To avoid these ads, REGISTER NOW!

1/2" torque wrench over 250 ft/lbs?

M

maplewood

Well-known member
Joined
Nov 24, 2015
Messages
56
I have a need to torque exactly two nuts on my race car above 250 ft/lbs, to 300-325 ft/lbs, the rear axle nuts. This is the only reason I'd need something above the 250 ft/lb limit of my current torque wrench. Are there any 1/2" that go that high? There seems to be a big jump in price for 3/4" stuff, and I'd hate to purchase a new torque wrench for what would be literally one job performed every few months. I have nothing else that requires 3/4" sockets, nor do I plan to, so I'm having trouble wrapping my head around the purchase.

Any alternatives I'm not thinking of, or so I just need to buck up and get the 3/4" stuff?

If anyone wants the fuller story... this is for a Miata with aftermarket rear hubs. The axle itself stretches when put under extreme loads on a road course with very sticky tires, down force, etc. The stretch lets the (staked) nut back off. This allows play in the hub and quickly ruins the bearing, ruining a weekend of racing, and requiring a bunch of work to replace. The answer to that problem is way over OEM torque on the axle nut, but 250 ft/lbs ain't enough.
 
To avoid these ads, REGISTER NOW!
K

KnurledNut

Well-known member
Joined
Jan 28, 2011
Messages
8,191
Location
n/a
-Borrow someones 3/4 drive. Torque it to 250, mark it, torque to final, mark again. Figure the additional degrees of rotation mark-to-mark. Then you can use your existing torque wrench + a breaker bar to set the additional angle. If you mark the corner of a nut the next corner that passes is 60°. But for that application the whatever-it-is-past-12-o’clock should be within range.

-Another option is to make a custom torque adaptor to use with your torque wrench. When you put an extension on a torque wrench the torque applied to the fastener increases as the lever arm extends.
  • M1 = M2 x L1 / L2
Where:
  • M1 is the torque setting of the wrench
  • M2 is the actual torque applied to the nut
  • L1 is the normal length of the wrench
  • L2 is the extended length of the wrench
Or follow these instructions to figure it:
https://www.terex.com/docs/librariesprovider7/tech-tips/techtip_53.pdf

This could also be achieved using a wrench extender without having to make anything.
 
Last edited:
A

Astro_Pneumatic_Tools

Well-known member
Joined
Oct 30, 2013
Messages
2,113
Location
South El Monte
mike93lx said:
Go git r done
Click to expand...
Been working on it for a bit now, prototyping making the drive out of the same stuff we're using for impact wrench anvils.
The real trick will be working on this without it being offered to one of the many brands we make tools for.
We sell a lot of torque wrenches, just not to ourselves yet
 
B

bcradio

Well-known member
Joined
Jan 30, 2012
Messages
6,017
Location
New Mexico
mike93lx said:
Huh? The torque wrench measures at the head. Length doesn't matter
Click to expand...
Correct! Adding an extension on a clicker type torque wrench will not increase the maximum torque. The torque is measured at the head of the torque wrench so it will just mean you need to apply less force on the handle to reach the exact same torque at the head. If you want 50 foot pounds on your torque wrench you just need to apply less pressure to the handle to get to that same 50 foot pounds. It will not increase the maximum torque. Maybe on a different style of torque wrench that might work, but not a clicker type torque wrench
 
To avoid these ads, REGISTER NOW!
K

KnurledNut

Well-known member
Joined
Jan 28, 2011
Messages
8,191
Location
n/a
bcradio said:
Correct! Adding an extension on a clicker type torque wrench will not increase the maximum torque. The torque is measured at the head of the torque wrench so it will just mean you need to apply less force on the handle to reach the exact same torque at the head. If you want 50 foot pounds on your torque wrench you just need to apply less pressure to the handle to get to that same 50 foot pounds. It will not increase the maximum torque. Maybe on a different style of torque wrench that might work, but not a clicker type torque wrench
Click to expand...
Sure it will. If you put it on the front end.
 
