Help understanding the Parking Brake (1 Viewer)

[BTLSHP]

I had a terrible time taking the passenger side rear rotor off our 1994 Landcruiser. I should have taken pictures, but the shoe material was either paper thin or broken and there was a metal edge on the shoe engaged with the rotor.

I got new shoes, rotors and hardware and got things back together. I was able to set the little stops correctly with cables off as well as the star wheel adjustment. But, within a few miles of driving there is a lot of heat around the passenger side hub and I get squeaking from what I assume is the parking brake (foot is off brake pedal).

When get under the car, here is what I see (drivers side/Pax side):

Two things strike me:
- The passenger side is missing the two prongs that support/protect the bell crank. There is also a plate missing under the stop.

- The springs on the passenger side are vastly less powerful than on the drivers side. I can stretch them easily not so on the drivers side.

I suspect the role of the four springs is to equalize the tension on the lateral cables keeping the shoes on each side roughly equidistant from the drum. Thus, until I figure out the springs I am going to b dragging the passenger side shoes with the weaker springs.

As to the bracket, it is part of the backing plate and appears to be out of production. Is it reasonable for me to assume the springs are linear in tension and that replacing all four springs with new is a likely solution?

Thanks

 

[Malleus]

You don't need the fingers to have working parking brakes. The 3rd generation 80s ('95-'97) don't have them. Someone must have thought strike protection was necessary, at one time.

The backing plate doubler was spot welded in place on the backing plate, when it was produced. It's there to prevent pull-out of the thin sheet metal backing plate. I have my doubts as to whether it actually does anything, since the cable can't pull the bellcrank through the backing plate, but it looks good. If you miss it, add one. You can rivet one on from the inside, if you can't weld/braze it on.

The springs are there to make certain the parking brake shoes release form the drum when the handle is lowered. I haven't had any on my DD since forever ago; I haven't missed them. They're on my bench, waiting for me to remember to install them. There are two of them to prevent side loading of the little pivot pin that supports the bellcrank. As to their being linear, I'm not sure I understand what you're asking. They're common extension springs, so they have a fixed spring rate, but the farther they extend, the more force they exert. That force is linear, as with all springs of this type.

Your shoes should not be dragging on the drums. If they are, they are not adjusted properly.

And those stoppers should have rubber feet on them.

 

[BTLSHP]

Okay,

I have no rubber ends on either stop fitting. Replace?

With the cable detached at both sides, I have the stop fitting one turn back from contact.
The new shoes are set to eight clicks back from engagement with the drum -both sides.
The cable once attached at the wheels was adjusted in the car so that at 9 clicks the brakes held decently, I could not measure 44 pounds, but I do not think I was close.

I took a quick drive around the block and the photo shows the position of the stops. I can push the Pax side in closer to the backing plate and watch the driver's side move.

If I remove the springs, Is there sufficient tension inside the brake to keep shoes off of the drum?

 

[Malleus]

The rubber foot is there to keep the noise down; I was giving you a hard time. They're cheap, though.

As I said, I don't have springs on my DD, and the shoes don't drag. When you installed new parking brake shoes, which should last a lifetime, BTW, did you install new return and tension springs, and hold-down springs and cups (inside the drum), too?

I had to replace a set once, because I lost a rear hub seal and it puked all over the shoes, on one side. I replaced the other side too, just to be consistent. They do have to be bedded in.

FWIW, I've never measured the pull force on the parking brake handle. I set it to 9 clicks and don't look back. 44 lbs is a lot of pull.

 

[BTLSHP]

The brakes have been abused by the 90 year old owner over the past few years. He drives it short distances at his retirement community planting blueberries and often has the brake engaged not thinking. He also like the feeling of a super tight brake....

