alternative TORQUE ADAPTOR for DRIVE SHAFT -to- FINAL DRIVE bolts

[gtgt_bangbang]

heres yet another candidate for a torque-wrench adaptor required to torque the 12pt bolts (attaching the drive shaft to the input flange of Final Drive).

Snap-On makes a 3/8" SPLINE ~ 3/8 DRIVE TORQUE ADAPTOR ( pn = FRES 12) .
Since apparently few people of Loud Sound Mind need a genuine 3/8" spline driver, there is a decent supply of v.lightly-used FRES12 on ebay around ~$20.

3/8 sockets often fit on a 10mm heads & vise versa, however this spline-type adaptor DID require a just a wee little dremel+diamond bit work to grind just the tips off the splines a fraction of a mm; after a few minutes grinding using a barrel-shaped diamond bit, the remaining splines fit nicely over the 12pt. screw heads. Still plenty of contact interface to drive the screws , the tool/splines are not significantly weakened by this mod.

Using this adaptor @ 90deg / right-angle to torque wrench handle allows the torque wrench readings to be 'close enough' that no maths are involved.

( for extra credit, I'll beat a deadhorse wrt; why the " adaptor-to-torque wrench " orientation is NOT REALLY 90deg, but that is ~close enough..., but pls dont make me dust off SOHCAOTOA-level summer school trig just to prove it !

To explain; orienting the adaptor at 90deg to torque wrench handle places the (imaginary line) moment-arm between the torque wrench's drive stub & the adaptor spline's center of rotation along the hypotenuse of the "right triangle" formed, which causes the torque applied to screw to be slightly HIGHER than the setting on the wrench (due to longer actual 'moment arm' between your hand on the wrench and the spline's socket ... Whew! BUT ) the difference will slight ... a more correct orientation would be slightly less then 90 ( roughly about 1 "ratchet click" ...

So now I can stop acquiring tools, as I finally rank a small token of Snap On buried under all that sundry brand ( can I still get a hoorah for
PennCraft ?? )


next up- a common ( especially "used 1 time!" ) Dana 44 axle "crown nut" socket is nearly perfect for the retainer nut on the final drive.
next post , me buckos, next post ...

 

[20774]

Are you sure about the 90-degree alignment that, if I read you right, produces a slightly higher than the reading on the wrench? Geometry says that if the adapter is 90 degrees to the length of the wrench and you pull the handle in a direction that is 90 degrees to the length of the wrench, the wrench reading will be exactly correct.

Maybe I'm missing something.

 

[gtgt_bangbang]

Im sure as any 7:30am-summer-section-Trig-For-Dummies-40 years-ago-modestly-passing-grade-Graduate can be,

later/soon I'll sketch up a diagram or two to show the difference
but I am also PDS ( pretty dang sure) the difference is 'negligible' for this purpose, using retail grade torque tools.

PS I have to RE-think about it; whether the true actual torque applied (with adaptor @ 90 to handle) is higher or lower than scale reading,
but its is a) definitely not exactly the scale reading and b) probably negligible

A clicker wrench isnt precisely reading the torque around the fastener, it is reading the friction / slip between toothed pawls pressed together by preloaded spring ,inside the wrench ... in an "equal but opposite direction" sort-of way roughly speaking ... this may be flipping my minds eye assumption about wheter higher or lower values ¯\_ (ツ)_/¯ .but hEy LEts FiND OuT soon !


In so many words;
with adaptor at 90deg to wrench handle, the MOMENT ARM , turning around the fastener, is the HYPOTENUSE of the right triangle formed , not the major leg ( 'adjacent ' ? leg

 

[20774]

A click or two LESS than 90 would be closer to " read the scale directly" values

I would certainly agree there. Heck, without an extension, if you had your hand on the handle and pulled at an angle to the length of the wrench, that would also create problems. You have to know how to use the tools properly!

