center of the handle to the center of the crows foot, with the crows foot installed in line with the wrench. Lets say that distance is 12".

Divide short (10") by long (12") = .8333. In this example, this is the factor you use times the recommended torque. Say the torque is 100ft/lb. Times .8333 = 83ft/lb.

Also double check this: I think you can turn the crows foot 90 degrees to the torque wrench, and no conversion factor is required, since the wrench portion of the crows foot is approximately the same distance from the center of the torque wrench handle (10").

Maybe someone else can validate this?

Bob

SHILOH · 02-06-2008, 01:38 PM

I just use a 24 mm socket that happenns to 1/2 drive. Try any autoparts or Sears.

I don't understand the part about adapators 1/2 to 3/8, etc, and the math, as there is no conversion due to an drive adaptor for sockets when using a torque wrench. But 24 mm sockets should easily be available in 1/2 inch drive.

However, as I just observed, your bike is a Bonneville, so a spocket will not work, ie unless you were to take the exhaust off.

So, a conversion is required for the crows foot wrench, but not any adaptor drive size adaptor. The crows foot will extend the lever arm of you torque wrench a certain amount and redue the value you torque wrench needs to be set at prorortionally to the increase in the length of your wrench.

Measure the length of the crows foot from the center of the bolt end to the center of the drive end.

This becomes your delta length.

Measure the length of your torque wrench from the handle pivot point to the center of the drive.

This becomes you base length.

Then solve this simple inverse ratio equation:

Torque-New / Base Length = Torque Orginal / (Base Length + Delta)

Sorry, I didn't read with enough detail to notice that you bike was a Bonnie.

Derby Boy · 02-06-2008, 01:43 PM

If a crowsfoot is used to torque the nut does the torque spec change because of the geometry difference between the crowsfoot and a socket?
By the way a 15/16" (.9375) is only .007" smaller than 24mm (.9448"). That's what I use and it fits fine.

ohiorider · 02-06-2008, 01:45 PM

Quote:

Originally Posted by SHILOH

I just use a 24 mm socket that happenns to 1/2 drive. Try any autoparts or Sears.

I don't understand the part about adapators 1/2 to 3/8, etc, and the math, as there is no conversion due to an drive adaptor for sockets when using a torque wrench. But 24 mm sockets should easily be available in 1/2 inch drive.

I'm thinking Lindsayt may be wanting to use a crowsfoot so he can work around the muffler (maybe when adjusting the chain, for example) without having to remove it or pull the shock bolts and drop the suspension to reach the axle bolt.

psasak · 02-06-2008, 01:56 PM

You need one of these: http://www.motionpro.com/motorcycle/...rench_adaptor/

I got one mainly for using Whitworth wrenches on the BSA, but now I don't have to constantly scrounge for sockets for the torque wrench!

T-Hundred · 02-06-2008, 01:57 PM

Quote:

Originally Posted by ohiorider

I've seen a bunch of crows feet at Sears Hardware, but don't know if they have what you want. Re the math conversion ......... as you know, with a crows foot, you need to do a little bit of math to use one with any torque wrench. I'd suggest you double-check my formula (it's from memory). However, putting a 1/2" to 3/8" adaptor on your torque wrench shouldn't make the math any more complicated, since the adaptor doesn't change the LENGTH of the torque wrench + crows foot. It just offsets the crows foot by perhaps 1/2" - 3/4".

Here's the math as I remember it. Lets use a wrench that measures 10" long from the center of the 1/2" drive to the center of the torque wrench handle. Next, install the crows foot and measure the distance from the center of the handle to the center of the crows foot, with the crows foot installed in line with the wrench. Lets say that distance is 12".

Divide short (10") by long (12") = .8333. In this example, this is the factor you use times the recommended torque. Say the torque is 100ft/lb. Times .8333 = 83ft/lb.

Also double check this: I think you can turn the crows foot 90 degrees to the torque wrench, and no conversion factor is required, since the wrench portion of the crows foot is approximately the same distance from the center of the torque wrench handle (10").

Maybe someone else can validate this?

Bob

Here's a link to the conversion factors for shorter or longer wrench extensions. Look near the bottom of the page.

http://www.engineersedge.com/fastener_thread_menu.shtml

lindsayt · 02-06-2008, 02:12 PM

Quote:

Originally Posted by MackDaddy

Here ya go.

http://tinyurl.com/2oapom

Excellent. You ever buy from those guys? That's a good price, and exactly what I need - but before I lay down the cash, you know anything about them?

lindsayt · 02-06-2008, 02:15 PM

Quote:

Originally Posted by ohiorider

I'm thinking Lindsayt may be wanting to use a crowsfoot so he can work around the muffler (maybe when adjusting the chain, for example) without having to remove it or pull the shock bolts and drop the suspension to reach the axle bolt.

Exactly. Thanks!