Help understanding the Parking Brake

[Malleus]

One question I haven't asked/seen posted is whether you resealed both sides at the same time, or are doing them one at a time. IMO, as is the case with brakes, you should always fit one side first and verify it's OK, against the other side, unless both sides are toast. Commercial shops don't do this because a) they're not working on their trucks (I have a funny story about that), and b) they are paid by the hour, the more work they do in the hour, the more valuable the hour is to them. If you're gaging the repair against a setup you haven't validated, then the temps (or rolling resistance) don't mean much in comparison.

 

[BTLSHP]

One question I haven't asked/seen posted is whether you resealed both sides at the same time, or are doing them one at a time. IMO, as is the case with brakes, you should always fit one side first and verify it's OK, against the other side, unless both sides are toast. Commercial shops don't do this because a) they're not working on their trucks (I have a funny story about that), and b) they are paid by the hour, the more work they do in the hour, the more valuable the hour is to them. If you're gaging the repair against a setup you haven't validated, then the temps (or rolling resistance) don't mean much in comparison.

I did both sides together along with brake pads/rotor and e-brake —-so about as many variables in the air as possible. I used new Toyota Rotors and bearings and seals. Getting the truck now and plan on only touching Pax side. First thing I will do is check the depth measurement…

 

[Malleus]

This falls under the heading of things you should know so that's why they aren't written into the manual: when you tighten a fastener to a given torque, it must be spinning loosely. You cannot tighten a "tight" fastener and achieve a predicted torque value. The reason is that static torque, which is what you see when tightening a "tight" fastener, is higher than dynamic torque, which is what you measure when you tighten a "loose" fastener.

Mr. Newton told us why long ago, "an object at rest tends to stay at rest and an object in motion tends to stay in motion, unless acted upon by larger force". I'm paraphrasing.

So, in order to achieve this

at step (c), you have to back the nut off in order to retighten it. The manual doesn't say that, because you're supposed to know that. In both cases, you're setting the bearing preload/stack height.

Then

Two points to consider here:
1) make sure the parking brake shoes are nowhere near the drums. It is not sufficient to merely back off one click. Back them way off.
2) new bearings, and by that I mean bearings which have never been loaded by driving, require torque at the high end (IME, 9-12 lb·ft); used bearings, and that means any bearing which has been loaded during driving, no matter how many miles, require torque at the lower end. Obviously, the more use a bearing has seen, the lower the torque required to properly seat it.

Don't load test a bearing installation and then try to reset the torque at the high end. It will be too tight.

Finally, in order to achieve this

you must loosen the nut. Never tighten the nut to get the marks to line up. If you feel that you have to loosen the nut too far to get this alignment, break it down and start over.

 

[BTLSHP]

This falls under the heading of things you should know so that's why they aren't written into the manual: when you tighten a fastener to a given torque, it must be spinning loosely. You cannot tighten a "tight" fastener and achieve a predicted torque value. The reason is that static torque, which is what you see when tightening a "tight" fastener, is higher than dynamic torque, which is what you measure when you tighten a "loose" fastener.

Mr. Newton told us why long ago, "an object at rest tends to stay at rest and an object in motion tends to stay in motion, unless acted upon by larger force". I'm paraphrasing.

So, in order to achieve this
View attachment 3735817
at step (c), you have to back the nut off in order to retighten it. The manual doesn't say that, because you're supposed to know that. In both cases, you're setting the bearing preload/stack height.

Then
View attachment 3735818

Two points to consider here:
1) make sure the parking brake shoes are nowhere near the drums. It is not sufficient to merely back off one click. Back them way off.
2) new bearings, and by that I mean bearings which have never been loaded by driving, require torque at the high end (IME, 9-12 lb·ft); used bearings, and that means any bearing which has been loaded during driving, no matter how many miles, require torque at the lower end. Obviously, the more use a bearing has seen, the lower the torque required to properly seat it.

Don't load test a bearing installation and then try to reset the torque at the high end. It will be too tight.

Finally, in order to achieve this
View attachment 3735819
you must loosen the nut. Never tighten the nut to get the marks to line up. If you feel that you have to loosen the nut too far to get this alignment, break it down and start over.

Thanks, had a bit of a delay but heading downstairs now!

 

[BTLSHP]

Thanks, had a bit of a delay but heading downstairs now!

Ok, I will admit to poor photo skills. I used a square and a vernier caliper to get my measurements and measured to a flat surface to all three screws. The steel rule is 25.34mm and total depth I got was 28.06/28.08/27.77

So, I am at 2.74 - 2.43mm vs a specification of 0.2 - 0.9mm YIKES!

So, what am I doing from here? The manual suggest simply removing the locking assembly and trying to reseat it. Is that going to work?

Ignore this reading, I had to flip caliper over to get a stable interface with the steel rule.

 

[Malleus]

Yes, break it down and out it together again. Same thing happened to me.

 

[BTLSHP]

It took longer than I want to admit to figure that axle housing and hub housing are very different. Here is where I am at the moment:

I would call things "provisionally" set. The process of moving the bearing lock nut from "hand tight" at roughly 12:00 to the housing alignment mark at 2:00+ took a socket wrench. Not 43ft lb, but more than a firm push. At this point there is zero play, but I have not tried loading on the tire. The force required to get the wheel moving averages out to 6lb over 4-5 tries. I realize the fish scale is not calibrated, but on the know 17.4 lb weight of my bicycle it registers 17.3lb.

I used a steel square to get my stack measurements. The one shown is 4.71mm - 4.44mm = 0.27mm to the left it is 4.79mm - 4.53mm = 0.26mm. I will admit that getting the caliper square and level was not easy and would impact the measurements.

I also added 1/4-1/3 cup of grease to level out area between the races. After doing this side with more rigor, I feel I have to go back to the other.

 

[BTLSHP]

Allright, we are buttoned-up and I took an 8 mile trip. Drivers side hub at 90.1 and Pax side a 94.5. I imagine some of the difference is the fresh grease?

 

[Malleus]

I'd say you're done. Have a beer.

FWIW, you can measure the depth of the screw head with a scale, as I did in my photo. The reason Toyota illustrated the two images is that you can only get one or the other. There's no chance you can get anything else, unless you use more or fewer parts than you should.

 

[Malleus]

That'll last for years, unless you submerge the axle.

 

[BTLSHP]

That'll last for years, unless you submerge the axle.

I can't thank you enough. If you feel like lunch sometime when you are in Alexandria send me a note, it will my pleasure. I have learned a ton over the past two days and while never an expert I am more confident and got a solid season in RTFM really closely.

I spent time growing up in Indonesia where the family car was a blue FJ45. Home to school routinely entailed axle deep traverses. I have told my daughter to keep the axles dry and think 2x about rock crawling. She will use it for weekend climbing adventures around Colorado.

Many, many thanks for your time and patience!