Brake Lines

[Carl'sMJ]

On my way home today I blew out the metal break line going to the driver side rear wheel... I was able to limp it home on the parking break and that was an adventure in itself during rush hour traffic with my 5 spd.

 

Anyway, now I need to get it fixed. I had a feeling this day was coming because all the lines have seen better days and replacing them has been on my to-do list.

 

I priced getting all new lines from a local shop and they wanted $200... The brake shop wants $350-$400 to do the job. Doest this sound reasonable?

 

I'm leaning toward having the shop do the work... If I was to do the job myself how hard is it?

[Pete M]

I've redone the entire brakeline system on 2 MJs now. One with off-the-shelf straight lines with fittings already attached, and once with bulk line and a flare tool (didn't have a choice, as I was integrating in a '95 XJ booster and those fittings are different than a '90 MJ).

For a beginner, I'd recommend the pre-flared straight pieces. Flaring bulk line can be a real pain in the butt. :fs1: I'd also recommend taking the opportunity to remove the rear prop valve from the system, plug the proper port up front, and run a single line to the rear. Also, now's a good time to replace the rear flexy line (I suggest the longer 95 Dakota line) and maybe the front flexy lines too (I suggest the longer YJ lines). Inspect everything associated with the brake system and take stock of what's needed and what should be replaced simply because it's 20 years old and now's a great chance to do it. If too much of your rear brakes are toasted/rusty/bad, I'd suggest looking into alternatives rather than a ton of money on a Dana 35 (I'm assuming that's what's back there).

[Eagle]

:agree:

 

Do it yourself. The prices you're getting are probably fair in terms of hours involved, but the job isn't difficult.

 

However, I'm having trouble understanding why you had to limp home on the parking brake. The rear brakes only do about 20% to 30% of the work in an MJ -- the front brakes do most of the stopping. I've driven both an XJ and an MJ around with a blown line to the rear. The peddle feels a bit lower and spongier, but the actual stopping is virtually unaffected. If you had no brakes because you blew a line to the rear, then you already had a serious problem and didn't recognize it.

[Carl'sMJ]

I'd also recommend taking the opportunity to remove the rear prop valve from the system, plug the proper port up front, and run a single line to the rear.

 

Why remove the rear proportioning valve? Is it a flawed system or something?

 

However, I'm having trouble understanding why you had to limp home on the parking brake. The rear brakes only do about 20% to 30% of the work in an MJ -- the front brakes do most of the stopping. I've driven both an XJ and an MJ around with a blown line to the rear. The peddle feels a bit lower and spongier, but the actual stopping is virtually unaffected. If you had no brakes because you blew a line to the rear, then you already had a serious problem and didn't recognize it.

 

I thought the same thing, but the pedal lost about all pressure and pressing it wasn't stopping anything just gushing brake fluid all over my spare tire :dunno: . The truck is ready for a brake job up front, but other than that it has been fine. Isn't the system all linked so if the line blows anywhere you would lose pressure. I think it is a fairly large break in the line judging from the amount of brake fluid.

[Pete M]

I'd also recommend taking the opportunity to remove the rear prop valve from the system, plug the proper port up front, and run a single line to the rear.

 

Why remove the rear proportioning valve? Is it a flawed system or something?

 

 

Sorta. Not one of them was functional in any of my MJs. There are no replacements available and the unit itself is not serviceable. I figure if you're going to do all the work of replacing the lines, now's a great chance to bypass it. You don't have to though. But you should replace both of the lines running from front to back if you keep it. The area next to the gas tank is especially prone to rust and failure.