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Anyone upgraded to DOT 5 brake fluid?

SyCo

NAXJA Forum User
Location
Spokane, WA
Planning on an all around brake upgrade soon, including ZJ discs on the rear and a ZJ proportioning valve. My question is as the subject states, has anyone evacuated the brake hydraulic system and refilled it with DOT 5? Was it worth it? Any differences? How was it done?

I know it's not supposed to be used in ABS, which is fine because I don't have it. Thanks in advance.
 
Re: Anyone upgrading to DOT 5 brake fluid?

I wouldn't do it. I would just go to super dot 4. To convert to Dot 5 I think you need all new rubber parts. plus the benefits aren't that great for it. Plus Dot 4 and Dot 3 can be mixed but Dot 5 can not. If you need fluid bad at a gas station good luck finding DOT 5
 
You definitely do not want to go to DOT 5. Besides having to completely flush your complete brake system of it's current fluid so no coagulation occurs and replacing any rubber seals and such , there really is no advantage you'll notice with your Cherokee. Stay with DOT 4 and replace your brake fluid every 2 years to keep it from getting too wet and you'll be fine.
 
Interesting, thanks for the replies guys. I think I'll drain the fluid from the MC with a turkey baster, fill with DOT 4, then bleed all lines until DOT 4 is flowing clear, sound good?
 
The previous replies are indeed interesting, but they are erroneous. I've been running DOT 5 silicone brake fluid in all my vehicles for more than 20 years. I haven't replaced any rubber seals, and I see no evidence of seal deterioration. DOT 5 silicone is compatible with DOT 3 and DOT 4 fluids, but if you mix them you lose the advantages of the DOT 5 silicone: higher boiling point, and it is non-hygroscopic.

You install it just as you should any time you install new brake fluid. Suck as much of the old stuff out of the master cylinder as possible, then fill with the new stuff and bleed until you see blue fluid come out the bleeder.
 
i run it to and i didnt really notice a diff...until i went down the mountain..its a 5% grade over 3 miles...my xj on 33's would be all over the road when i stepped on the brakes....changed the fluid and now not only can i stop on a dime but that wicked down hill dosnt make my butt pucker when i try and slow down. i run it in everything....i used a vaccum tool to draw out all the old fluid (mainly dirt) and flushed the system with dot 5...
 
That is interesting. Being a Mechanic I was told over and over that they shall never mix. I was just passing that info on. I still would use Dot 4 for the availability alone..
 
Something interesting to read about dot 5 on the AAA site

OH Beez, I think you got it wrong: dot 5 causes wobble.
wobble.jpg
 
Eagle said:
The previous replies are indeed interesting, but they are erroneous.
Eagle said:
Erroneous? Nice! :thumbup:

But Unless something has changed, DOT 5 has never, and will never be able to be used on a DOT 3 or 4 system without some extensive work. They can be mixed but need workto be switched just for the heck of it. DOT 5 brake fluid does have a higher boiling point yes, but besides that, there are very little positive reasons to use it. On a DOT 3 or 4 system, if rubber seals wear or detieriorate (sp?) the fluid is absorbed into the rubber, which causes it to expand. Preventing leaks. DOT 5 DOES NOT have that characteristic. They are more prone to air leaks and such.

To switch a system PROPERLY, you have to rebuild/replace you MC, and ALL Seals in the system. That includes wheel cylinders if applicable or piston seals.

Unless you are doing some SERIOUS racing, this is a totally unneccessary "upgrade". Maybe GRANT will chime in and enlighten us with what fluid they run.

Like I said, unles something groundbreaking has RECENTLY come out, DOT 5 IS NOT interchangable with DOT3 or 4. This is kinda the jist of it, most is on the DOT!:)

If I am misimformed, I will stand corrected. Until then, SPOBI! ( I always wanted to use that)

Matt


good article by the way!
 
Last edited:
Culinary_Hooligan said:
http://www.xs11.com/tips/maintenance/maint1.shtml


This should clear up some mis-information...
and no, slilicone (dot 5) should never be mixed with glycol based (dot 3-4)

One of the reasons I never changed over was because of that page. I was about ready to do it on my 81 XS11LH, which is also featured on that site, to eliminate the sweating of the dot3/4 that kept removing the paint on my handlebar brake cylinder and cover. I was almost going to do it after our unit changed all it's M-151 1/4 tons and blazers over to DOT-5 on my S-10, later my Trooper and then the XJ. Luckily I never got a satisfactory answer on how to prepare or flush the system to remove all the old DOT3/4 and add the DOT5. Basically the fear of it being a 'one way' change with no ability to 'back it out' w/o rebuilding the entire system was also a show stopper.
 
Scrappy said:
But Unless something has changed, DOT 5 has never, and will never be able to be used on a DOT 3 or 4 system without some extensive work. They can be mixed but need workto be switched just for the heck of it. DOT 5 brake fluid does have a higher boiling point yes, but besides that, there are very little positive reasons to use it. On a DOT 3 or 4 system, if rubber seals wear or detieriorate (sp?) the fluid is absorbed into the rubber, which causes it to expand. Preventing leaks. DOT 5 DOES NOT have that characteristic. They are more prone to air leaks and such.

The primary reason I use it is the non-hygroscopic nature of silicone fluids. DOT 3 and DOT 4 brake fluids attract moisture. If you don't flush the stuff out of the system regularly, wheel cylinders and caliper bores pit, and the steel lines rust out from the inside. With silicone, you just don't have that problem.

Scrappy said:
To switch a system PROPERLY, you have to rebuild/replace you MC, and ALL Seals in the system. That includes wheel cylinders if applicable or piston seals.

