17 replies to this topic

[ChrisA]

I'm getting ready to order up my fluids for this season and was thinking of switching brake fluids. I have been using Motul 600 and bleed/flush before each event, but with Castrol SRF's wet temp being so high I was thinking of switching. I've never had a fluid related issue with the 600, but perhaps I could get away with just a mid-season flush with the SRF. Thus saving some time and perhaps the cost of at least one bottle of Motul. Any thoughts?

[dstevens]

I don't see stock Miata brakes getting any great benefit from SRF compared to lower cost alternatives. Are you to the point where you boil the fluid? I used Motul in the F125 shifter for a while but ended up going with Castrol LMA which I used in the stock car as well.

[Rob Gibson]

I'm never one to suggest skimping on safety items like brakes, but a full flush before every event sounds like overkill with Motul 600. We have run the entire 25 Hours of Thunderhill multiple times with 600 and had a firm pedal to the very end each time. So I wouldn't think twice about running a few events without bleeding. That being said, we do a bleed before each event and a full flush 2-3 times per year just to be on the safe side. For non-flush bleeds with Motul we can do a bleed of both the brakes and the clutch at the start of the weekend, and then keep any remaining fluid for any unscheduled bleeds that may be necessary throughout the weekend. With that method you shouldn't need the entire bottle for a weekend unless there are other braking issues. But even for the quick bleeds it's much easier to break the seal on a $15 bottle of Motul than a $60 bottle of SRF.

Motul 600 is about 1/4 of the cost of SRF, and even though you get twice as much of the SRF, once you break that seal it will start absorbing moisture, so it becomes a Use-It-Or-Lose-It situation. In my experience with larger bottles, all you end up with is a lot of wasted brake fluid. We used to use ATE because it was 1L for the same price as 1/2L of Motul, but with all the waste, it ended up being about the same cost, so we switched to Motul.

Lastly, if you're getting a soft pedal as the weekend goes on, it's probably not the fluid but an improperly bled master cylinder or another component of the braking system. We replaced the master last year and bench bled. For the next few weekends we chased a soft pedal, bleeding at each corner early and often. It wasn't until we re-bench bled the master that the problem was solved.

[Rob Burgoon]

Lastly, if you're getting a soft pedal as the weekend goes on, it's probably not the fluid but an improperly bled master cylinder or another component of the braking system. We replaced the master last year and bench bled. For the next few weekends we chased a soft pedal, bleeding at each corner early and often. It wasn't until we re-bench bled the master that the problem was solved.

Or tapering brake pads.

You guys are such weenies. ATE Super blue, bled twice a season and replaced from a can that's been open all season.

Gibson does get a pass though since he doesn't want to risk ruining an enduro.

[dstevens]

Getting a good bench bleed on the master is key. Previously I've fabbed adapters with flare nuts and tubing bend specifically for bench bleeding. For the Miata I'll fab something to bench bleed both the proportioning valve and the master in one pass. Need to look at those hard lines and fittings too. anyplace where fluid and get out and/or air can get in needs to be addressed.

Dave

[Qik Nip]

I agree with the folks here. When I ran a Corvette, daily bleeding and pricey brake fluids (like Motul)was an absolute requirement. But whoaing down a 2,300 pound car from 115 is a lot different than 3,000 pounds at 160. I bleed every other event use good old off the shelf fluid in my SM and it works great.
Rick

[davew]

I learned this racing business working on Trans-Am cars. 180mph on street courses. Always used SRF on those beasts.

Blackhawk Farms is considered the hardest track in the country on brakes. Spec Miatas will barely make a double regional on one set of front pads. The track has four 4th gear (100mph) threshold braking zones, and another from the top of 3rd gear every lap!!!! With this type of abuse you need to be diligent about brake maintenance.

Even at Blackhawk, SRF is a waste of money in a Miata.

When run Castrol LMA in virtually all of our Spec Miatas. I have a couple guys who have used Super Blue for years and just don't want to change. We run a bottle of LMA through the system every time we prep the car. We take a couple pumps every night at the track. I don't remember every having a brake issue on the cars we maintain. Yet other people constantly have brake issues.

You guys who can go 1/2 a year on brake fluid are getting away toooooo easy. Come to Blackhawk and learn how to stop a car!!!!!!

Dave

[FTodaro]

Getting a good bench bleed on the master is key. Previously I've fabbed adapters with flare nuts and tubing bend specifically for bench bleeding. For the Miata I'll fab something to bench bleed both the proportioning valve and the master in one pass. Need to look at those hard lines and fittings too. anyplace where fluid and get out and/or air can get in needs to be addressed.

Dave

Share some pictures of your inventions.

[Eric Jones]

SRF is like $70 per liter. Or at least it was when I worked in Indy Lights and Champ Car. IMO it's overkill. Just use something that has a higher wet boiling point (ignore dry boiling point numbers)than the every day stuff. For a Miata, it's fine. I use AP 550 and Motul 600.

[dstevens]

Share some pictures of your inventions.

Sure, but there's not much to it. I'll dig out the stock car adapters, haven't gotten that far in the Miata. I get a new flare nut, flare the end of the tubing and bend it in a "U" so the MC outputs route back to the top of the MC. Wish I could say it's my idea but I learned from some old Bubbas at the track. You could also use some plastic fittings and rubber or plastic tubing. The manual MCs we use in the hobby stocks typically include a plastic barbed fitting for bench bleeding.

[ChrisA]

Thanks for the input guys. I'll probably stick with the Motul 600, since I've never had any issues with it and always a good pedal. Then again, SRF with a 518F wet rating I could probably flush it once a year and be done with it...?

[dstevens]

I didn't get a chance to get the circle track parts out today, Here's a vid from Denlor Tools that shows it in action.

[Ken Wilkinson]

Chris,
I have started using the Wilwood 570 fluid that comes in a 12 oz. bottle. Brakes have been fine in race conditions since I started using it and at about $6 a bottle, the cost is about the same as ATE and very little waste.
I have plenty and you are welcome to try a couple of bottles.
Ken

[ChrisA]

Chris,
I have started using the Wilwood 570 fluid that comes in a 12 oz. bottle. Brakes have been fine in race conditions since I started using it and at about $6 a bottle, the cost is about the same as ATE and very little waste.
I have plenty and you are welcome to try a couple of bottles.
Ken

Hey, thanks Ken I may look into the Wilwood, as that is not a bad price. I found I still have a couple unopened bottles of Motul, so I'm not pressed.

Is anything happening at SP-Main this June/July?

[wheel]

We've used the Willwood fluid in both the SM and the AS, with excellent results, especially considering the price. We bleed more frequently with the AS.
wheel

[ChrisA]

I found some of the info on this site interesting. http://www.volvoclub...Comparison.html

[wheel]

Here's a site you all might find informative.
wheel

http://www.westpennm...arison_List.pdf

[Jeff Wasilko]

Chris,
I have started using the Wilwood 570 fluid that comes in a 12 oz. bottle. Brakes have been fine in race conditions since I started using it and at about $6 a bottle, the cost is about the same as ATE and very little waste.
I have plenty and you are welcome to try a couple of bottles.
Ken

I've been using the Wilwood 570 as well and have had great luck. I don't bleed the brakes often (though my IT car has brake cooling ducts which may help some).

-j