How critical is pinion bearing preload

Rickb1b · Jan 14, 2018

The reason I ask is, I’ve come across quite a few conflicting post on this topic. My old chilton manual says it should be 25-35 inch pounds. I initially set mine at about 25-30 and it seamed really tight. So I started reading and came across quite a few post where people said it should be 13-15 range, these are all post talking about new bearings. So after much difficulty I got mine at 15 and they feel more acceptable to me. Seem reasonable. FWIW, I always wonder just how accurate these in pound torque wrenches are?

Nobody · Jan 14, 2018

You should set it to spec. The bearings break-in and loosen up. That’s why there is a break-in period where you drive short trips and allow things to cool off. Basically spec is just is before the bearing stops spinning smoothly, which feels pretty tight. For a used bearing, shooting for the lower end of spec would be fine.

Without knowing what axle you’re working on, or new/used, it’s difficult to offer anymore advice.

The bearings should be lubed, no pinion seal, and the carrier assembly removed. Yes the in/lbs torque method is accurate. As accurate as the operator anyway.

Rickb1b · Jan 15, 2018

I guess I should be more specific with my question, what is the spec. Multiple sources list a different spec. Some say 25-35 some say 13-15. In all cases we are talking about new bearings with oil seal removed.

Rickb1b · Jan 15, 2018

Ok. Guess I should read the instructions. Looks like the sheet that came with the gears says I should use 14-16 in lbs. Guess I got close.

cldonley · Jan 15, 2018

Torque wrenches are surprisingly accurate. I have Snap-on wrenches that are calibrated regularly due to the whole aviation thing, but I have friends who use Craftsman and they are just as accurate as my Snap-on according to the calibration lab. But, as is said above, you have to use them correctly. Steady pressure on the handle, avoid extensions if at all possible.

bmc69 · Jan 15, 2018

15 in-lb has always been my go-to number with new bearings. My Snap-on dial gauge only goes to 100 in-pounds...it's specifically for measuring torque when setting bearing preload...so I don't worry about accuracy. ;-)

But even cheaper beam wrench will get you close enough as long as it's overall range is not excessive. I have one of those that goes to 300 in-lbs and I'd trust it to measure 15...plus or minus a few.

ntsqd · Jan 15, 2018

I prefer beam type torque wrenches because you know when they're out of calibration. They just are not the easiest to use.

How critical is pinion bearing preload

Rickb1b

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Rickb1b

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Rickb1b

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