doh!!!!

[doozer]

yea so i was doing a little upkeep on my 400ex cause we are hitting silver lake sand dunes this satuday and i noticed my rear brake resivoir was a little low. so i walk over to my quad section in my garage and grab a can of brake fluid, and fill the resivoir up. then i noticed that the brake fluid i added was dot 3. i know it says only to use dot 4 fluid and i just figured since the can was there w/my other quad stuff it was right. will this be ok to run for even a short period of time or will it destroy my seal in my caliper or what?? i have no idea. the guy at the local dealership said it would be ok as long as i dont mix dot 5 with it. he says dot 3 and dot 4 or ok to mix. any info is appreciated. thanx.

[Pappy]

ive mixed them before..not by choice but by accident. i never had any problems although you should try and keep it the same.

chemically they are the same, its just that dot 4 has a higher boiling point.

dot 5 no...dot 3 i believe is ok..i did the dot 5 & brakes are now junk...all the rubber swelled up I am pretty sure because the boot inside the reservoir shot out it got so big after I took the cap off

[mustang]

the differance between them is the amount of heat they are designed for. dot 3 worst dot 4 better dot 5 best. you can mix dot 3 & 4 but if the system calls for dot 4 it needs dot 4 do to the heat load that break system is designed for, adding dot 3 will take away from the properties. and last dot 5 is not compatable with either i believe its a silicone base and yes it will turn your breaks to CHIT

[MOFO]

keep in mind, if your rear brake reservoir is low, its likely that your rear brake pads are worn. The more they wear out, the lower the fluid will be in the reservoir.


so before you just top it off next time, check your pads. :cool:

[redroost85]

Well said Mofo. This very thing is going on with my ride right now....low resevoir and worn rear pads.

Time to give a call to C&D again!:p

[doozer]

yes the dot 5 is silicone based i found out. yes my pads were worn and i replaced them a couple days ago. it does make sense that your fluid gets lower as you pads go because of the caliper piston is getting further and further out. thanx for all your help guys, hope to see ya ridin sometime.

[PhilMoore]

I put DOT5 in my rear brakes about 3 years ago, and haven't had any trouble. It was a lot of work though. I followed the instructions, drained out the old fluid, cleaned and rinsed everything with alcohol (per instructions), and put the DOT5 in.

I didn't do the front because the rear was so much work. I have never added fluid to the rear and they work solid.

You can't mix DOT5 with any other type.

[sickmojave]

so what is the advantage to DOT5 ? :confused:

[PhilMoore]

No advantage it was a waste of time.

[JOEX]

There are some advantages....
http://www.team.net/sol/tech/dot5.html

DOT 5 Brake Fluid

Mike Burdick (on the SOL list) says:
A while back when this topic came up, I posted excerpts from a Skinned Knuckles article on silicone brake fluid. They made the best attempt I've seen so far to actually address this issue with hard data instead of anecdotes. The data they used came from military tests in jungle conditions and tests from the original producer of DOT5 fluid (DuPont? I can't remember...). Even so, they were not able to come up with many conclusions about DOT5 fluid. In a nutshell, the conclusions were:


1. DOT5 does not absorb water and may be useful where water absorption is a problem.

2. DOT5 does NOT mix with DOT3 or DOT4. They also maintain that all reported problems with DOT5 are probably due to some degree of mixing with other fluid types. They said the proper way to convert to DOT5 is to totally rebuild the hydraulic system.

3. Reports of DOT5 causing premature failure of rubber brake parts were more common with early DOT5 formulations. This is thought to be due to improper addition of swelling agents and has been fixed in recent formulations.

4. DOT5 is compatible with all rubber formulations.

5. DOT5 doesn't eat paint.

They also made some general recommendations based on this data and personal experiences. These, along with recommendataions of list members included:

1. If it works for you, use it. You won't hurt anything if you do the conversion correctly. (See, #2 above)

2. Careful bleeding is required to get all of the air out of the system. Small bubbles can form in the fluid that will form large bubbles over time. It may be necessary to do a series of bleeds.

3. DOT5 is probably not the thing to use in your race car although it is rated to stand up to the heat generated during racing conditions. The reason for this recommendation is the difficult bleeding mentioned above.

4. DOT5 is a good choice for the weekend driver/show car. It doesn't absorb water and it doesn't eat paint. One caveat is that because it doesn't absorb water, water that gets in the system will tend to collect at low points. In this scenario, it would actually be promoting corrosion! Annual flushing might be a good idea.

[PhilMoore]

The water absorption issue is why I wanted to switch in the first place.

When you dissasemble old ATV's and old cars, the brake fluid is almost always filty, murky brown.

Rather than switch to DOT 5 on all my stuff, I just change fluid more often.

On my 400EX the front fluid gets discolored, but the rear fluid has been relatively clean in comparison. I have only done a drain and replace once on the rear with DOT5, I have done the fronts twice. This spring will be the third on the front, second on the rear.

Like I said it is a LOT of work to switch to DOT5 and I certainly didn't notice any performance gains that are worth the effort.

[JOEX]

Yea, it does sound like alot of work to do a conversion and probably not worth it for most people.

Thanks for being the guinie pig:p :D