Rigger's disc brake conversion

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This build-up has been a HUGE help to me....I find myself in the exact same situation as you....building a '74 FJ40...but I have a '76 FJ40 parts truck with front end disc brakes.

Just so I'm on the same page here....do you have the same ratio diffs in your early 40 as your 76? I know that Toyota went to a 4.11 (or so) differentials somewhere in the FJ40 timeline....and I think my 74 has a 3.8x ? ? I'm not sure about the actual ratios, but I thought I'd mention it. You gotta have matching diff ratios ya know :)

I thought you could take the front brakes off of the '76 and mount 'em right up to an earlier axle housing - without mods. Seeing what you've done, I may just swap out the whole axle into the '74 truck.

What are your thoughts on the diff ratios from a '74 to a '76?
 
Jeff, I am glad that this thread is a help to you. I wish I were moving faster with everything, but this truck is my hobby and it is sort of last in line right now!

I chose to build up a later axle mainly because it enabled me to work on the project but still keep my '40 running. Make sense? I was working the newer axle over while I was driving the '40 around last summer.

To the best of my knowledge, I have 4.11 axle ratios on the 1970 stuff and the 1976 stuff. I understand the axle ratio changed later. I will cross-check that issue.
 
ColoCruiserJeff said:
This build-up has been a HUGE help to me....I find myself in the exact same situation as you....building a '74 FJ40...but I have a '76 FJ40 parts truck with front end disc brakes.

Just so I'm on the same page here....do you have the same ratio diffs in your early 40 as your 76? I know that Toyota went to a 4.11 (or so) differentials somewhere in the FJ40 timeline....and I think my 74 has a 3.8x ? ? I'm not sure about the actual ratios, but I thought I'd mention it. You gotta have matching diff ratios ya know :)

I thought you could take the front brakes off of the '76 and mount 'em right up to an earlier axle housing - without mods. Seeing what you've done, I may just swap out the whole axle into the '74 truck.

What are your thoughts on the diff ratios from a '74 to a '76?
Click to expand...
Poser posted on the ratios in my Axle Identify thread awhile back.....
https://forum.ih8mud.com/40-55-series-tech/338977-axle-identify.html
 
Thanks, Mr. Jay. I was sure I did not have an axle ratio issue, and your info confirms this. The 40-series had 4.11's until 1979.

I saw some posts somewhere where they were debating wether it was 4.10's or 4.11's. Not sure where I saw that. But, whatever it is, my new front axle, which is from a 1976 FJ40, has the same ratio as the one I pulled off of my 1970 FJ40.

:)
 
Pretty sure when someone says they have 4.10 gearing they are just rounding to the nearest 10th. Its 9x37 stamped onto the ring gear indicating 4.1111111 or 4.11 ratio. Same thing.
 
Not necessarily. By the time the 80 series came along the Ring was 41 teeth and the pinion was 10, so 4.10.
:D
 
Okay. The weather is getting warmer, so I am thinking how nice it would be to have the '40 up and running. Time to get after this brakes project.

Where was I?

***

Problem 1: The linkage between the booster and the brake pedal is too short. Not sure how others are managing this issue, but because of the firewall spacer, the yoke on the end of the rod won't reach the brake pedal.

Solution: make a longer yoke. I have a machine shop working on that for me.

Here is the thread on the issue:

https://forum.ih8mud.com/40-55-series-tech/349644-new-brake-linkage-how-solve.html

I'll post up a pic of how I solved it.

***

Problem 2:

The fittings on the prop valve are 3/16" American, and on everything else I have, the fittings are 10mm metric.

Solution: Use two adapter lines. Got 'em from Napa. Short brake lines with metric fitting on one end and American fitting on the other. They had 'em right there on the rack!

I'll post more later.
 
I picked up bulk 3/16th brake line from car quest and am flaring my own lines. The master I picked up is from a late model toyota pickup and oddly enough, used the 3/16ths fittings. Same with the v6 calipers I got from the same vehicle. I could have sworn it was 10mm as well. Did they go to a "standard" 3/16ths at some point?
 
