Dot5 or DOT 3/4/5.1

[Phil P]

Hello All

I have one of the Kaiser / Jeep M35

When we got this truck, it had DOT5 brake fluid.

So, I have been using DOT5 fluid.

I [purchased a new master cylinder and wheel cylinder from one of the surplus companies.

The master cylinder cups have swollen up where it is stuck down. The wheel cylinder has all but lock the wheel.

Now Memphis tells me that there is no difference in the parts from DOT5 to DOT3 and they have had customers change from both DOT3 to DOT5 and from DOT5 to DOT3withput any problems.

So, I got a wheel cylinder kit and soaked the cups in DOT5 fluid and the swelled up almost double in sizes.

Memphis tells me the truck was originally built with DOT3 brake system and when they military changed, they just drained DOT3 out and filled with DOT5.

As you can see, I need some input!!!

 

[98G]

To my knowledge and experience, DOT5 is the fluid to use.

 

[m715mike]

My understanding is that DOT 3 fluid can attract/trap moisture causing corrosion on the inside of the hard break lines hence a preference for DOT 5 fluid.

 

[98G]

My understanding is that DOT 3 fluid can attract/trap moisture causing corrosion on the inside of the hard break lines hence a preference for DOT 5 fluid.

And DOT5 tolerates higher temps.

For most applications DOT3 is OK, if it's the only thing in the system. It's important to thoroughly flush the system when going between dot3 and dot5 as they are incompatible with each other.

You see a lot of people switch their trucks to DOT3 in the name of cost savings. You also see people who dont know what's in it bleed with DOT3.

DOT 5.1 is a different animal entirely .

 

[Elijah95]

To my knowledge, dot 5 exaggerates wheel cylinder failure. Dot 3/4/5.1 all absorb water and hold it in suspension, but Dot 5 rejects it and allows it to settle in the lowest point (wheel cylinders). Then it sits there until it ruins the cylinder and brake failure occurs. This is an issue because no matter how much you bleed you cannot get 100% of the water out with Dot5 due to small amounts becoming trapped. Furthermore, most folks want to save money and rarely ever flush Dot5 preventatively because of inherent cost and lack of availability.

Dot 4 will absorb the water and move it on through, spend $10 for a quart of dot 4 and flush that quart through once a year and you’re insuring whatever moisture has been absorbed is removed. It’s important to flush thoroughly through when converting either way, they don’t mix.


IMO Dot 4 is the most affordable and readily available to use, while being pretty safe as most of us aren’t going to load our trucks to the limit and exercise them as designed. Dot 3 is a waste of time, not enough safety net with boiling point. Your mileage may vary

If you want to know what you have, take a dropper and suck some up, or open a bleeder and catch some in a bottle, add water and shake it. If it absorbs and becomes cloudy, it’s 3/4/5.1, if the water drops down to the bottom and brake fluid stays the same, it’s Dot 5


Sent from my iPhone using Tapatalk

 

[Elijah95]

Sent from my iPhone using Tapatalk

 

[frank8003]

read this

Brake Fluid Flush

Beyond which DOT number brake fluid you use, how often do you flush the brake system and renew it? I’ve looked to see if any of the TM’s have fluid replacement schedules for the brake fluid (DOT 3 or DOT 5) and have yet to find any. Nor is it discussed (that I can find with my admittedly...

www.steelsoldiers.com

DOT 3, DOT 4, and DOT 5

What are those things in the title? Brake fluid is categorized as one of those three ratings. Most brake fluid that comes in a new car will be rated DOT 3. A few will Use DOT 4, and very few wil…

jimsgarage.wordpress.com

and many don't see them because they are NOT TM's they are TB's

Anywho, there is supposed to be sticker on the MC in the trucks, they had a little sticker saying to use only silicone brake fluid.

and for the others that need more data....

 

[Mullaney]

Hello All

I have one of the Kaiser / Jeep M35

When we got this truck, it had DOT5 brake fluid.

So, I have been using DOT5 fluid.

I [purchased a new master cylinder and wheel cylinder from one of the surplus companies.

The master cylinder cups have swollen up where it is stuck down. The wheel cylinder has all but lock the wheel.

Now Memphis tells me that there is no difference in the parts from DOT5 to DOT3 and they have had customers change from both DOT3 to DOT5 and from DOT5 to DOT3withput any problems.

So, I got a wheel cylinder kit and soaked the cups in DOT5 fluid and the swelled up almost double in sizes.

Memphis tells me the truck was originally built with DOT3 brake system and when they military changed, they just drained DOT3 out and filled with DOT5.

As you can see, I need some input!!!

