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Drum Brakes - Help!

Posted: Sun Jul 03, 2011 3:54 pm
by del_TJ
So I think I just did something stupid. I was trying to figure out why my emergency brake wasn't holding the jeep anymore and whether the rear brakes were working properly. While the drum was off, I had someone step on the pedal to see if the brakes expand under pressure. The left piston in the cylinder pushed out and I started leaking brake fluid - so yes, they work :lol:

I was able to partially disassemble the brakes and then carefully put the piston back in place after cleaning it - Here's a picture of it. Will it leak if I put it back together and run it as is? Do I need to replace the cylinder? I'm kind of new to this, so tell me what to do!
P1000297.jpg

Re: Drum Brakes - Help!

Posted: Sun Jul 03, 2011 4:18 pm
by beaker
If the seal is still in good shape, it should be ok to run it. Most importantly, did any dirt or crud get into the cylinder behind the piston?? Secondly, you will have to bleed that cylinder to get any air out.

Re: Drum Brakes - Help!

Posted: Sun Jul 03, 2011 4:20 pm
by del_TJ
How do I tell if the seal is okay? There was a little rubber piece behind the piston that was loose. Is that the seal? I don't think any crud got in there though.

Re: Drum Brakes - Help!

Posted: Sun Jul 03, 2011 5:19 pm
by 88jeepxj
The seal the the part of the cylinder that the piston touches. It is probably okay but as he said you're going to have to bleed it. This is where it could go south. The bleeders gut rusted in the cylinder and snap when you try to unscrew them leaving you having to replace it anyway. So try to loosen the bleeders on both sides and if they come out you should be ok, but dont worry they are cheap.

Re: Drum Brakes - Help!

Posted: Sun Jul 03, 2011 5:34 pm
by del_TJ
Well, it's all back together and with the drum on there's no leak when I pump the brakes. It's on a Dana44 Lou built for me a few years ago and he swapped over my old drum brakes at the time. I looked and the bleeder screws look like they're in good shape. I'll bleed it tomorrow and hope for the best.

Re: Drum Brakes - Help!

Posted: Sun Jul 03, 2011 5:39 pm
by DDewar53
As has been said - bleeding usually where this takes a bad turn, because the bleeder screws almost always seize in the cylinder. I've had success un-seizing by using a combination of methods. First is to apply heat to the cylinder around the screw. Not a whole lot, you don't want it glowing or anything like that. A propane torch should get it hot enough (you may want to disassemble the cylinder and remove all rubber parts). The second part of the method is to use a 6-point socket on a sliding T handle, then tap on the flat side of the T while applying rotational pressure on the bar. You don't have to whale on it, usually a few sharp raps is enough to break it free. Like I said, I've had some success on seized bleeders using this method.

If you round off the bleeder, or break it, you have 2 options, both of which involve removing the cylinder from the backing plate. Option # 1 is to replace the cylinder with a rebuilt - usually around $25 or so from your local parts store. Option # 2 is to drill out the old bleeder screw, tap new threads, and replace with an oversize bleeder. The big problem that I usually run into here is that the line running into the bleeder is also usually seized, and I usually ended up having to replace that as well.

Good luck, if you can wait until Tuesday I can swing by after work and take a look - I work up in Newton.

Re: Drum Brakes - Help!

Posted: Sun Jul 03, 2011 6:06 pm
by del_TJ
DDewar53 wrote: Good luck, if you can wait until Tuesday I can swing by after work and take a look - I work up in Newton.
Thanks for the advice and offer of help. I'll give it a try first and I'll give a shoutout if I run into trouble.

The original problem was that I was able to adjust the rear brakes so that they would grab the drum but the parking lever wouldn't hold the jeep on any incline. I adjusted the thread nut on the brake cable so 2 or 3 clicks stops it but it still didn't hold. That's when I started taking a closer look and saw the brake lever did work to expand the brakes with the drum off. There was lots of dust and dirt in there so I'm starting to think that's why it wasn't grabbing. It's gotten a good cleaning so I hope that helps.

Re: Drum Brakes - Help!

Posted: Sun Jul 03, 2011 11:41 pm
by nostaw
Drum brake wheel cylinders are dirt cheap and pretty common at parts stores... If you've already got it apart and will need to bleed it anyway see if you can just replace the whole cylinder. Just a couple bolts and the fitting for he brake line. You won't have to mess with frozen bleeder fittings either...

If you're going back to the parts store anyway you could also look at a new spring kit... Make it all shiny and new... ;)

JW

Re: Drum Brakes - Help!

Posted: Mon Jul 04, 2011 9:53 am
by DDewar53
I guess I'm still old fashioned. I still prefer to order kits (you can't get them in stores any more) online and rebuild. There's just something about paying $20 for a rebuilt, as opposed to paying $2.99 for a kit that sticks in my craw. Same for calipers, but the savings there can be more substantial. Ever price rear calipers for a Cadillac El Dorado? or a '70s Corvette?

Re: Drum Brakes - Help!

Posted: Mon Jul 04, 2011 12:27 pm
by beaker
DDewar53 wrote:I guess I'm still old fashioned. I still prefer to order kits (you can't get them in stores any more) online and rebuild. There's just something about paying $20 for a rebuilt, as opposed to paying $2.99 for a kit that sticks in my craw. Same for calipers, but the savings there can be more substantial. Ever price rear calipers for a Cadillac El Dorado? or a '70s Corvette?
Try $320 each for my other toy... and it has 6 of them!