Recently I replaced my rear Dana 35 on my Wrangler with a Dana 44. The new axle has 10" drum brakes which are bigger than the ones on the 35. Anytime, I have to stop suddenly or on slippery surfaces, the rear brakes will lock up on me. Obviously these brakes are overkill. What I'm wondering is, since the proportioning valve is not adjustable, how do I determine which valve to replace it with, or is there some other way to fix this?
Rear brakes
- Thread starter kkemp
- Start date
- Location
- Grand Junction, CO
Are you sure that's the problem? I'd think that since both axles had drum brakes, they'd take nearly equal amounts of pressure to stop without locking the tires up. If anything, the bigger drums would be harder to stop...? I'm not sure in my thinking, but that makes sense to me. The bigger drums have more surface area, which means more pressure is needed to stop, I'd think.
Have you talked to others that have done that swap? And have they had the same problem?
If the rear brakes are indeed locking up due to too much pressure the best thing will be to replace your proportioning valve with an adjustable prop. valve. They're not too spendy & pretty easy to install.
Have you talked to others that have done that swap? And have they had the same problem?
If the rear brakes are indeed locking up due to too much pressure the best thing will be to replace your proportioning valve with an adjustable prop. valve. They're not too spendy & pretty easy to install.
Brett
Meat-Hippy
- Location
- Salt Lake City Utah
Swapped my 35 out for a XJ44 and I've never had a problem with the brakes doing that on me.....bigger brakes too. Weird.....
More then likely it's improperly bled or mal-adjusted front brakes (stuck caliper pin bind...), usually drum/disk brakes are biased to about 70/30 front to back, the front does 70% of the work to stop you, the rear start to stop, then as the weight transistions forward the front brakes do the rest. so even if you significantly added to the braking force on the rear axle, you'd have to do a lot before it'd do what you said, they may just be making a prior problem more evident.
Everyone I know seems to have a problem with the front brakes locking up way before the rear. Come to think of it, I don't know of anyone who has even gotten their rears to lock up. I would try bleeding. I would seriously doubt it being with the proportioning valve. I have removed my proportioning valve and have discs on the rear, and my front still lock up before my rear.
- Location
- Grand Junction, CO
Did you pull the drums off & look at the brake pads when you installed the 44? Many times when your rear axle is locking up under braking, one of your outer axle seals has leaked diff fluid, contaminating the brake shoes & causing the tires to lock up prematurely.
This just happened to my wifes 4Runner, replaced the seal, new shoes & it was back to normal.
This just happened to my wifes 4Runner, replaced the seal, new shoes & it was back to normal.
waynehartwig
www.jeeperman.com
- Location
- Mead, WA
I'd try bleading your brakes first. Maybe there is still some air in the lines after I did the swap? I doubt it, but you never know...
Do the fronts lock up at all? With your upgraded rotors, they should be able to.
The prop valve only works in a panic stop situation. So if you are only noticing the rear lockign up first in a panic stop, then the prop valve is wrong for your setup and an adjustable may be the cure. I have two styles that I'll make you a good deal on...
But blead the brakes again, make sure there is no air in the lines. Also, make sure the front's can lock up as well. If they can't, then you might have a bad master cylinder or stuck proportioning valve.
Do the fronts lock up at all? With your upgraded rotors, they should be able to.
The prop valve only works in a panic stop situation. So if you are only noticing the rear lockign up first in a panic stop, then the prop valve is wrong for your setup and an adjustable may be the cure. I have two styles that I'll make you a good deal on...
But blead the brakes again, make sure there is no air in the lines. Also, make sure the front's can lock up as well. If they can't, then you might have a bad master cylinder or stuck proportioning valve.
Thanks for all the great input. I try to check it out this weekend. I don't know if I'll be able to get around to bleeding the brakes right away though. I'm kinda booked, but I'll definitely get around to it soon. I don't beleive the fronts lock up. But I'll find out for sure. I'll let you know what I find out.
Not beyond just doing the auto-adjust by backing up and stopping.
I went out it and tried it out and I think this problem must be intermittent because it seemed to work exacty way you guys described. On a slight downhill, the rear brakes didn't lock up but they were squeling. On a steep downhill, stopping hard, the front brakes locked up but not the rear. Sounds like the proportioning valve is doing it's job. However, recently on that same steep hill, I could just slightly hit the brakes and rear locked right up. Almost sounds to me the front brakes are the ones having the intermittent problem. Anyway, I'm going to keep and close eye them for the next few days and try to figure out what's happening.
waynehartwig
www.jeeperman.com
- Location
- Mead, WA
Pull it apart and make sure the rears don't have anything on them - oil, brake fluid, etc. Also make sure the drums look good still and not have a crack, or etc in them. If I remember right, everything was new, right? You did all of the new hardware, pads and etc. and then I put the new drums on right?
Also make sure the secondary shoe has the e brake cable on them, is the shoe with the longest lining, and is closest to the rear of the car.
Also make sure the secondary shoe has the e brake cable on them, is the shoe with the longest lining, and is closest to the rear of the car.