Dana 27 disc brake conversion not getting pressure

Hello everybody. I just converted my brakes to disc in the front (dana 27) and after bleeding them, I'm not recieving the brake pressure I was hoping for. The master cylinder is dual resivoir and as far as we can tell there is no leaking in the system. Brake pads are organic. I don't have a booster for it, but was led to believe I don't need one. The rear brakes are the stock drums and by the way its a 67 cj 5 with a 225. Also, I found the article on the conversion very helpful. Thanks

 

Did you double check the easy things? A loose/leaky connection could be responsible. When I did my disc brake swap I hadn't tightened one of the banjo bolt connections enough and had a slight leak there. Also did you make sure to bleed the brakes furthest from the master cylinder first? That's the proper way to make sure you get all the air out.

 

Very important step. I had the same problem. Make sure the front brakes are on the rear port (closest to the mount) rear brakes to front port. Made all of the difference in the world.
Great info here: http://www.earlycj5.com/forums/showthread.php?t=26819&page=5
Post #45, #46 make sure to click on the link in post 45. Read down a couple of posts, excellent info!

 

Did you use Herms kit?

I had / have the same problem but we made a work around ........ you most likly dont want to know. R)

Is it taking 2 or 3 pumps to get the brakes up to pressure and if you let all the way off the pedal you lose pressure ? But if you hold the pedal a little bit down its fine? Just like you have air in the lines that is impossible to get out no matter what you do , including ,regular 2 man bleeding 25 times, canister bleeding,pressure bleeding , vacuum bleeding , gravity bleeding , isolating parts of the brake system then bleeding , standing the jeep on end and bleeding , lifting one side and bleeding ,rebending the brake lines to guaranty that there will be no where for the air to hide and bleeding , removing the MC resdial valves ,replacing resdsial valves, adjusting the rear brakes tight, towing the jeep 40 miles away to a friends shop and let him play with it for a few days and re bench bleed several times . you get the idea . but none of that fixes it.

If so you have the same issue I had.

 

I think the master cylinder is junk even though I changed it last year. I pretty sure I had the rear brake lines going to the front resivoir and the front lines going to the rear cylinder closest to the fire wall. The MC actually has front and rear labled on the housing. Well before I sat in front of the computer I switched the lines and low and behold I have good pressure, and at this point I think the front lines are going to the rear and the rear lines going to the front. When we were bleeding the brakes yesterday I notices that the front (for rear brakes) resivoir was squirting brake fluid out while the rear (for front brakes) wasn't squirting much at all, just moving the level up and down a little. Is this the way it should be or should they both be squirting the same amount?



Also I got most of the parts from Oreilly's, new hubs from Krage, wheel studs from Napa, and the caliper brackets from a junkyard. All said and done under $300 I think btu I might need to add a new MC to the total. Oh well to be able to stop on an incline is well worth it.

 

When I did my brakes, I changed the MC as well. I could not get pressure or flow period, until I pulled the MC put it on the bench and pulled fuild threw it with the hand vac pump. I made sure not to pull the res dry. I put the MC back into the jeep, re-attached the line's like mentioned, filled the res, and pulled the fuild through the line's. I started with the right rear, left rear, front right.

 

Very important step is to bench bleed a new MC as stated above. My new MC took about 1 hour to bench bleed until there were no more bubbles.

 

Never did bench bleed the new master cylinder, so we'll give it a try. Also I initially did have the correct lines going to the correct resivoirs at first when I wasn't getting any pressure. So I'm thinking this might fix it or I a new MC will actually make the jeep street safe. I'm also thinking changing it to power steering, but one project at a time, then again I mention this for opinions and help.

 

Yep that most likly is your problem.

 

I'm gonna try a new MC today, we'll see what happens.

 

Finnally worked out the pressure problem. I had to get another MC which was set up for disc in front and drums in rear. I believe it came from and late 70's or early 80's jeep. Had to reroute the brake lines to the other side but that was no big deal. I'd like to thank everyone who helped out and if anyone reads this and is planning to do a brake conversion, I'd like to recommend the following.
I ended up getting new hubs from Krage (this was mentioned in the article) as my hubs where probably from the original jeep and quite possibly not ever taken out. Second the wheel studs I ended up using were for a 76-77 cj, same as the new rotors, at least that is what the Napa guy said. Caliper mounts were hard to find but enough persistance through a junk yard prooved good. Last, this wasn't mentioned in the article, but I was told your master cylinder had to be set up for front disc and rear drum. I didn't get a good result until I had this set up and Inline Tube would be a good place to get a proprtioning valve if one is needed.

 

im looking to do the disk break conversion on my dana 27 axel... what artical are you talking about with the info you used??

 

This would be one article on our board.
http://www.earlycj5.com/technical/brakes/early-cj-disk-brake-swap/
If you go to JP magazine there is another article there also heres the link.
http://www.jpmagazine.com/techartic...4_early_jeep_disk_brake_conversion/index.html