DOT 5.1 vs. DOT 4 for brake fluid [Archive] - Triumph675.Net Forums

: DOT 5.1 vs. DOT 4 for brake fluid


motojc
06-17-07, 01:38
anybody has knowledge on this? The store, the product and the internet all say the 5.1 is compatible with 4. Seems like the 5.1 has a even higher boiling point which is a good thing. The local Japanese store carries only 5.1 now.

So today, I put the 5.1 in, after everything is done, the bleeder nipple looks mist, all three of them, the left and right and master, everything was tight, and cleaned. it's coming out of the base where the bleeder goes in. at least the rubber covers are always wet, did I just do something real bad? is 5.1 eating my internal seals now? help!

The brake is performing very good afer the bleeding.

Thanks.

Lightsdarkness
06-17-07, 02:31
mine leaked out of the bleeder valve as well. I put some teflon tape on it and 3000 miles later no leaks.

Budo
06-17-07, 02:58
I am not an expert on this subject, but i was told that if you switch from DOT 4 to 5.1 you need to flush the system completely before swapping. In other words, you are not supposed to mix the slightest bit of 4 and 5.1

Like i said, i have no idea if its true or not... i was just told so... :P

jbj
06-17-07, 03:55
anybody has knowledge on this? The store, the product and the internet all say the 5.1 is compatible with 4. Seems like the 5.1 has a even higher boiling point which is a good thing. The local Japanese store carries only 5.1 now.

So today, I put the 5.1 in, after everything is done, the bleeder nipple looks mist, all three of them, the left and right and master, everything was tight, and cleaned. it's coming out of the base where the bleeder goes in. at least the rubber covers are always wet, did I just do something real bad? is 5.1 eating my internal seals now? help!

The brake is performing very good afer the bleeding.

Thanks.

No expert either, but DOT 4 and DOT 5 are NOT compatible...however, Motul in their wisdom decided to call their product 5.1...and as the label says its compatable...which means mixing is ok, but makes sense to get the benefit out of the 5.1 you want to bleed all the old stuff out and leaving the system with only 5.1...I used 5.1 in my last bike...and did the fluid swap myself using the mityvac...

motojc
06-17-07, 04:35
mine leaked out of the bleeder valve as well. I put some teflon tape on it and 3000 miles later no leaks.

were you using 5.1? was the leaking bad? mine is just moist, no dripping or anything, went for a ride, it's in control. Would dealer do anything about it?

JBJ, what's a mityvac?

I did not empty the system, but I bled it enough times to make sure the 4s should be out already. You think it's chemical reaction melting my seals?

Anyhow, since it's not dripping or getting worse, I relax a little.

More questions:

How often do you bleed your brakes? I believe it's the first time since 16k miles, and I was really losing alot of power before so now it's great again.

And do you keep the unfinished opened new fluid for future use? One sources says no but given how big the packaging is, I doubt this is what dealer does.

Thanks guys.

Devilfish
06-17-07, 05:13
A mityvac sounds like a vacuum pump tool for bleeding the brakes.

You are supposed to change out the fluid every 12000 miles (part of service maintenance) or if it discolors (it should be clear).

What makes you think seals are melting? They should be just fine since the fluid you used is OK.

You should never mix brake fluids in any way. You can change brands, and as in your case switch to 5.1 if you want. But always bleed out the old and replace with fresh new stuff. It's not even recommended to add new fluid to used fluid such as in "topping off" the reservoir.

You should always use brake fluid from a very well sealed container. Once opened it does have a shelf-life of 12 months, but it must be kept tightly sealed... Moisture is its enemy!

You should be fine as long as your bleeders are not leaking... I'm not sure what you meant by mist but it seems you've got it under control and your brakes are working better too... That makes me want to bother with the hassle of doing my brakes now too!

Lightsdarkness
06-17-07, 11:54
it was a little bit of leaking but your problem is that the bleeder valve isn't making a tight seal. Just use teflon tape.

ducnut
06-17-07, 13:00
DOT 4 and 5.1 are compatible. DOT 5 is silicone based and is not.

As posted, why mix? Just flush the whole system and take comfort in knowing that you have fresh fluid. I flush mine after every track day. It always amazed me when a "Winger" would come into the shop with calipers that were seized (caused by moisture in the system that rusts the pistons to the sleeves). He would have every piece of chrome available for that 20yr old POS, but, had never had the bike properly serviced. Why? Well they always site the cost of shop labor as being too much. Generally, their suspensions were wallowing nitemares. Again, it costs too much to have the fork serviced. Ugh! I can tell you more stories like that, especially about their tires.

