72Golf

Rear axle nut torque questions

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Putting the ass end back together and wondering if there are any tricks to getting that castellated nut torqued down to the whopping 289 +51 ft/lbs.

Do you just use your best impact and give it the old German "guten tight" or spill for a 3/4" drive torque wrench? My 1/2" only goes to 250.

Do you fab up a prop brace across the wheel studs to hold it while you torque it down or just snug it up, put the wheel on and then tighten to spec?

Should I use a new castellated nut or is the old one OK?

Any advice appreciated.

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One way to tighten to desired torque is to take a rod of known length to use as a torque multiplier, stand on a bathroom scale and add appropriate torque. I.e., if use a 3-foot rod and add 50 lbs to your scale weight when applying torque, torque at end of rod will be 150 lb-ft. What I did was get a 6" half-inch extension, cut it in half, drill two holes in an appropriate length of 1" square tube, and weld them in place to make a torque extender for my torque wrench. I can post photo tonight if you would like.

To hold wheel I snug nut, lower car onto ground, chalk wheels with a 4x4 and apply torque. If you are pushing down that helps hold the wheel to the ground. (Edit: However, if you are using the scale method you must pull up so as to add weight to the scale you are standing on.) I have re-used the 36mm nut, but they are not expensive and will be on there a long time, so might as well get new if possible.

Best,

Fred

'74tii

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stand on a bathroom scale and add appropriate torque. I.e., if use a 3-foot rod and add 50 lbs to your scale weight when applying torque, torque at end of rod will be 150 lb-ft.

I admit to being a little slow but you totally zoomed me here. It's kinda like " if two trains leave the station at the same time, what time is it in Cleveland?"

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Oops, I did not mean to be opaque. If you had a one foot rod and applied 50 lb of force to it at one end, the torque at the other end would be (50 lbs)*(one foot)=50 lb-ft. If you had a two foot rod, the torque would be (50 lbs)*(2 feet)=100 lb-ft. If you use a four foot rod it would be (50 lbs)*(4 feet)=200 lb-ft. The bathroom scale trick may not be super-accurate, but works pretty good.

Somewhere I have a good article on torque extenders, but here's a few pics:

Best,

Fred

post-16466-13667620176388_thumb.jpg

post-16466-13667620177316_thumb.jpg

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My method: I figured I weighed about 175 so I stood somewhere between 18-24 inches out on the end of a cheater bar. Four+ years later and the rear hasn't fallen off yet so I figure I got it about right.

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Here's a photo of my torque multiplier. It's length is equal to that of my torque wrench from head to mid-handle, so it doubles my applied torque. For the rear hub I set the torque wrench to 135 lb-ft and get 270 lb-ft at the nut. The multiplier must be in line with the wrench (straight), if it is at an angle the effective lever arm is less and the torque will be less.

BTW, I believe the correct torque for the 36mm castellated nut is 216.9 + 54.2 lb-ft, not 289 +51 ft/lbs as you indicated. This has been discussed before on the FAQ, not sure where the higher number comes from. See torque spec in my photo of factory manual below.

Fred

post-16466-13667620194505_thumb.jpg

post-16466-13667620195475_thumb.jpg

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I use Matthew's method, but I weigh 220+ these days

and my bar is (wait for it)...

...

...

2 feet long!

Haven't stripped a nut or a stub yet.

And they don't work loose.

t

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BTW, I believe the correct torque for the 36mm castellated nut is 216.9 + 54.2 lb-ft, not 289 +51 ft/lbs as you indicated. This has been discussed before on the FAQ, not sure where the higher number comes from.

Fred

BMW changed the tightening torque for this, see footnote 2

Question is when the Tenifer treated spacers really were introduced, as there is no supersession of the part number in the catalogs.

My older shop manual, that cover NK & 02, shows the same as the earlier spec on Fred's sheet on a sheet that covers only 02 models.

Here's the image from the later 2002 shop manual, with the higher spec.

Need to ask BMW to clarify the VIN breakpoint, as this is a safety issue (stub axles will fail earlier at the lower torque spec.)

rear_axle_tighten.jpg

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John--many thanks for posting where the higher spec comes from. --Best, Fred

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Tenifer... hmmm.... high school girlfriend?

Funny that the sleeve was the soft part of that equation.

t

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