Stripped rear drum brakes

[conrad_the_mj]

While bleeding the brakes today, I stripped out the threads on the rear drum breaks that the bleeder valves go into. So it’s not the actual little valves you unscrew, but it’s the threads on the drum brake. What’s my best option? I’m thinking just steal a whole new assembly off an xj at the junk yard, although I would love to upgrade to disc brakes in the back. Has anyone done a disc brake swap? Is it worth it? And has anyone some a drum brake assembly swap, anything I need to be careful about?

[Dzimm]

All you need is a brake cylinder.  They are really cheap and available at any auto parts store.

[Eagle]

https://www.autozone.com/brakes-and-traction-control/wheel-cylinder-rear?filterByKeyWord=rear+wheel+cylinder&fromString=search&isIgnoreVehicle=false

 

When you get a new one, take out the bleeder screw and put anti-seize on the threads.

 

[mjeff87]

Depending on condition, I would start soaking down the flare nut on the end of the brake line that goes into the wheel cylinder now with your penetrant of choice.  They like to rust-weld themselves into a single piece.  Use a good quality flare nut wrench to loosen them also.

[gogmorgo]

You can grab disc brakes off a ZJ. There should be threads in the DIY index. 
Quickest, easiest, and cheapest would be changing the brake cylinder. They don’t cost enough to make it worth getting a used one.

And like Jeff said, be careful with the flare nut on the brake line. Get some penetrating oil on it as soon as you can, reapply a few times. Once you get a tool onto the flare nut pay close attention to the line itself. If you’re twisting it at all, stop. Get a little heat onto the nut and try again – no need for red hot, even a small butane torch will help.

Once you’ve got the new one bled, there’s no need to mash the bleeder in. You just need it to not leak.

[Pete M]

yeah, if this were me I'd use this as the perfect excuse for an upgrade.  

[conrad_the_mj]

Thanks for the advice! I’m just gonna pick up that wheel cylinder from autozone this next week and start soaking the flare nuts on the hardline today. 

[Eagle]

Just remember that the wheel cylinders are specific to one side.

 

For the cost, I'd recommend buying both and replacing them.

 

[Pete M]

that's a good idea.     I would also do both.  good insurance against 30 year old parts.    maybe even replace the soft lines too since I would have to bleed everything anyway.  oh, and be sure to inspect the condition of the hardlines up above the fuel tank where they like to go bad.

 

don't forget that MJs have a specific brake bleeding procedure.

[BeatCJ]

On 5/17/2020 at 4:53 PM, Pete M said:

Don't forget that MJs have a specific brake bleeding procedure.

Say what?

 

Where do you find the process? Does that go for a late model booster swap, too?

[Pete M]

it applies to any vehicle with a rear prop valve.   I think it's in the link in my sig.

[gogmorgo]

It comes down to simulating a front brake failure by loosening one of the front bleeders while bleeding the rear, then close the front bleeder and bleed the rear again and then front. The goal is to get the rear bypass line bled. 

[Dzimm]

On 5/17/2020 at 6:20 PM, Eagle said:

Just remember that the wheel cylinders are specific to one side.

 

For the cost, I'd recommend buying both and replacing them.

 

They are the same for both sides aren't they?  They always just say the fitment is in the rear, I've never seen them as two different part numbers and have never noticed any differences in them.  

[JustEmptyEveryPocket]

Definitely different per side.

[AZJeff]

1 hour ago, Dzimm said:

They are the same for both sides aren't they?  They always just say the fitment is in the rear, I've never seen them as two different part numbers and have never noticed any differences in them.  

Usually, the right and left wheel cylinders have the bleeder location and inlet tube location inverted from one side the the other, and thus are side-specific.

[gogmorgo]

Looks like there’s a change for 1990, at least going by the part numbers on RockAuto. Before ‘90 they’ve got just one version for both d35 and d44, left and right sided, but ‘90 has the same left and rights for the d44 and a new number for the d35 that doesn’t specify sides.

[Dzimm]

7 hours ago, AZJeff said:

Usually, the right and left wheel cylinders have the bleeder location and inlet tube location inverted from one side the the other, and thus are side-specific.

For calipers yes but the wheel cylinders are symmetrical side to side, bleeder on top, brake line underneath.

[Dzimm]

7 hours ago, gogmorgo said:

Looks like there’s a change for 1990, at least going by the part numbers on RockAuto. Before ‘90 they’ve got just one version for both d35 and d44, left and right sided, but ‘90 has the same left and rights for the d44 and a new number for the d35 that doesn’t specify sides.

Ah yes I see that now as well.  I've only ever seen this style where it fits both sides. 

Could the older ones be replaced by the new style so it's universal or is the mounting entirely different as well?

[AZJeff]

2 hours ago, Dzimm said:

Ah yes I see that now as well.  I've only ever seen this style where it fits both sides. 

Could the older ones be replaced by the new style so it's universal or is the mounting entirely different as well?

If that is a standard MJ cylinder, they are universal for both sides.   It's been so long since I looked at an MJ/XJ wheel cylinder, I became confused and gave the wrong answer in my above post.   In thinking more, I answered that there were different for each side based I what I remember about FORD wheel cylinders, which, of course, doesn't help much for an Jeep owner.

 

Sorry for my bad information above.

[Dzimm]

12 minutes ago, AZJeff said:

If that is a standard MJ cylinder, they are universal for both sides.   It's been so long since I looked at an MJ/XJ wheel cylinder, I became confused and gave the wrong answer in my above post.   In thinking more, I answered that there were different for each side based I what I remember about FORD wheel cylinders, which, of course, doesn't help much for an Jeep owner.

 

Sorry for my bad information above.

From the ones I'm seeing and as Gogmorgo pointed out, prior to 1990, they were different per side, the inlet for the brake line was offset to one side rather than over/under.  After 1990 they are universal like the picture I posted.  1990 is the oldest I've done which is why I was confused.  Just one of those other subtle year difference things on these Jeeps that we don't all know about.  My bad causing the confusion on it but definitely a good thing to learn!

 

As for the OP, being that he has an 89, it would be different per side as you guys said.

[gogmorgo]

It’s hard to say whether the new style would be interchangeable or not without having both styles in my hand. My initial guess from looking at the pictures is the newer ones would bolt directly on and work fine with the brake assembly, but I’m not convinced the brake line would come in at the same angle between the two, and there may not be enough give in the line to allow for that. There is however a difference in the bore diameters of the cylinder. The older style is 7/8”, and the newer is 3/4”. This would mean given the same amount of pressure in the line, the newer style wheel cylinders would only give you roughly 73% as much brake force.

[conrad_the_mj]

I got the old style ones delivered today, and got them on. It worked great! The newer “universal style” would not work on these older ones. It’s angled on the old ones so the newer, flat ones wouldn’t fit right. Plus you’d have to plug up the other hole.

On 5/19/2020 at 6:59 PM, gogmorgo said:

It’s hard to say whether the new style would be interchangeable or not without having both styles in my hand. My initial guess from looking at the pictures is the newer ones would bolt directly on and work fine with the brake assembly, but I’m not convinced the brake line would come in at the same angle between the two, and there may not be enough give in the line to allow for that. There is however a difference in the bore diameters of the cylinder. The older style is 7/8”, and the newer is 3/4”. This would mean given the same amount of pressure in the line, the newer style wheel cylinders would only give you roughly 73% as much brake force.

 

[Eagle]

Here's a link to the procedure for bleeding the rear brakes if you have the height-sensing proportioning valve:

 

 

I have never disconnected the proportioning valve connecting rod. It's easy to do, though, so why not do it right?