As for the moist bleeders, that's of no worry. I use brake cleaner, a paper towel wrapped around the bleeder area, and lightly spray into the end of the bleeder to remove any residue. You're on your own using teflon tape. I've seen the stuff plug all kinds of orifices. I won't take that chance.

As for topping off, there's no need to worry about having the reservoir completely full. Brake fluid does not circulate in the system. The reservoir is just there to supply fluid as the brake pads wear down. I run mine about 1/2 full.

I run Motorex 5.1 for a few reasons.
1. It's clear as water. I can monitor its condition because it'll start to turn yellowish when its life is being expended. There is no varying shades of yellow like most fluids. It's either clear or it's not. Simple.
2. The stuff works great. I've never experienced fluid related fade. No boiling ever.
3. Excellent packaging. The square metal can is non-porous, so it can never absorb moisture. Plastic containers are porous. The ingenius pour spout never drips. The lid has an overlapping seal with the spout to form an air-tight seal.

Mityvac is a vacuum pump that is handy for many uses. I use it to siphon the fluid from the reservoir. It can, also, pull fluid through an un-bled brake system. Put Mityvac in the search function and past info will result.

I use paper towels anytime I service a brake system. I throw them away after use. If you use rags, there's always the chance you'll use that rag to wipe something else and you end up ruining the finish on that something.

I hope these tips help someone. :wink:

jbj
06-18-07, 01:32
thanks ducnut, well put and good info :)

motojc
06-18-07, 18:45
Thanks ducnut. That's about everything I always wanted to know about 5.1 but was afraid to ask. :lol:

FastOF
06-19-07, 02:23
Well, had posted a response, but Ducnut's post was so complete and so much better I deleted it.

Good on ya!

caki
06-21-07, 14:58
Just in case you are wondering why you can't mix dot4 with dot5... Dot4 is petrolium (sp?) and dot5 is silicone based. Dot5 is better (last longer, higher boiling point, safe on paint & doesn't absorbe moisture) but it has i a major draw back. If you switch to dot5 you will need all new lines and seals. Just FYI. This is why it was so nice when they came out with the dot5.1.

PSUdaemon
06-21-07, 16:20
Just in case you are wondering why you can't mix dot4 with dot5... Dot4 is petrolium (sp?) and dot5 is silicone based. Dot5 is better (last longer, higher boiling point, safe on paint & doesn't absorbe moisture) but it has i a major draw back. If you switch to dot5 you will need all new lines and seals. Just FYI. This is why it was so nice when they came out with the dot5.1.

Does DOT 5.1 have some of the same drawbacks as DOT 4?

I'm assuming from the context of this thread that our bikes come with DOT 4 fluid?

motojc
06-21-07, 23:09
he draw back I see is it still absorbs moisture. I might have let some in there when I changed it: the rubber gasket/cover that seals the reservoir must have caught a fair amount of moisture because after i put it back in, I saw the back side was "sweating". So today I went to the track, after just one lap, my brake weakened at the end of a long straight, I squeezed it normally, nothing came up, I went right into the runoffs, thank god it was there. The rest of the day, I just had to squeeze it really hard and hold it fo rthe power to come on. Looks like brake work again this wknd.

Questions, how often do you need to rebuild/replace the pistons? I usually only take the pads out and clean the casing with cleaners.

ducnut
06-22-07, 09:48
motojc Posted: Thu Jun 21, 2007 9:09 pm Post subject:

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he draw back I see is it still absorbs moisture. I might have let some in there when I changed it: the rubber gasket/cover that seals the reservoir must have caught a fair amount of moisture because after i put it back in, I saw the back side was "sweating". So today I went to the track, after just one lap, my brake weakened at the end of a long straight, I squeezed it normally, nothing came up, I went right into the runoffs, thank god it was there. The rest of the day, I just had to squeeze it really hard and hold it fo rthe power to come on. Looks like brake work again this wknd.

Questions, how often do you need to rebuild/replace the pistons? I usually only take the pads out and clean the casing with cleaners.


I don't know for sure what you've got going on. However, your bike isn't old enough for the pistons and seals to need replaced. Inspect the calipers and make sure nothing is hanging up with the pads. Completely flush the system with new fluid. Make absolutely sure no air is getting pulled in. Problems with the brake mechanics of a new bike are unheard of. It's usually something that someone did to the system that causes the problems. If you're not 100% positive in what you're doing, have a good shop do it for you. The risk is not worth it. Be safe bro'.

