Everything about disc conversion. Input pls

Discussion in 'The whoa and the sway.' started by Troys69GS, Apr 6, 2008.

  1. Troys69GS

    Troys69GS Well-Known Member

    So far Ive done alot of research and here is what I found

    Scarebird conversion
    440.96 to 497.96 plus tax and include new booster and mastercylinder parts all local stores.

    Problem, alot of parts and all buick if you cross refrence them but still alot of parts.


    Next is Speedway Motors dot com
    Factory or aftermarket 239.99 plus shipping Good deal unless you need booster. Spindles are 149.99 for a pair. So for 390 plus shipping you get factory 11 inch brakes, no lines, all buick replacement.

    http://www.speedwaymotors.com/p/462...4-1972-GM-A-Body.html?itemNo=gm a body brakes.

    Next is Performance suspension dot com
    Full setup everything including booster is 484 according to craigslist or 499 online. You guys have to pay shipping, I would pay 8.2 sales tax. Mix and replace parts later, not all buick.

    http://www.performancesuspension.co...9/c1_5985_6061_6093/index.html?sort=2a&page=1


    Finally ALL Buick replacement parts converts your drum to disk and how much you might ask. Well all the parts for your 68-72 at your local parts dealer and 65 plus shipping. Thats right 65.00

    Go down to the middle of the page and look for the caliper bracket and that is all you need. You dont have to have a shield. Scarebird doesnt nor do corvettes. Why not.
    http://www.inlinetube.com/disc brake conversion/dbrake.htm

    I just hope the drum and the disc spindles are the same per info I recieved a while back. If so then this might be the way to go. Local cost plus 65 bucks for stock discs is 461.38 including booster.
     
  2. Geoemojr

    Geoemojr Guest

    I think you maybe a little high on some of your pricing on scarebirds stuff. Cause all your purchasing from them is a bracket some bolts and a spacer on your spindle to keep rotor in proper spacing. The rest is buy as cheap as you can get and you could buy from as many different stores as you like. And all kits are gonna have basically the same amount of parts. Haven't you ever worked on brakes before?:laugh: And I think there is a difference on drum and disc spindles. Otherwise you could just get the parts at a store without getting a special bracket or new spindles.
     
  3. Troys69GS

    Troys69GS Well-Known Member

    I pulled all the prices online and my cost wholesale is going to be a little cheaper but most guys cant get wholesale. The scarebird price was with the 121 cost booster and mastercylinder. None of the costs that I quoted included the adjustable proportioning valve either for 40 bucksish.

    I have done alot of brakes and no the parts are not the same. A set of 69 discs are 120 and good monte discs are 176.

    Sometimes cheaper is not always better especially with chinese metal.

    As for the spindles Im going over to my fathers house today to gander at the difference in spindles. Even the body manual is not specific but they both use the same bearing. Once again I was told they are the same and its almost a secret. lol
     
  4. Troys69GS

    Troys69GS Well-Known Member

    Well there is no difference in spindles. The Top bolt that holds the bracket and backing plate needs to have the head thickness cut down or ground by 1/4 inch or more.

    Backing plate is 45 bucks
    Caliper is 86 for the pair without cores. Cores price is 25 bucks

    Basically you can now do your own kit from the store and just order the back plate and caliper bracket from online sources. Ha....the secret is out or at least I wasnt told about it. 11 inch rotors ......:dollar:
     
  5. white72gs455

    white72gs455 Going Fast With Class!!!

    Anyone else do this? Not doubting you troy! just want to be sure or atleast hear some feedback before i start grinding on the front end. What else is to this? got any photos? ill give you or anyone my email. I want to swap my drums to disc real soon... thanks for all your help!
    Jerry
     
  6. staged70

    staged70 RIP

    Someone put pics of the correct disc spindles compared to disc spindles. Why have we all been searching the disc spindles for so many years? I happen to have 2 one set for each car thats getting a conversion. Upon inspection one set has larger upper bolts. Now I bought both sets from board members here as disc spindles and pitched my drum parts because no one wanted them. If people know this why keep that a secret? I looked at Georges site and nothing is mentioned about the parts being the same.
     
  7. Troys69GS

    Troys69GS Well-Known Member

    My conversion will be done during the next 2 weeks. I will take pics and post them as I go. Heres a hint. Look up the bearings required for disc and drums. They are the same size. I just finished ordering all of my parts from my local account and I will post my cost as well.

    No grinding on the front suspension, just 1 bolt head.
     
  8. nekkidhillbilly

    nekkidhillbilly jeffreyrigged youtube channel owner

    troy is right on this
     
  9. Todd69GS

    Todd69GS Silver Level contributor

    When you order a disc brake kit from Wilwood to convert from drum you only need to drill and tap one bolt larger. Of course their kits could be designed for drum brake spindles.
    I'm curious to see how this turns out. I wonder if the geometry will be correct when everything is bolted on.
    You're right John. I wonder why we haven't seen this come up before. Or maybe I just missed it.:Do No:
    Let us know Troy.
     
  10. Hector

    Hector '79 Buick Limited


    Just adding fuel to the fire:Brow: .I have never worked on A body spindles other than removing some for resale and salvage the caliper brackets,dust shields etc.,all this I did before the aftermarket made those parts available.Just for reference,when I wanted to go with discs on my '66 Nova,I found that the only difference between the drum and disc spindle was the threaded boss where that top bolt holds the bracket/dust shield was longer for the drum application.In order to reuse the drum spindle for the disc set up,the boss needed to be machined about .600" so the bracket sits flat on the spindle and make the caliper parallel to the surface of the rotor.I have heard people suggesting that the operation could be performed by grinding or hacking the boss until it was close enough,I would not recommend that aproach and suggest to use a machine shop to properly mill the metal off to assure a correct alingment of the parts.A side by side picture of the drum and disc spindles will be a great help on this thread.Good luck.
     
