| Author | Message | ||
| Bill Sebestyen (Bill308)
Member Username: Bill308 Post Number: 347 Registered: 5-2001 |
Eric, If a brake fluid, like silicone, is not hygroscopic, how does water get into the brake lines? Is it that the brake fluid specific density is less than 1.0 and therefore water enters the brake lines by gravity? Is this the mechanisim? For DOT 3 and 4 fluids, which are hygroscopic, moisture present in the resevoir will gradually be absorbed by the fluid and during brake applications be introduced into the brake lines. Over time, the moisture will build up and require purging to avoid problems. I think I understand this mechanism. | ||
| Eric Dahl (Brembo)
New member Username: Brembo Post Number: 30 Registered: 8-2002 |
All brake systems will collect moisture. Brake fluid gains about 3.5% moisture in a 12 month period. DOT 2,3,4 fluids absorb water for the reason that it is then kept away from components and cannot corrode them as quickly. It is fluids that do not absorb fluid that can cause quick corrosion due to water collecting at various points in the system and corroding components. That is the point, all brake systems will collect moisture, the job of the fluid is to absorb the water and still be able to perform hydraulic work. | ||
| Joe Craven (Rscapri2600)
New member Username: Rscapri2600 Post Number: 3 Registered: 7-2002 |
I've been using the Syntec Valvoline brake fluid in my race cars with good results. I replace fluid quite often, so I do not have to be concerned with the wet boiling point although the Valvoline product is quite good. The main problem for low use vehicles is that the DOT 3,4 fluids absorb water, which can cause corrosion and brake failure. There is also some newer DOT 5.1 fluid, which is fully compatible with DOT 3 or 4 and is NOT silicone based. I tried it in my race car but the Valvoline stuff is cheaper. Here's a link with some info. http://www.synlube.com/brake.htm | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1086 Registered: 1-2001 |
I rest my case...;) | ||
| Eric Dahl (Brembo)
New member Username: Brembo Post Number: 29 Registered: 8-2002 |
Greg, Stay away from synthetic brake fluid for street or racing use. Use a DOT 3 or 4 fluid. Synthetic or silicone based fluid (Dot 5)does not absorb water, so when water enters the hydraulic system, which it will, the boiling point (wet) of your fluid is now that of water (212F). Mineral or Poly glycol ether based fluids (Dot 2,3,4)absorb water into their chemical mixture. Depending on the fluid the boiling point of the wet fluid will still be significantly higher than water. Racers only worry about the dry boiling point of fluid because they change it before it becomes wet. Street cars keep fluid for some length of time, so keep an eye on the wet boiling temp of the fluid, because any street car generally has wet fluid. Here at Brembo we sell our own DOT 4 fluid, LCF 600, which has a dry boiling point of 601 F, and 400 F wet. Motul 600 for comparison is 585 F dry, and 421 F wet. | ||
| Lawrence Coppari (Lawrence)
Member Username: Lawrence Post Number: 271 Registered: 4-2002 |
Here is my 0.02 worth. For the past 20 years or so I have been using Prestone or Castrol Dot 4 in all my cars. One car has been tracked nearly monthly since 1996. No problems experienced with any of them. I purchase which ever is on sale at the moment. Brake fluid is replaced yearly. | ||
| Greg Owens (Owens84qv)
Member Username: Owens84qv Post Number: 531 Registered: 10-2001 |
Whenever I post here, I always look forward to Ric's commentary. I've used Ric's DIY instructions for much of the general maintenance that I've done. Picked up brake pads today. Red caliper paint is on order. We're gonna have some fun. | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1072 Registered: 1-2001 |
Ric -- If you've been using Valvoline Syntec, I think you've been mixing in engine oil! (  Sorry, just a joke -- isn't it Castrol Syntec?) Greg -- I think sometimes the term "synthetic" is (wrongly) used as exact equivalent for only the newer DOT5 brake fluids so this gets things confused. I've not regreted following Ric's advice and use the Valvoline SynPower DOT3/DOT4 in all my (street) cars -- JMO. | ||
| Ric Rainbolt (Ricrain)
Member Username: Ricrain Post Number: 252 Registered: 2-2002 |
I've run Valvoline Syntec in 4 Ferraris for a while now (4+ years). My 308 GTB and 348 have seen quite a bit of track time, with aggresive pads and heavy braking (Turn 2 at TWS it a good example). I've never managed to fade the stuff. It's 100% compatible with DOT 3. It's dry boiling point is 513F vs. ATE's 536F and better than Motul and Castrol LMA. It's cheap (1/2 as much as ATE). It's available everywhere (Wal-Mart, Autozone, etc.). Try and find ATE when you're on a road trip somewhere... YMMV | ||
| Greg Owens (Owens84qv)
Member Username: Owens84qv Post Number: 529 Registered: 10-2001 |
Thanks everyone for the input. I also checked with a friend (Ferrari owner) about using Sythetic brake fluid...he was cautious. I did check a website for the AP550 and ATE Blue. Looks like the ATE Blue is best suited for what I need and pretty reasonably priced. | ||
| Dr Tommy Cosgrove (Vwalfa4re)
Member Username: Vwalfa4re Post Number: 298 Registered: 5-2001 |
Tom, Do you mean don't use DOT 5 if the owners manual calls for DOT 3? If so, what problems could be created by using DOT 5 even after a fairly good flushing of the DOT 3? Thanks for your advice | ||
| mike 308 (Concorde)
New member Username: Concorde Post Number: 25 Registered: 8-2002 |
DOT 3 and 4 are fully miscible together without problem. | ||
| TomD (Tifosi)
Intermediate Member Username: Tifosi Post Number: 1369 Registered: 9-2001 |
I meant don't use dot 5 when dot 3 is called for | ||
| '75 308 GT4 (Peter)
Intermediate Member Username: Peter Post Number: 2024 Registered: 12-2000 |
Ford High-Performance DOT 3 has just as high a boiling point as AP 550 (hence the number: 550°F) This is more than you'll ever need for street driving and the Ford fluid is avaliable EVERYWHERE... | ||
| TomD (Tifosi)
Intermediate Member Username: Tifosi Post Number: 1346 Registered: 9-2001 |
make sure it has the right DOt spec. I high DOT number can be a problem | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1062 Registered: 1-2001 |
I use the Valvoline SynPower synthetic also. As Ric R. previously observed (IIRC) -- decent performance, readily available (US), not high cost. Do a search on "SynPower" to get some previous relevant posts. | ||
| David Burch (Merlyn)
New member Username: Merlyn Post Number: 16 Registered: 8-2002 |
AP 550, You probably don't need AP 600. Castrol LM is a good street fliud, but not if you're going to use it hard on the track. ATE makes a very good fluid also, I think it's called ATE blue, but I have never used it. I'd stay away from any silicon fluid. | ||
| Greg Owens (Owens84qv)
Member Username: Owens84qv Post Number: 528 Registered: 10-2001 |
I'm getting ready to do brake work on my 308QV and wanted to get some opinions (on this site?) as to the better brake fluids to buy. Valvoline makes a synthetic fluid that would seem to be pretty good, but I wanted to get some input...fire away! |