Front Disc Brake Tutorial

[Focker]

Please read the whole thread...It's been updated as others have encountered various issues.

The information presented here was acquired from various EarlyCJ5 threads and a simple article from fourwheeler.com. I had to ask a lot of questions…Thanks to those who assisted me. If you gather all the parts in advance you should be able to swap your brakes over the weekend. The parts cost me $305.10 including tax and shipping. I know it can be done somewhat cheaper but it all depends on the junkyard deals you can get, caliper cost (I didn't have cores for exchange) and if you can avoid the $35 in shipping! I spent a bit of time looking for the best bargains. I did a mixture of local parts houses, Amazon, RockAuto and the junk yard. I suppose the advantage to having the local shops order for you is possible overnight free shipping.

I think the biggest factor in the new brakes feeling great and worth the swap was "wearing" in the new pads. I bought the cheapest pads and maybe that was a contributing factor to the initial poor performance? Drive the Jeep a mile or two with your foot on the brakes a little (thanks jpflat2a). I completely forgot about this and was disappointed at first. The more I drive the Jeep the better the brakes function. Take your time bleeding the brake system and adjusting the rear drums. I also upgraded the rear drums to 11" at the same time and that made it hard to tell if the disc conversion was worth it.

The Jeep:
1971 CJ5
Stock D27 with 10” front drum brakes and Warn locking hubs.
Floor pedals and stock floor mounted dual chamber master cylinder with 1” bore.

The parts I used:
Caliper mounting brackets from the wrecking yard - '81 Chevy 1/2 ton 4WD (K10).
Caliper - '71-'78 Chevy K10 - Oreillys Part #: 18-4046 Left
Caliper - '71-'78 Chevy K10 - Oreillys Part #: 18-4045 Right
Organic pads - '71-'78 Chevy K10 - Oreillys Part #: LD52 (too cheap...Go up a price point)
Rotors (1.12 or 1-1/8" thick) - '77-'80 Jeep CJ - Raybestos 3550R
Brake hoses - Napa Part #: 36761
Banjo bolts - Napa Part #: 82698
3/16" Brake line ... 3/8"-24 To 7/16"-24 - Napa Part #: 813-5502
Wilwood 2lb residual pressure valve w/fittings - Part #: 260-3278
10 qty lug studs Dorman - Part #: 610106
2 qty plastic plugs for the knuckles (found in my parts bin)
12 qty Grade 5 - 1" fine 3/8"-24 thread bolts and lock washers

Special tools recommended:
Front axle nut socket.
Master cylinder bleeding kit (if you pull your MC to ease the removal of the brass seat and 10lb check valve).

Things to consider:
You may have to get your hub machined to accept the rotor - See Post #8 (I didn't have to, but others have).
New wheel bearings, seals and axle nuts & washers.
Servicing your steering knuckle bearings and seals.
I didn't have this issue but if your new discs rub on the caliper brackets you'll need a spacer (approx 1/8" spacer). The following has been edited to include the part number mentioned.

...You need the thicker race, Timken part #LM501311. This will space the hub out like you need. I'd recommend using national seal # 8430s. You won't be able to drive it in all the way due to the bearing being spaced out, but this seal will stay in place. You want to drive it in until just before the lip of the seal rubs on the bearing.

Alternate race size as mentioned by 45es in post #36 of this thread.

I researched and found bearing race P/N LM501314 which is 0.6537" wide. This gave me the clearance I needed for the brake pads and allowed full engagement of the locking nut.

Enough lead in…Let’s do this.

This is what started it all. The Jeep started to pull due to a leaky wheel cylinder.

Remove the stubborn brake hoses using 3/8” and 5/8” wrenches. Set the “S” line aside…We’ll come back to this later…I have an idea!

Use a 3/4” drill bit and enlarge the brake line bracket.

Take out your grinder and remove just enough material to allow the new brake line to slip through.

Perfect.

To remove the hub and drums, start by removing the six 5/32” allen screws from the Warn locking cap and remove cap. Then remove the six 9/16” hub bolts. To remove the Warn setup you have to remove the snap ring from the axle shaft. Once removed you will have access to the axle nut.

Warn parts...These have been cleaned and ready for lite greasing.

