Rear Drum Automatic Adjustment for 2006 DC

Hello Everyone,

I've recently joined the forum, but I've visited these pages many times and appreciate all the information you have shared. I wanted to bring up a topic that doesn't appear to be properly answered in these forums.

I own a 2006 DC Tundra with 299k miles. To celebrate her upcoming 300k birthday, I've been knocking out a lot of maintenance items on the truck. I've always experienced a soft pedal and loose parking brake on this truck, so I've referred to this forum for guidance on getting the rear drums properly adjusted. There seems to be a difference in the as-built layout of my rear drums compared to how they're shown in the FSM and how they've been discussed in this forum.

It's frequently stated that our trucks have automatically adjusting rear drums, and the adjustment comes from actuation of the parking brake. When the parking brake is engaged (and functioning properly), the Parking Brake Lever pushes the shoe against the drum (to hold the vehicle in place) and also lifts the Automatic Adjusting Lever up a notch on the Adjuster star. If there is a gap between the shoes and drum, the Automatic Adjusting Lever will tighten the Adjuster star upon release of the parking brake and relaxation of the Parking Brake Lever. This closes the gap between shoes and drum, and will continue with each parking brake actuation until the Adjuster star is tight and doesn't allow the Automatic Adjusting Lever to turn it anymore. This system is described in detail at the below thread and is shown in the video below.

https://www.tundras.com/threads/rear-brake-adjustment-theory-and-practice.99575/#post-2540029

https://www.youtube.com/watch?v=ZZoChjn_1KM

This system is shown in the 2005/2006 FSM. Please note that the below schematics represent the Driver side of the vehicle, and the subsequent photos from my truck will also show the Driver side. We know this is the Driver side because the Bellcrank enters on the right (rear) and the Parking Brake Lever is mounted on the left (forward.)

Please note:

• The Adjuster star is located toward the front (left) of the drum brake assembly in the schematics below.
• The Automatic Adjusting Lever interfaces with the Adjuster star on the outboard side of the brake assembly.

Here's a photo from another thread of how this assembly should look. The Automatic Adjusting Lever interfaces with the Adjuster star on the outboard side of the vehicle and is connected to the Parking Brake Lever. The Adjuster star is oriented toward the front of the drum brake assembly as shown in the FSM. This photo also shows the Driver side.


Credit: https://www.tundras.com/threads/drum-brake-star-adjuster-lever-revisited.94151/

My 2006 DC

When I look at my vehicle, I notice that the drum layout is entirely different.

• I do not have a Automatic Adjusting Lever, and I instead have a lever that is attached to the rear drum. This lever interfaces with the Adjuster star on the inboard side of the brake assembly. On my truck, this lever only keeps the Adjuster star from loosening. It allows the Adjuster star to click and "ratchet" when tightening the drums with a flat-screwdriver from the adjuster port in the top rear of the brake housing.
• My Adjuster star is oriented toward the rear of the vehicle. It cannot be flipped, as it would be inaccessible relative to the adjustment port.

Based on my assembly and configuration, the parking brake will have no way of automatically tightening the Adjuster star and keeping the drums properly adjusted and tightened. The brakes will have to be periodically manually adjusted by tightening the Adjuster star with a screwdriver from the rear adjuster port.

Am I misunderstanding this system on my 2006 DC? Or did my layout get screwed up over my truck's 17 year lifespan? I cannot imagine that Toyota would move AWAY from an automatically adjusting system by the time they built my 2006 DC.

This difference was noted in the following thread, but the reason was never figured out.
https://www.tundras.com/threads/drum-brake-star-adjuster-lever-revisited.94151/

(All photos below show my Driver side.)

 

Yeah, thats a head scratcher.

I don't even know if this is possible on our trucks, but I was trying to fix the parking brake on a VW (with drum brakes) once and couldn't figure out why nothing was fitting, and I eventually figured out that someone had at some point, swapped left and right brake internals, which made no difference as far as the hydraulic brakes, but made it impossible for the parking brake parts to work.

 

Thanks for the reply. Agreed, but swapping sides would lead to issues hooking up the parking brake lever to the cable that comes from the bellcrank and would never allow access to the Adjuster star through the rear port.

My layout doesn't appear to be incorrect, as I'm finding evidence of this setup on other trucks. These videos both show the exact same layout as mine, so I do not believe I have an installation issue but rather a different "version" of rear brakes on my DC than what the FSM is showing in the above diagrams. I'm sure plenty of other folks on this forum are in the same boat as me, so it would be great to understand how/if these things automatically adjust so we can take proper care of them.

https://www.youtube.com/watch?v=6wjT8Iz43zk

https://www.youtube.com/watch?v=NFcFMmzZ7y4&t=385s

 

Yeah, this seems the most likely explanation. It would be annoying if there was no auto adjuster on those, as its actually pretty tricky to get it adjusted right manually, and of course, is something you would have to do over and over again as the brakes wore down.

 

I have a 2006 DC as well and have been going through this same issue. The rear drums on mine look the same as yours and currently do not appear to auto adjust. I was planning on pulling them apart and cleaning/greasing them with the thought that maybe they were put together wrong, were stuck, or that I was missing something but I'm glad I'm not the only one. I manually adjusted mine and they do work much better, but it seems impractical to have to do that regularly. In that thread you linked it seems the culprit there was an aftermarket star wheel adjuster that was not fitting quite correctly leading to a misalignment with the lever.
I hope you or someone comes up with a solution, I will try to get some pictures/video of mine when I pull the drums off next.

 

I went by the local dealership last week to pick up a couple of parts. I asked them about this and it appears to be a model year difference in the trucks. Per the drawing they printed me below, the automatically adjusting rears were in vehicles built from Feb 1999 to Aug 2002 (assuming model years 2000-2003) highlighted in yellow. My 2006 DC has the adjuster star lever as shown highlighted in purple.

I think it's fair to assume that the newer trucks do not have automatically adjusting rears. Are we stuck having to frequently adjust the rear drums to keep them working properly? I was hoping to resolve this issue and get a consistently firmer brake pedal.

 

It's a good question. I'll need to go back and look at pics from when I fixed my wheel studs that sheered off, see if I've got the same.

 

My 04 DC is the same setup, it's the same in theory but should rely on the rear shoe movement to adjust instead of the parking brake.
https://www.toyotapartsdeal.com/oem/toyota~lever~rear~brake~automatic~adjust~lh~47644-35040.html

In reality neither version works well, or for that matter any self adjuster on any vehicle I've ever had.

 

Great point @Festerw that would make sense. What you're saying is: As the rear brake shoe moves outward, it allows the star adjuster on my truck (as shown in my photos above) to move up a tooth in the star adjuster and tighten the star once the brake relaxes? This would make sense to me and maybe was considered by Toyota to be an "upgraded" self adjusting system, as it should adjust with each actuation of the brakes rather than relying on actuation of the parking brake... That being said, I don't think it works very well.