75 Disc Brake Conversion

Greetings,
I recently bought a 1975 CJ5, This is my 4th jeep, my others all have been later CJ5's. This one has the Dana 30 front end with 11" drums. I thought I had done my research and homework to swap the drums over to disc's, but I guess I did not do enough. I have gotten all the parts and I think it will work, but I have two major issues, that I can not work through. I am about to throw the drums back on. I miss driving the jeep.

1) the rotor face is machined, but the hub backing is not. One of the swap over items is to pull the hub, drive out the old studs, put the rotor behind the hub and drive in the new longer studs. The rotor face is a machined surface, the back of the hub is not, this would not allow the hub to sit flush with the rotor. It would cause brake chatter issues. I am thinking I will have to get the hub machined to fit the rotor? But I can not find anyone else who has had this issue. I seem to be odd, before I spend more money and time, I would like to know if anyone else has seen this.

2) I got the longer Studs, The studs are not longer, but the press in part of the stud is. The rotor stud hole is a touch bigger then the stud, so they do not press into the rotor, but they will press back into the hub. my issue is that there is only at best 1/8 of a inch being pressed in, I do not see how this little amount of press fit stud will hold the stud when torquing. I am really worried in a while of taking the wheels on and off, that the stud one day will simply spin and I will not be able to pull the wheel off.

Any suggestions? Does anyone sell new hubs that are already machined? Is there something I am missing?
I have looked through the postings and can find all sorts of information about this swap, but nothing with my issue.

Thanks for any help

BTW, I was really keeping a good log of what I bought, what I paid and my thoughts of the swap to be my intro into the Forum...but that is on hold till I get her back up and on the road.

 

Moved to proper forum. Just as an FYI on this board Early CJ's are '71 and older and Intermediates are '72-'75.

Yes the backs of the bearing/wheel hubs will need to be machined or replaced with disc brake bearing hubs. It's been discussed here in most of the threads discussing disc conversion but not all the old threads discussed it so could be missed.
What parts are you using to convert? There are a couple ways to do it and what you need are different depending on the conversion being done. If using 1/2 ton GM calipers and mounts and using your drum brake spindles you will also need a different inner bearing race and seal to space the bearing hub/rotor correctly so the caliper will line up. More information on what parts you have would be helpful. There are tons of writeups on doing this and some are better than others.

 

Your best bet with the least amount of headaches is to Just find a later cj dana 30 with disc's and just swap everything from the knuckles out. Just this year alone I have already bought two of them for under $125 each. If you do it this way you are guaranteed to find parts available at almost any parts store and not have to source each and every part. You can literally have disc's in a day if you get all your parts off before hand. Make sure to get a proportioning valve and the correct master cylinder . I always get the same year master cyl as the front brake setup. Always works out great.

 

Thank you for the reply. I am sorry I posted it in the wrong spot. I will look again for the posting with the details. Thanks again for the help in pointing me in the correct direction.

I have already vested in the chevy swap, so I am going to stay the course. All I am really missing is the disc hubs and the bearings, found the hubs for 50 each. I am guessing it will add about 150 into my set up. I looked for a later axle, but the only ones I could find were 200+ and are few and far between. If I had to do it over, I would go that route and find the right axle. If I could return all my parts, I would.

Thanks again.

 

I just finished installing disc's on my 75 CJ. I grew tired of trying to find the correct parts and deal with a bunch of junk yard stuff that was rusty etc.. I ended up buying a disc kit from R&P 4WD in Oregon City Oregon. And a plus was that it was on sale at the time.. I'd give em a call and see if they will sell you what you need for parts..

Other than grinding a bit off the knuckles for caliper clearance it was rather painless.

 

I installed R&P's kit as well. This is their 1/4 ton kit, which is slightly cheaper. Install was easy, and I'm very happy with the end product (haven't driven it yet though)

 

what does a kit like this go for?

 

$549 on sale.. For this vehicle/axle. I'd call em first. They are very helpful..

http://shop.rp4wd.com/product/kits-disc-5

 

Are you sure you have the right wheel studs? R&P can supply the right ones if you feel you don't. I'd call them with measurements of what you have and compare to what they have. I've found some have more spline contact than others.

