Rigger's disc brake conversion

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I tried running my march 1970 stock F engine without that diaphragm hooked up and it wouldn't idle at all.....just die out. Starting it was impossible without the choke, put the choke in (pulled choke knob out) and it starts but it won't idle, just dies out. Tried a couple different ways...first disconnected the vacuum, won't idle.....disconnected the two linkages to the carb, won't idle. It did seem to idle better and then die out with the vacuum line plugged.

1. Can someone explain what that diaphragm does?

2. Why is my rig dying without it?

Thanks for your help.

Trying to squeeze a booster in here is proving to be difficult.
 
From the pictures, it looks to me like if the booster could be slid back closer to the firewall by an inch or so, it would clear the carb diaphragm.

Has anyone tried making the adapter a bit shorter and then trimming the stiffener rib on the firewall just a smidgen?

***

FYI, I'm working on some other things right now, and I have a bit of summer traveling to do. I'll be back after the disc project probably in September.
 
I've used several old mini boosters from the pick and pulls and if you put some vacuum to them and they hold you are proable good to go, did you get the inline stop valve as well? cheers, Larry
 
brew8 said:
I've used several old mini boosters from the pick and pulls and if you put some vacuum to them and they hold you are proable good to go, did you get the inline stop valve as well? cheers, Larry
Click to expand...

I did not get a valve. Oops! Was I supposed to?

Maybe I'll be headed back to the yard!
 
Rigger said:
From the pictures, it looks to me like if the booster could be slid back closer to the firewall by an inch or so, it would clear the carb diaphragm.

Has anyone tried making the adapter a bit shorter and then trimming the stiffener rib on the firewall just a smidgen?

***

FYI, I'm working on some other things right now, and I have a bit of summer traveling to do. I'll be back after the disc project probably in September.
Click to expand...

On ours it's as close as it's gonna get. It may look like an inch but it's much less. The issue is the booster diameter interfering with the carb diaphragm. We're gonna run it though. Workin' on lines this weekend.

brew8 said:
I've used several old mini boosters from the pick and pulls and if you put some vacuum to them and they hold you are proable good to go, did you get the inline stop valve as well? cheers, Larry
Click to expand...

****... I forgot that. Good catch brew!
 
Over the past few days, I have been pondering the next step. Sooner or later, I will be at the end of my "pre-building" and parts hunting, and I will have to put the '40 in to the garage and tear it down. I am dragging my feet a bit on that, because it is currently driveable and I love putzing around town in it. I may push that off into the fall, maybe September or October.

It occurred to me that once my new disc brakes are in place, it would be very handy to have a functioning emergency brake in case I need it on my test drives! My e-brake does not work at the moment. I mean not a bit. Nothing. It is so helpless, it feels like the cable is disconnected. I climbed underneath and tried to tighten that 10mm bolt. The bolt is loose, and it moves side to side as I try to tighten it. Tightening it does nothing in the way of getting the brake shoes to grab. So, project size creep sets in again! The job keeps getting bigger! If anyone has advice on parking brake fixes, feel free to post up, 'cause I need to fix that thing. I have to tear into it, I guess.
 
I'm done. Did I win? Well... almost done. Gonna have to add a proportion valve, figured I would.

C'mon Rigger!! Where's the beef!!

(BTW, who needs a parking brake, that's what trees or your buddies rig are for. :hillbilly:)
 
Life is busy, man. I have kids, we've been camping, fishing, traveling. Now that school has started, things should cool out a bit, and I can get back to it. My next FJ40 item is to figure out the e-brake rebuild, and get that done. (However, the heater on my FJ62 is sub-par and it needs a Saturday's worth of work, too.)

Yeesh, the to-do list is too long.
 
I hear ya, nothin' wrong with that!! Family first!

FWIW, I added a prop valve, helped some but even with it adjusted all the way out (rear press minimized) the rear still locks up first. Nothing nasty but it appears the prop valve will not shut the rear off completely.

Anyway, all in all not a bad conversion.
 
Tross,what kind of prop.valve did you go with? I have been keeping an eye on this thread,nice work Rigger! You will get it done man,it takes lots of time! I am doing a rear disc.conversion on my 69 40 also using the nice Poser brackets& rotors,Monte calipers,ect.same parts list!
John
 
Well shoot, not sure of the make. The part doesn't have any info on it and the package is long gone. Bought it at a local hot rod shop.

DSC03463.jpg


Also FWIW, I've done a Monte rear disc conversion on an '85 truck using a Summit (Wilwood) prop valve and a 2# residual valve with almost the same results. I say almost as the bias is good but the adjustment is all the way out. Go figure...

DSC03040.jpg
 
Yea Tross,I think I am going to go with the summit one.It's like $38+s/h,Summit also had a Wilwood one for just a few bucks more $41 ?.I like how you hooked up the porp.valve,most folks mount em' on the firewall.I guess I will have to pick up the 2lb.res.valve,Summit had those also.
What kind of MC/Booster are you using? It looks like it just barely clears the carb.& air cleaner.
Thanks,John
 
Okay, enough slacking. Time to get moving again.

I cleaned most of the junk out of the garage. Sold some parts, hauled some household stuff to the Goodwill store, swept up a bit. Then, I brought the '40 out and drove it around some. Dang, that thing is nice! Then, I removed the top, sides, and doors. Put them into cold storage for a bit.

Got under the thing tonight. Got to get the e-brake working. That is job one. I drained the t-case, removed the drive shaft flange and removed the center nut. Pulled the drum off.

Have a look. No wonder the e-brake doesn't work!
Ebrake 008.webp
 
The shoes are shot, and the adjuster is a bit of a mess. Got to order the whole kit. I'll get that from SOR, I guess.

I also noticed lots of gumpta under the truck. One of these days this thing will be clean, but first things first.

Oh, I also ordered some new front shackles, bushings, and tie rod ends. When the new axle goes in, some newer springs are going in, too, so I may as well freshen up the whole front end. I also got a center arm rebuild kit coming. That job may wait a while, though. Got all those coming from Kurt at Cruiser Outfitters.

Also ordered a booster and master from Mark's Off Road.

Onward and upward!
 
Holy high milage! You musta' been riding around with the parking brake on!! (gotta keep that 1f under control ya know :lol:)

Good to see your working on it!
Got snow?
 
TRoss said:
Holy high milage! You musta' been riding around with the parking brake on!! (gotta keep that 1f under control ya know :lol:)

Good to see your working on it!
Got snow?
Click to expand...

Since I have owned this truck, I have never used the parking brake. The PO must have set it and then drove on it for a long time!

BTW, I do not see a need for a speedy sleeve; the drum shaft is in pretty good shape. I did pull the T-case seal, though, and I will install a new one of those. The lower end of the e-brake cable doesn't look good; I have to have a close look at that, too.

Here's a tech question: The transfer case output shaft is in the way of using a conventional seal driver. Do you guys use a piece of pipe or something as a driver to install the seal, or do you pull that back section of t-case off, install the seal on the bench, and then re-install?

I'm hoping to get this put back together this weekend.

We have had a bit of snow; nothing too serious, though.
 
Cleaned and painted the backer and the drum. I was amazed at the thick accumulation of gumpta on that backer plate - Yeesh! And how am I gonna get all that crud off of the transfer case, short of pulling it off and hot-tanking it?
MoreOnBrakes 002.webp
MoreOnBrakes 003.webp
 
New seal in place. Tapped it in gently with a hammer. Used a PVC pipe coupler to seat it in flush.
FriEbrk 001.webp
 
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