Brakes: Advice on Trail-Gear FJ40 Knuckle Swap Kit for Disc Brake Swap + Drum Brake Help

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talibraza101

talibraza101

Joined
Jul 16, 2025
Threads
11
Messages
87
Location
Maryland, USA
Hi guys,

I am at my wits' end with trying to get my 1970 FJ40's drum brakes to work. I installed updated 9/71-1975 drum brake hardware and replumbed all the lines, but just can't get them to give me a solid first pedal (they need pumping).

At any rate, I wanted yall's thoughts on this kit I found on Trail-Gear: https://allprooffroad.com/fj40-knuckle-swap.html

If I truly cannot get these drums to work, I'm seriously considering biting the bullet and going 4-wheel disc. Would this kit from Trail-Gear be viable? Does anyone else have any other options in mind? I understand donor axles are the best way to go, but I can't seem to figure out how to find/purchase them. I would ideally like 4-wheel discs.

Thank you!
 
talibraza101 said:
At any rate, I wanted yall's thoughts on this kit I found on Trail-Gear:
Click to expand...
That's an awfully big kit to fix a really small problem. Of course you can make your drum brakes work.
 
Pighead said:
That's an awfully big kit to fix a really small problem. Of course you can make your drum brakes work.
Click to expand...
I feel you man. I'm just at a total loss for what could be wrong with them at the moment. Bled the MC, bled 3 gallons of fluid through quickbleeders until clean, adjusted the shoes outwards until tight, the list goes on. I'm worried there may be some sort of microscopic air leak happening in one of the fittings preventing me from getting a firm pedal, even though I tightened everything down pretty snug. This is my first brake job so my confidence is definitely taking a hit right now :facepalm:

Gonna try expanding the shoes all the way out again and bleeding once more when I get home today. Been hesitant to post my troubles because of how many posts there already are on here!
 
talibraza101 said:
Hi guys,

I am at my wits' end with trying to get my 1970 FJ40's drum brakes to work. I installed updated 9/71-1975 drum brake hardware and replumbed all the lines, but just can't get them to give me a solid first pedal (they need pumping).

At any rate, I wanted yall's thoughts on this kit I found on Trail-Gear: https://allprooffroad.com/fj40-knuckle-swap.html

If I truly cannot get these drums to work, I'm seriously considering biting the bullet and going 4-wheel disc. Would this kit from Trail-Gear be viable? Does anyone else have any other options in mind? I understand donor axles are the best way to go, but I can't seem to figure out how to find/purchase them. I would ideally like 4-wheel discs.

Thank you!
Click to expand...
Send me your axle housing, Ill build your disc brakes for you.
 
I understand the frustration. I made the decision to switch to disc brakes due to the larger tires and faster speeds. I originally wanted to keep stock brakes, but everything played against me. If you do decide to switch, change your master cylinder as well. I installed Man-a-Fre's dual cylinder, and it's been great ever since.
 
That kit is overkill. I would try to find discs sort of locally. Talk to JDC. You can go to the classified section and on top of the thread you can click on "watch" and you will be notified when a new ad is posted. You can post a wanted ad too. You can do the same for your areas in the Clubhouse section too. Reach out to the local groups in the Clubhouse section. On the 2nd page in the classifieds is this add. Maybe see if he'll sell the frt end. It sounds like a weekend road trip. Watch and search marketplace and Craigslist.

Toyota Pickup Axles

For sale Minitruck  Toyota Pickup Axles

Tallassee, AL, US
Toyota truck axles for sale. The front is from a ‘82, the rear is from a ‘87 (IFS width, Approx. 3” wider than the front) According to the data plates from both the trucks I removed them from they are 4:10s. They should be rebuilt before using. $650, obo. Located in Tallassee, Alabama
$650.00
1 watching

I think one of the problems with the drum brake lines is the horseshoe line on the back of the backing plate which creates a high spot and makes it difficult to bleed.
 
If I recall you have a ball and claw frt end. I think you probably need a FJ40 or FJ55 complete frt end.
 
talibraza101 said:
Been hesitant to post my troubles because of how many posts there already are on here!
Click to expand...
Brakes is one of the few things that we take seriously here and we have walked people through harder jobs. If there weren't a lot of posts, Woody would be out of a job.
I was quite proud of my drum brakes and only went to discs for the SOA. A fix for the double pump will probably cost less than $2799.99
We need pics, lots of pics.
 
Try the 2 person brake bleed.
Fought like with my drums, till I put the kid in it to help bleed....huge improvement
 
Thank you for all of your responses.
Pighead said:
Did you install a dual-circuit master?
Click to expand...
I sure did. No leaks there. I will send more photos soon!
DD56B68C-C308-4112-9EA3-6665F8EC421B.webp
 
Pighead said:
That looks good. What residual valves are in it?
Click to expand...
Hmmm, I’m not sure what residual valves are in it. How do I check? This MC came in a bundle from CruiserCorps (https://cruisercorps.com/products/brake-master-cylinder-1)

On a side note. It seems i can always bleed the wheel cylinders to clear fluid without bubbles. But as soon as I close up the quickbleeder screw and unhook my clear tubing, then rehook my clear tubing and open up my quickbleeder screw again, the same old bubbles are back. Pedal feels firmer right now because I’ve fully expanded the shoes, but still requires a pump or two ☹️.
 
One thing I’m considering trying is swapping my new shoes that came in my brake overhaul kit to the older ones that came with my truck. Maybe the older shoes fit more flush to the round of the drums and make better contact? Attached is an image of my old shoes (Non-US) and my current (new, US) shoes.

IMG_2811.webp

IMG_4022.webp
 
If you don't have risidual valves that is probably your issue
 
talibraza101 said:
Hmmm, I’m not sure what residual valves are in it. How do I check?
Click to expand...
sometimes, search helps...

lostmarbles

Thread 'What ARE these?'

My toyota manual says these are "check valves".

Question.webp

My understanding of a "check valve" is that it is a "non-return valve". (In other words it allows a flow in one direction but not the other.)

If they were truly "check valves" isn't it true that the brakes would never release? (The valves would allow the fluid to flow from the master cylinder into the wheel cylinders when the brakes are applied but then prevent this fluid from returning to reservoir afterwards!)

So has toyota labelled them wrong? And if so, what is their real purpose?

Any help would be greatly...
 
Pighead said:
sometimes, search helps...

lostmarbles

Thread 'What ARE these?'

My toyota manual says these are "check valves".

Question.webp

My understanding of a "check valve" is that it is a "non-return valve". (In other words it allows a flow in one direction but not the other.)

If they were truly "check valves" isn't it true that the brakes would never release? (The valves would allow the fluid to flow from the master cylinder into the wheel cylinders when the brakes are applied but then prevent this fluid from returning to reservoir afterwards!)

So has toyota labelled them wrong? And if so, what is their real purpose?

Any help would be greatly...
Click to expand...
Apologies!! Its hot out here 😅. I reached out to Cruiser Corps to ask whether my MC came with residual valves or not. Thanks guys.
 
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