Handbrake/emergency/parking brake clean/adjust (710M)

[StuartL]

As some of you know (from other threads or discussions in person) I've had some handbrake trouble. When I purchased the truck the handbrake worked, just. Very quickly it stopped working at all and last weekend the handbrake seemed nothing better than a sprung lever to impress the girls.

So today I built up the courage to take a look. I'm lucky enough to be furnished with a service/repair manual but I intend to document here what I did so that others can do it without the manual.

There are four stages to this process:

1) Removal and disassembly.
2) Cleaning.
3) Assembly and installation.
4) Adjustment.

Throughout all of the above I used very basic tools and needed nothing special. However I am lucky enough to have access to an air compressor (bought very cheaply from Aldi years ago) and the air tools made certain stages of this process much easier. If you can find an air compressor and associated tools that fit your budget I would recommend purchasing them.

Removal and disassembly

The handbrake sits between the rear diff and the towing cone. To get to it you must remove the towing cone. Prior to removing the towing cone:

Remove the handbrake cable from the lever. This can be found at the left hand side of the tow cone. The handbrake cable is attached with a stud and a spring clip. Remove the spring clip from the stud and push the stud through. I used an old allen key and a club hammer. Impact engineering at its finest.

The lever should now move freely restrained by a large but soft spring on the left hand side of the tow cone. Remove the front part of this spring. It can be done by hand.

The right hand side of the lever is retained by another spring clip on a stud integral to the tow cone. I needed to remove this to allow the lever to clear the chassis. The allen key/hammer combination pushed this spring clip out in seconds and the lever was then moved out of the way.

I found the easiest way to make space for the tow cone to come off was to jack up the body and remove the three rear-most chassis mounting bolts (24mm hex head). One of these is accessed through a hole in the bottom of the tow cone (socket extension required) and the other two are just inboard and forward of the rear wheels. These bolts were done up VFT (very F tight) and I needed a long lever and a lot of shoulder strength to even move them. Once the heads had been broken they were still FT (F tight) and I used the air impact socket driver on the air compressor to remove them completely. I've seen on other threads that some people didn't need to remove them completely. I did.

The rear-most chassis mount is a free bolt screwing into a large flanged free nut in the body. Access to this nut is via a gap on the forward side of the mount, completely invisible from the rear. You'll be able to feel your way in reasonably easily. When you undo the rear bolt it's possible for that free nut to move or fall out. Watch for it and save it for later. There's also a rubber shock absorber between the tow cone and the body, keep that safe too.

Once you've done this you should have a few cm of gap between the tow cone and the now raised body.

Loosen the five capped studs (19mm hex head) around the tow cone attaching it to the rear diff. These were also VFT and to make matters worse the upper-most one was almost completely inaccessible by anything in my toolbox except my 19mm ring spanner. As this nut was undone the ring spanner became trapped between the nut and the rear chassis mount so make sure you have multiple 19mm spanners/sockets or you'll end up juggling tools.

With the handbrake lever out of the way and the body raised a wiggle of the tow cone should be enough to remove it completely. Mine came off by hand but I could imagine that you may need some impact engineering on more corroded ones. On my disassembly three of the studs came out with the nuts, including the annoying top one, which isn't much of a problem on disassembly but proved to be awkward on reassembly.

When withdrawing the tow cone be prepared to catch it, it's fairly heavy.

When I removed my tow cone the rear-most brake disc made a bid for freedom and rolled across the driveway. If this happens to you you'll need to clean it to get the newly acquired crud off it.

The handbrake assembly itself can now be removed from the same studs. Ensure you catch both brake discs (one front-side and one rear-side which may have already falled off).

Cleaning

The handbrake assembly itself is likely to be full of carbon dust. This stuff is nasty and gets everywhere. I started using brake cleaner (aerosol) and tissues but soon got frustrated.

In the end I used an air duster on my compressor and that made cleaning effortless. As it's an air-jet it's also pretty easy to direct it into the handbrake mechanism without taking that apart. I checked that pulling the handbrake mechanism using the actuation lever separated the two central discs, cleaned it up and blew out all the carbon and crud. I also made a point of cleaning the two discs which form the braking surfaces on the rear diff and tow cone.

At this point I chose to take a gamble that the only reason my handbrake wasn't working was due to crud accrual and bad adjustment. I chose to reassemble it.

Reassembly and installation

Putting the handbrake back together is as simple as putting the forward brake disc onto the spline on the rear diff, putting the handbrake mechanism onto the studs, putting the rear brake disc onto the spline and then sliding the tow cone back into place.

Simple? No. The tow cone has to be juggled to get it into place and I found that I kept losing the rubber mount between the body and the tow cone, a mount that can only be fitted before the tow cone. If you have a second person to hold the rubber mount you'll be fine. I didn't and I ended up jamming it in place with the air hose for long enough to reinstall the tow cone.