The friction material had come off the old shoes in chunks and was at the bottom of rotor. I replaced:

Shoes - Bosch
Rotor
Pins/Caps
Star Wheel
Flat metal retainer at top where shoes come together.
(Except Shoes all parts Toyota)

I have gotten confused over sequences for reassembly. Mine has been:

- Remove cables from Bellcrank lever
- Adjust shoes, backing off 8 "clicks" from tight with rotor held on with 2 lugs
- Set the Bellcrank stop (happy to replace)
- Attach cables (the first time I did not touch the length adjustment at the lever and so when I reattached the pax "stop" pulled way out from the backing plate)

Today I tried to "loosen" the cable up front but still ended up with the pax stop as in the picture and some dragging. At this position, the lever feel is pretty loose and sloppy with little engagement at 7-9 clicks.

It took me a bit to notice the difference in the springs Drivers vs Pax side. The drivers side appear original, the pax are longer and have far less tension. I suspect the pax side springs were changed when that plate reinforcement came off as it has the mounts for the springs. I have ordered a new set of springs, but I am not certain they will mount in the holes left by the broken plate.

You comment about not using the springs intrigues me because of my broken plate.

I would appreciate any help in understanding why the left side bellcrank "opens" and how to get it to stay at the one turn out position while still have some engagement at the lever.....

Thanks in advance.

 

[BTLSHP]

I got it, finally. The challenge was two things: the cable tension near the lever was too high and the springs on the pax side backing plate had relatively little strength and were completely slack when the brake was in the released position. I initially set things up with the cables off and did not pay attention to th fact that after re-attaching the cable the driver side springs were tugging on the cable and causing the drag. Took me a while to figure out that I need to correct the lever

I am not certain the backing plate springs play a fundamental role other than cable feel. But I put one new original spring on Pax side and it is anchored in a whole where I guess the reinforcement was spot welded to the backing plate. I was able to get things set up and working nicely.

These backing plates are NLA, these are otherwise in good shape but I am worried the revised actor point for the spring. Is this a reasonable solution? Or is there a better alternative?

With this I am down to the front hubs and interior and it is ready to move out to Denver.

 

[BTLSHP]

Been away for a bit, but still struggling with Pax side brake.

For reference, though not ideal here is the back of the parking brake. The reinforcement broke off at some point and what was there for return springs were two of the top spring which has almost no tension in the photo below. I added a new return spring and it has tension retracting the lever. I understand the "stop" is not in the correct position per the manual, but this is where it reliably comes back to at this point ant the point at which I have set the star wheel tension. The levers on both sides move freely and are well lubricated.

My problem is I am experiencing elevated temps on the pax side. By elevated I mean after 12 miles of mixed highway and urban 35 mph roads (with no use of the parking brake) here is what I measured within 3 minutes of parking:

Driver's Side / Pax Side
Hub Outside Wheel: 89f / 103f
Disk Rotor "hat":
Towards rear of car: 112f / 249f
Towards front of car: 107f / 156f
Disk Rotor surface 97f / 190f

I do not feel the car "pulling" to the right as I drive. Drove the car about 7 miles yesterday and checked the similar temps only to find them within 10f side to side. Unfortunately I did not record them. The pattern was the same. On the drive I cycled the parking brake from 20 mph to a stop in neutral several times.

The heat has been a recurring issue since I rebuilt the hubs and parking brake. So, yesterday I got out the FSM and sort of started over. Per my fish scale, the hub once the axel is removed begin to move at 7lbs. Tire on wheel up, there is no side play horizontally or vertically. I do not really know how to test the caliper, but the pins have new rubber, the piston rubber looks fine and there are no signs of leaks or damage.

I did find my top return springs were in the correct position but upside down at the top anchor. I corrected this by the only way I could which was to put a 180 "twist" in to orient the open side correctly. I used two lug bolts to stabilized the rotor then tightened it to a lock and backed off 8 clicks. This seems to get me in a decent spot on the driver's side every time. On the Pax side the rotor moves freely without any scraping, so at that point I feel I am ok.

There is no noise when I drive, and I feel no drag - but I have not checked fuel mileage.

Any ideas? Clearly I have an issue and based only on my IR temperature readings I am thinking it is within the parking brake.

