Torque multiplication - via cheater bar

Reprise

Lifetime VIP Supporter
#1
Ok, this is for *tightening* only...LOL And I'm a better writer than mathematician, to be sure...

I know multiplication devices exist - but I can't get my hands on one in a timely basis - without paying $200-$600 for it. Not spending that kind of money for 'today'.

For today, I need to get to 222 ft/lb or so. My 1/2" torque wrench goes to 250 - so it'll technically make it, but it's gonna take a lot of effort to get it there w/o multiplication. Later on, I need 260 ft/lb. And probably more than that at some point in the future, especially on a 3/4 ton truck.

I don't want to purchase a 3/4" TW and sockets for *very* occasional use (over $100 outlay in itself); the HF version only goes to the low 300's, IIRC.

Long-term, I know where to get a 1/2" in / out multiplier, but I can't get it 'today'. And HF only carries a 3/8" multiplier that goes to about 147 ft/lb.

Yes, I know T=f(orce) * r(otation) (in general terms; when GMTNation gains mathematical font capabilities, I'll revise that...lol)

My question - given a fixed lever (1/2" torque wrench), and knowing the length of that wrench (head to handle), what length pipe would I need to attach to achieve an exact doubling of torque (and where would it need to be attached to the wrench)? I've seen anywhere from 'end of wrench' to 'midpoint', to anywhere in between.

(For our purposes, I'm fine with (+ / - ) 5% variance, where 'exact' is concerned; the wrench itself is only spec'd to within 4%, either way)

I'd like to get the end of the pipe just behind the head end of the wrench, for ease of use (much easier than figuring out how to securely attach to the lower / midpoint of the torque wrench, while tightening the fastener in question).

Should the pipe length be:
- exactly double the total length of the wrench?
- double the length to the midpoint of the knurled 'grip' section?
- something else?

Yes, I know this may be overkill - but if I weren't interested in 'precision', I'd just use old skool German torque specs (sortatite, gudentite, fuchentite). These are for brake calipers; the larger torque spec of 260 ft/lb that I'll need later on (listed above) is for my hitch riser height, swapping from Envoy > Sierra

If you know how to calculate the needed lever (pipe) length for a 2x conversion (bonus: link to it online), you'll have my sincere thanks.
Meanwhile, back out to the garage while waiting for the right one of you to see / respond? LOL
(I think I know who might, but I won't 'finger' them at the moment) :wink:
 
Last edited:

MRRSM

Lifetime VIP Supporter
#2
This is a problem that involves the Rules of Archimedes ... The Greek Genius who instinctively understood the use of Levers, Fulcrums, Ramps and ultimately Block and Tackle as Force Multipliers increasing Natural Human Muscular Power over incredibly heavy objects. Before you can calculate the “Tool Parameters” you must know the Absolute Failure Limits of the Nut and Bolt combination you are trying to fasten together. In the case of Very Large Lug Nuts for example... Rather than increasing the Length of The Lever... The Force Multiplier involved is accomplished in the same manner that Transmission Gears use combinations of Gears to Increase the effects of Torque.

In essence... what you require here is a Wrench with a Gear Box that will get cranked X number of times in order to Tighten Large Fasteners... in extremely small increments... but inexorably reach impossible levels of Torque by any other means. If you visit sites like www.cheaterwrench.com ... and after watching the Video, you'll get a better idea about what to look for to obtain the proper tool for this otherwise difficult job.

Generally Speaking... you would be applying Numerous Repetitive "Low Stress" Cranks to gradually achieve the proper level of snugness... so the Golden Ratio would be One Hell of a Lot of Cranks... producing an Output of Rotation that Baby Steps the Fastener tighter and tighter. Once you know what your Starting Torque Level is... you can calculate just how many Cranks to employ to reach the Final Goal..and Stop.

Archimedes Once Famously Said:

“If You Give Me a Place to Stand... and a Long Enough Lever... I Could Shift The Earth...”
 
Last edited:
OP
OP
Reprise

Reprise

Lifetime VIP Supporter
#3
Well, I guessed right on the 'who' - but didn't quite get the answer I was hoping for on the 'what'... LOL No worries, though - I appreciate the reply.

I've seen similar devices on Amazon / eBay / etc. But I don't think they would meet my needs on the 'non-lug' tasks (which is most everything else - I can get to 140 ft/lb for my Sierra's lugs, without much trouble. And loosening them isn't difficult at all - just put some weight on the breaker bar, with a 22mm socket attached. )


BTW, I found this online (and on Amazon, here - same item/seller), but it's not a 'prime' item, meaning I'll have to wait for delivery). For the price, the ability to use it in confined areas (without bracing) and the fact that it works natively with 1/2" drive (on both input / output), I'm going to pick one up. Alternatives are hella expensive (I'm sure they're worth the $, but for a shop / business that uses them constantly - there's no way I can justify paying $500 and up for one, for the likes of what I do).