As soon as the cone was in place I removed my air hose and juggled the rubber mount back into the right place. I tightened the nuts as tight as I dared and reinstalled the activation lever onto the stud on the right hand side of the casting.

Reinstalling the body mounts turned out to be a little bit of a faff. The side mounts were easy enough, requiring some drive and patience to get the bolts to engage on the captive nuts, but they went in fine. The impact wrench helped here too to get the bolts inserted enough to then be done up FT.

The rear body mount, once the rubber was in place, was tricky to align the bolt and in the end I laid under the vehicle with the bolt balanced in a 24mm socket and guided the bolt up into the hole by torchlight. That worked well but because the head of the bolt was sat deep in the socket I couldn't push the bolt far enough in to reach the free nut on the other side of the mount. Using a smaller socket allowed me to reach the head of the bolt in a positive way but I couldn't put enough force on it to push the screw thread through far enough to attach the nut on the other side.

In the end I used my 19mm socket on an extension bar and lined it up nicely with the head of the bolt and used my jack to force the bolt up through the gap. This had the bonus of pushing the tow cone up into the body and revealed enough thread for me to reach around the gap in the front of the mount and reattach the nut with a turn or so.

I dropped the jack and reattached the 24mm socket and then hand tightened with a ratchet until I could feel it start to bite properly on the nut. Then I "went for it" and tightened this and the other body mounts.

I double-checked all of the bolts were as tight as I dared.

Adjustment

Before reassembling the actuation lever I decided to do some adjustment of my own. I ignored the recommendation in the service manual instead preferring to "wing it" on my gut instinct on physics and years of adjusting brakes on RC cars.

I firstly reattached the spring onto the actuation lever.

My first step was to adjust the nut on the actuator so that the lever had a reasonable amount of travel before it bit but didn't move very far after the brakes had bit. I actually ended up with my "winging it" with about the recommended 100mm of movement at the end of the lever when going from fully disengaged to fully engaged. I suspect that this isn't coincidence but I specifically wanted to have the brake engage as soon as possible when actuated without dragging when unactivated.

This left me looking at my handbrake cable. My handbrake cable has clearly stretched over years of use and abuse and pulling the handbrake lever didn't end up moving the actuation lever much.

The handbrake cable is adjusted by undoing the lock-nut (the forward nut on the thread) and then rotating the whole u-shaped piece. You'll need to hold the threaded portion of the cable using something like a pair of pliers. Ensure you grab the fore-most portion so that you don't damage the threads while adjusting.

I carefully rotated mine with the handbrake completely disengaged until the cable was just taut. This meant that the expansion/contraction in heat/cold shouldn't engage the brake and the pulling of the lever should immediately start moving the actuation lever. You don't want a loose handbrake cable when the handbrake lever is completely disengaged but this cable should not be tight.

Once you have it in the correct position reinstall the u-shaped piece, reinstall the stud and the spring-clip and test operation. All should now work well.

Tighten the lock-nut on the handbrake cable and double-check all of your bolts.

Make tea.

[edzz]

Nice write up, however you left out one item. Do you now have a functioning parking brake?

[StuartL]

Yes

[krick3tt]

Just did this procedure. Takes a novice the better part of an afternoon. I really don't time myself on projects, just do it till its done.

Did have a devil of a time putting that rubber mount above the tail cone. Held it in place with a bit of copper wire. I took the pintle off
and it was easier to remove the tail cone (lighter) and also better to put the long bolt back in. Disassembled the whole thing, roughed up the
surfaces a bit, cleaned things and back together she went. Brake works real good now. Stops it strong, even on my sloped drive.

While the dog house was off I noticed a bit of tapping from the valves. Tomorrow a valve adjustment.

Changed the oil, filter and cleaned things up from the trip to NWMF. Next week I am going to order new tyres and she will be back in business.

When I loosened the body mount bolts to get the necessary clearance it was far enough that the drivers side bolt would not go back in the hole.
Used a 'C' clamp to compress the thing and get the bolt in. Amazing the things one learns working on a vehicle. Feel lots better now that the brake works.

Really like that I don't have to jack the thing up to get under it. Just chock the wheels so it doesn't move on me.

Didn't make tea...had a beer.

[krick3tt]

Now for an update on the parking brake...

Did all that stuff in the previous post...it worked for awhile.

Now it is not holding again. Adjustments don't make a difference. Is it time to reline the disks?
Looked at SAV for disk relining parts, about $95. Includes the rivets and disks. I am guessing it is better to have them set on at a brake shop.

Anyone done this procedure?

[PINZ 716]

Yep get them relined by your local brake guy they are a standard size so you should be able to get them relined a lot cheaper.

I did a set here in the UK £35

[krick3tt]

Update:

I bought the new shoes.

Then...I oiled the shaft at the handle in the cab. The brakes now hold just fine.
Simple fix...who would have guessed?

But, I now have new shoes and will some day have them on the disks when I take the thing apart. Ha.