Using a fish scale to set wheel bearing preload (1 Viewer)

[sjpitts]

I am trying to follow Romer's technique for putting setting the wheel bearing preload that is found in the FAQ:

Set pre-load. This step has a difference of opinion. Some folks use a fish scale and some do it by feel. Most agree that the way they do it is the right one.

I'll repeat the steps from the FSM. Install the adjusting nut.

You adjust the pre-load using the 54mm socket. Torque the adjusting nut to 43 ft-lbs

turn the hub right two or three times. Torque the adjusting nut to 43 ft-lbs again.

Loosen the nut until the hub can be turned by hand.

Torque nut to 48 in lbf (Yes thats inch pounds) and make sure there is no play.

Using a spring tension gage (Fish scale) measure the pre-load. s/b between 6.4-12.6lbf. Adjust as required. You do this by hooking one end of the scale to the hub and seeing how much it takes to move the hub.

My question is on the last step. I have a fish scale-- but it just measures pounds-- not lbf. Do I need to do some math to figure out what pounds I need to read on the scale to get between 6.4-12.6lbf? It seems to me that I need to account for the radius to the wheel bolts or something like that. It has been a long time since I took physics . . . .

OTOH, maybe I am just over thinking this . . . .

 

[sjpitts]

Ok, I maybe have just found my answer:

lbf is pound-force, not foot-pounds. So I really can just take the numbers off the fish scale. No radius calculation needed.

Right?

I guess I did not mention in the first post that I was assuming that lbf meant foot-pounds. And in hindsight that was dumb given that Romer's post clearly labeled foot pounds as ft-lbs.

 

[Chester]

^^correct^^

I'm not the expert, but I use an old Buroughs strain gauge where for other purposes the release point is what's measured, where static becomes motive, I believe a fish scale works the same way.

 

[Corbet]

Personally I'd just set them by hand. The FSM calls for the fish scale method but I've found it hit and miss in practice. If you've ever set up bearings on a bike hub or anything else for that matter its all the same concept just bigger. Follow the initial 43ft/lb procedure then do the final setting by feel. Just my $.02

 

[Pin_Head]

Setting wheel bearing preload can tolerate a considerable degree of variation, so we always did them strictly by "feel". After tightening the adjuster and spinning the wheel, back off the adjuster until it has no preload and then tighten it until preload just starts to rise and then tighten it another 20-30 degrees.

Some things are critical: Make sure that you do not shear off the inside tab of the star lock washer when you tighten the outer adjuster nut. That means you have to watch it when you tighten the outer nut to make sure it doesn't rotate. Make sure the outer nut is properly torqued. Then bend over tabs of the star washer on both the inner and outer adjuster nuts.

 

[sjpitts]

My problem with feel is that I don't know how it is supposed to feel.

As I said, I am trying to follow Romers method, but I don't get to 6 lbf on the fish scale until I get to 125 in-lb on the adjusting nut. But this is using a 10 dollar fish scale and 40 year old ABCO Mossberg rotary dial in-lb torque wrench-- not sure what to believe.

The last time I did this I think I used the method described in Spector's front axle booklet. I wonder what I did with that . . .

 

[Corbet]

My problem with feel is that I don't know how it is supposed to feel.

Basically you just don't want any play in the bearings. So tighten up the preload nut until there is no play and add 20-30 degrees. Set the lock nut and star washer, you should then be fine.

Every time I used the FSM (Romer's) instructions I ended up with play in the system after driving it.

 

[sjpitts]

Basically you just don't want any play in the bearings. So tighten up the preload nut until there is no play and add 20-30 degrees. Set the lock nut and star washer, you should then be fine.

Every time I used the FSM (Romer's) instructions I ended up with play in the system after driving it.

This makes a lot of sense.

It seems to me that the the fish scale doesn't seem to tell me much.

I followed the Romer procedure again-- measuring the preload with the fishscale at each step. When I torqued the adjusting nut to 43ft-lb, spun it around, and torqued it again to 43 and checked it with the fish scale I only got 10lbf on the fish scale. I was expecting more.