Before you can remove the axle nut you will have to bend back the washer enough to turn the nut. Remove the axle nut and washer, then remove the final nut. Pull the hub assembly off being careful not to drop the bearings. Now remove the six 9/16” spindle nuts (toss them in your parts bin) and pull off the spindle and backing plate until you're here (pic). At this point you should inspect the knuckle grease. I used John Deer Corn Head Grease.

I might just be lucky? I was able to gently but firmly knock out the wheel studs without resorting to the BFH. Les Schwab wanted $70 in labor to remove and install new studs.

I did a test fit with the old studs, rotor and hub before installing the longer Dorman studs to ensure everything lined up…No problems.

To install the new Dorman studs I ran the old studs through the back of the new rotor & through the hub. I used my air gun on its lowest setting to secure the rotor and hub. I then removed one stud at a time and drove them in with one hit of my BFG being careful not to bend the hub.

I worked in a star pattern one stud at a time flipping over the rotor and using the impact gun on its highest setting to suck the new stud through. If you plan to use your old lug nuts you could risk flattening the tapered end.

 

[Focker]

That's all the easy stuff...Now to the dirty work.

My junk yard brackets were hammered.

I made relief cuts in the thinner material and wiggled them back and forth in the vise until they crumbled off.

I cleaned the caliper mounting brackets and painted them using BBQ paint.

Take a couple of the new 1” spindle nuts and lock washers and slip them through the caliper bracket, spindle and screw it into the knuckle.

Test fit the caliper and its clearance. You will have to grind some or A LOT of the knuckle & caliper material in order to allow the caliper to "float".

You can see I removed a lot of material. I suggest painting over the grinding you made on the knuckle.

Paint over the caliper's raw metal too.

It's hard to tell from this angle but I had plenty of room...I can push the "floating" caliper all the way towards the knuckle without interference.

I used a recessed knuckle filler hole plug as seen here.

Once satisfied with the clearance you can start the reassembly procedure. I used Loctite 243 thread locker on the spindle bolts and followed the Factory Service Manual's instructions – “Steering Knuckle Support to Knuckle Arm to Wheel Spindle Bolt = 45-55 ft lbs."

I know...I know...I'm bouncing from passenger to driver's side in this tutorial. Sorry.

Install the axle bearing per the FSM - "Rotate the wheel and tighten the adjustment nut until the wheel binds.
Note: Front tire and wheel must be rotated by hand as the adjusting nut is tightened to ensure positive seating of the bearing. Then back off the adjusting nut about one-sixth turn making sure that [the] wheel rotates freely without sidewise shake. Replace the lock washers and locknut. Bend over the lock washer lip."
Tip - Use a mid sized cats claw or pry bar to bend over the washer...It feels like you might break something but it works just fine.

Read this update before moving on with the install - Post #60 of this thread

Install calipers and pads on your 40+ year old CJ! I had to grind a little material off the inside pad in order for it to slip into the calipers. I used a hand held grinder and kept test fitting until it fit. Wearing in the pads is important and commonly forgotten or not mentioned.

Tip - If you can't get the snap ring back on the axle because the axle's in too far...Grab a bolt from your parts bin, screw it into the end of the axle and pull with some pliers. Finish reinstalling the locking hubs and move to the brake hoses.

Master Cylinder:

In order to use the stock MC you have to remove the brass seat and check valve from the MC's front brake outlet and reinstall just the seat.
Tip - Use a screw and be careful not to ruin the seat. I totally screwed mine up (but that's another story...A long story with a sad ending).
This image borrowed from the internet.

Optional - Remove the MC and give it an overhaul. I used Simple Green and a wire wheel on my drill press (and a brush too)...I gently honed the piston cylinder. The piston condition was good enough to reuse without buying a rebuild kit.

Remember the "S" line? This turned out perfect. Make sure you run the lines according to the picture. It's been noted in multiple threads that your lines could have been switched by a PO and be backwards from what is labeled here.
(Disregard the freshly tapped holes in my MC...Those are for a remote reservoir hack I did).

Bench bleed the MC.

Install the MC and put a slight bend in the new Napa brake line and you're good to go.

Finish bleeding and bleeding and bleeding the brake system. Go for a test drive avoiding school crossings.

Here's a great video psted by Scott.

I installed the new Master Cylinder and still had problems. I was fighting a low pedal until I found this video. I had air in the Master Cylinder. Now the brakes work great.

 

[FinoCJ]

Damn Nice! - thanks. Might be worth a sticky somewhere - or at least a bookmark.

