49 GMC Progress Report

Discussion in '1947-1954' started by e015475, Jun 20, 2015.

  1. 52wasp

    52wasp Member

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    Phil,
    One more thing I thought of (I still owe you math) was where you transition from the HB rod to the brake lever, I don't see any adjustability. I will be cutting off the end of the HB actuator and threading it so I can fine tune length (to minimize "play" in the linkage) with a threaded sleeve, double nutted.
     
  2. e015475

    e015475 Member

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    Thanks for the thought. I put a rod end on it that's threaded for adjustment, but it is just a guess for range. I think the cab is on the chassis for the last time, so need to get the final geometry done.

    Still interested in your pedal ratio calcs if you can find them.

    Here's a recent pic of the truck chassis in my brothers shop having the brackets for the IRS welded in-[​IMG]

    The cab back on the chassis for the final fit. Looks like I'll have some interference between the headers and the inner fenders I'll have to address
    [​IMG]
     
  3. 50 Chevy LS3

    50 Chevy LS3 Member

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    Looking top-notch, Phil.
    Do you have any pictures of your bedsides, and the finished custom inner fenders? I would be interested in seeing details.

    Steve.
     
  4. e015475

    e015475 Member

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    Sorry it has taken so long to get pics of the tubs for you. This is going to sound pretty lame, but the camera icon disappeared on my iphone yesterday - fixed now.

    Will take some photos tonight for you.

    Phil
     
  5. e015475

    e015475 Member

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    50 Chevy LS3 - Here's the wheel tub on my truck. It is just a trailer fender cut in half with a skirt welded to it - sorry it is a little dusty-
    [​IMG]
    Here's a little more detail-
    [​IMG]
    Here's what it looks like from the outside (underneath the fender)
    [​IMG]
    The tub flange is spot welded to the tub and bedside to minimize warpage, then seam-sealer applied to make it moisture proof.

    Here's a little on progress - this should be the final fit of the door. Making progress final sanding for topcoat
    [​IMG]
    I'm skim coating the exposed interior panels to get them ready for feather fill and blocking - this is my improvised lighting - cheap fixture and bungee cords- My elbow is darned sore from sanding
    [​IMG]
     
  6. 50 Chevy LS3

    50 Chevy LS3 Member

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    Wow, Phil, that is really nice looking work! I think the way you made the flange around the tubs, match the bedside flange is the best I've seen.
    I like the way you attached the tubs to the bedsides, also. Most guys seem to try and weld the tub to the bedside on the visible side, bed interior. I was thinking all along, I would try something like you did.
    I was also considering using a bead-roller to stiffen the thin gauge panels on the tubs, with some sort of horizontal stiffening pattern. Now, I'm thinking that might not look as good as I thought, against a flawless smooth bedside. I'll give that some more thought.
    You really seem to be moving along nicely on it, now.

    Thanks for the pictures, and for bringing us along!

    Steve.
     
  7. e015475

    e015475 Member

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    Thanks Steve.

    I made the tubs, but Wyatt Tichenor, my body guy, formed the flanges and spot welded the tubs in. He uses pretty basic stuff - a HF shrinker/stretcher, a bead roller with a tipping die (to form the edge to look like the factory bed strips) and a hammer/dolly. He always tries to 'make it look like it might have come from the factory that way'. The only thing he has that's a little unusual is a spot welder, but you can always plug weld with a MIG

    I've seen tubs with a stiffening rib in them that looks like the rib in the front inner fenders and it looks very cool. A raised panel formed using the bead roller on the tub's apron would be nice too.

    Thanks for the comments on my progress - it sure doesn't seem like I moving very fast from my perspective, though. I'd hoped to be at the painter by now, but my dad passed in November and cleaning up his estate has set me back a month or so. I'm back to work full time after they denied my voluntary lay-off submittal, but I try to go to work at 5:30 am so I can knock-off early and go to Wyatt's shop and get a couple hours in on the truck before dinner. My new goal is to have the truck back home painted and in my shop by the end of March - that's the plan anyway

    Phil
     
  8. 52wasp

    52wasp Member

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    Phil,
    First, I am sorry for your loss. Dad's are irreplaceable. May he rest in peace.