 

Thank you all for the help, I ordered the parts on Monday, they got here today. The Disc hubs will solve both of my issues. The back are machined so the rotor will run true. The disc hub also looks much thinner where the studs go through. The studs I have are correct, they are just two short for the drum hubs. I am really hoping I can get out there in the morning and finish the jeep up.

Just in case any one is 2nd guessing and saying they can do it cheaper then the R&P version, they are wrong. I have carefully tracked my expenses and I am at 518.84, so far. This does not include the weeks of gathering and sorting parts. No way would I try to put a kit together again. Yes, it is cheaper then the SS brake conversion, which I have not heard good things about. But the $550 R&P really seems to be the way to do it. If I had to do it over, I would go that route. I bet I have 4-5 weekends just sorting out the front disc brakes. I am completely overhauling the whole brake system.

Again, sorry for not finding the forum's faster and not being able to key into the information I needed. Maybe this post will help someone down the road. Thank you again for your help, I hope I have all the issues solved.

 

Just to clear up a point, the 518.84 is only for the front disc conversion. I have 773.86 for the whole brake system, including the Front conversion. This is everything, hard lines, new drum hardware, MC. The only parts I am using again are the rear drums, they were like new and about 50 bucks each at my local autoparts.

 

One would think I have never worked on a car before...I guess I am starting to form a mental block on this project.
I finally got a weekend off to finish this up. With the weather turning nice, I am ready to get the jeep back up and running.

I thought I had it all figured out, I had to get the proper wheel bearings to insure the proper offset. Well I guess I messed that up as well. I talked to a Jeep store and he told me what bearings I needed, I also had to get a new set of inner races.

This is what I got (All Timken Brand and part numbers)
LM501349 marked inner on the box (Bearing marked LM501349 425-08 )
LM501311 Marked inner (Believe this is the race alone)
LM501349 Box is gone (Bearing marked LM501349 778-08 )

I put it together like the boxes said, and it all lines up and rotates fine. I put on the 2nd large nut and it tightens up, but does not have any threads showing after the nut, so it is barely on there, but it has been fully threaded.

I go to put on the locking hub snap ring and there is not enough axle sticking through to get the snap ring on. I pulled the axle out fully and tightened the hub down and still not enough room to slide the snap ring on. I have gone back over to make sure everything is in it place. everything seems good. The races are fully seated.

The only thing I see that could be a issue is the bearings getting mixed up and I am putting a inner one on the outer race.

Has anyone seen this issue before? Any clue?
I am about to toss all these parts in the can and get the kit to insure this is correct.
I still think the studs are to short, but that is a different topic.

 

uh...I guess 0 8 ) makes a smiley face...the last number is 08...not a smiley face.

 

You can turn off the smileys in the "Advanced" reply. 8) R)

Leaving out the snap ring on the end of the axle shaft won't have any effect. Back at the Jeep dealer, maybe half of the Jeeps that needed spindle/hub service were missing the snap ring, with no noticeable effect.

Can't help you with assembly though.

 

Did you have the disk brake spindles and use a drum brake seal? the disk brake spindles are larger in the seal area.

 

The company that sold me the bearings and disc brake hubs also sold me the seals. I do not think the seals are the issue.

Thanks again everyone.

 

As I recall R&P said to ditch the snap ring as there is no room for it. I did get both nuts on though.. My brake kit from R&P came with bearings and seals. The races were pressed in as well.. I could take mine apart and take a photo for a, but I am out of town for the next three weeks.

 

I've been explained that the snap ring is important in off-road condition. With the snap ring you make suer that axle u-joint stay in the center of rotation of the knukkle. Without the snap ring the axle could move and can be a cause of breaking.

M2c.

 

I called and spoke with the guy. He said it is normal, because of the offset of the new bearings and race that it moved everything out and you loose the snap ring. I am going to put it all back together ASAP.

I do not push it off road so I am not worried about the axle breaking.

Thanks again.