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**Tech Week** Shoebox Ford Big disc brake conversion with flipped spindles

Discussion in 'The Hokey Ass Message Board' started by Brock49Ford, Sep 3, 2012.

  1. Brock49Ford
    Joined:
    Aug 20, 2002
    Posts:
    502
    Location:
    Miltun, Warshingtun

    Brock49Ford Member

    Here is something that I have been working on slowly this summer. A big brake kit for flipped spindles on a Shoebox Ford. I wanted to get disc brakes on my '49 and was not finding what I wanted. I have changed pretty much all of the front suspension already over the years (flipped spindles, dropped steering arms, custom springs from Eaton, KYB shocks, Volvo steering box, Camaro idler arm, dropped drag link, bumpsteer kit, and sway bar.) The brake kits that I have seen say that they will not work with dropped or flipped spindles. To get what I wanted I was going to have to make it myself.

    I run the relatively hard to find 16" rims for 1949-51 hubcaps. This part is key for this conversion. This will only work (and it barely clears) with a 16" or larger rim. (Sorry fans of the 15" stock rims.)

    First off I decided that I wanted to reuse the stock hubs. They had fresh bearings and races and would maintain the stock wheel mounting surface distance. This was one less variable that I had to deal with. The stock wheels studs were removed and the drum was removed from the hub. (Note: This was more work than originally anticipated and I had to use the hydraulic press to get the studs to budge and the drum off.) New studs were installed and I used the TIG to tack them on the back side. (I also used a punch and "distorted" the hole so that the new studs were tighter, not totally satisfied though so they were tacked as mentioned.)

    I used some 12" (11.89" actual measurement) x 1.10" thick from a Dodge Nitro/ Cherokee (Duralast 43159). This allowed the 5 on 4.5" bolt pattern to be retained as well. The hub register is also slightly larger than the '49 hub OD. This worked to my advantage as I planned on making the rotor mount be hub centric instead of locating off the wheel studs. I found some DOM tubing that was close and turned it on the lathe so that I got a nice fit over the hub and into the rotor. Once finished I tacked it to the hub in 3 places.

    The calipers are the big 3" piston GM pickup that have the 7/16" banjo bolt. I went with this to get more pad area on the big rotor and that piston has more travel. (It is actual for a 1.25" rotor) (Centric semi loaded 141.602045/141.602046)

    I started mocking up different caliper mounting ideas and eventually settled on this design. I was originally trying to do everything out of one bracket, but discovered that would be way more work than it was worth. A sample was made out of some 1/4 and 3/8 poplar wood with the scroll saw. This allowed me to get some pretty realistic measurements and be able to mock things up more. Once I liked where things were going, a pair of each bracket was flame cut. I tacked the brackets together so that I could drill both sets at once to assure that they were the same side to side. I made up a few threaded and shouldered spacers to be used for the caliper mount and bracket to bracket attachment. (I was fortunate that the spacing worked out so that both were the same height) The holes were drilled and the spacers were pressed in and TIG welded on both sides. I sanded the welds flush where the caliper mounts.

    The spindle and Dust shield did require minor modification. I did have to nip the ear off the corner, essentially loosing one of the bolt holes. This was required in order to keep the depth/strength in the caliper bracket. There is a notch in the bracket due the casting of the caliper. This notch is very close to where the corner of the spindle is/was. I wanted to leave the spindle alone, but my friend (Engineer) advised me to make the modification. You can't tell when the bracket is on, and that one bolt was not going to really help that much anyway, so off it went. I cut the dust shield with a set of snips and used a cut off wheel on the spindle.

    The caliper was mounted and I used an adapter fitting on the stock frame bracket. It was a 3/8"-24 internal flair female to a -3AN male. This went right in the tab and the stock clip was used to secure it. Then a 13" braided -3 brake line. I used the 7/16" Banjo bolt and copper crush washers that came with the calipers. The Banjo itself has a -3AN male fitting to hook the line to. I did have to grind a bit of the "shoulder" from the caliper so that the hex on the brake line would clear. If I would have left it where it was designed to be the hose would kink pretty badly and at full bump and full lock it would have hit the frame. Not very like with a tire on, since it rubs the sway bar before full lock, but I wanted the piece of mind. It was only a few minutes with a grinder and file. I have yet to do the line on the Driver's side where the crossover line connects, but will update with a picture when I get to that point.

    An 1/8" thick wheel spacer will be required to guarantee wheel clearance. I have tried 3 different rims on the front and 2 cleared and one rubbed. With the 1/8" spacer all 3 spun freely. I am going to use a 1/4" space for the bleeding and getting the pads bedded in just to be sure. Then I will knock the wheels off and double check everything and switch to the 1/8". Not necessary probably, but I have the spacers so why not. Once the pads get a few miles on them and the slides on the calipers are broken in that one wheel may clear just fine and no spacer would be required. Individual results may vary.

    I am also converting the master cylinder as well. Shoebox master cylinder conversions have been covered in great detail so I won't get too into it here. I will post pictures of what I came up with once all of the lines are bent and plumbed. I'm using a Wilwood tandem, high volume type under the floor with the stock pedal assembly. I have made a heavy duty, adjustable pushrod. There will be a 2lb residual pressure valve (RPV) front and a 10lb RPV rear. Also a Wilwood rear brake proportioning valve and a stop light switch.