Ironically, I do remember the story about Archimedes and the lever - from when I was a small child. At the time, I could read / understand the story, but not conceptualize it in the abstract. Was much better with fluid displacement by weight / mass (good 'ol Archimedes was a helluva guy, eh?). Now, I understand exactly what he was getting at with the concept of (physical) leverage. Doesn't help me get these caliper bolts tightened any easier, however... :sadcry:

Oh, well... time to grab a sammich and head back out. Got both calipers changed out on the back; just have to bleed & tighten the bolts... actually, as I check again...only to 162 ft/lb (220 N/m) - w/ blue Loctite, per GM. That's not terrible. But I still need a multiplication device.
 

MRRSM

Lifetime VIP Supporter
#4
By the way... you can have your "Finger" back now... Ouch! LOL
 
#5
OP
OP
Reprise

Reprise

Lifetime VIP Supporter
#6
Waking this thread back up, because after ordering the multiplier I referenced above on Amazon, and testing it out (in my limited, non-lab capacity...lol), I can recommend the tool (I may do a separate thread in 'Tool Time' for those looking for something like this). Tested it at multiplied values of 80 and 225 ft/lb, and it was right on, when I rechecked the 'actual' torque (with both the same torque wrench, w/o the multiplier, and a different wrench entirely).

While I ostensibly got it to *tighten* bolts with... I'm thinking it's just as valuable for *loosening* them, as you only need 1/5th the leverage you normally would.

The other nice thing is that it works in a tighter space than a 3/4" wrench. You use this with 1/2" wrench & sockets - way easier in tighter spaces than a 3/4". Found this out first hand.

Using it on the obverse side turns it into a speed multiplier, but I don't really have any long bolts right now that it'd be worth testing that part out on.

Not a perfect tool, and who knows how long it'll last (I just saw now that it's got a HF-type warranty - 90 flipping days! - but for what I use it for / how often I'll need it, it does the job well enough - and at less than half the cost of the next cheapest similar item. Recommended.

https://www.amazon.com/dp/B01CLWVX1O/?tag=gmtnation-20

PS: It's not a 'prime' item, but it was sent same day I ordered, from Michigan - and I got it the next day, here in IL (yeah, I know - not a far distance. But at least I didn't have to wait for it to arrive from the country of manufacture...ROFL)
 

littleblazer

Gold Supporter
#7
Just for future reference, adding a pipe onto a torque wrench will not multiply when it clicks as it is measuring applied torque at the bolt head. (That is if I am reading that right.) T = force * radius or the distance from center. You apply 50lbs 1 foot away perpendicular to your lever you have 50 lb-ft. At 2 feet you have 100 and so on. The only problem is that this assumes right angles as illustrated below. So let's just say you'll use 80lbs and want 227 lbft on the bolt. 227/80 gives you 2.8375 feet from the center of rotation. Now the only problem is if you're able to take more load or the bolt stretches then you run into an overtprque situation.

Generally though, anything above 200 is really f-ing tight. That is a scientific term and SAE approved. It means as friggin tight as your body will let you.:tongue:
20180823_224543.jpg
 
OP
OP
Reprise

Reprise

Lifetime VIP Supporter
#8
You'll forgive me...but I trust your math skills better than I do your reading comprehension...LOL
I absolutely suck at math (and readily admit it,) so it's not my intent to throw rocks at a glass house.

The only thing I saw to be incorrect with your formulae / diagramming was the tool used - I'd *never* use an open-end wrench on something I was cranking on at these limits! LMAO


To clarify...

- I didn't use a cheater bar, but a multiplication device (yes, I'll admit the original thread title is probably confusing, here)

- I didn't set the wrench at 80 to get 227 (actually 225). Rather, those were two different torques that I tested (with a 5:1 ratio, I set the wrench at 16 and 45 ft/lb respectively - on two different bolts - then used a second wrench to validate that the end results were at 80 and 225 - with no further tightening needed.)

And for those asking: "If your specified torque was 221, why did you go 225?"
I wanted an even product, and 225 was the closest whole number ( >= 221) that could be obtained using '5' as the multiplier. Just for those curious enough to ask...
 

littleblazer

Gold Supporter
#9
An open ended wrench is much easier to draw than a ratchet, thus why it was there lol.

I get the multiplication device as well. What I was saying was if you use a standard ratchet and just apply a weight at a desired distance, for example a 50lb weight, you could calculate your applied torque that way. The torque multiplier is achieving the same thing as offsetting the drive of the torque wrench however many times the distance away from the fastener. (Roughly)

In other words if you used a 5 foot long crows foot with your torque wrench in it and set to what ever you needed to reach 225, it would do the same thing. The way you described it originally it seemed as though you wanted to extend the handle on the torque wrench hence my confusion as that would have changed nothing.
 
