Short Brake Pedal After Swap

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Cactus Camper

Cactus Camper

SILVER Star
10 Year
Joined
Feb 21, 2012
Threads
33
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426
Location
Tucson to Dallas
Hey all, seeking guidance from the cruiser gods on issues with my new brake setup - I’m experiencing a hard brake pedal, even before bleeding the air out.

Background: 1977 FJ40 with front discs and rear drum single cylinder (7x axle retrofit).

Swapped out my original brake booster and newish dual reservoir master cylinder for the City Racer booster and the non ABS master with adjustable prop valve. Prior to swap brakes worked great. The primary driver for the swap was to gain more real estate under the hood for the sniper. Installed following the city racer installation instructions including setting rod lengths.

I’ve set the brake pedal height per FSM, play seems to be with spec. With the engine off and non bleed brakes, I press the pedal and it feels hard and not a lot of travel. The reason I point out non bleed is I would have expected the pedal to feel spongy at this point. Also noteworthy, originally I set the pushrod clevis to match the old booster. Since then, I’ve moved the clevis in and out to try and improve pedal to no avail. Another note: when I did try to bleed the brakes, I gained full travel and softer pedal with one of the rear axle bleeder valves opened. I bleed each corner and saw fluid expel and air bubbles exit. Pedal was still hard. No noticeable difference with engine vacuum applied either.

Sharing these bits of information so someone smarter and wiser can point me in the right direction. Based on my research, hard pedal could indicate a kinked brake line. I did gently bend the lines to fit the new non abs master. And to the best of my knowledge, flow seems okay.

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When you bench bled the master did you get a full stroke of the piston?
 
Jdc1 said:
How is the adjustment on the rear brakes?
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At first I had the prop valve installed backwards. Corrected the orientation after re-reading the wilwood instructions. I have the knob all the out to provide max braking reduction to the rear. Pedal actually felt the same before and after the orientation fix.
The rear brakes themselves I’ve never touched. Georg rebuilt the entire axle for me and before the booster and MC swap it operated great. If you think I should check something specific, I’m game to report back. Great question!
 
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pb4ugo said:
When you bench bled the master did you get a full stroke of the piston?
Click to expand...
Back when I did the bench bleed I recall the stroke getting harder as the air bleed out. I used a bamboo chop stick as the implement to push the piston and it seemed to reach full stroke. Is there a measurement or method I could use to check I have full stoke? I can compare it to my dual reservoir MC sitting on the bench

Thinking about your question and it gave me the idea to separate the MC from the booster and exercise the pedal to check operation up to that point.
 
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Cactus Camper said:
At first I had the prop valve installed backwards. Corrected the orientation after re-reading the wilwood instructions. I have the knob all the out to provide max braking to the rear IIRC. Pedal actually felt the same before and after the orientation fix.
The rear brakes themselves I’ve never touched. Georg rebuilt the entire axle for me and before the booster and MC swap it operated great. If you think I should check something specific, I’m game to report back. Great question!
Click to expand...
If i’ve got too much pedal after a brake conversion, backing the rears out a little usually helps(after i’ve checked the pushrod between the booster and master). Then I’ll dial in the rears after Indona few panic stops to see how she acts.
 
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Before bed I separated the brake MC from the booster. With the MC off, I exercised the brake pedal by hand and it moved smoothly with much more travel.
This data point tells me that the restriction is downstream of the booster - either the MC or a kinked brake line. One idea is to swap in the dual reservoir MC to isolate the brake line suspicion. I will also double check the pushrod length.
Please chime in if you have questions or recommendations. Appreciate everyone’s time and inputs so far!
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This isn’t my wheelhouse, but the master you bought is 1” bore. That’s moving ~30% more fluid than the stock 7/8” bore. I don’t have a 70, but my recollection is they’re the same rear brake drum design as late 40s/60/62. I believe all those rigs used 7/8” bore masters. Maybe that’s the limitation…pushing more fluid, less stroke.
 
Proportioning valve? I too have limited knowledge of braking systems but I thought you used a residual valve for front disc/rear drums and a proportioning valve for 4 wheel discs.
 
For what it’s worth, this is what I used on my FJ43. I have FJ62 knuckles and discs and late 40 single cylinder drums. This was perfect for me, my rig didn’t have any brake fluid sensors to deal with.

cruisermatts.com

OEM Brake Master Cylinder 1981-1990 FJ40 FJ60

Aisin (OEM) made brake master cylinder which works on 8/1980 and newer Land Cruiser models with disc front brakes. FJ40, 43, 45, 60, 62, as well as many 70 series models. Also works well as a replacement for NLA 75-80 FJ40 master cylinder with minor brake line mods. Cap not included, available...
cruisermatts.com
 
Your master is a dual piston/reservoir master. It just has a large reservoir with a divider in it, so one side wont go dry if the other piston/component fails. One line for the frt and one line for the rear. Typically on a disc/drum brake setup rear brake adjustment determines pedal height. That how you can tell if the rears need adjustment. Does your pedal move at all? I would look for an issue in the rear brakes. Do your wheels turn freely with no pressure on the pedal? Do the brakes work when pressure is applied to the pedal? Do the brakes release after pressure was applied then released? A bad flexible line may not release pressure if it has an internal crack in it. The pressure can create an internal bubble in the line. A metal line could be kinked. The rear brakes could be overly adjusted too.
 
I put the same MC/Booster but a different Proportioning Valve on my 74 with 83fj60 front discs. CityRacer for the win.

I have a feeling your adjustable valve may be turned wrong way???? possible?????

My swap went really smooth, checked Booster rod length compared to old booster/ Bench bleed the MC / and then gravity bled from rear passenger around to front. Fabbed a little bracket out of old muffler hanger for the valve.

I got lucky, had immediate great brakes.

PS. I bought a roll of brake line and made my own bends, my practice "S" came out good enough that I slapped it on there. And the flare wrench, gotta have it.

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all the way out is max reduction of line pressure AFAIK

all the way in... is least

test it by turning it 1/2 way in and see what it does
 
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