Brake fluid question, replacing brake lines, new advice.

VeruGE*144

VeruGE*144

Caught the Bug
Hi all recently I was able to make a trip to the off-road park and got a chance to flex out my jeep. I flexed out the rear quite a bit, but it looks like it will flex even more. Looking at this pic it looks like my brake line is almost stretched to the max
IMG_4938.jpg

I have new brake lines, I was hoping to swap them out today. I went to the auto store I have noticed there is two kinds of brake fluid. Just a regular and there is also a synthetic. Does anyone know what is in there from factory? Is it ok to add any kind of fluid for bleeding after new lines have been installed? Or should I flush my entire system. Also which one is better synthetic or regular?


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JKbrick

JKbrick

Active Member
Don't know about synthetic versus regular but I would buy enough to flush the whole system while you're at it. Just keep bleading them till you get clean fluid and then you'll know it's all been replaced. I've read not to let the reservoir get empty due to the ABS if you get air in it you'll have a problem


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VeruGE*144

VeruGE*144

Caught the Bug
These are the two I found in my local store. I really don't know which one to get as I don't want to mess anything up.
Synthetic
IMG_5025.jpg
And a regular I assume, since this one is not labeled synthetic
IMG_5026.jpg


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WJCO

WJCO

Meme King
The cap on the master cylinder will tell you what to use. Likely any dot3 fluid will be compatible. Brake systems are very sensitive, so I would just stick with approved basic dot fluid. If your fluid is still a yellow or amber color, I wouldn't flush the whole system, but that's just me.
 
VeruGE*144

VeruGE*144

Caught the Bug
WJCO said:
The cap on the master cylinder will tell you what to use. Likely any dot3 fluid will be compatible. Brake systems are very sensitive, so I would just stick with approved basic dot fluid. If your fluid is still a yellow or amber color, I wouldn't flush the whole system, but that's just me.
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Would a synthetic or nonsynthetic work? Can the two be mixed do you know?


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VeruGE*144

VeruGE*144

Caught the Bug
Destroyer said:
Like WJCO said, check the cap. I changed my fluid 2 years ago on my JKU 2013, and I used the standard DOT3 Prestone. No issues on my end.


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Click to expand...

WJCO said:
The cap on the master cylinder will tell you what to use. Likely any dot3 fluid will be compatible. Brake systems are very sensitive, so I would just stick with approved basic dot fluid. If your fluid is still a yellow or amber color, I wouldn't flush the whole system, but that's just me.
Click to expand...

Thanks guys,
Look my local pep boys carry lol. I probably overpaid but my OCD will let me sleep at night.
IMG_5027.jpg


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jtpedersen

jtpedersen

Caught the Bug
VeruGE*144 said:
...I went to the auto store I have noticed there is two kinds of brake fluid. Just a regular and there is also a synthetic. Does anyone know what is in there from factory?
Click to expand...

Your JK comes from the factory with DOT3. This is the sort of thing you're best off confirming for yourself, rather than blindly relying on 'the internet.' It's cast into the reservoir, in the owner's manual (downloaded version), and MOPAR sites. To be frank, if you're not prepared to exert the effort to pop the hood and look, you may want to reconsider doing this yourself.

VeruGE*144 said:
...Is it ok to add any kind of fluid for bleeding after new lines have been installed?
Click to expand...

Not all fluids are interchangeable. Both DOT3 and DOT4 are glycol based. You may use DOT4 in place of DOT3. You -cannot- use DOT3 in place of DOT4. One-way substitution only. DOT5 is silicon based, purple, and not used nearly as broadly. Do NOT use DOT5.

VeruGE*144 said:
...Or should I flush my entire system.
Click to expand...

Guidance will vary here depending on a number of factors. DOT3/4 fluids are hygroscopic; absorbing moisture. If it's been over two years since your last flush, I would recommend it. If you've got good fluid, there's no 'need' to replace it all neither is there anything wrong in doing so.

VeruGE*144 said:
...Also which one is better synthetic or regular?
Click to expand...

I have two friends who are brake engineers. Summarizing their comments, it's all synthetic, but building on the 'oil-based' push for synthetics, it's really just marketing when applied to brake fluid.

This is not a hard job to do, though can be a tad messy and you don't want brake fluid to get on anything. After going through this a couple times recently on my JK, I'd definitely recommend a higher quality brake line. I've been very pleased with the ones recommended, here, from Crown Performance.

Cheers
 
VeruGE*144

VeruGE*144

Caught the Bug
jtpedersen said:
Your JK comes from the factory with DOT3. This is the sort of thing you're best off confirming for yourself, rather than blindly relying on 'the internet.' It's cast into the reservoir, in the owner's manual (downloaded version), and MOPAR sites. To be frank, if you're not prepared to exert the effort to pop the hood and look, you may want to reconsider doing this yourself.



Not all fluids are interchangeable. Both DOT3 and DOT4 are glycol based. You may use DOT4 in place of DOT3. You -cannot- use DOT3 in place of DOT4. One-way substitution only. DOT5 is silicon based, purple, and not used nearly as broadly. Do NOT use DOT5.



Guidance will vary here depending on a number of factors. DOT3/4 fluids are hygroscopic; absorbing moisture. If it's been over two years since your last flush, I would recommend it. If you've got good fluid, there's no 'need' to replace it all neither is there anything wrong in doing so.



I have two friends who are brake engineers. Summarizing their comments, it's all synthetic, but building on the 'oil-based' push for synthetics, it's really just marketing when applied to brake fluid.

This is not a hard job to do, though can be a tad messy and you don't want brake fluid to get on anything. After going through this a couple times recently on my JK, I'd definitely recommend a higher quality brake line. I've been very pleased with the ones recommended, here, from Crown Performance.

Cheers
Click to expand...

Thanks for clearing this up for me. Lol I did pop my hood open and looked, as well as checked my manual. Under hood the only thing it says is DOT 3. In the Manual I get the number SAE J1703, which what I got. I still might consider flushing the whole system, but I don't think it's necessary at this point.

Also I did not skimp out on the lines.

[emoji482]


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