  11. staged70

    staged70 RIP

    I am understanding that they are very similar. What I am saying is that the 2 sets I have the top bolt is a different thread diameter. This is where the upper caliper mount bolt goes in the spindle. I was wondering which is the Disc and which is drum as I no longer have drum parts to compare them. Also if a person had spindles off say a 67 or 68 firebird will they bee the same ? If by chance the disc had the smaller bolt would you them have to drill the caliper mount out to match this larger bolt?
    Have members selling these as disc spindles been taking advantage of misinformation . I was alwasy told you needed the disc spindles. I'll be pissed if I find out that I threw away 2 sets of perfectaly good spindles because I couldn't sell them for 5.00
     
  12. Troys69GS

    Troys69GS Well-Known Member

    CORRECTION TO MY PREVIOUS STATEMENT.


    The Boss or the area where the top bolt holding the bracket has to be milled down .25 inch or so. Not the bolt itself. The spindles are exactly the same except for that casting area. I had both pairs in my hand today and had to learn that from a Chevy guru. All that is required is a straight edge and some tape to mark the area to be cut. I will post everything as I complete it. Im going for a NO dust shield installation and the 1/16 of an inch wont make a difference in my caliper positioning.
     
  13. Troys69GS

    Troys69GS Well-Known Member


    Sorry friend. No bolt size change, just the platform. Stay tuned for picture day. Troy
     
  14. staged70

    staged70 RIP

    One more thing, I just had school on these from a machinist. As you mentioned the boss needs to be machined. The large upper bolt that mounts the caliper bracket has to be the size it is to hold the bracket secure. Also the charge for machining the pad , redrilling the hole and threading is 127.50 for me. You still need that large bolt. Keep in mind that the whole caliper mounts on 2 bolts. So the upper gets more stress thats why it had a larger bolt than drum which spread the load around the backing plate. So after paying 100 for some supposed disc spindles a couple years ago I need to spend another 127.50. to make them work. Not too bad at todays prices .Also when removing the material from the spindle this needs to be set up in a Bridgeport or similar milling machine so that the surface is exact and straight or your caliper bracket will sit crooked. Using a grinder while it might work is not considered correct machining and can cause the whole system to sit cockeyed. This will cause the pads to wear uneven and you will eat pads and rotors.
     
  15. Hector

    Hector '79 Buick Limited

    I was thinking along the the same line.Even though the '66 X body (Nova) is different,I used '71 Nova parts on my conversion,that's the beauty of sticking to a GM platform.The NNN or National Nostalgic Nova Association,performs the machining and last time I checked was $75.00 for the pair with cores.Having my own equipment,I made my own jig or fixture and machined my own spindles and about four other sets about 7 years ago.Keeping the relationship of the caliper and the rotor is paramount and the caliper brackets vary,I've heard from .250" to .750" to mill out.My set up took about .558" on one side and .625" on the other to set everything on the same plane.Some of the spindles have to be redrilled and tapped for deeper threads on the top bolt but any competent machine shop should be able to do it.I like using factory parts myself,maybe some of the aftermarket is up to par.
    We still need a visual comparison on this thread to see what we're talking about,anyone?
     
  16. lark69

    lark69 Well-Known Member

    i researched this as you all have months ago and i believe there is a pic on the team chevelle website of the noted difference in the 2 types of spindles.
     
  17. Troys69GS

    Troys69GS Well-Known Member

    The threads of the top bolt are not compromised. The stress on the bolt can not be more then the stress on the bracket. There is no way in hello that the stock size bolt is going to snap before the bracket tweaks out. Thats just common mechanical advantage sense. If your that concerned just upgrade the bolt.
     
  18. staged70

    staged70 RIP

    Troy. The whole statement about the bolt came from a machinist. He was showing me the difference. If you use the smaller bolt that the drums used it will require a shim to hold the caliper bracket as the top hole in it is for the larger bolt. I asked why the larger bolt and got a lesson in stresses. With the loading onthe bolt being much greater than factory drums which grab all the way around the drum the load is dispersed through the whole spindle/backing plate assembly. As you know there are 2 bolts holding the caliper bracket on and 2 others holding ther caliper to the bracket. When going forward the pressure is much greater on the top bolt when the brakes are applied. When driving in reverse its the other way around. That said a good bolt might not brake but since the hole in the caliper bracket is larger than the bolt in the drum spindle you will need a spacer or a shoulder so to speak so that the bracket doesn't move. I agree this will work and my guy who charges 85.00 per hour says he can make a drum spindle exactally like a Disc one for 127.50. Then you can get the correct shouldered upper bracket retaining bolt or a shoulderd bolt that has a shoulder the size of the hole in the bracket.
    While I am not disputing that this can be done at home and made to work I have found that most times the manufacturer did things for a reason. If not the spindles would be the same.
     
  19. Troys69GS

    Troys69GS Well-Known Member

    The stock disc spindle and the drum spindle I had in my hand looked to be the same size bolt hole. Ill call tomorrow and see if he can measure them for me. Good question now.
     
  20. Geoemojr

    Geoemojr Guest

    Also the scarbird stuff had a spacer you slide over spindle. So when you mount rotor the rear seal went perfectly over it to keep the grease in. Maybe their is a little difference there. I don't know for sure cause I haven't seen a disc spindle vs drum side by side.:puzzled:
     

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