    I found >some of< my master cylinder math... it looks like this:
    Leg force x pedal ratio= pounds of force. Area of the master cylinder piston is Pi x R squared. Force divided by area = PSI

    Assumptions: Leg force and desired PSI are constants, and total volume delivered (bore x stroke of MC) is sufficient. The 2 variables are pedal ratio and MC bore. The Astro Van master cylinder bore measures at 1.265 inches. The pedal ratio as I recall (the pedal is in storage... or I would re-verify) is 5:1. Since Leg force, Pi and PSI are constant, the equation looks like:

    Old Pedal Ratio/[(Old MC bore/2)^2] = New Pedal Ratio/[(New MC bore/2)^2]

    So, given my that Wilwood MC has a cylinder bore of 1.000",
    5/[(1.265/2)^2] = 3.125/[(1.000/2)^2]

    My new MC has a smaller area, so the pedal ratio must be less to achieve the same force.
    OLD 100lbs force x 5:1 ratio/3.14 x .6325 x .6325= 397.83 lbs force
    NEW 100lbs force x 3.125 ratio/3.14 x .500 x .500=397.88 lbs force

    As I recall, the pedal ratio of the AD brake lever is ~6:1, so the pivot will need to be longer on the MC side (by nearly 2x)
    Disclaimer: the Astro MC has a retaining ring I have not removed, so the >actual< piston bore may be different, I need to verify this. Use the aforementioned info at your own risk.
     
    Last edited: Jan 10, 2017
  9. e015475

    e015475 Member

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    The internet says the Astrovan piston diameter is either 1.25" or 1.3".

    My pedal ratio is even higher than a stock AD truck because I had to shorten (not lengthen) the MC side of the lever to get it to line up with the hydroboost unit.

    My conclusion from the info you provided was that the force on my setup would be about half that of an Astrovan. It is going to be very twitchy/sensitive.

    My first option is to ditch the Corvette master cylinder in favor of the larger Astrovan master. That'd increase my pedal effort about 30%

    If it is still to0 sensitive, I'll have to find an even larger master. I can't change the lever ratio on the AD pedal by lengthening the arm to the hydroboost because the hydroboost will interfere with the header.

    There's a truck master with a 40mm bore (1.37") but I may have problems clearing the reservoir. Arrrgh!

    I see why guys just mount a booster and master on the firewall
     
  10. 52wasp

    52wasp Member

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    Phil,
    Looking at your HB/MC bracket, is it possible to push the HB rearward? Maybe with a boxed "standoff" of sorts, then you could lengthen the brake lever- you said it was the HB that is close to the headers, not the lever, and the actuator rod would grow in length (although it would be at an angle). In regards to the 1.25 or 1.3 Astro piston, I measured the bore outside of the retaining ring at 1.265- so it is possible the piston is 1.25, but it cannot be 1.30.

    Mounting the booster and MC on the firewall was on the "NO" list from the first day I decided to "deviate from stock"- it just doesn't look right. I considered the Astro MC, but the reservoirs are at an angle, and filling them would be very inconvenient to say the least. The Wilwood I selected was the only one I saw with remote reservoir(s).
     
  11. e015475

    e015475 Member

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    I need to take a look at it again but I think the arm on the brake lever is within about a quarter inch of the headers and ditto for one of the hydroboost fittings. I'd have to move the hydroboost back quite a way to get out of the headers.

    Think I need to get a master cylinder out of a junkyard Astrovan and see if I can machine a fitting for a remote reservoir.

    I bought an extra battery cover to make an access cover for the master and hydroboost on the floor of the truck, and my bodyman wants to know where to put it. I'm beginning to wonder if I should default to a conventional Jag booster and master and ditch the hydroboost.

    Thanks for all your help and suggestions - very much appreciated.
     
  12. 52wasp

    52wasp Member

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    Phil,
    I took another look at your pictures in post #93. It looks like if you were to move the HB back to the rearmost portion of the bracket, and trim the HB/clutch flat plate a bit you could move the setup rearward, and closer to the frame rail at the same time- gaining you a bit of header clearance (at the expense of clutch reservoir access). If the actuator rod is at a slight angle, it shouldn't be a problem. Also, you mentioned you rotated the HB to get it and the clutch cyl to fit. You are correct in that the HB cares not about orientation. BUT, if it were oriented at a different angle, would you have better header clearance? It would (naturally) require an adapter plate between HB and MC to achieve said angle. And a subsequently longer pushrod, of course.
     