BTW, It takes quite a while (years?) for enough moisture to accumulate and cause problems inside the system. The "sweating" you saw was on the backside of the seal itself. I always completely clean that seal with brake cleaner every time I pull the cap. I do it mostly to avoid fluid dripping on something.

motojc
06-23-07, 01:44
wouldn't break cleaner contaminate the fluid once the cap is put back in? even when most of it evaporates? When I last did it, even though the sweating was on the back, the front was completely wet, I thought it was old fluid, which it was, so oculd that be the source where moisture got trapped in? Also, cold the bleeder be a source of leak if it's moist which indicates a small leak? Anyhow, I'll do it again this wknd and see what happens then.

Thanks Ducnut.

ducnut
06-23-07, 10:10
motojc Posted: Fri Jun 22, 2007 11:44 pm Post subject:

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wouldn't break cleaner contaminate the fluid once the cap is put back in? even when most of it evaporates? When I last did it, even though the sweating was on the back, the front was completely wet, I thought it was old fluid, which it was, so oculd that be the source where moisture got trapped in? Also, cold the bleeder be a source of leak if it's moist which indicates a small leak? Anyhow, I'll do it again this wknd and see what happens then.



I just cup the gasket/diaphram in a rag and spray the crap out of it using the rag to dry it off. Yes. The cleaner does evaporate away, but, wiping it further cleans any residual fluid from the rubber.

I don't see where old fluid on the diaphram would cause any problem. There's not enough to be of a worry.

I think the moistness of the bleeders is residual fluid from bleeding. I've never had any accumulation on the bleeders when using cleaner to clean the residual fluid from them. Just make sure to spray inside the end of the bleeder. That is probably where the source of dampness is coming from.

Sometimes I wish I could just step through the computer. I'd be glad to give you a hand. :wink:

motojc
06-25-07, 02:26
Sometimes I wish I could just step through the computer. I'd be glad to give you a hand. :wink:

Yes, the helping hand was definitely felt. :lol: Thanks. I think I found the problem today. I took the brake apart. the pads are all at 1.5mm, which is the replacement mark (which is not bad since they have about 16Kmiles on them). Not only that, the pistons are not working equally. Some got held up while others moved freely. and as a result, the pads were worn tilted (one end thicker than the other, slightly). It's rather strange because I think I took them apart like 2 months ago. Hmmm... so I put the stock ones back in since I don't have the EBC HH on hand. The performance is consistent now, but I still feel a slight loss of power maybe due to using lower grade stock pads. I'll upgrade in a few weeks.

And yes, the bleeders are dry. Must have been the same case in the past as well. But since I was not using a different grade of fluid, I did not pay attention to such details.

All good now.

ducnut
06-26-07, 09:30
Excellent! :D

motoman_AZ
07-19-07, 17:13
Info Provided by AFCO Racing.....

Automotive brake fluid has many responsibilities. Corrosion protection and lubrication of brake system components are only a portion of the role brake fluid must play.

All automobiles that have a hydraulic braking system must use brake fluid in order for the brake system to operate. The type of fluid used can depend on the type of vehicle and the demands of the vehicles brake system.

The two most common brake fluids used in the automotive industry are fluids that contain Polyalkylene Glycol Ether and fluid that contains Silicone or Silicium-based Polymer. Both Fluids are common but very different in regards to the manner in which they perform. Fluids containing Polyalklene Glycol Ether are more widely used and are the only fluids that should be used in racing brake systems.

Because brake systems may reach extreme temperatures brake fluid must have the ability to withstand these temperatures and not degrade rapidly.

SILICONE BASED FLUID
Fluids containing Silicone are generally used in military type vehicles and because Silicone based fluids will not damage painted surfaces they are also somewhat common in show cars.

Silicone-based fluids are regarded as DOT 5 fluids. They are highly compressible and can give the driver a feeling of a spongy pedal. The higher the brake system temperature the more the compressibility of the fluid and this increases the feeling of a spongy pedal.

Silicone based fluids are non-hydroscopic meaning that they will not absorb or mix with water. When water is present in the brake system it will create a water/fluid/water/fluid situation. Because water boils at approximately 212 F, the ability of the brake system to operate correctly decreases, and the steam created from boiling water adds air to the system. It is important to remember that water may be present in any brake system. Therefore silicone brake fluid lacks the ability to deal with moisture and will dramatically decrease a brake systems performance.

POLYGLYCOL ETHER BASED FLUIDS
Fluids containing Poly glycol ethers are regarded as DOT 3, 4, and DOT 5.1. These type fluids are hydroscopic meaning they have an ability to mix with water and still perform adequately. However, water will drastically reduce the boiling point of fluid. In a passenger car this is not an issue. In a racecar it is a major issue because as the boiling point decreases the performance ability of the fluid also decreases.

Poly glycol type fluids are 2 times less compressible than silicone type fluids, even when heated. Less compressibility of brake fluid will increase pedal feel. Changing fluid on a regular basis will greatly increase the performance of the brake system.

