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That Ain't Gonna Work.

Discussion in 'Builds and Fabricators Forum' started by Jw60, Nov 24, 2022.

  1. Nov 27, 2022
    Andrew Theros

    Andrew Theros Member 2023 Sponsor 2022 Sponsor

    Los Osos, CA
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    Interesting…mine is setup as @Fireball indicated his is, but the FSM says the same as @Focker said in the link above.
     
    Jw60 likes this.
  2. Nov 27, 2022
    garage gnome

    garage gnome ECJ5 welder

    Western MA
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    3,083
    Yes, you have to remove the original master cylinder mount. Then it will tuck into the frame rail.
     
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  3. Nov 27, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    Already hacked that off, the issue now seems to be that mine is originally a 4cyl but now has a 4.3 that shifted to the driver side.
    After removing the original mount i went ahead and ground the top of the frame rail back 1/4" (not the greatest option) so the master cylinder will tuck over more than normal. I've massaged the block and bellhousing as far back as I dare (i'm about to get into bellhousing threads. My motor mounts are the D18 torque arm doughnuts with circle track brackets on the motor and short ears off the frame. The engine side circle track brackets are slotted and I had washers welded over the slot to locate the motor. Those washers broke free and It seems I've been hard on it so all the mounts are getting looked over. I'm thinking i'll need to change the transmission mount and driver side motor mount to better manage the for/aft and side to side motion... I'm going to Saginaw steering while this is all torn apart so the motor mount rework is needed anyway to clear the shaft.
    I'll also need to do something about the sloppy pedals the frame pivot is loose and the brake arm bore is bad.
     
    Last edited: Nov 27, 2022
  4. Nov 27, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    Found a picture from before the grinding, black on black but just try to judge from the threaded hole on the side of the block to the bellhousing surface and the horizontal rib above it...
    [​IMG]20221024_003014 by Joe with a jeep, on Flickr

    The rib is basically gone now
    [​IMG]20221126_191629 by Joe with a jeep, on Flickr

    I got just a minute today to flatten out the little love handle on the bellhousing
    [​IMG]20221127_143635 by Joe with a jeep, on Flickr

    Now I'll clean up the brake pedal arm and mock everything up again with the master cylinder pulled over into the frame.
     
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  5. Dec 3, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    Ok, does anyone have a trick to drill the top two holes in the frame to match the mount on the inside?
     
  6. Dec 3, 2022
    73 cj5

    73 cj5 Not ready for the junkyard yet

    Clinton, Mississippi
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    Have room for a right angle drill to drill on the inside of the frame?

    Edit: Welding the bracket on out of the question?
     
    Last edited: Dec 3, 2022
    Jw60 likes this.
  7. Dec 3, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    No room. Nor do I have access to one. I've pretty well accepted I will be drilling two 1" holes in the floor of the tub then putting hole plugs in. It's the alignment of the planets that I'm struggling with.

    I eyeballed the rear hole to the floor and I think I am close enough there going through the floor. I have a drill press fixture for a drill, that doesn't look promising.
    Thinking on it I might use the 3d printer to make a jig. I have 1/4" drive bits so my jig can center a drive extension and be c-clamped in position. That'll take a lot of time to process.
     
  8. Dec 4, 2022
    Lockman

    Lockman OK.....Now I Get It . 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Silver Hill,...
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    Joe , Me think's that you have to view the attack as if the Tub was off ? The one inch tub floor holes are a great idea for access. Some how, project frame hole locations up to the bottom of the tub, measure to a common point underneath that would be able to be replicated from the inside of the tub . Drill your access holes there. Measure many times , to " triangulate ".
    Easy Peasy .......:beer:
     
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  9. Dec 4, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    I was thinking of welding a few 3/4 in beads after bolting. Not much adjustment once welded but I think I'm getting close with the bracket at least. I'll see how I feel once the first top bolt is done.
     
    73 cj5 likes this.
  10. Dec 12, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    I'm slowly and methodically working on this.
    I believe I have the frame ground down where I want it. I have a master cylinder that I was going to rebuild but couldn't find a kit before it rusted into a brick.

    [​IMG]20221212_124851 by Joe with a jeep, on Flickr

    I ground down the last of the frame rail where the reservoir will rest then clearance the bracket for the arm. I need to service the brake arm bore and the clutch pivot.

    [​IMG]20221212_130030 by Joe with a jeep, on Flickr

    I'll take @73 cj5 suggestion and simply weld it in place on the top of the bracket.
     
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  11. Dec 13, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    Bracket is burnt in, it's been a while since I welded and this is a new machine and I was not able to see what I was doing. The moon might have been showing but the stars, not so much...
    [​IMG]20221213_130310 by Joe with a jeep, on Flickr

    New master cylinder is on. Rear line reaches easy but I need to splice in the residual pressure valve and the proportioning valve.

    [​IMG]20221213_134006 by Joe with a jeep, on Flickr

    I'll toss the brake light switch on the front distribution block for now. I have a mechanical switch to install but...
    ...
    ...
    The pin on the brake arm doesn't reach...
    The clutch shaft is worn out.
    I want to put a bearing in place of the support ear from the master cylinder bracket to the clutch shaft.
     
    melvinm, 73 cj5, dozerjim and 3 others like this.
  12. Dec 14, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    Not sure if you, my favorite reader knows... but I want something to protect the clutch linkage heim joints. This may be an opportunity for the 3d printer but I feel like there should be a boot or something in existence already.
     