I backed it off to hand loose for the next step and measured with the fish scale and got 4 lbf

I torqued the adjusting nut to 48 in lb and measured with the fish scale and maybe got 5 lbf. Even after going to 110 in lbs the fish scale was only 7 or 8. Now that is within the range you want, but it freaks me out when I need to go to 110 in-lbs and the FSM said to go to only 48.

I think I am going to sleep on this. Try and figure out if I can tell where the bearings start to not have any play in them to give your technique a shot.

 

[subzali]

If it's too tight it will get hot when driving, if it's too loose it will have play. So when you get it together take it for a 10-15 minute drive at 45+ mph and check to see if the hub is overly hot.

 

[SHREDwagon]

Now use the "Tools Method" (25 ft/lbs), after giving up on the fish scale. No problems since.

 

[shfd739]

Now use the "Tools Method" (25 ft/lbs), after giving up on the fish scale. No problems since.

Same here. Every time with the scale they were loosening up. No issues now that I use this way.

 

[sjpitts]

I spent some time looking at the FSM-- and I discovered that this 48 in lb step isn't in my FSM (my FSM is the 94 version). Mine just gives general language for adjusting. So maybe I shouldn't be so freaked out that it takes me 110 in lb to get to 7 or 8 on the fish scale?

Now use the "Tools Method" (25 ft/lbs), after giving up on the fish scale. No problems since.

I don't know this method. I will see if I can find it.

 

[sjpitts]

I found the "Tools(TM)" method:

My bearing setup method: Assemble everything out to the first bearing adjustment nut, install the wheel (I use it as a flywheel, making spinning of the hub easier and better "feel"). Spin the wheel, snug the adjuster nut, spin, loosen, spin, repeat several times. This is to "settle" the tapered bearings into the proper alignment, each time the nut is snugged, it should stop at the same place, if it continues to move the bearings are not properly "settled". Once I'm satisfied with that, torque the inner nut to 25 ft/lb and finish the job. I always recheck for zero play after driving ~100mi.

I don't see how consistent results could be achieved with the fish scale method. The difference in rolling drag is huge between new and used seals, etc. The goal is to apply even preload on the bearings and seal drag covers that up, gets in the way of consistency.

Depending on, ambient temp, brake usage, length/speed of the drive, etc, the hub temp is going to vary. Checked mine this morning, after a ~13mi drive, some traffic and highway, left 128F, right 130F at the drive flange.

 

[js93cruiser]

People way over think this... Torque inner to 50ftlbs, spin, loosen spin, repeat. Torque inner to 25ftlbs and leave it, I've done dozens of sets like this with zero issue

 

[sjpitts]

People way over think this...

Clearly I am one of those people

 

[sjpitts]

Ok, I am undoubtedly still over thinking this--- but here is more stream of conciseness thinking on this.

The Romer method starts with 48 in lb, and adjusts from there until you get the desired fish scale reading. The Tools(TM) method uses 25 ft lb. That is 300 in lb.

I was freaked out when (using the Romer method) I had to torque above 100 in lb to get even in the low end of the right fish scale range. That has been my mistake all along. I should have realized that the 48 in lb is just a starting place, and I should not have been surprised when it took much more to get the right preload.

That being said, I am now just going to use the Tools(TM) method. I know where he lives. Or at least where his shop is. If the Tools(TM) method fails me I will be dragging my 80 to his shop so he can fix it

 

[Tools R Us]

... If the Tools(TM) method fails me I will be dragging my 80 to his shop so he can fix it

Good plan, but we are booked, so .

 

[western flyer]

Good plan, but we are booked, so .

Classic.

 

[1FZj80]

This may be obvious, but make sure when you measure preload that the brake pads and drive hub are removed so the hub spins freely.

 

[Tools R Us]

... Make sure that you do not shear off the inside tab of the star lock washer when you tighten the outer adjuster nut. That means you have to watch it when you tighten the outer nut to make sure it doesn't rotate. ...

Yep, we apply a skin of grease on the side of the nut that contacts the star washer, reduces the chance of tab damage.