Torque wrench how to question
 

I need to torque a bolt to 305 foot pounds. I have a 1/2” Snap On that goes to 200 and a 1/2” Kobalt that goes to 250.

If I use one of them set at 100 ft lb and use a 3’ cheater tube on it, will that get me 300 ft lb?

I need to get this installed tomorrow, and looking online, I don’t see one available nearby.

This link should help.

https://www.terex.com/docs/librariesprovider7/tech-tips/techtip_53.pdf?sfvrsn=1371ae74_10

No, but it will make it a lot easier to torque 100 lb-ft

You meant to say 30 foot cheater, right?

15 pound barbell weight, tied to a 20 foot cheater, on a 3/4 drive breaker bar is 300 ft/lbs.

So is a 100 pound weight tied to a 3 foot cheater bar.



Just take biggest breaker you have, and stand on it. You'll get close enough.

Yep, can't use your current torque wrenches to make this happen.

300 ft/lbs on a 1/2" torque wrench will probably be best using the Snap-off brand.
(Round-off is the correct 12pt socket to use)
I've used those before while jumping on cheater bars.
You'll get brand new tools as a bonus.

See if someone (tractorsupply/bigbox/autoparts) carries torque multipliers and impact sockets.

I think them saying 305 foot pounds is just a polite way of saying "Get the bolt tight as hell."

No, but it’ll get you to 100 ft lb easier!

I have the same issue currently. I need 325 ft lb. on a front crank hub nut.

I went to a long time shop in my area to see what they do. I was surprised when they told me they don’t have a torque wrench that goes up that high, they just do it “as tight as possible.”

It took all of my effort with a 4.5 foot breaker bar to get the nut loose.
And that’s with PB Blaster and a propane torch.

When I typed my question, it didn’t sound right for torquing a bolt. I’ll torque it to 250 and see what I can do after that. I used a six point impact socket on a 18 inch breaker bar and a 3 foot galvanized pipe to break it free. I wasn’t sure my the flywheel pin would hold.

Yea, have to agree.

Other options: 1/2" electric impact will get you 300 lb-ft easily.

A 2' bar with a 150 lb person will do it....

Axle nut?

Last option: stop at a diesel mechanic shop. 300 lb-ft is finger tight for them.

Curious what is this bolt on?

Maybe you said above but didn't see it.

errrr...use the same effort and tools but in the opposite direction?

I'm guessing 305 is about 250 plus a 1/16th-1/8th turn.

BMW 330ci crankshaft bolt.

In replacing the lifters on the car, I decided to go ahead and change the timing chains, ramps, etc.

I like how it's 305, not 300, not 350, 305. It would have been even better if the spec said "307.3"

German engineering.
Anything out of .005% tolerances results in the front wheels bouncing a foot off the ground at highway speeds.

415 Nm

This ^

A 200 lb person stand on a 1.5-ft bar will do it too.

Are you 305 lbs? That makes the math easy...

LOL

nicely played.

Alternatively two 100lb strippers with 1.5 ft of their dance pole cut out would go well beyond satisfying the minimal requirements and permit the OP to simply supervise the task.
Hehe, it's important to not overthink this....

For the nut on the rear axle of my 911 the torque value is some crazy number like 360 pound feet. I would have to look it up to get the exact number and it is irrelevant right now.

I stood on a scale, and pushed down on a 3 foot bar until I weighted the proper amount on the scale. Again, I don't remember the numbers, as it does not matter. I then knew I was pretty close, but I don't do "good enough" when it comes to holding my rear axle on. I brought my socket to a local truck stop and pulled up by the work bays. Of course an old guy in a 85 911 with a $20 bill in hand attracted some attention. One mechanic walked over and I told him I would give him the 20 if he would torque the two nuts to the proper number. He grabbed his 4 foot long torque wrench, and click click twice and he made 20 bucks. I went home and put the cent caps back on and I was done.

I think 300ft lbs is right on the edge of most half inch drives capacity. Can grab a decent ratchet and torque til it breaks and you will be close

if you have the right 3/4 drive socket and breaker bar you can get something like this for relatively reasonable amount. https://www.amazon.com/Neiko-20743A-Digital-Adapter-Foot-Pound/dp/B009GLITFW/ref=sr_1_2?dchild=1&keywords=torque+adapter+3%2F4& qid=1632147711&sr=8-2

Do the strippers need to be clothed or is your math based on them at the end of their act?

I have a DeWalt 20v impact. Used it for axel nuts that are around the same torque. Prior to that it was a 3/4 drive socket and 3.5 ft breaker bar with my fat ass standing on it.

Any really strong impact wrench should do it. You would need to torque it to 250, or however tight you can accurately get it with your wrench, mark the bolt with paint and then blast it with an impact that moves it a hair. Just a hair, at those torques. Threads only stretch so much.

The suggestions about having strippers or 4 German Shepards standing on a pipe assume that there is no friction to overcome in initially moving the fastener. That is an incorrect assumption.

This is the winning post and what I've done in the past for axle nuts but those are easy because you can get them part of the way tight and then drive to a tire shop or somewhere with a huge torque wrench. It's a little tougher with a crankshaft bolt.

So if that is true, how does a torque wrench set for the correct value account for that any more than the strippers or dogs do?

The torque value is given with drag torque included. Where it is not, then it would have to be measured and added to the total torque, and the torqueing procedure would indicate that.

TQ wrenches aren't exactly accurate at the top of the scale they are rated for. Min / Max tq. measuring capacity +/-20% IIRC.

I'd seek a tool rental place out, frankly.

rjp

No, they do not. If a fastener is already tight, (i.e. anywhere close to final torque), it needs to be loosened slightly and then torqued. Torque wrenches absolutely do not account for initial friction and would *click* below final torque in that circumstance. They are made to measure while moving.

I’ve always read the bottom and top scales of the torque wrench are not as accurate. That said, I torqued it to 250 and then used my breaker bar with a 3 foot cheater bar to move it a little more.

Speeder is correct. Torque a moving bolt, not a tightened bolt. And adding lube for good measure may not be advisable.

The accuracy is typically a percent of full scale. So you want to use your torque wrench near the top of its range. The top end is the more accurate region.

Is this accurate? I've always tried to pick a torque wrench where the "desired" torque is in the middle of the wrench's range and not the upper end... but I dunno.

I will modify my statement to say 'it depends on the wrench'. Read the docs that came with your wrench.

What I stated is 'typical'. So it might be both accurate and repeatable...

I'm gonna have to take your word for it.... what docs :D?

I have 20 year old Craftsman TWs ... anyone know about them?

Learned something new.... thanks!

I'm surprised that BMW would have torque value like that rather than a pre-torque value and then a turn X degrees number. That's what modern Porsche's do for flywheels and such.

Torque wrenches aren't super accurate for determining bolt stretch anyway. You could calculate the turn by degree method with the thread pitch and desired bolt stretch.

Just give it 7 Ugga Duggas and you should be fine.

This is correct.