    I have included several photos that will help fill in some of the details. I will try to add more as I finish up. Disc brakes were one of the things that I put off doing because what I wanted was not available. The car has driven just fine for the last 10 + years with the drums and single reservoir master cylinder, but I really think that this will be a great addition to the car. The increased stopping power is almost a must in today's traffic (especially the way I tend to drive). Hopefully this is some help to the Shoebox crowd and may help others decide to jump in and build their own kit.

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  2. Great tech write up!
  3. Brock49Ford
    Joined:
    Aug 20, 2002
    Posts:
    502
    Location:
    Miltun, Warshingtun

    Brock49Ford Member

    I got a little work done on the master cylinder part of the conversion as well so I figured I'd add to this thread.

    I took an old stock master cylinder and cut the reservoir off and where the stock piston was. I did this because I am using the stock clutch pedal and modified linkage. I forgot to take a picture before I installed it, I added a few pictures that kind of give you an idea. I left the grease fitting and bushing on the front so that the clutch cross shaft can get greased.

    I bought a master cylinder mounting bracket and added a little more too it so that I could get the height right on the frame. I mounted the M/C and tacked the bracket where it looked like it should go. Once I had an approximate location I went to work on the pushrod assembly. The Wilwood tandem, high volume M/C had a threaded rod held in by a retainer plate and snap ring. I used a 3/8" RH threaded tube adapter, a 12" piece of 7/8"x0.058" 4130 tubing, a 3/8" LH threaded tube adapter, and a 3/8" LH rod end and made an adjustable pushrod. (Note: a reason for the long pushrod is that it stays under the removable transmission crossmember. That way I don't have to mess with the brake system if I drop the trans crossmember. Line routing will come into play as well, but I am not that far yet.) This will let me fine tune the pedal travel. Once the pushrod was mocked up and attached to the stock pedal I went back to the M/C location. (My installation got a little tricky as the exhaust is already there, and I was not going to start cutting on it.) The pushrod travel was a bit of a challenge due to the increased length. The frame tapers as it gets wider. You don't want the bore of the M/C to be in a different plane than the pushrod travel side to side. Up and down travel also needs to be taken into account. I used a shim where the old M/C piston used to be and the return spring to get the vertical travel figured out. I split the difference and used that as my base. (I did cut the tacks loose at this point and used a few magnets since I did not have a helper.) The pushrod is up a little when there is no pressure and the return spring has the pedal at its highest point. It is totally parallel as pressure is applied, the sweet spot. and drops at full pedal. This is with no hydraulic pressure as well, so it will get better instead of worse. I can move the M/C piston more now that when there will be fluid. (Note: Be careful not to bottom out the piston or have it bind in the bore. Found this out on a Harley M/C the hard way years ago.) I was also able to adjust the side to side action in the same manor. The old M/C being there was helpful as it provided a point of reference. I watched my new pushrod and marked the bottom, where the old piston was, to see how much it was moving. The rod end/ heim joint in the front really helps this situation. It allows that slight amount of misalignment to take place. A little bit of manipulation and the bracket was where it wanted it. I removed the M/C and pushrod and welded it up the one side. I will place a gusset on the rear of the bracket as well. This will stop any flexing of the bracket under hard/panic braking.

    One nice feature of the Wilwood M/C is that it has outlets on both sides. In my case I will plug the ones that are to the inside and use the ones that are close to the frame. Plumbing might get a little tight, but it looks very realistic. I am going to use a 2 lb RPV for the front and a 10 lb for the rear (drums). I will also plumb in a Proportioning valve. In one of the pictures you can see my "notes to self" on the M/C. Since the M/C is in a sense mounted "backwards" the lines will have to cross. The primary/large port of the M/C is closer to the rear of the car and the secondary/smaller is towards the front. Laying on your back looking up you can get twisted up pretty quick. I am also thinking about making a small heat shield for the exhaust in this area. Probably a larger section of tubing sliced open and corners rounded with a few small spacers/mounts for hose clamps on the back. (I am thinking about getting this small piece ceramic coated as well. I have seen similar ones on other forums and they say it works really well.)

    I will try to get pictures up of the plumbing once completed. May be another week or so.

    Lastly, I included a better picture of the rotor and hub adapter ring with the wheel studs included. The original post did not have to good of a picture. This is the driver's hub and rotor assembly. This shows how well this went together.

    Let me know if there are any questions. I will do my best to answer them either in the post or via PM. Like I stated before... Hopefully this is some help to the Shoebox crowd and may help others decide to jump in and build their own kit.

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  4. msalamanca
    Joined:
    May 25, 2011
    Posts:
    525
    Location:
    Westminster, Ca

    msalamanca Member

    Nice.
    Fatman Fab also sales the kit for the drop spindles.

    But you cant beat making them on ones own.
    Register now to get rid of these ads!

  5. Brock49Ford
    Joined:
    Aug 20, 2002
    Posts:
    502
    Location:
    Miltun, Warshingtun

    Brock49Ford Member

    It has the dropped arms, albeit modified, from fatman on there. This may work with a dropped spindle as well. Years ago I "flipped" the stock spindles and was content to run drums. I have never seen a kit for flipped spindles. You actually get more drop from a "flip" than a drop....Drum brakes no more.

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