Waggy Rear Disk Brakes and Hydroboost

[COLORADOCRAWLER]

I completed a rear disk brake install this weekend and thought I would post it up for you guys. I will complete the Hydroboost next weekend.

The pile O'parts I started with.


Once the brakes came off I had to do some cutting. At this point you can consider yourself committed. I cut out the center of the drum backing plates to make a spacer so the axle and bearings all go back together as AMC intended.


The brackets are intended for a 3" tube but the tubes flare out to accept the bearings where they will be welded on so they had to be ground out to be larger.


Used two lug nuts to center up the rotors and fit the caliper/brackets to the axle.


Everything tacked in place. Note the tiny amount of clearance between the OEM 15" wheel and the caliper. It does however fit...barely.


Big pile of scraps.




All done!

[COLORADOCRAWLER]

Initial impressions: The pedal feels much better now, the brakes stop better, and servicing these brakes in the future will be a heck of a lot easier. Overall this was not too difficult, but you have to pay attention to several small clearances while setting these things up. It can be done in a day if you have everything right there and you aren't distracted too much. I had several start and stops with the kids and "honey do's" so it took me two days.

I still need to install the parking brake cables but I am waiting for a new front cable from BJ's. I never replaced it during the 5.3 swap and needed a longer one because the transmission crossmember is now in the rear set of bolt holes. It looks like I can just trim an inch or so of the small spring sheath off of the cable end by the ferrule and that will let me match it up to the caliper bracket. I would then have to move the cable mount brackets a few inches further back on the frame.

The project cost me about $300 so it isn't much more expensive than drum brake replacement anyway. The most frustrating part was that most of the OEM hard line fittings were seized. I had to cut/flare/replace the main 1/4" upper fitting to the tee-hose. The 2 hard lines that split off from the tee-hose needed replaced anyway because the calipers are metric and have the bubble style ends. I just used a 50" metric line from Napa and cut it into two lines, then put 3/8" x 3/16 fittings on the cut ends and flared them. Then you just have to bend up the lines to fit. I had originally planned on just cutting the OEM lines out at the ends and installing a metric end but I don't have the bubble fitting flare kit. The replacement hardline was about $8 so that made the decision to replace the hard lines easy.

[bigun]

Parts list?

[lkmarsh]

x2 on the parts list. Which calipers?

[COLORADOCRAWLER]

These are all Napa part numbers unless otherwise noted:

2ea. A & A Manufacturing weld on small GM metric caliper brackets, Heavy Duty (P/N: AA-113-C)
2ea. 79-85 Cadillac Eldorado rear calipers (P/Ns: SE4689, SE4690)
1ea. 79-85 Cadillac Eldorado rear brake pads (P/N: 105-01540)
2ea. Rotors (11.61" Diameter, 2.31" Height, 1.03" Thick, 3.09" bore) (P/N: 4885977)
2ea. Rear brake hoses (you have a lot of options here, they just have to be metric. I chose to use 2000 Cadillac Deville hoses because I had the brackets that I pulled off of a salvage yard car)
2ea. Soft line brackets and clamps with banjo bolts (free, salvage yard didn't charge for these bits)
1ea. 50" metric pre-fabbed brake hard line with bubble style end flares

I was able to reuse a couple of the waggy brake line 3/8" fittings to put on the metric hard line. Upon closer inspection of prices, the disk project cost me just over $400. You could do it for less with parts from O'reillys, Autozone, ect. Keep in mind that there are some expensive core charges for the calipers so you need to go to a salvage yard and pull some calipers for cores to keep the prices down.

Of course you will also need a double flare tool kit and tube cutter for the hard lines, and basic welding/fabricating tools.

[AwesomeJ10]

Very nice!

Added benefit is that when you break the rear axle shafts, the calipers will hold the assembly together for a short while, allowing you to pull over out of traffic!

[COLORADOCRAWLER]

Just edited the caliper bracket P/N: it ends in C

[COLORADOCRAWLER]

If I had to do this over again, I would have built a spacer between the caliper and the outer axle flange with thru-holes for the axle retainer bolts. You could then replace those bolts without having to cut the caliper brackets off. I am not too concerned about it though, in the years that I have been working on rigs, I have never had to replace those bolts. Now that I've said that I'm sure something will fail back there and cause me to have to replace that hardware...

I never looked into it too hard, but I wonder if a metric banjo fitting bolt would work/seal properly with an SAE brake hose? If so, that would allow you to keep all of your hard lines with 3/8" x 3/16. If this is possible, then the only metric crap you have to deal with is the banjo bolt itself and the bleeder plug.

[Gumby]

Very nice, I may have to start looking into this.

[Cheap Hobby]

Thank you. Did you have any problems seeing up the parking break action?

[COLORADOCRAWLER]

Thank you. Did you have any problems seeing up the parking break action?

