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  #1  
Old December 5th, 2014, 15:15
heshhash heshhash is offline
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Brakes- booster/MC crapped out, debating swap to synthetic fluid during swap

So, my booster crapped out other day. I got an 89 cherokee with original booster and cylinder. I have already replaced everything else (hard lines, soft lines, calipers, rotors, wheel cylinders, drums, and hardware) within the last 2 years. So i have been contemplating switching to synthetic fluid now when i do the booster/cylinder. Thoughts on this?
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Old December 5th, 2014, 18:15
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8Mud 8Mud is offline
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Re: Brakes- booster/MC crapped out, debating swap to synthetic fluid during swap

I'd read the destructions very carefully for fluid compatibility. The problem may be the left over DOT 3 in the system, it is doubtful you can get it all out. And are your seals and other rubber (generic term) parts compatible with the new fluid?

I remember when DOT 4 first came out, it was supposed to be the answer for many of the issues with DOT 3. It may have been the answer, but it wasn't very long before many people discovered DOT 3 and 4 aren't compatible and shortly thereafter they came out with DOT 5. And shortly after that, many car manufacturers went back to DOT 3.

You can't always believe the claims by the manufacturer of the fluids, as far as fluid, metal, and rubber (generic term for the synthetic blends used in seals, "O" rings or whatever) compatibility is concerned. Trouble may not show up for years.

I've purged brakes line and what came out looked kind of like metallic cottage cheese. Fairly obvious somebody put the wrong fluid in there.

DOT 3 isn't perfect but it works well enough. Just make sure you use a closed container that has no possibility of having any moisture in it. And purge the old fluid out periodically with a name brand replacement. You never really know if the budget stuff is just the premium stuff relabeled (generic) or a blend by a less than reputable company.

Last edited by 8Mud; December 5th, 2014 at 18:21.
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  #3  
Old December 5th, 2014, 19:44
jworth jworth is offline
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Re: Brakes- booster/MC crapped out, debating swap to synthetic fluid during swap

It's my understanding that DOT3 and 4 are 100% compatible and synthetic doesn't change that. Now, go to silicone DOT5 and things get a little different. I realize this is at variance with what the previous poster says. Nevertheless, my 2 cents.
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Old December 5th, 2014, 19:58
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Talyn Talyn is offline
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Re: Brakes- booster/MC crapped out, debating swap to synthetic fluid during swap

Dot 3 and dot 4 are compatible. Dot 5 is silicone based and is incompatible with all others. It also shouldn't be used in a vehicle that has ABS. Even if you don't have ABS the DOT 5 fluid would require replacement of all seals and through cleaning of the brake system.

However, it is best to flush your system if switching brake fluid. As with all other fluids it brakes down over time and should be changed periodically.
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Old December 5th, 2014, 21:45
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Re: Brakes- booster/MC crapped out, debating swap to synthetic fluid during swap

Quote:
Originally Posted by jworth View Post
It's my understanding that DOT3 and 4 are 100% compatible and synthetic doesn't change that. Now, go to silicone DOT 5 and things get a little different. I realize this is at variance with what the previous poster says. Nevertheless, my 2 cents.
I may have my DOTs transposed, but when DOT 4 first came out we had compatibility issues with it, back in the mid 70's. They usually reformulate and rename it, they may have just tweaked the formula and kept the same label?

We had to flush and fill a whole fleet of trucks and tractors back then (thousands), not the kind of thing you forget. Maybe it was just a bad batch?

Like I said, read the label and buy premium stuff.

Last edited by 8Mud; December 5th, 2014 at 21:51.
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Old December 6th, 2014, 07:14
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cruiser54 cruiser54 is offline
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Re: Brakes- booster/MC crapped out, debating swap to synthetic fluid during swap

I'd be doing a wJ booster and master swap and skipping the high performance fluid altogether. My 2 cents.
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Old December 6th, 2014, 08:48
heshhash heshhash is offline
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Brakes- booster/MC crapped out, debating swap to synthetic fluid during swap

Well, guess i will skip that and stick with what works. Thanks for the input. Stock it is¡
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Old December 6th, 2014, 08:57
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cruiser54 cruiser54 is offline
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Re: Brakes- booster/MC crapped out, debating swap to synthetic fluid during swap

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Originally Posted by heshhash View Post
Well, guess i will skip that and stick with what works. Thanks for the input. Stock it isí
The wJ booster swap is incredible......
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