.
Logic says: Yes, DOT 3 was in the truck when it rolled off the assembly line. Many mentions above my post about not mixing brake fluids. Everybody has an opinion, but the DOT 5 shouldn't hurt anything - and it has better temperature characteristics and helps stop rust from forming in the wheel and master cylinders. It won't make existing rust disappear though...

I have ordered hundreds of the rubber cups that go into wheel cylinders. Never seen any cups that are specific to Dot 3, Dot 4, or Dot 5. Little more information below about the fluid differences.

 

[98G]

.
Logic says: Yes, DOT 3 was in the truck when it rolled off the assembly line. Many mentions above my post about not mixing brake fluids. Everybody has an opinion, but the DOT 5 shouldn't hurt anything - and it has better temperature characteristics and helps stop rust from forming in the wheel and master cylinders. It won't make existing rust disappear though...

I have ordered hundreds of the rubber cups that go into wheel cylinders. Never seen any cups that are specific to Dot 3, Dot 4, or Dot 5. Little more information below about the fluid differences.

View attachment 843862

A note on color - new DOT5 is purple, but it turns yellow after a while. This is useful for determining when you've flushed all the way through with new fluid.

 

[HDN]

I plan on running DOT5 in all my trucks. My dad runs DOT5 in all his trucks, though he's considering switching to DOT3 with his halftrack out of fear of messing up the motor with silicone brake fluid if the hydrovac malfunctions. Apparently that's not as big an issue with DOT3.

 

[MarkM]

Dot 5.1 is pricey and made for high performance brake applications. I use it in a car of mine with AP-Racing 4pot calipers. I would recommend DOT 4 for most uses and as already stated DOT 5 is great stuff but can settle water to the lowest point and rust out lines and is $$$. If you do change from DOT 5 to a mineral based fluid just make sure you flush ALL the old fluid out with fresh new fluid. I need to do this for my M101A2 before the winter.

Mark

 

[Tow4]

Having experienced the DOT5 water in the wheel cylinders myself, I switched to DOT3. I don't care how often you flush a brake system filled with DOT5, you will never get the water out because the bleeder is at the top of the wheel cylinder and the water is at the bottom. If you flush a system filled with DOT3, the moisture is suspended in the fluid and you will see the discolored, contaminated fluid come out. When the fluid comes out clear, the contaminates have been removed.

As to the boiling point of DOT3, I drove my Deuce in stop and go traffic and on the highway quite a bit. I checked the hubs and brake drums every time I was at a destination, fuel stop, etc. I don't remember the brake drums ever being too hot to hold my hand on. The only time the hubs were too hot was when I changed the seals. That only lasted until they wore in.

The bottom line is you need to service the brakes on a regular basis. I much prefer flushing the DOT3 once a year to changing all the wheel cylinders after one fails suddenly while you are trying to stop.

 

[glcaines]

I use DOT5 in all of my vehicles. Never had an issue in any vehicle in the past ~20 or so years. I bought DOT5 in bulk on Ebay many years ago for a cheap price.

 

[HDN]

What are people doing that causes water the infiltrate the brake system? I can see frequent off-roading being one thing, but for mostly paved driving I imagine infiltration would be pretty low. That's not to say the truck's previous owner might've done some fording, though. I think some trucks are at a higher risk than others based on usage.

 

[Elijah95]

What are people doing that causes water the infiltrate the brake system? I can see frequent off-roading being one thing, but for mostly paved driving I imagine infiltration would be pretty low. That's not to say the truck's previous owner might've done some fording, though. I think some trucks are at a higher risk than others based on usage.

No system is completely air tight, and humidity is one of the most common infiltration methods.


Sent from my iPhone using Tapatalk

 

[m1010plowboy]

Our wrench twisting Mattech found some compromised rubber in a NOS rebuilt M135 brake system with DOT 5. It all comes down to the question......

What type of Rubber is not compatible with DOT 5 brake fluid?

Here's some previous valuable info https://www.steelsoldiers.com/threads/dot-5-seals.51445/


"""""""DOT 5 is a silicone fluid. The types of rubber NOT recommended for use with silicone fluids are silicone rubber and fluorosilicone rubber""""""


Now if we have some of that silicone or fluorosilicone rubbers in your wallet /brake system then swapping to DOT 5 would be bad.

https://www.canadarubbergroup.com/en-ca/blog/fluorosilicone-rubber

Since this fluoro mess us up silicone rubber was developed by DOW in the 50's.....it lends some logic that it's out there.