BlackDiamond72 said:
I picked up bulk 3/16th brake line from car quest and am flaring my own lines. The master I picked up is from a late model toyota pickup and oddly enough, used the 3/16ths fittings. Same with the v6 calipers I got from the same vehicle. I could have sworn it was 10mm as well. Did they go to a "standard" 3/16ths at some point?
Click to expand...

I could be mistaken here, but the lines are 3/16 (OD?) and the fittings are 10mm.
 
Poser said:
Pssssst:


41/10 started with the FJ-62 in the USA... :meh:




:beer:
Click to expand...


We'll soon see!

I thought the 41/10 coincided with the change in the differential carrier bearings in the 80.

I'll have my 62 open in the next few months and will post back.
 
Tezmac said:
I could be mistaken here, but the lines are 3/16 (OD?) and the fittings are 10mm.
Click to expand...

I agree.

I am using 3/16" lines, which I buy from NAPA. They are preflared and have 10mm metric fittings already on them. (10mm is the hex wrench size that fits the metric fittings.) I know of no Japanese parts that use an American thread. BlackDiamond implies that his Jap parts have American fittings, but I have never seen this. I scammed a bunch of junk off of late-model Toyota pickups at the pick-and-pull and all have 10mm metric fittings.

There is a similar size American fitting that is called a 3/16", but it has a coarser thread pitch. At first glance, it looks like a 10mm fitting, bit it is different. I actually purchased adapter lines that have a 10mm fitting on one end and a 3/16" fitting on the other end. I am using these to adapt to my proportioning valve.

It took me a while to understand all this terminology. I think I understand it now.

:)
 
Problem:

When plumbing in the booster, I noticed that the check valve is a small size vacuum line, and the vacuum line off of the intake manifold where I need to tie in is a larger size. So, I need a reducing tee fitting.

Solution:

Pick & Pull to the rescue! The nice folks at Hanser's said "no charge" on this little item! Thanks!
Tee 001.webp
 
Rigger said:
I agree.

I am using 3/16" lines, which I buy from NAPA. They are preflared and have 10mm metric fittings already on them. (10mm is the hex wrench size that fits the metric fittings.) I know of no Japanese parts that use an American thread. BlackDiamond implies that his Jap parts have American fittings, but I have never seen this. I scammed a bunch of junk off of late-model Toyota pickups at the pick-and-pull and all have 10mm metric fittings.

There is a similar size American fitting that is called a 3/16", but it has a coarser thread pitch. At first glance, it looks like a 10mm fitting, bit it is different. I actually purchased adapter lines that have a 10mm fitting on one end and a 3/16" fitting on the other end. I am using these to adapt to my proportioning valve.

It took me a while to understand all this terminology. I think I understand it now.

:)
Click to expand...

Hmm, I screwed in the fittings into my master and brake calipers and it seemed to go in until it bottomed out. I'll have to check again.
 
I installed the front axle hard lines on Saturday. I decided to put new hard lines on the calipers, too, because those are in rough shape. I also sourced some aftermarket soft lines. The pic shows the original hard line (painted black) installed between the dust shield and the caliper, but I am going to replace them, both sides.

I pulled the clutch master. You can see it has been leaking for a while. I am going to order a new one of those, too.

Here's some pics:
Sat_More_Brakes 001.webp
Sat_More_Brakes 005.webp
 
I think I have mentioned this before, but I am also replacing all the heater hoses. On Saturday, I worked on installing a new block drain, too. Got it put in. That thing is hard to get to!
 
Poser said:
Pssssst:

41/10 started with the FJ-62 in the USA... :meh:

:beer:
Click to expand...

Gosh. I hate to disagree with the mighty Poser. 4.10:1 started with the FJ80. I'm pretty sure the FJ62 still had 4.11:1. I have a FJ62 diff in the garage. I'll count tonight.
 
pappy said:
Gosh. I hate to disagree with the mighty Poser. 4.10:1 started with the FJ80. I'm pretty sure the FJ62 still had 4.11:1. I have a FJ62 diff in the garage. I'll count tonight.
Click to expand...

Yeesh! Knock it off! You guys go settle your "diff-agreement" in another thread. This is MY thread!

:mad:
 
Good progress Rigger! Stay after it... warm weather is just around the corner (even tho we got a brief snow shower here in Ga today... go figure)
 
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