 

[Patrick]

Stuck!

 

[wheelie]

Well done, sir. Great to have all the pertinent information in one thread. I just may try this now when a front axle gets built. Thank you.

 

[timgr]

Technical articles are always welcome. Good job!

 

[Focker]

Well done, sir. Great to have all the pertinent information in one thread. I just may try this now when a front axle gets built. Thank you.

You hit it on the head...There's a lot of excellent disc swap information on this forum but it's somewhat scattered. I hope that most can use the info in this thread to complete their conversion, whether they're skilled or somewhat novice like myself. I'm by no means an expert on this subject and I had a couple of "phantom" issues but through perseverance and help from the ECJ5 gang I prevailed!

Thanks...
nickmil
timgr
47v6
SFaulken
jpflat2a
WorkInProgress (tool loaning)

 

[scott milliner]

I ran into a problem where the rotor wouldn't fit flat on the back side of the hub. I found that the hole in the rotor was to small to fit over the hub. I had to take the hub to a machine shop and have the radius removed. I found out the hard way after bending a disc.

Edit:
Here is an image I found on Google to show the difference.
~Focker

 

[dharmabum]

I ran into a problem where the rotor wouldn't fit flat on the back side of the hub. I found that the hole in the rotor was to small to fit over the hub. I had to take the hub to a machine shop and have the radius removed. I found out the hard way after bending a disc.

Great write up, I've done at least a half dozen of these conversions and I believe with every one I have had to machine the back of the hub to get the rotor to sit true. This could be why Focker had to grind his inside brake pad a little bit, if the back of the hub was machined the rotor would sit that fraction of an inch closer to the hub and allow more room for the pad. Also it is great you replaced the spindle bolts with longer ones, this is a necessity when doing this conversion and often overlooked. To take it one step further and make things even safer I like to use button head cap screw bolts and insert them through from the back side of the knuckle and then use nuts to hold the spindle and caliper bracket on. I have done this ever since I had my spindle separate from the knuckle on me about a week after a disc conversion, luckily it was at low speed.

 

[64pete]

I redrilled my caliper brackets half way between the existing holes, rotating the caliper up about 30 degrees. Needed much less grinding on the knuckle. I also trued up my hubs where the rotor sits on a brake lathe, guaranteed flat and true. The only "problem" I have with mine is with the thicker inner race, I can't get a full nut worth of thread on the outer spindle nut. Probably not a big deal, but worth mentioning.

 

[SFaulken]

I didn't need to have my hubs machined, they sat flat as it was. I did have to use the thicker race, but yeah, I've got the same issue with the outer spindle nut. I figure with the lock washer between it and the inner nut, it's probably fine though.

 

[1955jeepcj5inabox]

Nice write up,
You talk about having to remove some of the pad to get it to fit. On mine I have a 3/8 inch space between the pad and rotor. Did I get a wrong part or? Thanks

 

[Focker]

Did I get a wrong part or?

What rotors did you get?

I guess it depends on the parts you sourced?

 

[1955jeepcj5inabox]

Pads. Brake Select SC52

Calipers. Brake Best 18-4046

Rotors. Brake Best 3552 RGS

Thanks again

 

[Focker]

How thick are the rotors? They should be 1-1/8".

 

[1955jeepcj5inabox]

My rotors are about 7/8" thick. They were for a 78 CJ5. That's what I asked for.

 

[Focker]

The Raybestos 3550R are the right thickness. I'm not sure why they (Jeep) used other rotor sizes?
*Updated 1st post for clarification.

RockAuto's parts list, shows the rotors will fit a CJ5 from '77 - '80...Confusing.

 

[Daryl]

77-78 were 1 1/8" rotors. 1979 and later were 7/8" thick.

 

[47v6]

If you use GM calipers you need to use the 1 1/8 rotors.

77-78 were 1 1/8" rotors. 1979 and later were 7/8" thick.

 

[SFaulken]

there are two different rotors. I've heard reference to the 1-1/8" thickness as being "Big Brakes" or "Six-Hole" brakes (I'm assuming the six mounting bolts in the bracket is that reference) vs a "Two-Hole" disc brake, which uses the 7/8" rotor. Rockauto actually lists both for 77-78 CJ's You need the 1-1/8" thick rotors to work with the Chevy Calipers and brackets.