FVMQ

Fluorosilicone rubber (FVMQ) offers good weathering resistance, ozone resistance and thermal stability

www.rado-rubber.com

""""""" It is used to manufacture parts such as O-rings, seals, hose liners (e.g. in turbocharger hoses) and automotive diaphragms, primarily for fuel systems at temperatures of up to 250°C. Other applications include natural gas installations, natural gas production equipment and aerospace engineering. Since fluorosilicone compounds have a high shrinkage rate, products made from this material are often produced in different ways from those made from other elastomers. """"""""""

Fluorosilicones - an overview | ScienceDirect Topics

www.sciencedirect.com

One then must ask if DOT 3 is hard on rubber and that hunt is a little less straight forward.

Brake fluid dissolve rubber

www.saabcentral.com

""""""DOT3 is an aliphatic polyether.
DOT4 is borate ester based. Both of these fluids are designed for use in braking systems fitted with rubber cups and seals made from styrene-butadiene rubber (SBR), or a terpolymer of ethylene, propylene, and a diene (EPDM).""""""""

What rubber is compatible with brake fluid? | ContextResponse.com

Standard brake fluid compatible material is EPDM rubber (just like a radiator or heater hose). This is also a water-compatible materialbut doesn't like petroleum oils. Most petroleum-contacted o-rings are Buna-N or nitrile rubber.

everythingwhat.com

"""""""""Standard brake fluid compatible material is EPDM rubber (just like a radiator or heater hose). This is also a water-compatible materialbut doesn't like petroleum oils. Most petroleum-contacted o-rings are Buna-N or nitrile rubber.
Click to see full answer.

"""""""""Similarly, it is asked, is brake fluid good for rubber?
All polyethylene glycol-based fluids will not harm healthy rubber parts. If the brake fluid becomes unable to control the pH or other corrosive elements, the rubber and metal parts will deteriorate over time. If you have an older vehicle and are worried about boiling the fluid, use DOT 4 or 5.1 brake fluid.
Also Know, is nitrile resistant to brake fluid? Nitrile or Buna-N O-rings produce general purpose seals that are tear-resistant and can withstand abrasive treatment. Nitrile O-rings are not advisable for use with automotive brake fluid, ketones, phosphate ester hydraulic fluids, and nitro and halogenated hydrocarbons.
Likewise, people ask, what hose is compatible with brake fluid?
Their cloth braided fuel hose is compatible with brake fluids. I use two sizes, 5mm and 7mm, and both are fine.
Are all DOT 3 brake fluids compatible?
All DOT 3, 4 and 5.1 brake fluids are compatible with each other and with all systems. All polyethylene glycol-based fluids will not harm healthy rubber parts. Also, the additive packages will not damage or distort any rubber parts."""""""""""

What we know is DOT 5 has chewed up or rather, melted rubber, in some of the older brake rubbers. We know DOT 5 has settled water in low lines or wheel cylinders. We had one DOT 5 line freeze and split open.....but we're up in Canada so eventually everything freezes and splits open.

 

[Mullaney]

Our wrench twisting Mattech found some compromised rubber in a NOS rebuilt M135 brake system with DOT 5. It all comes down to the question......

What type of Rubber is not compatible with DOT 5 brake fluid?

Here's some previous valuable info https://www.steelsoldiers.com/threads/dot-5-seals.51445/


"""""""DOT 5 is a silicone fluid. The types of rubber NOT recommended for use with silicone fluids are silicone rubber and fluorosilicone rubber""""""


Now if we have some of that silicone or fluorosilicone rubbers in your wallet /brake system then swapping to DOT 5 would be bad.

https://www.canadarubbergroup.com/en-ca/blog/fluorosilicone-rubber

Since this fluoro mess us up silicone rubber was developed by DOW in the 50's.....it lends some logic that it's out there.

FVMQ

Fluorosilicone rubber (FVMQ) offers good weathering resistance, ozone resistance and thermal stability

www.rado-rubber.com

""""""" It is used to manufacture parts such as O-rings, seals, hose liners (e.g. in turbocharger hoses) and automotive diaphragms, primarily for fuel systems at temperatures of up to 250°C. Other applications include natural gas installations, natural gas production equipment and aerospace engineering. Since fluorosilicone compounds have a high shrinkage rate, products made from this material are often produced in different ways from those made from other elastomers. """"""""""

Fluorosilicones - an overview | ScienceDirect Topics

www.sciencedirect.com

One then must ask if DOT 3 is hard on rubber and that hunt is a little less straight forward.

Brake fluid dissolve rubber

www.saabcentral.com

""""""DOT3 is an aliphatic polyether.
DOT4 is borate ester based. Both of these fluids are designed for use in braking systems fitted with rubber cups and seals made from styrene-butadiene rubber (SBR), or a terpolymer of ethylene, propylene, and a diene (EPDM).""""""""

