[pbedrosi]

I am finishing up the bearing/hub/brake Job on my son's E91. The rear axle spindle nut (M27) calls for 310 ft-lb's. I only have 150 ft-lb torque wrench, and I can rent 250 ft-lb wrench but nothing higher.

I know the calculation for extending the length of my torque wrench, another 12" would double the torque to 300 ft-lb's but the extension has to be between the axle nut and the torque wrench. I don't have such a device.

I was wondering if I could rent the 250 ft-lb torque wrench to first tighten to 200 ft-lb first and mark the nut rotation, then mark again at 225, and finally at 250. I should be able to use the angles to estimate the additional rotation to reach ~310 lb-ft. The axle threaded shaft should not have much "stretch" and torque vs. angle should remain linear.

Any thoughts?

[The Nightman]

M27 nut on E91 calls for 420 NM or 310 ft-lbs

[pbedrosi]

yep....and most people, if they have a torque wrench at all have maybe 150 ft-lb max, few may have 250 ft-lb or rent one, but anything bigger I've only seen the Porsche owners that have a GT car with center lock wheels.

[mattanderson]

That's a lot of torque.

[Tambohamilton]

Just do it up FT. It's not particularly sensitive. Max out whatever torque wrench you've got, then give it more with a breaker bar.

[Brian86]

https://belknaptools.com/extensions-calculator/

[eljay]

Originally Posted by pbedrosi

I am finishing up the bearing/hub/brake Job on my son's E91. The rear axle spindle nut (M27) calls for 310 ft-lb's. I only have 150 ft-lb torque wrench, and I can rent 250 ft-lb wrench but nothing higher.

I know the calculation for extending the length of my torque wrench, another 12" would double the torque to 300 ft-lb's but the extension has to be between the axle nut and the torque wrench. I don't have such a device.

I was wondering if I could rent the 250 ft-lb torque wrench to first tighten to 200 ft-lb first and mark the nut rotation, then mark again at 225, and finally at 250. I should be able to use the angles to estimate the additional rotation to reach ~310 lb-ft. The axle threaded shaft should not have much "stretch" and torque vs. angle should remain linear.

Any thoughts?

Torque value does not correspond to rotation, so don't use that method for approximating torque values.

When I did mine, I used the breaker bar, which I used to remove them in the first place. You likely have one too.
Mine is 1/2" 2-foot long bar.
If you put 200lbs at the end of that bar, you have 400 ft-lbs. So, I calculated where I need to put my own weight, marked that spot and then I stood on that spot to approximate the final torque value.

For example, if you weigh 200 lbs, to get 310 ft-lbs, you stand on that bar at 18-19" from the nut.
Make sure you use a good socket that will not slip off the nut and you end up hitting your body work with the bar as it flies off or worse you slip and injure yourself.

[pbedrosi]

Extension formula I have - But it won't let you put the extension on the torque wrench handle, it has to be between the nut and torque wrench. otherwise, I think the torque wrench would simply click at set torque.

I won't reveal my weight, but I don't know how reliably I can get my entire weigh at the end of a breaker bar but I'll try. I do have a proper socket for it.

[Tambohamilton]

I used a jack to support the head of the breaker bar, to help the socket stay in place

[Snertz]

https://www.harborfreight.com/hand-t...ter-58707.html

[pbedrosi]

Originally Posted by Snertz

https://www.harborfreight.com/hand-t...ter-58707.html

That looks like it could work.

Here is my contraption. Used a 2x4 on a jack stand to stabilize the socket and extension. Rented a 250 ft-lb torque wrench from O’Rilleys. It was super tough to hit the max torque, maybe because it had a 15” handle.

I think axle will stay on for a. It at 250-ft lbs. but I definitely need a bigger bar to put any additional torque.