Slant Six Forum :: Disc Brake Conversion

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Disc Brake Conversion https://slantsix.org/forum/viewtopic.php?t=26460	Page 1 of 1

Author:	runvs_826 [ Sun Dec 30, 2007 9:46 pm ]
Post subject:	Disc Brake Conversion
After having my Duster for a long time, and making the motor faster than my Dad thought the slant six could ever be we decided that it was time to change the brakes and upgrade the suspension. Actually it was cause they don't make any cool wheels for the Small Bolt. The Duster had a stock set of 10in drums. We looked for a while to find the stock disc brakes for up front and couldn't really find anything around here that were the price I was expecting. Here's the build up we did that was very cost effective and worked fairly well. After lot's of measuring we learned that the spindle diameter allowed bearings from multiple hosts. All the "salesman" I talked to were certain I should have disc brake and was confused about the year, besides that small fact I would too assume the majority of people wanting to do this would have earlier vehicles too! So the essential last piece to this would be to measure the spindle and refrence it to my year. After scouring the junkyard for a hour we found a '85 Diplomat that would be an excellent candidate. Now I believe it is true that your cannot steal the whole disc brake assembly because the A-arm geometry will cause bumpsteer. However, you can steal the Diplomat: Rotors, Hubs, Calipers, and Brackets. We stole a Slider Calipers in which you can simply just steal the cast iron bracket at the junkyard, and buy the rest at your local auto parts store. Note: Knowing what we know now I would use a pin style brake system, which would make somethings easier, shoulda woulda coulda. The Caliper Bracket shown above took some trimming so it wouldn't hit the spindle. We than made a bracket that would attach the bracket to the spindle that took some engineering. So after lot's of fitting we got the bracket to connect to the spindle that than held the calipers. The bearing were exactly the same as what came off the Duster so it was simply repacking some new ones from the local parts store.

Author:	runvs_826 [ Sun Dec 30, 2007 9:58 pm ]
Post subject:
Well, your not quite done yet. You still have the master cylinder to deal with and the brake lines right? Right. So the master cylinder was simply stealing the nice aluminum one off the Dippy. I'm sure you can order one of these if junkyards are a bit scarce. It took a simple bracket make out ot 1/4 which is what we used for the bracket earlier. I bought old metal from Cherry City Metals up the road, these brackets are also real easy for me to cut because I have a plasma cutter, but i could do it with an O/A as they are relatively simple. This bracket was a simply a square that had multiple holes. Weld two bolts in the middle holes, and cut the head off. As you might have noticed in the previous thread we moved the calipers to the front of the spindle, unlike what mother mopar orginally planned. So to move the break line we made a J-hook of hardline that connected to the original rubber hose. The original bracket that they connected at was attactched to the new middle bolt that was an original hole for the spindle that was drilled through the hub.

Author:	andyf [ Sun Dec 30, 2007 10:37 pm ]
Post subject:
Wow, talk about doing it the hard way!

Author:	runvs_826 [ Sun Dec 30, 2007 10:45 pm ]
Post subject:
Well... one would say that. One would also say I'm a college student who did all that for $100. Just an option for what people could do, also I think these are pretty heavy duty. Just hope people get some insight and ideas.

Author:	DusterIdiot [ Mon Dec 31, 2007 7:50 am ]
Post subject:	Lol...
Quote: Wow, talk about doing it the hard way! Yeah, andy just lives a couple of exits up I-5 and has the MC adapter plate in aluminum. Not to ask, but did your calipers have the phenolic pistons or the aluminum versions? (The late models like that Dip, might have the phenolic versions, which have been known to not be as durable as the older versions found in the 70's). Neat work though, -D.idiot

Author:	Joshie225 [ Mon Dec 31, 2007 8:13 am ]
Post subject:
I would have just used the Diplomat spindles. It's not a bump steer issue using the taller spindles. It's a perceived possibility on the part of Rick Ehrenberg that the upper ball joint would be subjected to a greater angle than it's design dictates. The height and resulting upper ball joint angle difference is actually pretty small.

Author:	tophat [ Mon Dec 31, 2007 4:50 pm ]
Post subject:
I have to agree with Joshie. I am running Volare spindles and they work GREAT Volare and Dippy spindles are identical. Also a 74 Roadrunner disk master bolts right on the firewall, no adapter needed. TopHat

Author:	andyf [ Mon Dec 31, 2007 6:23 pm ]
Post subject:
Well by the looks of your drum knuckles you have a 1973 or newer car. Which means the FMJ knuckles would've been a bolt in and you would not have had to fabricate anything. In fact, if you grabbed the parts from a late 80's car they would've come with a rear hung caliper that works with a rear hung hard line. All you need is a simple hose with the correct fittings on each end and you're done. The aluminum MC adapters are fairly inexpensive and would've saved you a bunch of fabricating time. You could've sold your late model drum knuckles to someone who wants to do the Viper on 11.75 conversion since those are the knuckles needed for that trick.

Author:	runvs_826 [ Tue Jan 01, 2008 1:05 pm ]
Post subject:
Well, hopefully the info here will help someone else that's reading this thread. I didn't know about all this, but very cool stuff. Yes, I have a 74 duster, I thought I said that but must've slipped my mind. If it's possible to switch in the FMJ body disc why don't more people just do that? Or is it comon knowledge? Like I wrote, the previous readings was that the F-body spindles would give you nasty bumpsteer. Thanks for the offer or something about the MC adaptor, that actually was the quickest thing of the whole project, I think about 40min from pulling the old one, to having the new one on. What's the info about this viper set-up?

Author:	dakight [ Wed Jan 02, 2008 3:14 am ]
Post subject:
A large percentage of folks doing the disk brake conversion are working with a 72 and earlier A-body car. Those require a swap of the upper control arms as well as the spindle which means that they must still find an a-body donor for those parts anyway. There's an informative write-up about the whole issue on bigblockdart.com in which the writer analyzes the issues with the F-body spindles. It isn't so much bump steer that is the concern as incorrect "Ackerman" which is the toe-out on turns. Their conclusion is that the issue is of little or no concern.

Author:	tophat [ Wed Jan 02, 2008 4:32 am ]
Post subject:
I noticed 6 months or so ago that the 73-76 A body UCA's are getting hard to find, and are expensive on eBag. I used the tubular UCA's from www.reillymotorsports.com on the bigblockdart board. At $300.00 for the pair ready to bolt on they are not "cheep" though they are (in my opinion) worth every penny. The alignment and adjustment options are well beyond anything you can do with a "stock" UCA. These were by far the most expensive part of the conversion, but very well worth it. After 6 months or so of daily driving the potholes, I mean streets of Charlotte NC I have had no problems with them at all. I highly recommend these, especially if you don't ride at stock height, as with stock arms as low as I am, setting camber and caster is nearly impossible. TopHat

Author:	slantzilla [ Wed Jan 02, 2008 4:44 am ]
Post subject:
Quote: It's a perceived possibility on the part of Rick Ehrenberg that the upper ball joint would be subjected to a greater angle than it's design dictates. Blasphemy!!!!!!!! E-booger is the second coming of Christ! How can you not obey his word???????????????

Author:	andyf [ Thu Jan 03, 2008 6:45 pm ]
Post subject:
I talk to Eberg a few times a month but that is one subject we just agree to disagree on. In my book the taller, lighter, late model FMJ knuckle is the one to use. I base my 13 inch Viper conversion kits on it and I recommend it to my customers. When you combine the FMJ knuckle with the tweaked upper control arms from FFI you really have a nice setup. That is what I put on my B body car and it is what we've run at the track.

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