 

[nrpetersen]

I took EngrStatics over 65 years ago, but using the proposed setup, a bending beam type torque wrench with a simple swivel handle would yield perverted results if there is any radial force component delivered to the wrench handle by the operator. In other words, when handle force is not perpendicular to the wrench axis.

The same would be true for a "clicker type" torque wrench (my less than favorite kind).

The error torque sensitivity and error polarity to any applied radial force would depend on the length of that Snap-On adapter. A shorter adaptor could be fabricated for less potential for error. i agree the error would probably be insignificant however.

 

[gtgt_bangbang]

90 proof

oh the poor poor horses; after this beating , beer wont suffice, they need 90 proof like the mens.

IMHO the proper geo-maniacal relationship ( to read the scale on-tool) is
90degrees between the FASTENER "line" and the FORCE applied . Like the middle diagram.


aside; Clicker wrench have a clicking "slip joint" (words fail) inside the handle.
The Torque Arm TA is usually ( w/ no adaptors) the length between the "socket" (or center of ratchet) and that slip joint.
Normally , torque arm length = BC diag 1

Adding the adaptor at 90deg to TOOL means the torque arm is now line = BA
(and line length BA > BC , as apparent in the cartoon or the Pyth'y maths),

so I want to imagine that the tool joint SLIPS clicks just same as it did before , but does so at LESS actual applied force,
cos I have MORE advantage, due to the longer BA line.
So the fastener is UNDER torqued. by 1%. ok, I can loose 1% of my sleep.

I think the proper set up is 90deg on the 'imaginary" line between fastener (or perpendicular tangent ) and applied hand force, like diagram 2.
This is actually about maybe between 2 & 3 click on my sears finest 3/8 clinker lol

also with this little wrench , and AC = 2" ( adaptor ) , BC = 12" (always) then BA = 12.08" .... less than 1% error

Airhead being the best BMW ever made, some physics^physician^philosopher reading me will probably point out that the applied force F is no longer applied at an accurate 90degress to the fastener's original 90deg "tangent line"

and performing all that ugly parallelogram trig ( QUIG-onometry ??? ), something like the 3rd pix, means just put the darn thing back either/or/at 90-to-handle, and pipe down.

I do believe the quigonometry-aspect is what Dr. (Hon.) Mr. NRPetersen is referencing , but I only speak F-fluent Curmudgeon at this time.


PS No matter where you HOLD the wrench, the position of the slip joint is the same length from ratchet center.
So no matter where you grasp tool... Just got to hold the tool "flat" to W/R/T rotation

PS no WONDER my bike aint done. I'll one attaboy credit to anyone who does the quigonometery in the last pix.

diag 1



diag 2



diag 3

 

[20774]

I'm not sure what you're doing with the last two pictures but the first picture is correct for a 90 degree adapter. The lever arm is a"...not c"...and if you pull on the handle as you indicate, the dial on the wrench will read the right value.

 

[gtgt_bangbang]

I'm not sure what you're doing with the last two pictures but the first picture is correct for a 90 degree adapter. The lever arm is a"...not c"...and if you pull on the handle as you indicate, the dial on the wrench will read the right value.

In diagram 2 , I basically 'flipped" the right triangle over to put the 90 on the fastener ( which is turning jut like it did before)
verses the ratchet center ( which is NOT turning, so to speak)

dunno how to say it any different; I disagree.

the "moment arm" between point of force (clicker mechanism ) and the fastener , is line BA ( = c") , not BC ( =a")
c" > a" . by ~ 1%.


I would think that a click wrench in good condition is accurate to about 5% full scale


with the adaptor , the SUM of two of the (many possible) torques contributions around the faster
(aka ; torque applied through arms BC and AC ) sums up to that applied via BA

 

[20774]

I respectfully disagree. The moment arm for your first picture is BC.