  13. Dec 18, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    I posted some of this in my main "build" thread but felt like I need to keep everything for the master cylinder swap together here. I'm rolling the clutch alterations in to this because it may or may not affect anyone's attempt to recreate a dual master cylinder swap.
    Now I have the master cylinder in place. If you are doing this yourself I would say to try to be closer to the pivot rather than farther away because you can shim away from the bracket if needed. I pulled the brake line that went from the single bore master cylinder to the front and used a couple dozen adapters to relocate the hydraulic stoplight switch onto the 1/4" port. Then the 3/16" line from the front junction to the rear was removed. I used an 8" preflaired section (it's cold and I don't need to fuss with flares) from the front junction block to the residual pressure valve which is now above my frame horn. From the RPV to the master cylinder is a 20" section of 3/16" line to the front port of the master cylinder. The Lockheed cast master cylinder I am using for mockup is very clearly cast with "front brakes" on the front port with the smaller bore. This should in theory be like cross multiplication. My wheel cylinders are all the same where a front normally has larger wheel cylinders and smaller on the rear so let's say 1" front and 7/8 rear with a 7/8" single bore master cylinder is "normal". The front wheel cylinders are moving less than the master cylinder and less than the rear cylinders and all the pressure is the same in the system.
    I am using the smaller bore to push less fluid to the front and the larger bore to the rear then the proportioning valve will further reduce the overall pressure to the rear.
    On front disk rear drum there is such a difference in wheel cylinder bore it is possible to use the larger master cylinder bore to feed the larger front calipers and small to smaller rear cylinders because they are not as close in size at the wheel.
    [​IMG]20221217_162005 by Joe with a jeep, on Flickr

    Got it? Great!
    Now some less technical fun, I cut the pedal assembly off... to eliminate the slop.
    My plan here is to make an assembly similar to a bicycle pedal and frame. Pedal spins on shaft and the shaft spins in the frame all with bearings but hopefully I can use sealed bearings. In my case the brake arm is the pedal I'll need to bore it to be round again then put the thinnest shell bearing i can find in it. The clutch pedal shaft will remain the same diameter on the frame and clutch side and the frame bracket will have bearings that fit over the clutch arm mounting diameter. The brake arm side will be smaller to fit in the brake are bearings and an additional support bearing off of the master cylinder bracket... simple. Now to measure and order bearings, then i get to turn a new pedal shaft.
    [​IMG]20221217_163636 by Joe with a jeep, on Flickr
     
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  14. Dec 18, 2022
    73 cj5

    73 cj5 Not ready for the junkyard yet

    Clinton, Mississippi
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    I'd imagine a pillow block bearing will do the trick. Well, that was my plan if mine ever becomes unuseable.
     
  15. Dec 18, 2022
    Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Pullman, WA
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    This is incorrect. the pressure is not the same in both circuits with a stepped master cylinder. The force coming in from the pedal is the same but the pressure going out is dependent on piston size.

    For example with 100 lbs of pedal force:
    • I measure 12 1/2" from the pedal to the brake pivot and 3 1/4" from the brake rod to the pivot for a pedal ratio of 3.85. That would 385lbs at the master cylinder.
    • The front circuit with the 7/8" bore (0.60 sq inches) will be creating 641 psi with less fluid movement.
    • The rear circuit with the 1" bore (0.79 sq inches) with be creating 487 psi with more fluid movement.
    You can not move different amounts of fluid and create the same pressure. That's not how hydraulics work. It's basically the same thing as a mechanical lever. On the output end less movement=more force. More movement=less force. The opposite applies to the input end.

    The correct balance of master/wheel cylinder sizes depends on pedal ratio/travel, manual/power brakes, the available piston sizes for front/rear disk/drums, their relative effectiveness (which includes size, design, and friction material), the ideal proportioning curve for the center of gravity location/wheelbase, and any proportioning valve being used to target the ideal proportioning curve.

    In the real world that is difficult to calculate so you make sure you can lock up both the fronts and rears and then dial the rears back with an adjustable proportioning valve until the fronts always lock up just before the rears.
     
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  16. Dec 19, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    I guess I didn't word it well trying to differentiate my system from a typical system with different cylinders front and rear. Big thank you for the feedback.

    Mine has 2.953" bore calipers on all corners.
    I'm using a stepped bore master cylinder with the .875" bore feeding the front and the 1" bore feeding the rear.

    I'm expecting the front to run at a higher pressure than the rear because they are the same at the wheels.

    I believe the adjustable valve will be dialed to a minimal.

    @Fireball I believe this is consistent with your feedback if I want 641psi front and 487psi rear with 100lbs at the pedal.
     
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  17. Dec 19, 2022
    Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Pullman, WA
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    Yep. You are doing the right thing.
     
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  18. Dec 20, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    All the brake lines are in place, pedal assembly is scrubbed up and ready to measure and throw some primer on. I was eyeing the steering bellcrank bearings for the frame pivot of the clutch. i'll need to make a bracket to support the rear valve assembly and another for the mechanicalstoplight switch (79 k10 switch which isn't weatherproof). I don't expect to do much more on this aside from measuring and ordering bearings till after the holidays.
     
  19. Dec 20, 2022
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
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    You might want to check out Herm the Overdrive Guy's kit: http://hermtheoverdriveguy.com/brakes/master-cylinder-kits/cj-applications

    There are others out there I'm sure, and the MC mount from a '68-'71 Jeepster (I think) will work. I think that's what I used in my CJ-2 but I did have to cut the frame boxing out to make room for it.
     
  20. Dec 20, 2022
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    What's a "kit"?:rofl:

    I bought this all back in May 2021.
    I just wasn't expecting the boxing for the single bore to be raised off the frame. There's also the aspect of this being a chevy 4.3 and my clutch pedal shaft n pivot is all worn out. i do like how this stock bracket aligns with the pedal pivot holes in the frame.
     
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