Use of Line Locks to immobilize a Tacoma during winching operations

[ferretlegger]

Hello,
I live in Moab and have a built Tacoma. in the last two years I have had a serious problem with the rear drum brakes after doing some hard winching. It appears that the brake shoes can essentially weld themselves to the drum if there is enough pressure applied to them. When one releases the brakes and goes to drive off, the truck will not move until a bit of throttle is applied. Then there is a huge BANG! as the brake shoes (glued to the drum) destroy the pivot point at the bottom of the brake shoe assembly and are ripped out of alignment inside the brake drum. This causes the brake cylinder pistons to be pushed out of the brake cylinder. As a result, all the brake fluid gets dumped onto the ground and the brakes ( both front and back) do not work.

I have had this happen twice, and in addition to being awkward and expensive to fix, it leaves me kind of uncertain about using them this way again. As a result, last winter I put a Dana 60 rear end in, with FJ Cruiser disc brakes on each side instead of drum brakes. There is still a small drum for a parking brake (as with FJ Cruisers and 4Runners), but it is pretty small and not at all going to hold against a hard winch pull. The main advantage is that there is no way that a blown parking brake can take out the disc brakes.

So the question now is how can I keep the truck from moving during a hard winching operation? I do carry and use two BEEFY wheel chocks, but I would like something in the brake system to keep the truck motionless while on a steep incline so I can get out of the vehicle and place the chocks. One solution is to stand on the brakes, which works great as long as the engine is on. But when I turn the engine off the only thing keeping it motionless is the (tiny) parking brake, which is not very effective on a really steep hill. Certainly I cannot winch against it.

Some discussion with local offroad gurus in Moab have pointed me at Line Locks as a possible solution. A Line Lock is a solenoid valve in series with the brake line coming from the master cylinder to the disc brakes. When de-energized, the brake fluid passes unrestricted to and from the brake. If the brakes are pressed firmly and the solenoid valve is actuated, either electrically or manually, the brakes in the circuit are isolated with the applied pressure continuing to hold them pressing on the rotor. Line locks are frequently used to lock the front wheels during burnouts. I have been assured that most of Rory Iverson's rigs in Moab use manually operated line locks as high strength "parking brakes" during rescue operations.

So my question to you is: What do you think of adding line locks to the front (or rear or both) brakes for use in critical holding situations? Apparently having a Line Lock in series with a brake is legal as long as there is a separate mechanical parking brake and the line lock is not used as a parking brake on streets. In my case, since I have ABS and ATRAC, to lock all 4 wheels I would have to install a line lock in each of the 4 brake lines (or pair of lines), and energize them (if using electric solenoids). That seems both expensive and hard to do, although it could allow for front digs.

Questions: Does anyone have any sources of electronically controlled Line Locks to suggest. It would be great to find one with 2 separate channels controlled by one electrical line to actuate either the front or rear two brakes simultaneously.

Also does anyone have any experience doing this? Pitfalls? Downside? My hope is that this will foster some discussion about how people control their rigs when winching, as I cannot be the first person to have this problem.

Thanks for any insight you might have, and I look forward to seeing you in Moab!
Cheers,
Michael

 

[Hulk]

Hi Michael,

I don't know enough about line locks to recommend them. But they do meet TLCA vehicle inspection requirements for a service brake.

 

[On the RX]

I am curious on how these work out for you. It would be nice to be able to engage the front rotors on my 4runner while pinching from outside the truck!

 

[ferretlegger]

Hello,
I have been looking at how a line locker might be added to a Tacoma and a plan has emerged. I THINK it may be usable on a 4runner. What generation is yours? I have Gen 4 and Gen 5 and can verify if the plumbing is the same.