I took your first picture and added two black dotted lines. (Discount the fact that your initial length of the wrench is not truly vertical.) If your line of force at the handle is along the dotted line, that dotted line remains parallel to the dotted line that goes through socket head of the wrench. The distance between these two lines remains the same. Therefore, the read torque is the correct torque.

 

[gtgt_bangbang]

a "clicker type" torque wrench (my less than favorite kind).

.

ha yeah I hear ya. When only cockroaches are left scurrying over the ol' Torque Ranch and the slip pawl & spring has clciked its last rusty snap ,
those beam wrenchs will still be in " calibration " ( +/- 10% ,,, prolly)

Especially that mid -ized one ( note it has both a 1/2" and 3/8" drive lol) It hurts my neck to use the 3/8. No wonder Sears went down like Forman.

The 3/4 drive 300 ft*lb is too large for even a herd of cockroaches but $10 at a garage sale = priceless .
Worked OK for a 944 rear drive shaft lock nut ., or almost flipping a R100S over on its side ...
But then so did 200# of me standing 1.5 foot out ( balanced one foot on the tape mark lol) on a BA breaker bar.

 

[gtgt_bangbang]

I m tapping out , & soitanly mean no offense, as sometime soon I will just sits & thinks about your contention some more,
which is sort of what I was trying to express in the parallelogram , 3rd cartoon ...


but torque, here (and by definition ??) , actually turning the bolt, results from (only the component of the ) force which is acting parallel to a
reference "tangent" , that reference tangent which is 90degs to the line between the fastener axis and the 'point' of applied force.

That distance between assumed Point of Force and the bolt axis IS the 'momemt arm' length in the calculation.

In my top diagram, arm BC contributes some fraction of total torque ( see it?) AND arm CA contributes some fraction of the total torque .
The two components of the torque due to BC and CA sum up , are = = to the torque applied via moment arm AB .


You could really do the same thing with any triangle imaginable; sort of like how a 500 ft long torque wrench with a 499 foot long adaptor , aimed straight back at the wrench handle would give , net , 1 foot long torque arm .( ie a really really tall very narrow right triangle) Doesnt matter where the angles are located wrt to the turning axis, just the net net ,

the only thing I see is a possible misaigment of applied force ( ie , no longer is ALL the force directed perpendicular to axis / tangent)

this is why I should have become a brewer or candle stick maker instead , sigh

 

[20774]

Hmmm...I'm still not understanding what you're saying. Here's something that I found. It basically computes the correction factor C for the reading of the wrench. The correction is:

C = Lw / (Lw + La)

If La is zero, as in the case of the 90 degree situation, no correction is needed to the wrench reading.

If La is greater than zero, as in the case of the image on the right, the value of C will have to be less than 1.0 which means that if you want to apply 50 ft-lbs, you must shoot for a wrench reading of 50 * C, or some value less than 50. In this case, you have to use geometry to figure out what the length La is.

In the lower image, it's pretty easy as we can clearly see that the true length is Lw +La or the entire length. Again C will be a number less than 1.0 which must be applied to your desired torque to get the wrench torque you look for.

 

[lkchris]

heres yet another candidate for a torque-wrench adaptor required to torque the 12pt bolts (attaching the drive shaft to the input flange of Final Drive).

Snap-On makes a 3/8" SPLINE ~ 3/8 DRIVE TORQUE ADAPTOR ( pn = FRES 12) .

The heads on these screws are NOT spline drive. Any 12-point box end wrench works fine and you can very likely find a torque adapter in 12-point as well.

 

[gtgt_bangbang]

oh but allow me to convince you!