Thanks,

 

[BTLSHP]

Ugh! I have been working off of this diagram from th FSM. My challenge this above was the rear return spring had jumped off the mounting stud. The reason it did so was that to get the open end of the hook pointing up I had put a 180 degree twist in it.

The dealer is telling me there are only two springs for the rear shoes PartSouq/Amayana seem to imply the same:

One spring is yellow the other is orange. Since my original rear spring was yellow I went with yellow to the rear and orange to the front.

These work perfectly on the driver's side. To achieve the correct orientation on the Pax side I added the 180 degree twist and the rear jumped off. So, now on the passenger side I have the open end "flipped"

Is there an issue? It seems to me there should be mirror image springs left/right.

f

 

[Malleus]

90016-DY008 (reddish) goes on the front side, 90905-A6001 (yellow) goes on the rear side:

This is the right rear wheel.

Note: the front spring has to go on first. If you had to twist the rear spring to get it to seat, try swapping it end for end.

 

[BTLSHP]

Thanks! That is what I moved to yesterday after deciding the 180 degree twist to match the FSM image was a bad idea. The only other "odd" thing I have noticed is this bend in the backing plate. I think it is only in the thin metal as the caliper mounts correctly and the rotor is always cooler than the hat. The leading shoe fits tightly against the backing plate. This is to say mounted as it is there is no ability to wiggle is laterally at the top. The trailing shoe is a bit different, I can perhaps get a 32nd" of lateral play as you see it here. Is that my problem?

[parse] [/noparse]

The hub with rotor spins freely and with no obvious noise as I am turning the opposite wheel. I drove it last night for about 4 miles and the pax hub was 30 degrees or so warmer than the drivers side.

 

[Malleus]

Yeah, that's one problem. Neither shoe should drag on the backing plate.

If the hubs aren't with 5° of each other, your bearing is too tight.

 

[BTLSHP]

Yeah, that's one problem. Neither shoe should drag on the backing plate.

If the hubs aren't with 5° of each other, your bearing is too tight.

I’m thinking the hub is conducting heat from the rotor hat and is otherwise fine. I have no play at the wheel and after pulling the axel yesterday my fish scale showed 7 lbs when the wheel started rotating- same place I set it to and on the low side of the FSM spec.

It seems to me my heat source is in the area of the hat.

 

[Malleus]

No, it's not. You're bearing is too tight. Break it down and put it back together again.

 

[BTLSHP]

No, it's not. You're bearing is too tight. Break it down and put it back together again.

Ugh! Okay, easily done at this point

 

[Malleus]

I sympathize; when I did this last year, the ten minute assembly job took 2 hours until it was right. For some reason, which I never identified, no matter how the pieces went together, the bearings wouldn't seat properly. I pulled the hub off three times before it set right.

It's important that the clearance you measure is within the specification in the manual

You can see here that it's too far in:

Trust the temperature gaging. It's far more accurate than the fishscale at measuring the running clearance. I don't mean to run down the fishscale; it's a valuable tool, IMO, but it's only valuable for setting a starting point.

 

[BTLSHP]

Okay, I am going to order new axel seals and go at Sunday, other things intervene. Here is what I got today:

Rockville to Gaithersburg - 5.3mi
DR Hub (end)- 81 Rotor Hat- 105 Disk-113
PX Hub (end)- 88 Rotor Hat- 151 Disk-113

Gaithersburg - Clarksville - 8.3mi - back roads
DR Hub (end)- 93 Rotor Hat- 104 Disk-117
PX Hub (end)- 103 Rotor Hat- 135 Disk-119

Clarksville - Gaithersburg - 9.4mi Interstate
DR Hub (end)- 99 Rotor Hat- 113 Disk-106
PX Hub (end)- 106 Rotor Hat- 142 Disk-121

I would feel a whole lot better if I found a problem with the bearing preload.

Next I need to figure out the challenges of replacing just the lower bit of the passenger frame cushion just in front of the Cats.