What rubber is compatible with brake fluid? | ContextResponse.com

Standard brake fluid compatible material is EPDM rubber (just like a radiator or heater hose). This is also a water-compatible materialbut doesn't like petroleum oils. Most petroleum-contacted o-rings are Buna-N or nitrile rubber.

everythingwhat.com

"""""""""Standard brake fluid compatible material is EPDM rubber (just like a radiator or heater hose). This is also a water-compatible materialbut doesn't like petroleum oils. Most petroleum-contacted o-rings are Buna-N or nitrile rubber.
Click to see full answer.

"""""""""Similarly, it is asked, is brake fluid good for rubber?
All polyethylene glycol-based fluids will not harm healthy rubber parts. If the brake fluid becomes unable to control the pH or other corrosive elements, the rubber and metal parts will deteriorate over time. If you have an older vehicle and are worried about boiling the fluid, use DOT 4 or 5.1 brake fluid.
Also Know, is nitrile resistant to brake fluid? Nitrile or Buna-N O-rings produce general purpose seals that are tear-resistant and can withstand abrasive treatment. Nitrile O-rings are not advisable for use with automotive brake fluid, ketones, phosphate ester hydraulic fluids, and nitro and halogenated hydrocarbons.
Likewise, people ask, what hose is compatible with brake fluid?
Their cloth braided fuel hose is compatible with brake fluids. I use two sizes, 5mm and 7mm, and both are fine.
Are all DOT 3 brake fluids compatible?
All DOT 3, 4 and 5.1 brake fluids are compatible with each other and with all systems. All polyethylene glycol-based fluids will not harm healthy rubber parts. Also, the additive packages will not damage or distort any rubber parts."""""""""""

What we know is DOT 5 has chewed up or rather, melted rubber, in some of the older brake rubbers. We know DOT 5 has settled water in low lines or wheel cylinders. We had one DOT 5 line freeze and split open.....but we're up in Canada so eventually everything freezes and splits open.

.
That is a lot of reading m1010plowboy .
Lots of really good information shared here!

Explained a lot of things for me. Thank you!

 

[m1010plowboy]

My pleasure. Rustystud did all the experiments and saw the results. We were sure lucky to have him share his knowledge.

The mystery of compromised rubber in a DOT 5 Master Cylinder MC, while the wheel cylinder rubber was still ok, was nice to solve. The wheel cylinder rubber was new and never tasted DOT 3 so it was ok with DOT 5. The MC, rebuilt with the old DOT 3 tasting seals because they 'felt and looked' ok, began to glob off rubber.

When 'certain types of?' rubber tastes DOT 3 it appears it is not happy with DOT 5. A switch to DOT 5 should include switching out to new rubber. Results appear to be inconsistent with some posts claiming a flush was all they needed. Looking at "brand names" and tracking which years or flavors of seals that have problems could help folks out down the road.

The lines in the M135 are a mix of rubber and steel. We have not seen the same break down, softening or shedding of hose rubber so.....we keep looking.

 

[Mullaney]

My pleasure. Rustystud did all the experiments and saw the results. We were sure lucky to have him share his knowledge.

The mystery of compromised rubber in a DOT 5 Master Cylinder MC, while the wheel cylinder rubber was still ok, was nice to solve. The wheel cylinder rubber was new and never tasted DOT 3 so it was ok with DOT 5. The MC, rebuilt with the old DOT 3 tasting seals because they 'felt and looked' ok, began to glob off rubber.

When 'certain types of?' rubber tastes DOT 3 it appears it is not happy with DOT 5. A switch to DOT 5 should include switching out to new rubber. Results appear to be inconsistent with some posts claiming a flush was all they needed. Looking at "brand names" and tracking which years or flavors of seals that have problems could help folks out down the road.

The lines in the M135 are a mix of rubber and steel. We have not seen the same break down, softening or shedding of hose rubber so.....we keep looking.

.
It was interesting as I was reading your post. Second paragraph or so, I was thinking that the rubber brake lines.... And as I kept reading that was already part of the discussion. A whole LOT of research went into that piece of learning!

 

[V8srfun]

I am not going to get in the debate of what is better 3 or 5 but I will say I use 5 in my truck. But on to the more pertinent question that has not really been dealt with. Your wheel cylinder cups swelling 2x it’s original size is a major problem and is not related to what fluid you use as these parts are compatible with both fluids. You must have gotten a faulty part because that should not happen regardless of what fluid used. I would return them and find a different source as that is just not normal or acceptable.