Brake fluid???

[JeepSnake]

Hi guys,

I know this topic has been hashed & rehashed, but I need to ask more questions...

1) I know that DOT 5 silicone is off limits.
2) I know that DOT 3 is recommended for the clutch, and it is what I flushed that system with a few weeks ago in an emergency type situation when it boiled.

Now, I am preparing to flush & fill the brake system. I don't know what I've got now, but I assume it's probably DOT 3. (John, if you read this, can you tell me what you used in the car?)

So, my question is this: where does DOT 4 fall in this scheme of things?

Specifically, I've picked up a couple of bottles of Valvoline SynPower "Synthetic Formula" that says "Exceeds DOT 3 & DOT 4." The label then says it is "compatible with conventional brake fluids," and on the back it is called "SYNPOWER ABS synthetic DOT 3 & DOT 4 motor vehicle brake fluid."

Has anyone had experience with this stuff? I intend to run it through the system till I have fresh fluid coming out all the bleeders, but I don't want to destroy any seals or gum up any pistons, etc. Is anyone running it successfully in Wilwood components? Has anyone introduced it into a system (without incident) that previously held straight DOT 3?

Thanks for the help - I guess I'm just a little nervy about doing anything concerning brakes. Especially right now, since making a big mess would ground the car for the Pigeon Forge weekend.

[Jerry Cowing]

Zack,

I've been using Valvoline SynPower for DOT 3 for 5 years with no problems. It has a much higher boiling point than standard DOT 3 fluids. I wouldn't use anything else.

Jer

[eliminator]

The Valvoline Syn Power stuff is good as Jerry pointed out. Just don't use it in the clutch cylinder.
I have used it in the front and rear brakes and no problem. Butch Capps recently used it a VIR on the track events and no problem, he tells me they were running 135 - 140 MPH on some of the straightaways. So it must work good. I have had good luck with the Wilwood High Temp fluid in the clutch, it is a dot 3 fluid with a very high boil point. I actually used it all the way around, brakes and clutch. Only problem, a littly pricy.

[Naumoff]

I use the Wilwood 570 DOT 3 in the clutch and brakes. No problems with 6000miles.

[jhaynie]

I was using that Valvoline Synpower as well. Never had it boil off though.

John

[JeepSnake]

Thanks everyone!

John - the brake systems are both fine, fluid in the masters looks clean. I boiled the clutch, though. That would have to be termed extreme circumstances: July 4th parade, air temp at 100 deg +, engine coolant temp crept up to 230, at which point I shut the engine down but left the fans running. Parade route was downhill through town, so we just coasted along. Then, when I restarted at the end to pull off on a side street is when the clutch was gone. We limped home, then flushed the system after it cooled off enough to risk reaching into the engine compartment - no problems since.

I'm just planning to flush & bleed the brake systems before Pigeon Forge.

Looks like I'll jump on it tomorrow afternoon; tomorrow AM is going to be spent repairing wind & lightning damage around the farm. Mom & Dad were at home during the storm - said it was the worst 40 minutes of nearly continuous lightning they've ever seen. 3 1/2" of rain in 40 minutes, and wind that curled the tin roofs up on a couple of our outbuildings.

[Ric S.]

Looking to learn something from your exchanges with Jeepsnake. You said the clutch fluid boiled while in a parade. First, no parading for mine once built. But why would idle and slow speed actions even in high temps boil the fluid??

[pgermond]

Ric,
The proximity of the hydraulic line (and slave cylinder if you are using one) to the headers - the lack of airflow causes everything to heat up very quickly.

Zach,
I'm using Willwood EXP 600 Plus - pricey, but haven't had any problems (I also have a reflective sleeve around the lines and slave cylinder.

[JeepSnake]

Ric,

To answer your question, I believe the biggest culprit is routing of the hydraulic line going to the clutch slave cylinder. The original builder (before John, and then I, came to own the car) routed the clutch line over the foot box to the firewall, then along the firewall and down the side of the footbox directly to the clutch slave. To make sure that drivetrain vibration & movement didn't twist up or kink the line, they put a couple of "S" bends in the line in the vertical run down to the slave.

Guess what is about 1 1/2" away from these two pretty "S" bends? Yep - the rearmost exhaust primary tube on the headers. You'd be hard pressed to route the line to catch more radiant heat than what it gets! So, take away the cooling airflow blowing across the lines & headers from vehicle movement - the heat radiating from the headers increases, and the heat absorbed by the line & fluid increases, and - vapor. I just finished covering ALL of the brake & clutch lines in the engine compartment with Thermo-Tec insulation to help prevent in the future. This winter, I will probably reroute the clutch line altogether, as well as add the SPAL puller fan.

FYI - our friends' '72 big block Vette boiled the brake fluid in another parade over the 4th. That was even more exciting than losing our clutch!

[will butterworth]

When we were all looking at the car yesterday, Phil,s comment made me think of it, I noticed the front wheel wel vents were covered right behind the tire. We need to look at them tonight whilst we getem up brakes.Never mind , thats different from front brakes, ya,ll are talking about the line to clutch.I,ll catch up with you in a minute.Will-alabama

[Jerry Cowing]

Zack,

If I had to do it again, I'd route the clutch and brake lines inside the foot box and then cover them with the carpet so they are not seen. This will get them away from the headers.

Go from your master cylinders directly into the top of your foot box and then out the bottom of your footboxes to your clutch and brakes.

[Master]

Zach, I use dot 4 in my clutch slave cyl and brake master cyl and it does not turn dark or black. Butttttt. I have insulated the clutch and slave lines. I choose dot 4 because of slightly higher boiling point that dot 3 and it is not synthetic.

[souzape]

Zach- I've been using the Valvoline Synthetic brake fluid in brakes and clutch for about a year with no problems. My lines are insulated around the headers (351C in an FIA body).

Phil Souza

[jhaynie]

Kind of a late reply Zach, but that happened to me once in that car as well. I had to bleed the clutch slave and master and then it was fine. It was summer time as well. I think you are on track with the idea of rerouting the lines. Either that or insulate them.

John

[JeepSnake]

Thanks, John. I'm looking at rerouting the lines sometime this winter, but for now I've put Thermo-Tec insulation over all of them; if it works as good as it looks, things will be fine!

Now, off to buff the wirewall & footboxes with Scotchbrite, and clean 'er up for Pigeon Forge...