 

[Malleus]

It's not helpful to measure the rotor, or any area near it, since it sees disc friction, which increases the heat. Measure at the end or circumference of the hub.

How much grease do you have in the hubs? The bearings should be packed full (until it squeezes out) and the hub should be packed with enough grease that a line down the bore of both bearings just touches the grease in the hub.

The point of grease in the hub is to keep the bearings from slinging grease out of the cones when they're turning. Nothing that isn't a bearing "needs" grease. Too much grease could affect the rolling friction. Just a thought.

It took mine a total of 100 yards to heat up. I wasn't keen on driving it miles until I got the temps to equalize. If it was me, I'd want those temps to be closer.

FWIW, before I had a dedicated seal driver, which set the depth and guaranteed axial assembly, I bought twice the number of seals I needed for a job. Very cheap insurance. And cheaper than a dedicated driver, too.

 

[BTLSHP]

I used the better part of 3/4 of a one pound can of red Valvoline and an old spatula to get to roughly your photo. Bearings were packed and I wiped off my gloves on the spindle. By seals I mean the paper gaskets at the axle flange. I have access to both the race drivers and rear seal driver. For the inner seal, I used a race driver.

 

[BTLSHP]

Ok, it is wet here today, so I am altering my plans and will try and redo the pre-load on the bearing. I have read a pile of posts and some of your comments on the topic. Is this a reasonable approach? #9 Comment

80 series rear hub preload procedure question

i'm looking at the aussie 2 gear low video on this that i will link below and i wanted to make sure i had this correct. i wasn't clear on what happens between preload and aligning the matchmarks. it seems to me it is 1 torque to 43 ft lb 2 spin hub 3 torque to 43 ft lb 4 loosen to "hand tight"...

forum.ih8mud.com

 

[Malleus]

That's hard to give an opinion on, since that thread is all over the place.

There are, in my mind, two points being made in the service manual procedure, which aren't explicitly discussed (pet peeve of mine, since I've spent a great amount of time professionally writing procedures for assembly).

First is the need to "seat" the bearings. Tapered rollers have an assembled height/width (depending on your point of view) that is measured under a specific load, when they are ground. The purpose of the torque value for the inner nut is to meet this stack height, and ensure that the rollers in the cone are fully supported by the cup. This cannot be measured directly, because there are no reference surfaces on the outside of the hub which are related to the bore depths inside the hub. This is a very common situation with mounted tapered roller bearings, and there is a tolerance for assembled height/width which guarantees that the bearings won't fail prematurely if the procedure in the manual is followed.

Use the initial nut torque.

Second is that there is no way to guarantee the "correct" amount of grease in the cone, so the procedure is written to squeeze most of it out, leaving only what is necessary for operation. The procedure doesn't state this is what you are doing, but it is what happens when you torque the nut and spin the hub back and forth. The result is that metal to metal contact is made between the cone, rollers and cup, with a thin film of lubricant between, and the rollers are thus fully supported.

My guess (and this is based on my experience building axles) is that extensive testing was done at Toyota to determine how to repeatably set the wheel bearings without using the measuring devices on the assembly fixtures, possibly with windows in the hub to expose the bearings for direct measurement, and what you have in the service manual is the result of that experience. I would not discount it out of hand.

You can read an unlimited number of personal accounts of people performing the procedure "exactly as written", but I can tell you from my time on an axle assembly line that even assemblers who do this all day long, day in and day out, screw it up, and claim they followed the procedure exactly as written. When they are observed, they deviate from the written procedure and when it's brought to their attention, the response is always, "Oh I didn't do that, but that doesn't really matter, what matters is...".

My advice, and this is just my advice, it's not gospel, until you've built several axles and verified that you can do it repeatably, follow the instructions in the manual as best you can. Make adjustments for used parts (especially bearings which will not seat using the same nut torque as new bearings - the torque required is much lower) as operating results tell you.

There are absolutely more ways to do this than what is written, and if I did it, I'd probably use a little of my own judgement from time to time, but I've built quite a few.