R

ronkz650

Well-known member
Joined
Oct 29, 2022
Messages
221
Location
Denver, CO
Putting a cheater bar on the handle does in fact change the torque being applied at the head, but it's not the same for all torque wrenches so not a reliable means to alter torque being applied.
I tested this theory a few months ago, as it seemed by logic the head would apply the same torque and click the same time regardless of handle length.
Some wrenches it didn't matter, some it matters a large amount. The dial wrench from Precision Instruments didn't care, my old 1982 Digitork from Sears it didn't matter, Snap on Techangle it matters, CDI clickers it matters, Snap On split beams it matters the most of any of them. Just for info.
 
M

msharley

Well-known member
Joined
Sep 20, 2021
Messages
14,157
Location
Central Pennsylvania
maplewood said:
I have a need to torque exactly two nuts on my race car above 250 ft/lbs, to 300-325 ft/lbs, the rear axle nuts. This is the only reason I'd need something above the 250 ft/lb limit of my current torque wrench. Are there any 1/2" that go that high? There seems to be a big jump in price for 3/4" stuff, and I'd hate to purchase a new torque wrench for what would be literally one job performed every few months. I have nothing else that requires 3/4" sockets, nor do I plan to, so I'm having trouble wrapping my head around the purchase.

Any alternatives I'm not thinking of, or so I just need to buck up and get the 3/4" stuff?

If anyone wants the fuller story... this is for a Miata with aftermarket rear hubs. The axle itself stretches when put under extreme loads on a road course with very sticky tires, down force, etc. The stretch lets the (staked) nut back off. This allows play in the hub and quickly ruins the bearing, ruining a weekend of racing, and requiring a bunch of work to replace. The answer to that problem is way over OEM torque on the axle nut, but 250 ft/lbs ain't enough.
Click to expand...
A good used 3/4" Torque Wrench & socket of desired diameter can be found on FleaBay.

Sometimes? Even here on GJ in the CLASSIFIED!

(Big shout out to all the GJ members I have purchased stuff off of !!)
 
O

Odd-job

Well-known member
Joined
Aug 13, 2017
Messages
2,299
Location
SF Bay Area
For a poor man's setup I bought a 3/4 digital torque adapter from Harbor Freight to stick on my 3/4 ratchet so I don't go over the 250lb threshold of my Eclatorq on the big boy bolts. Then I ended up with a Proto torque multiplier because of that darn warehouse thread in hot deals.
 
OP
M

maplewood

Well-known member
Joined
Nov 24, 2015
Messages
56
Awesome, thanks for the feedback guys. I'll take a look at some used tools (hadn't occurred to me!), along with the torque multiplier route. Appreciate the help.
 
D

dnschmidt

Well-known member
Joined
Oct 3, 2014
Messages
7,287
Location
Phoenix, AZ
Astro_Pneumatic_Tools said:
Been working on it for a bit now, prototyping making the drive out of the same stuff we're using for impact wrench anvils.
The real trick will be working on this without it being offered to one of the many brands we make tools for.
We sell a lot of torque wrenches, just not to ourselves yet
Click to expand...
If you do Chris don't make the mistake of making it too short. You need to be the Hunk to turn Precision Instruments 1/2" split beam torque wrench to 250 ft-lb because it's just too short. My best friend nearly broke his nuts using my split beam PI on his Powerstroke diesel.
 
H

HoneyBadger

Member
Joined
Dec 18, 2024
Messages
6
There's no shortage of cheap 1/2" Torque wrenches on Amazon that go to 300 ft./lbs. or higher.
But I think getting either a digital torque adapter or a 3/4" Torque wrench make more sense than buying a 2nd presumably lower quality 1/2" Torque wrench for this task.
 
B

Benito

Well-known member
Joined
Apr 10, 2018
Messages
213
HoneyBadger said:
There's no shortage of cheap 1/2" Torque wrenches on Amazon that go to 300 ft./lbs. or higher.
But I think getting either a digital torque adapter or a 3/4" Torque wrench make more sense than buying a 2nd presumably lower quality 1/2" Torque wrench for this task.
Click to expand...
Link to 1/2" digital adapter or torque wrench that goes higher than 300?
 
S

Steve_P

Well-known member
Joined
Sep 15, 2010
Messages
5,185
dnschmidt said:
If you do Chris don't make the mistake of making it too short. You need to be the Hunk to turn Precision Instruments 1/2" split beam torque wrench to 250 ft-lb because it's just too short. My best friend nearly broke his nuts using my split beam PI on his Powerstroke diesel.
Click to expand...