Please cite your source for this information, because as I said, I've been running it in my vehicles for over 20 years. I have never replaced a master cylinder, wheel cylinder, or caliper to make the conversion, and I have never experienced a problem.

Scrappy said:
Unless you are doing some SERIOUS racing, this is a totally unneccessary "upgrade".

Most upgrades are unnecessary. That doesn't mean they aren't upgrades. I'm so satisfied with silicone DOT 5 in my brakes that when I replaced the clutch in my '88 XJ I converted that to silicone, too. That was three years ago and I haven't seen any problems yet.

Scrappy said:
Like I said, unles something groundbreaking has RECENTLY come out, DOT 5 IS NOT interchangable with DOT3 or 4.

It doesn't require anything new or groundbreaking. 20+ years of experience is worth more to me than some magazine article. Just at a rough count, I've used the stuff in probably half a dozen vehicles, including a competition autocross/hill climb sedan, and the total mileage has to be over half a million miles. The '88 XJ alone is now at 243,000 and I converted it for the first full winter, so it was probably at about 15,000 then. You can say it isn't interchangable, but the container sitting in my garage says it is, and my experience hasn't shown me any problems.
 
Did any of you READ that article, rathert than looking at it and seeing what you thought proved your point(s)?

1. He did NOT say that silicone attacks the seals in brake systems. He said that silicone is not compatible with some outer caliper dust boots. Big difference. If the system doesn't leak, the fluid will never get to the dust boots.

2. He did not say that silicone and glycol fluids could not coexist in the same system. He said they won't MIX -- the silicone will remain in one part of the system and the glycol in another part. The system will continue to function.

3. It isn't the combination of silicone and glycol that creates "goop" in the system. It's the combination of silicone with sludge from the old glycol that creates goop. The sludge isn't good under any circumstances, and that's part of the reason a brake system should be flushed out periodically.

After reading the article, the only caveat I see is to flush the system when converting, and if you bleed each wheel until you see clean blue juice coming out, you will have done that.
 
Eagle said:
Did any of you READ that article, rathert than looking at it and seeing what you thought proved your point(s)?

1. He did NOT say that silicone attacks the seals in brake systems. He said that silicone is not compatible with some outer caliper dust boots. Big difference. If the system doesn't leak, the fluid will never get to the dust boots.

2. He did not say that silicone and glycol fluids could not coexist in the same system. He said they won't MIX -- the silicone will remain in one part of the system and the glycol in another part. The system will continue to function.

3. It isn't the combination of silicone and glycol that creates "goop" in the system. It's the combination of silicone with sludge from the old glycol that creates goop. The sludge isn't good under any circumstances, and that's part of the reason a brake system should be flushed out periodically.

After reading the article, the only caveat I see is to flush the system when converting, and if you bleed each wheel until you see clean blue juice coming out, you will have done that.


you totally skirted around the whole DW thing.....

wimp.
 
I've seen it done, we spent several weekends shuttling 1/4 tons between our armoury and bordentown nj where they, full time support people, did the conversion, took about 30 min or so for each vechicle. No major difference, no major improvment just that tantalizing 'won't soak up moisture' thing.
Basically they had us drive up on very high ramps, stuck hoses on all the bleeders and sucked the old fluid out, put some kind of cleaner in and sucked that out too, then poured the blue stuff in, then we drove off and headed back for the next round. I think the main reason the guard changed was that the normal vehicles sit for weeks at a time and rust and corrosion is a big issue as all the vehicles are stored outside.
On the bike I was leery of the change because of it's unique braking system. That model and that year had a unified braking system that tied the rear disk and one front disc to the foot pedal master cylinder, the handlebar brake only controlled on front disc. Did not want to mess with it or mess it up because the rebuild kit for it was very expensive.
 
As of this moment i am unable to get my sources out. But unless my memory serves me wrong, which it does now and then, that is the case. I am in the process of unpacking from a recent move. I wont be getting to my books for a few weeks, with the lack of time i have.

for future searches and a solid answer... is there a concensus for a answer?

Matt
 
Eagle said:
After reading the article, the only caveat I see is to flush the system when converting, and if you bleed each wheel until you see clean blue juice coming out, you will have done that.

I have to agree with your reasoning. I had always been told not to change to DOT 5 without a complete rebuild. The misconception that mixing was a 'no-no'. I think most problems come from incomplete flushing, which leaves a lot of the DOT 3 and crud in the system or the use of a petroleum solvent flush, which destroys the rubber seals.
You have evidently sufficiently flushed the whole braking systems clean when changing over to DOT 5. Real world experience is a good thing. Unfortunately, you have to get old to get it<G>

I use Ford's HD DOT 3 (it has a higher boiling point than standard DOT 3). Flushing every two years is easy using a power vacuum bleeder. In the past a Mighty-Vac hand pump was used for bleeding, now it has been replaced with a 1 qt. jar and a vacuum pump made from an old drinking fountain compressor. It takes less than two hours to do all four vehicles.

DOT 5 should stay much cleaner unless the seals leak. It still should be flushed occasionally to get rid of any water that has entered. Since water does not mix with silicone, it settles in a low spot, where it sits and rust. In a perfect world, DOT 5 vehicles would have calipers and wheel cylinders with bleeders on the bottom for draining off accumulated moisture
 
Re: Valvoline Syn Compat with Dot 3 & 4

I use the Valvoline Synthetic which states that its compatible with 3 & 4 (I drained and replaced it all) and I use it because the boiling point is over 500 while Dot 3 & 4 are in the 250 range. Available almost everywhere.
 
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