The heads on these screws are NOT spline drive. Any 12-point box end wrench works fine and you can very likely find a torque adapter in 12-point as well.

you are correcto , sir! but what's your 12 point anyway ? a spline drive is kind of a universal socket.
im not making you do it, just saying it worked here. its purty too

I guess 1 could even hang this 11mm/10mm combo box off t torque wrench. at 90, IM a convert lol

but the 3/8 spline I showed ,

+ a little deft diddle by a small-d diamond dremel,
it fits like a champs glove.

and Snappy made this sweet one , probably never set eye on a nut before me , and its one that even I can afford!
dont get one. its ok.

but for those in the room whom twisting a spline drive clicks their wrench,
check out this pair of old craftysman ; double-sided , 'drives anything" splines, ratcheting box wrench;
Pack 8 metric socket sizes ( & about 7 SAE , a couple of torques , in 2 wrenches , yeah Drives em crazy every time


and the big hefty one makes a GREAT convincer need be

 

[stevenrankin]

Final drive to transmission torque

LOL, Until I rebuilt my RT this past winter, I have NEVER used a torque wrench to tighten these bolts.

This past winter I picked up an adapter for my torque wrench and found out what I knew all along, they need to be tightened damed tight and given the constraints of my tools and muscles, in the past I have been properly torquing the bolts sans torque wrench.

I am all for torque wrench and use them a lot but I don't go out of my way to complicate things. St.

 

[gtgt_bangbang]

I get myself a tube of 242 Blue every Christmas whether I deserves it or not

 

[nrpetersen]

LOL, Until I rebuilt my RT this past winter, I have NEVER used a torque wrench to tighten these bolts.

This past winter I picked up an adapter for my torque wrench and found out what I knew all along, they need to be tightened damed tight and given the constraints of my tools and muscles, in the past I have been properly torquing the bolts sans torque wrench.

I am all for torque wrench and use them a lot but I don't go out of my way to complicate things. St.

I love it! and that's how I've done it too.

Some thoughts -

Most of the above analyses (? plural? ) miss the error introduced by the hand-generated force axis on the wrench system not really being known. IOW what is the effect of an unknown radial force?

Maybe it is time for the airhead pros to minimize the arm length of the adapter by cutting a regular box-end wrench extra short, and brazing it to a 3/8 inch torque wrench square adapter. Brazing is amazingly strong.

On the clicker type wrench - Yesterday I was helping a friend install a wood propeller on his 85 Continental Aeronca Super Chief. He tightened to the average spec'ed torque range with his clicker, but for grins, I followed him with my genuine 3/8 drive Sears bending beam type. All his torques were at least 20% under mine, especially when there was obviously still some deformation to go under the crush plate. I maintained the minimum torque on each bolt for a couple of seconds, but quit when I got to the minimum specified torque with my beam type. These were six 3/8 inch X 5 inches long fine thread aircraft bolts tightened to about 225 in lbs by clicker, but I got a lot more deformation stopping at 200 in lbs. (WTF?)

 

[RPGR90s]

LOL, Until I rebuilt my RT this past winter, I have NEVER used a torque wrench to tighten these bolts.

This past winter I picked up an adapter for my torque wrench and found out what I knew all along, they need to be tightened damed tight and given the constraints of my tools and muscles, in the past I have been properly torquing the bolts sans torque wrench.

I am all for torque wrench and use them a lot but I don't go out of my way to complicate things. St.

Well said.

I love math, trigonometry, geometry and torque wrenches as much as the next guy, but 42 years and 300,000 miles riding/working on Airheads, and all I've ever done with the driveshaft bolts was tighten them pretty damn tight with a normal length box wrench and some medium (blue) loctite.

Not one single failure.

 

[gtgt_bangbang]

beam wrenches are forever as accurate as they were out of the box, until the beam is bent or indicator is off.
I keep wanting to make a female - female square adaptor , to use a beam to check my clickers.

seems like a weak magnet or other very loosely sliding marker would give a "max " reading off the beam so your eye dont have to keep up with the very brief peak

 

[guenner]

As far as I remember on my '19 R100GS, these bolts were a bit elastic and with the recommended torque stayed in the elastic range.

With higher torque the bolts will eventually become plastic and it defeats the intended purpose of using these special bolts.

I don't know how much you have to over torque to get to that point.