  13. 50 Chevy LS3

    50 Chevy LS3 Member

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    OK... I'll do it.. I'll ask the dumb question.
    Have you considered just going manual brakes? Four wheel discs, mean less rotating mass. Large diameter discs would give much better grip.
    We are dealing with light weight oldie pickups, here.
    My truck, way back when, driven by a scrawny, high school boy, was pretty easy to lock-up, on four wheel original drums.

    Steve.
     
  14. 52wasp

    52wasp Member

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    Steve,
    There are NO dumb questions, only dumb answers. It's funny, I thought the same thing for Penny. You remember Penny, right? The thing about Hydroboost I found interesting is the actuator rod in the actual unit is straight thru. Meaning, if you lose hydraulic assist, you still have a "direct" connection, ie manual brakes. The best justification I have for power brakes is the "nugget" between the frame rails. Stock AD= ~84 horsepower. Yours? Phil's? Mine? somewhere around 5X that.

    One more thing... that scrawny high school boy wasn't rolling on big, fat, sticky tires. (I know THIS scrawny high school boy wasn't).

    Phil,
    You need a live-feed web cam so we can solve this issue, real-time, in your garage.
     
  15. e015475

    e015475 Member

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    When I was in high school, I had a 67 Chevy pickup with no air, three-on-the-tree and no-boost drum brakes. I still remember how difficult it was to parallel park a long bed truck with no power steering to get my driver's licence. (I practiced in the DMV's parking lot on a Sunday for an hour or two and had sore arms and shoulders to show for it.)

    The nostalgia for those days is strong and drives my motivation for this project (and there were AD truck hot rods in the high school parking lot I admired and wanted more than my 67) but I'm way too old and fat to go without the creature-comforts now. Gotta have power brakes, steering and AC!

    52 Wasp - I could send you a static picture of my shop that'd be just about as good as a web-cam, because nothing is happening there. Darned job is interfering with my projects: this is unacceptable and has to stop! (I'm working on it, but suffering from analysis paralysis)
     
  16. Zig

    Zig Member

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    Great workmanship, Phil! I can't wait to see some paint now!
     
  17. 52wasp

    52wasp Member

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    Phil,
    The planets aligned, and I found the Astro brake pedal. The ratio is indeed 5:1, 12.5" from pivot to pedal pad, and 2.5" from pivot to actuator pin.

    Mike
     
    Last edited: Jan 17, 2017
  18. e015475

    e015475 Member

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    A short update.

    Check fitting front sheet metal and clearancing the inner fenders to the headers...........

    [​IMG]


    Wyatt clearanced the inner fenders to look blend in with the other stiffeners and pockets. It is very subtle and factory-looking (my opinion anyway)

    Here's an up-close on the passenger's side.............clearance roughed in but still needing planishing and skim coat-

    [​IMG]

    The machining of the wheel face on the front wheels did a world of good to getting some clearance to the tire on the front. Wyatt's doing the fitup of the front fenders........

    [​IMG]

    Have to get back to work................
     
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  19. 50 Chevy LS3

    50 Chevy LS3 Member

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    Fantastic.
    I wish I could do metal work like your guy does.
    Beautiful, smooth firewall, inner fenders... just, excellent looking work.
    What wood are you using to finish the bed floor? Store bought or home finished?

    Steve.
     
  20. e015475

    e015475 Member

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    He's offered to teach me his metal working skills. Says it doesn't require any skill, just patience (yeah right). I had two extra rear fenders I started bumping out with a hammer and dolly with instruction from Wyatt. I dropped the dolly on one of my toes and broke the toe (at home) - that's my last and final attempt.

    There's another geezer customer of his that comes to his shop twice a week to work on his car. Wyatt taught him how to use the english wheel, make replacement panels, gas weld and planish - I'd just rather do other fab work on the truck and leave the metal work to him.

    No decision on bed wood. Arizona is really tough on exposed wood.

    Thought about making them from aluminum and having them sprayed with black bed - liner then use stainless trim strips. I might not even put any wood in it until I get tired of looking at that Jag IRS
     

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