As stated above, I am waiting for a parking brake cable to come in the mail before I will know exactly how well the parking brake is going to work. With that being said, once everything was installed and welded in I removed the return springs from the calipers and manually actuated the parking brake levers so the pads would adjust to the rotors. With this type of caliper you have to set the parking brake once in a while so that the internal ratcheting mechanism adjusts to take up excess play caused by pad wear. Overall the setup is pretty easy and I don't see what all of the fuss is about. As long as you use your parking brake once in awhile it keeps itself adjusted and you have to take a couple of extra steps to retract the piston when you install new pads.

This bit of knowledge got me to thinking about my wife's mini-van and how crappy the brakes are on it. It has four wheel disks but doesn't like to stop as well as you would think a newer car should. So when I looked underneath, low and behold, there are the same style ratcheting calipers in the rear of the mini-van! I pulled the parking brake lever a couple of times and now the van stops much better. The trouble with these types of calipers is that they are installed on cars with automatics and nobody ever sets their parking brake. Your brakes subtly get out of adjustment over time and I am sure that 90% of the owners out there don't know about the parking brake adjustment thing.

Due to the internal ratcheting mechanism, when you go to change your pads, you have to do a little more than just push the pistons back in with a c-clamp. Here is some info I found online regarding the adjustment/setup and how to retract the pistons:

Rear Disc Brakes and Parking Brake Adjustment

This is a critical item that many people miss when upgrading to rear disc brakes. Our rear disc brake calipers that are equipped with an parking brake are self-adjusting. Every time you use the parking brake they adjusts themselves for pad wear by clicking to the next stop on the internal ratchet. If you do not use your parking brake during normal operation of the vehicle, over time the pads will wear and there will be insufficient contact between the pads and the parking brake mechanisms. When this happens the parking brake will never engage. This step should always be performed prior to bleeding.

To adjust the parking brake while installing or servicing the calipers, use the following directions. Failure to adjust the parking brake can result in no parking brake, brakes dragging, overheating and premature brake wear.
1.If you are adjusting the parking brake after the system has been bled, remove the master cylinder lid and make sure that the fluid level is no more than 1/2 full, this is so that in the following steps when the caliper piston is pressed back, fluid does not overflow the master.
2.Remove the parking brake spring and lever arm. Remove the seal and nylon washer from the adjusting screw and place them in a clean location.
3.Turn the adjusting screw counterclockwise to tighten it and collapse the pads until the pads are tight against the rotor.
4.Note that the adjusting screw clamps the pads closed when tightened counterclockwise. When the adjusting screw is turned counterclockwise past a certain point, it turns the internal ratchet. This is how it is adjusted. Adjusting the screw can be tricky because when the it is tightened all the way, its hex head recedes into the caliper body and you can't get a wrench around it.
5.Turn the adjusting screw in counterclockwise by hand until there is resistance.
6.To push the adjusting screw back out to provide access to it's hex, use two channel-locks to squeeze the rear brake pad and compress the caliper piston. Place the wrenches on either side of the pad locating the jaws on the pad bracketry and the body of the caliper.
7.Then use a wrench to turn the adjusting screw counterclockwise to change the position of its hex and slip the internal ratchet.
8.Back the adjusting screw out by turning it clockwise, place the lever arm over the adjusting screw hex and apply a medium amount of hand force clockwise to the lever arm to push it past the lever stop on the caliper. Once the force has been applied, the lever should be located within 1/4" of the lever stop and should be easy to put on the adjusting screw head. There should also be mild contact between the pads and the rotor when properly adjusted. It is highly likely that this will need to be done a number of times before it is properly adjusted.
9.Remove the lever arm and replace the nylon bushing and seal, then replace the lever arm and secure with the nut.
10.Replace the return spring.

[Cheap Hobby]

Thank you Rick. I have read all complaints about using the Eldorado calipers and only 1 clear discussion of setting the parking mechanism, now 2. I grew up in dealerships and learned early to use the parking brake correctly to keep everything adjusted and take pressure off the auto trans.

[COLORADOCRAWLER]

As promised, here are some pics for the Hydroboost install. Holy crap will that thing will stop now! The rear disks made an improvement, the Hydroboost made it a whole other truck.

Looking down at the lines going to the steering gear.




I don't have a functioning vise so a C - clamp and a baby Jeep work just fine in a pinch for the bench bleeding procedure.






There is alot of bending on the suggested OEM GM hoses. If I did this one again I would flip the Hydroboost upside down to hide the lines and would have used adapters and AN fittings with braided steel lines. Sure it would cost more but it would look cleaner and would have actually been easier to route than the OEM stuff.

I forgot to buy a 1" spacer from Elliot and had to build something. Wish I had just remembered to order the thing, it would have saved quit a bit of time.

Got the parking brake cables in. The jury is still out on whether the Eldorado calipers are the way to go since the parking brake doesn't seem to hold well enough to justify the extra dough. I'll keep fiddling with it and see if it is up to par.

All in all, the Hydroboost mod is the first thing anyone should do to their rig. It just flat works. The only real aggravation was that most all of my brake hard line fittings were seized in place and required me to do alot of tube bending and flaring on the brake lines.

Baby Jeep in action at Moab UT.


and somewhere in lower Alabama.