Tacoma rear brakes on FJ40 axle

[orangeyz]

I might have parking brakes soon. We'll see if this works out.

All that's left now is take the axle home, put it back under the truck, hook up the brake lines, and figure out a way to attach these cables to the parking brake lever.
Easy-peasy.

 

[orangeyz]

Why Tacoma?
Because there's a Tacoma in my driveway that I could study.
Also 2005 to 2023 have the same brakes so parts availability is infinite.

Starting at the local salvage yard:

Tacoma's are also a semi-floating axle, but instead of C-Clips at the diff, they have pressed on collars at the bearing flange.
The thing I liked about this is that it's only 4 bolts for the parts guy to take out and then the whole axle assembly slides off. So it was easy to get all of the brake parts for the price of an axle shaft.
Saying "Oh by the way I need the parking brake cable intact" probably cost me about two weeks before they found someone willing to do the job, but everything here was $295.

The downside of that design is needing to come up with a fixture to press the shafts out of those housings and free up the brake plate. It would have been a lot easier to go to the Toyota shop and just have them do the first 1/4 of a wheel bearing job.

Apologies for the picture quality on wheel bearing removal day.
When I learned about the design of these things, I got a little worried that a "press fit" was the only thing holding the wheels on my truck.
But it turns out it's about a 0.010" interference press fit, and took every bit of twenty tons to get off.
You could hang eight Tacomas from one rear wheel and it wouldn't fall out.

Before pressing them apart I measured the distance from the wheel mount surface to the edge of the brake plate and came up with 2.35"

 

[orangeyz]

Mocking the Tacoma brake plate on the FJ40 axle showed that it would need to be moved about 0.100" inboard.
I pulled the dust cover off and measured the original distance before going too crazy.

Made the plate with 0.150" movement inboard to have some room to work with if it wasn't perfect

Should have just gone and bought some 5"x1/2" bar stock, this was silly:

But it got done

 

[orangeyz]

One last look

And there's no going back now

That was a lot of grinding. If I do this again, it will be worth it to make up a fixture to put the whole axle on the mill and mill the old flange off.

I was originally thinking I would make a fixture to maintain the new flange's distance from the end of the axle tube, but thought of something better and easier

Hammer the new flange all 0.150" to the end
Bolt the new brake plate on
Reinstall the axle shaft with the brake drum
And knock the flange back out until the position was what I wanted and consistent all the way around.

Four tack welds, measure everything again, take it all off, and blast the weld in complete.
While the area was hot from welding, it was really easy to knock the wheel bearings out.

 

[cruisermatt]

neat project, and this will work well, but you know I make bolt-on adapters for this already though, right?

 

[orangeyz]

Problem: the pilot diameter on the FJ40 brake drum (and therefore the axle) is 4.18". On the Tacoma it's 4.25.
This would have been a lot easier if it was the other way around.

I had considered doing this weld and cut down operation on the axle shaft, but don't have a lathe big enough to turn it down. I talked to a friend with a bigger lathe and could have done it, but at the last minute changed my mind to "modify the cheapest part"

 

[orangeyz]

neat project, and this will work well, but you know I make bolt-on adapters for this already though, right?

NO! WHAT THE HELL!?!
I searched every form of FJ40 brake mod I could think of and nothing like this came up!

Seriously, I was thinking "That's weird that nobody seems to have even thought of doing this, but whatever here we go!"
It's always seemed to be chopping down FJ60 axles and swapping the entire thing.

 

[cruisermatt]

Well, my adapters are for the +8/80 brakes, which are basically the same as the Tacoma brakes you are using but without the issues of the drum pilot or backing plate offset.

You could also just put a whole FJ60 axle in. They’re only 3” wider overall, and you just have to move the spring perches. That works really well as well.

 

[jlizar]

Nice Job!!

I did the same using parts from a 2003 4Runner with disc brakes, welding the OEM hub to my axle. Everything turned out pretty well.

 

[jlizar]

I also used this Jeep Wrangler cable brake bracket to support my cables, and with the 4Runner splitter, the handbrake works perfectly.

 

[bikersmurf]

Nice Job!!

I did the same using parts from a 2003 4Runner with disc brakes, welding the OEM hub to my axle. Everything turned out pretty well.



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Looking at the lengths he was going too, I’m surprised he wasn’t adding disc brakes. If you are ever crossing through water you will understand. I have gone through deep water with drum brakes… only to find I had no brakes when I was going down the next descent. It’ll get your blood pumping.

A friend went out onto the street with wet drum brakes. One side dried out faster, and he almost went off the road when it pulled very hard to the right.

 

[orangeyz]

Finding something with disk brakes occurred to me after buying the Tacoma parts, and by then I was already down this path and sticking with it.
The cables reach all the way into the cab and I got a splitter made after a few days of measure 3 times, think once, measure again and then cut.

Anyways: It boggles my mind that "I have to be picky with transfer cases in my project because of the parking brake situation" has been a recurring problem for decades, but "Chop the flanges off and weld something else on" is something I literally never heard of until starting this thread and now they’re coming out of the woodwork.

 

[bikersmurf]

25 years ago I converted my FF rear axle to discs using extra beefy Chevy Blazer rotors and Callipers… now there are so many other options. That said, if what you have works run it. There’s no reason I’d change course now.

Besides, when I’m towing a trailer with lots of tongue weight, I don’t regret the choice for a moment. It’s pretty awesome when a 40 can stop a 4000 lb trailer, without brakes, quickly and in a straight line.

Not that I would ever do that.