FLUID SPECIFICATIONS All brake fluids must meet federal standard #116. Under this standard is three Department of Transportation (DOT) minimal specifications for brake fluid. They are DOT 3, DOT 4, and DOT 5.1 (for fluids based with Polyalkylene Glycol Ether) and DOT 5 (for Silicone based fluids).

MINIMAL boiling points for these specifications are as follows:

Dry/wet

DOT 3 401F 284 F
DOT 4 446 F 311 F
DOT 5 500 F 356 F
DOT 5.1 518 F 375 F

Racing brake fluids always exceeds the DOT specifications for dry boiling points. Wet boiling points generally remain the same.

DOT 3 VS. DOT 4 and 5.1
AFCO's 570 brake fluid is a DOT 3 type fluid. However, it has a dry boiling point that is 52 higher than DOT 5.1 specifications, 124 higher than DOT 4 specifications and 169 higher than DOT 3 specifications. AFCO's 570 fluid meets or exceeds all DOT 3, 4, and 5.1 lubrication, corrosion protection and viscosity specifications.

AFCO's 570 racing fluid meets but does not exceed federal standards for wet boiling point specification; therefore, its classification is DOT 3. Because AFCO's 570 fluid is intended for use in racing type brake systems that undergo frequent fluid changes, exceeding federal standards for wet boiling points is of little concern. Racing brake fluids always exceeds the DOT specifications for dry boiling points. Wet boiling points generally remain the same.

WET VS. DRY BOILING POINT
The term boiling point when used regarding brake fluid means the temperatures that brake fluid will begin to boil.

WET BOILING POINT
The minimum temperatures that brake fluids will begin to boil when the brake system contains 3% water by volume of the system.

DRY BOILING POINT
The temperatures that brake fluid will boil with no water present in the system.

MOISTURE IN THE BRAKE SYSTEM
Water/moisture can be found in nearly all brake systems. Moisture enters the brake system in several ways. One of the more common ways is from using old or pre-opened fluid. Keep in mind, that brake fluid draws in moisture from the surrounding air. Tightly sealing brake fluid bottles and not storing them for long periods of time will help keep moisture out. When changing or bleeding brake fluid always replace master cylinder caps as soon as possible to prevent moisture from entering into the master cylinder. Condensation, (small moisture droplets) can form in lines and calipers. As caliper and line temperatures heat up and then cool repeatedly, condensation occurs, leaving behind an increase in moisture/water. Over time the moisture becomes trapped in the internal sections of calipers, lines, master cylinders, etc. When this water reaches 212 F the water turns to steam. Many times air in the brake system is a result of water that has turned to steam. The build up of steam will create air pressure in the system, sometimes to the point that enough pressure is created to push caliper pistons into the brake pad. This will create brake drag as the rotor and pads make contact and can also create more heat in the system. Diffusion is another way in that water/moisture may enter the system.

Diffusion occurs when over time moisture enters through rubber brake hoses. The use of hoses made from EPDM materials (Ethlene-Propylene-Diene-Materials) will reduce the amount of diffusion OR use steel braided brake hose with a non-rubber sleeve (usually Teflon) to greatly reduce the diffusion process.

THINGS TO REMEMBER
Brake fluids dry boiling point is more important then wet boiling point when used in a racing brake system.
Passenger cars very rarely will undergo a brake fluid change making the wet boiling point more important.
Racing brake system fluid is changed often and a system with fresh fluid will most likely not contain water.
Because of this, racers should be concerned with the dry boiling point.
Racing fluid exceeds DOT 3, 4, and 5.1 dry boiling point specifications.
Never use silicone based fluids in racing brake systems.
Using racing brake fluid will increase performance of the braking system.
Never reuse fluid. Never mix types or brands of brake fluid.
Use smaller fluid containers that can be used quicker.
If fluid remains in container be sure to tightly seal and do not store for long periods of time.
Purge system (complete drain) and replace fluid often.
Immediately replace master cylinder reservoir cap following any maintenance.

Ricekrispy
07-20-07, 12:43
I recomend using a mityvac to do any brake bleeding jobs, it just makes things so much easier. I don't have any experience with the speed bleeders, but have heard good things and ease of use about them.
Lots of good info in this thread, and if unsure pay a trained pro to do the job, you are in deed putting your life on the line and expecting those barkes to stop you.
Ride safe.

Father Azmodius
07-20-07, 13:41
I've said it before and I'll say it again ( whenever I'm asked, and sometiimes when I'm not ) that the speed bleeders are the best thing since spiral sliced honey baked ham. I will conceed though that a vac system would probably be even easier.