TCI makes an electrically operated Line Lock, TCI part # 861200. The Summit part number is TCI-861200. it looks like this:


Among other vendors, Summit Racing has them for $104. This is a high pressure capable, waterproof continuous solenoid valve. It is intended to be put in series with a brake line. With no power applied brake fluid can freely pass through it. If the brakes are applied and it is powered ON (12 V, 1 amp), then it closes and the pressure applied to the brake stays at whatever it was when turned on, even if the brake pressure on the other side goes to zero. It has 2x 1/8" NPT ports. To connect between two flared M10-1.0 brake lines, one would buy (qty 2): M10-1.0 (Toyota's standard brake line fittings for Tacomas and 4runners) inverted flare fitting to 1/8: male NPT adapter, which would screw into the Line Locks 2 ports. Summit sells the adapters as part number EAR-02102ERL. it looks like this



On my Gen 2 Tacoma there is a 90 degree junction block with M10-1.0 Inverted Flare fittings (2x, at 90 degrees) . This is bolted to the frame rail right above the wheel. The top line comes from the master cylinder and has a spiral of a few turns to give it flexibility. The line exiting horizontally to the left makes a U turn and connects to the flexible hose running to the front caliper brake. The brake lines on the right and left sides of the truck are LOOK the same but are different functionally (although there is an identical junction block on both sides). This is because the Master Cylinder has separate brake lines to all 4 brakes for ABS and ATRAC. To lock both front brakes, a Line Lock would have to be installed in each line.



My plan is to replace this right angle fitting with a Line Lock modified with the M10-1.0 to 1/8" NPT fittings, one straight in and one with a 90 degree elbow so as to fit the orientation in the picture. As noted, the top line has a coil (not seen here) which gives quite a bit of flexibility. I would do this also on the other front brake, and wire the solenoids in parallel.

An interesting issue is HOW to switch them on and off. A simple SPST to the battery will accomplish the job and the current draw is a few amps. HOWEVER having the line locks engage by accident while driving could be catastrophic. My plan, still forming, is to have 2 switches in series for safety. Since this is intended only to help immobilize the truck when winching, my idea at the moment is to have a LOCK toggle switch (or other switch) with a safety cover in series with the switch that I use to actuate the big solenoid which supplies power to the winch. Since that solenoid (and thus the winch power) is never on when I am driving, the LOCK switch would only have power to actuate the Line Locks when the winch was powered on (that is to say, the winch has 12 volt power to it's system, not when the winch is operating). I have 2 large red indicators right in front of me for my 2 diff lockers to make sure I absolutely know when the lockers are engaged. I plan to add a third big indicator to indicate when the Line Locks are applied to the brakes. If I can find a 12 volt line that indicates that the transmission is in Drive or Reverse perhaps I can use that signal to lock out the application of the line lockers.

I would invite anyone to critique this plan or otherwise chip in with their thoughts before I do something stupid. One sad thing I have just found out is that the TCI Line Lock solenoid valve mentioned above has dismal reviews on Summit Racing. However there are many more of different configuration and specifications available. I will start calling manufacturers tomorrow and see which ones might be suitable for the available space and brake line configuration of my front brakes, as shown above.

Thanks all !
Cheers,
Michael

 

[On the RX]

I have a 2001 4runner.

 

[ferretlegger]

Hi Adam,
Check the frame rail right above the wheel. Look at how the brake line runs. If it is clear with good space around it it may be easy to install a line lock. However, if you have no ABS and a master cylinder which has only 2 lines, one running to the front brakes and the other to the rear brakes, then putting the line lock in the (single) line running out of the master cylinder to the place where it splits to go to the left and right brakes that should work.

Understand, I am not an expert. I have a serious problem with regard to immobilizing the truck during winching, and line locks appear to offer a path to achieving that. It is early days for me and I am learning about it. There appear to be a variety of "line locks" available. some apparently have internal check valves, others are at this point not suitable. The obviously suitable ones are manual, simply on/off valves. For my rig, manual is not a practical option since I have 4 brake lines, so need a minimum of 2 manual line locks to operate the front (or rear) brakes. It appears that most of the "line locks" which are electrically operated have very limited ON times, i.e. are not continuous duty. I will be calling manufacturers next week to see which ones are good choices. I will update this thread when I learn more.

Cheers,
Michael

 

[On the RX]

Thanks Micheal, I just interested to see where this goes for you, in other words, keep the i for coming with what you experience

 

[BritKLR]

Ask any of the tow truck operators/fleet mechanics in your area since they tend to use them for locking down the tow truck for difficult recoveries.

Fire trucks and other speciality EM equipment also tend to have them.

I've only played with them while working crash scenes and moving trucks around. Once set you can't move the truck without releasing them.

The ones I've played with have a large red push button that's in the dash or next to the driver seat on the floor. It usually says "brake lock" or "line lock". You push it down to engage and simply lift up to disengage.

Goodluck.