OP
OP
Reprise

Reprise

Lifetime VIP Supporter
#10
This is where I kinda get lost, myself - what would the difference be between the crows foot and the handle extension on the TW? (not being facetious, although I realize it might get to be a long response, getting me 'to bright' on this). Given that both are using length as the force multiplier, I see no difference?

Anyway, the real reason I responded (besides to say I was relieved to find that you had apparently taken no offence at my earlier comment - none intended, of course) - was to say that I used this tool again today, on the other front caliper bracket. This, after firing up the compressor with a new impact gun rated at 1150lb torque - and not seeing the bolt move at all (which tells me that my problem all along has been 'not enough air' - but I digress).

Anyway, I attached the tool to a standard ratchet - which works better for this than a breaker - and watched those bolts break free with a couple of medium-weight pulls on the ratchet. Very pleased.

Like I said yesterday -- this thing is just as valuable at *loosening* bolts, as it is at *tightening* them. If nothing else, it'll keep me out of the HF store looking for a two-stage air tank. :nono:
 
#11
This is where I kinda get lost, myself - what would the difference be between the crows foot and the handle extension on the TW? (not being facetious, although I realize it might get to be a long response, getting me 'to bright' on this). Given that both are using length as the force multiplier, I see no difference?

Anyway, the real reason I responded (besides to say I was relieved to find that you had apparently taken no offence at my earlier comment - none intended, of course) - was to say that I used this tool again today, on the other front caliper bracket. This, after firing up the compressor with a new impact gun rated at 1150lb torque - and not seeing the bolt move at all (which tells me that my problem all along has been 'not enough air' - but I digress).

Anyway, I attached the tool to a standard ratchet - which works better for this than a breaker - and watched those bolts break free with a couple of medium-weight pulls on the ratchet. Very pleased.

Like I said yesterday -- this thing is just as valuable at *loosening* bolts, as it is at *tightening* them. If nothing else, it'll keep me out of the HF store looking for a two-stage air tank. :nono:
The difference is simple, extending the handle allows for you to exert less force to achieve the same torque as the measuring point remains at the bolt. By using a crows foot, the torque wrench is now measuring the force or torque applied at a specified distance away from the fastener.

To make it simpler, increasing your leverage allows you to break bolts free easier. That's why you yank on a ratchet but easily pull on a 5 foot cheater on the same bolt. Now the force needed to make the bolt turn hasn't changed but your advantage has. The wrench is still just measuring what's going on at the bolt. Move it a foot away now. So the math, to keep it simple, is you have a 2 foot torque wrench set to 50 lbs. That means you push on it with 25lbs of force to make that click. Now move the head a foot away. You push down and it clicks at 50 again. The wrench is measuring 50lbs of torque at that point but because you are 3 feet total away from the pivot of the fastener, you are actually applying 75 lb-ft of torque to the fastener. Hopefully this makes sense?
 
#12
Back to the tool, this would be very useful when tightening the crank pulley/balancer bolt. It needs a metric ton of torque that I even had trouble with the breaker bar. A major torque to yield type.
 
OP
OP
Reprise

Reprise

Lifetime VIP Supporter
#13
Hopefully this makes sense?
It did, once I finally looked up what the purpose of a crowfoot wrench was. Until last night, I always thought they were for 'restricted access', not 'torque measurement'.

I actually could've used one when I finished up my idler arm / bracket last night (to load the arm with the pivot / bracket, one must use an 8mm hex on the stud, while turning the nut - no way to do that with a socket. Instead of loading to 46 ft/lb, I counted 4 threads visible on the bolt of the old assy, and duplicated that on the new one. Inexact, to say the least.
Suffice to say, I'll be picking up a set of crowfoot (crowfeet?) wrenches on my next HF run.

Thanks for humouring me and taking time to reply - appreciate. I was good with the theory behind extended leverage, but not (all) of the physical tools commonly available to achieve it.



Back to the tool, this would be very useful when tightening the crank pulley/balancer bolt. It needs a metric ton of torque that I even had trouble with the breaker bar. A major torque to yield type.
Yep. With the 3/4 ton, I expect a lot of this kind of thing, so I'll (hopefully) get a lot of use out of it, depending on how sturdy it is. I'm generally not too rough on my tools, although I do wish it came with some sort of blow molded case, etc. Perhaps v.2 will have that. Especially if some entity like HF comes along and purchases the distribution rights, as they have the marketing / distribution muscle (that just doesn't seem to be there right now, IMO.)

When you reach the desired tightening torque, the 'click' on the wrench head sounds a little different, a little softer - but it's there. I find myself double-checking more often - which is fine, considering I'm now saving 80% (?) of the effort. :thumbsup:

Whether one purchases this one, or another brand - I'm now convinced torque multiplication devices are essential for truck owners, with the higher torques used on our vehicles. Especially something like this one, which can be used for both loosening / tightening.
 

Latest posts

Top Bottom