74 drum brake system tech

[rsbcruiser]

10/74 drum brake system tech

This thread is intended to be a semi-comprehensive overview of the issues related to repair and maintenance of drum brake systems standard in the manufacturing period of and around 1974. I am an amateur mechanic (at best). This thread does have the potential to mislead you on some facts related to this topic. Before attempting any repairs related to this subject I strongly encourage you to have and understand the following manuals. The factory service manual. A repair manual such as Haynes. Other resources offered by Ih8mud. There are real mechanics here. Better equiped to offer advice than I am. Consult the FAQ (frequently asked questions). There, you will find many good topics relevant to this subject and a phenominal listing of usefull documentation.

All repairs in this thread will be performed on a 10/74 Totota FJ55 Landcruiser.

I would like to thank Jeff Zepp for granting permision to include his comments concerning Landcruiser brake maintenance in this thread. Per his request, a link to TLCA. Toyota Land Cruiser Association

Jeffs' comments concerning Landcruiser brakes
Land Cruiser Drum Brakes

Jeffs' home page: Jeff Zepp's Home Page

If you don't want to wade through all of the painfull details in my thread then read Jeffs material instead.

Ih8mud, the individuals offering advice, the resources offered herien and myself are not in any way liable for your rigs safe function. Having been a plaintiff in Civil litigation I can guarantee you one thing and one thing only. There is NO compensation for pain or death.

 

[rsbcruiser]

Brake related fluids and lubricants.

synthetic brake fluid question

This thread will help you make decisions related to what type of brake fluids and lubricants to use in your brake system. It is also a good example of the excellent resources available on this site. I would like to offer a big thank you to malcb. His contibution to the above thread is both apparent and very informative. Thanks malcb!

 

[rsbcruiser]

Inclusion conclusion

If there are other threads that could offer information relevant to this topic please feel free to offer them. Like all threads here, this one will be best served if it is interactive and inclusive.

 

[rsbcruiser]

Diagnosing an issue related to your brake system

It might be as simple as your brakes losing effectiveness, pulling to one side, changing behavior at random times, those darn brake lights staying on, whatever. The place to start is the drums. Here is an easy one. drive your rig, park it, get out and touch all drums to see if they are hot. Be prepared to get a burn though. If they are that hot and you have NOT just descended Pikes Peak then you have an issue. A stench similiar to clutch burn is another dead giveaway. In my case, all but one of the drums were warm. Not good!

 

[rsbcruiser]

drum removal

No matter your current actions, a master cylinder replacement, regular maintenance, whatever, here is the best place to start. The foundation of any good brake system. The drums. I begin wheel removal by relieving some of the mass of the vehicle on one wheel only. Repairs are made one wheel at a time. With the floor jack supporting the wheel just enough to start raising the wheel off of the ground I slightly break the torque on each lug using the standard star pattern to loosen. Next, I raise the wheel completely off of the groud and support the axle with a jack stand, a must! Now that the wheel is removed you can go after the drum. First, back off the brake adjusters so that the drum rotates freely. One of my drums was stuck to the hub by rust so I jammed that little pry bar in the big hole shown, popped it with my brassy and off it came. If you are forced to use a chisel to remove a rusted drum, take extreme caution. The chisel will leave a burr that must be filed flat before reinstalling the wheel.

 

[rsbcruiser]

The wrong way!

As the title says, I did it the wrong way. See those coil springs? One of them should be on the back. They have been that way for years, OOPS! Special mention to Coolerman on this one. Coolerman has a FJ40 build thread showing how to do this the right way.

Coolermans 2-71 Build Thread

I have included Coolermans build thread here as an example of the threads available on this site because they are a hidden resource for alot of the information relevant to your Landcruiser. There is a large group of these build threads available in FAQ. Special thanks to Coolerman for granting permision to include his thread.

 

[rsbcruiser]

Removing the keeper

Removal of the keeper springs is simple and straight forward. I reach around the back to hold the keeper shaft in place, use my thumb to depress the spring and my free hand and the pliers shown to rotate the shaft into alignment with the slot in the spring. Check out post number 109 for an easier method to do this proceedure.

 

[rsbcruiser]

Brake shoe orientation

Notice the end edges shown. One side is thicker than the other. This is important to know when reassembling the brakes.

 

[rsbcruiser]

The reason why

Notice the slots on top of the wheel cylinder assemblies. One is wider than the other. The brake shoes should be assembled to match this feature.

 

[rsbcruiser]

Brake shoe condition

Picture shows what is wrong with putting the return springs on oriented to the same side. The keepers had to fight this tendency to pivot outward. Notice the heat checking and uneven wear. Picture is from the right front axle. Wear material thickness is still acceptable. These shoes should be replaced due to excessive heat checking.

 

[rsbcruiser]

The problem is obvious

I used my vacuum bleeder to drain the brake fluid. Seperated the seal from its' seat prior to pulling the piston. What you are looking at is rust in the cylinder. I suspect this is what caused my brake peddle to fail to return to its' resting position. Really tried hard and wasted alot of time before I finally went here. Grrrrrrr. rust, imagine that! It rains alot here.

 

[rsbcruiser]

Removing the wheel cylinders

I removed the bleeder valve first. Disconnected the brake line using a line wrench.

 

[rsbcruiser]

Removing the four bolts

With my left hand holding the wrench on the bolt head, a gentle tap breaks the torque on each of the four bolts mounting the wheel cylinders.

 

[Coolerman]

Keep'em coming. Drum brakes seem to be the topic of much debate lately.

 

[rsbcruiser]

Keep'em coming. Drum brakes seem to be the topic of much debate lately.

Thanks again for the help Coolerman. And just curious, what do you have in that cooler? Don't tell me it is Miller. Bud what be ok though .

 

[rsbcruiser]

Two birds, one stone

If you go to remove the brake adjuster with the tensioner in place then I suggest sticking something in there to protect your rubber boot from damage. Prying that little arrn there is no big deal since it is spring steel but don't overdo it. The other little birdy that almost flew the coop. Here you are looking at the innards of your brakes. Picture shows them dry. If there is lubricant in there then do not jump to the conclusion that it is brake fluid. The other possibility is that your axle seals have failed letttiing gear oil from the axle leak onto your drums. Fairly important subject, consider that you might be rebuilding a brake system because you think it leaks. All your efforts for naught because you replaced a functioning part and now your new drum shoes are soaked in gear oil. You will be doing this .

 

[Coolerman]

Thanks again for the help Coolerman. And just curious, what do you have in that cooler? Don't tell me it is Miller. Bud what be ok though .

Beer? In MY cooler? I don't drink watered down horse piss...

Only TEQUILA gets to be in my cooler, preferably Patron...

 

[rsbcruiser]

Difference of opinion

Looking at the back of your wheel cylinder, notice there are two different types of threaded recievers. The bottom of the holes look different. I mention this here because I think it is possible to install these things upside down. Possibly causing damage to your brake line, bleeder valve or the wheel cylinder. Now, this would be pretty hard to do considering the fact that the adjuster would end up opposite the access slot but I bet I could do it. So, something to watch for.

 

[bajaphile]

Cool writeup, one thing that I had problems with were tightening the wheel cylinders (backing off the shoes) so I could remove the drum. I found that moving the adjusters outwards from the axle, and towards the outside on each adjuster would do this. Is this correct?

 

[rsbcruiser]

The tensioner clicky thingy

Dismanting this little guy? The tensioner arm. If so take care to notice that little lock washer. The arm has a degree of freedom in movement probably neccesary for proper function. Reassembly without it will muck up the works.