Yeah, it really needs to be 36"+ long above 250 lb-ft. Like you said, it takes a lot of muscle to get a 24" wrench to 250 on a smooth pull.
 
T

tak1313

Well-known member
Joined
Feb 4, 2018
Messages
658
Assumptions:

Torque wrench with an effective length of 20 inches.
Desired end torque = 325 ft lbs
Torque adapter/extension length = 6 inches (I have "made" my own using a dual closed end wrench)
Torque wrench setting to achieve 325 ft lbs = 250 ft lbs.

The main variable is if the adapter/extension can handle 325 ft lbs without bending/snapping.
 
OP
M

maplewood

Well-known member
Joined
Nov 24, 2015
Messages
56
Just wanted to close the loop here. I ended up buying a Westward 3/4" clicky torque wrench from Zoro: https://www.zoro.com/westward-mcrmtr-trq-wrnch-120-to-600-ft-lb-34-55jc01/i/G3721445/

Total came out to $208 - inclusive of 20% off coupon, free shipping, and tax.

Also picked up this 8 piece set of 3/4" impact metric sockets. I don't see a need to have both chrome and impact, hence just getting the impact ones. Anything this big, at least for my use cases, doesn't need the thinner sockets, nor will I use them enough to worry about differences in wear or anything. https://www.tekton.com/3-4-inch-drive-deep-6-point-impact-socket-set-4889

That set came out to $86 total. Really just needed the one socket, but it is GJ and they could come in handy some time...

All in for under $300, not too bad. Have to find a spot for the wrench, I knew it'd be big but didn't really think too much about it... It is very big. Not the highest quality stuff but seems accurate enough compared to my 1/2" where the torque range overlaps, good enough for my needs.

FWIW I did look on eBay, but couldn't really beat the Zoro Westward on price.

Just wanted to follow up in case someone in the future has the same problem, looks online and figures they have to spend a bunch of money. Thanks again all.
 
O

Odd-job

Well-known member
Joined
Aug 13, 2017
Messages
2,299
Location
SF Bay Area
Curious what the country of origin is on that torque wrench? 72T I suspect Taiwan, but Zoro left out the COO in the product details somewhat conveniently.
 
S

SwissMetric

Well-known member
Joined
Dec 28, 2024
Messages
186
Location
Switzerland
There are various Stahlwille Manoskop 80-400 Nm / 60-300 ft lb dual scale metric/imperial with 1/2" ratchet, I'd recommend the removable ratchet which can also be replaced by a 3/4" ratchet.
Best are the old models without plastic lens.

Avoid the series with a green rotating plastic knob or yellow plastic cap at the end of the grip (the large ones with rotating knurled steel knob are not concerned) and a window in the 2-component grip, the release mechanism is the same as in the other corresponding models but they're much more fragile and a major PITA to repair, it requires a lot of time and the setting mechanism is uselessly complicated and some parts are expensive. The only difference is that the sliding part of the release mechansme is moved by a complex mechanisme while it is directly moved by the slider in the more reliable models.

The versions with the slider are much more reliable and robust.

Be careful to not get a series 755 Manoskop, that doesn't have any scale and require a torque calibration device to set the torque.

When getting a Manoskop with a removable ratchet head, make sure the distance "S" (see catalog) of the ratchet head is the same as the default distance "S" mentioned in the catalog for the torque wrench, otherwise the setting value has to be corrected which is annoying (the corrected value to set has to be calculated or looked up in some table).

Overall I'd rather get a good old Manoskop than any modern torque wrench. The best ones are an intermediate generation with an improved shock resistance but it can't be determined without opening it (no idea about the serial number ranges) but before the negative improvement with the plastic lens occurred. Spare parts are available for most non-electronic classic models.
The current versions with plastic parts beyond the very easy to replace black grip and the small red cap which only hides a screw are more fragile.

Electronic Manoskop are fragile, I wouldn't recommend any unless really required, especially for logging purposes in mission-critical applications. There ware also some questionable electronic circuit design flaws and some feature an ill-designed battery compartment with poor polarity indication.
 
P

pbon

Well-known member
Joined
May 14, 2017
Messages
3,498
Yes, the expensive Snap on. But you could buy less expensive 1/2 plus 3/4 for less total and have an even greater range.
 
You must log in or register to reply here.
To avoid these ads, REGISTER NOW!
Top Bottom