Dot 5 Fluid and CSSB Warning

[Patrick B.]

Re: Dot 5 Fluid and CSSB Warning

Thank you Patrick. I didn't realize the rule change proposal was withdrawn. I found it somewhat difficult to decipher what that rule document was getting at, so thank you for the clarification that it was focusing on rubber compounds and not fluid compositions. I read something about the EPDM compound being evaluated but wasn't clear on what became of anything.

I assume that brake component manufacturers as well as those offering rebuilding, like Lonestar and CSSB, must have some sort of testing and safety assurance evaluations in place, yes? For example, do stainless sleeved calipers meet or exceed SAE/NHTSA/etc. braking requirements? Do the assembled components also have to pass any sort of evaluation?



I presume the comment about silicone fluid as polish is a bit tongue in cheek. How difficult is it to repaint a surface that had silicone fluid exposure? Will a standard fish-eye eliminator eliminate any problems? If I do get a spill, is it probably good practice to wipe the area with a silicone solvent like naphtha or paint thinner?

You would be mistaken if you think Lonestar or CSSB have to do anything to satisfy the federal regulations. The federal braking standards are vehicle performance standards that only apply to the manufacturer of the vehicle. A few standards such as for lamps and brake fluid are equipment standards that apply to aftermarket equipment such as replacement headlamps and sealed beams but most standards really only apply to the original vehicle manufacturer. The federal standard for brake fluid is loosing its ability to protect the public. If the types of rubber in brake systems is changing from SRB types to EPDM types (and who knows what Lonestar uses, maybe not even them), you should be worried when the brake fluid you buy in the auto parts store is required to be compatible with SRB rubber but is not even tested with the kind of rubber your car has in its brake system. I retired from NHTSA long ago but I think I see what is happening here. If politicians require agencies to rescind two rules for every one proposed, rulemaking to keep regulations current will cease. After thinking about this, I would not buy any brake fluid not called out by name in my car's owners manual. The DOT certification means nothing if your car does not have SRB rubber seals.

[Owen L.]

Re: Dot 5 Fluid and CSSB Warning

You would be mistaken if you think Lonestar or CSSB have to do anything to satisfy the federal regulations. The federal braking standards are vehicle performance standards that only apply to the manufacturer of the vehicle. A few standards such as for lamps and brake fluid are equipment standards that apply to aftermarket equipment such as replacement headlamps and sealed beams but most standards really only apply to the original vehicle manufacturer. The federal standard for brake fluid is loosing its ability to protect the public. If the types of rubber in brake systems is changing from SRB types to EPDM types (and who knows what Lonestar uses, maybe not even them), you should be worried when the brake fluid you buy in the auto parts store is required to be compatible with SRB rubber but is not even tested with the kind of rubber your car has in its brake system. I retired from NHTSA long ago but I think I see what is happening here. If politicians require agencies to rescind two rules for every one proposed, rulemaking to keep regulations current will cease. After thinking about this, I would not buy any brake fluid not called out by name in my car's owners manual. The DOT certification means nothing if your car does not have SRB rubber seals.

Wow, that's a sobering paragraph!

[Jill J.]

Re: Dot 5 Fluid and CSSB Warning

From what I understand is the chemical makeup of Dot 5 was changed at some point during the previous Administration. There was a certain additive included in the Dot 5 fluid that causes the rubber seals to degrade fairly quickly. While at the Corvette Chevy Expo in Galveston a couple years ago, I asked Lonestar if military grade Dot 5 would degrade the rubber components. The two gentlemen were unsure so they provided me a couple of rubber seals to try out. If the military grade Dot 5 silicone fluid had the additive, the rubber seals would swell. I ordered 1 gallon of the military grade Dot 5 silicone fluid (so I was using the newest on the market) and let the rubber seals soak for about a week. Guess what? No swelling. I contacted Lonestar to let them know my finding.

Afterwards, I filled my master cylinder with the military grade Dot 5 I recently purchased and performed the necessary brake bleeding procedures. Needless to say, the Dot 5 has been in my braking system for the past year with no issues. There are no leaks anywhere.

Also, my husband is a military vehicle buff and we have used the military grade Dot 5 silicone fluid in our military vehicles, while some have sat for over 20 years, and still have no issues.

The military grade Dot 5 runs From $50-$80 per gallon but is well worth paying the price. The military grade fluid can be purchased on eBay or surplus yards.

Hope this helps.

Jill, 59140

[Patrick H.]

Re: Dot 5 Fluid and CSSB Warning

I left current-era seals for 2 months in the DOT 5 fluid I have used.
No swelling, but I still got leaks.
No swelling noted when I removed the seals from the calipers either, even after they had been installed for a year before they developed leaks.

FYI, O-rings fit much tighter in the calipers than the lip seals. That may help decrease leaks as well.

[Joe L.]

Re: Dot 5 Fluid and CSSB Warning

I left current-era seals for 2 months in the DOT 5 fluid I have used.
No swelling, but I still got leaks.
No swelling noted when I removed the seals from the calipers either, even after they had been installed for a year before they developed leaks.

FYI, O-rings fit much tighter in the calipers than the lip seals. That may help decrease leaks as well.

Patrick------


I think to do the seal degradation test properly the fluid has to be kept at a temperature of about 250 degrees F and the seal kept in the fluid for about 72 hours.

[Patrick H.]

Re: Dot 5 Fluid and CSSB Warning

Patrick------


I think to do the seal degradation test properly the fluid has to be kept at a temperature of about 250 degrees F and the seal kept in the fluid for about 72 hours.

I know that none of the seals I installed when this car had DOT5 in it ever hit 250 degrees. I count the distance driven in yards, not miles.

[Owen L.]

Re: Dot 5 Fluid and CSSB Warning

I think to do the seal degradation test properly the fluid has to be kept at a temperature of about 250 degrees F and the seal kept in the fluid for about 72 hours.

That doesn't sound like a test reflecting real-world conditions. Wouldn't a more realistic test be cycling temperatures with complete cool down to ambient and repeat for some period of time?

I keep returning to the Google for information on this as new comments are made. I can't find anything concerning a chemistry change of DOT 5 fluids, either during the Obama admin or ever. Wouldn't that need to go through DOT testing if such a thing were to have occurred? It seems all the stuff I've come across are postings and enthusiast-oriented publications articles with little (no?) reference to testing.

I really don't want to beat a dead horse, but I don't think this nag is dead yet! What is the quality of the origins of the DOT 5 controversy? If it were detrimental to the safety of the system, wouldn't you have DOT or NHTSA or whomever pulling the product?

[Edward D.]

Re: Dot 5 Fluid and CSSB Warning

I have been running DOT5 in SS sleeved lip seal calipers for 25 years now, no leaks at all. Last year I had a customer with leaky calipers that wanted the new O ring calipers and DOT5. So I obtained Lonestar rebuilt calipers, flushed out the lines, and used the DOT5. Car never even left my shop before calipers started leaking. Called Lonestar and they gave me the story about how DOT5 changed formulation and you can't use it in their calipers anymore. They claimed that both the o-ring and lip seal calipers would leak with DOT5, but the lip seals would take longer to leak. They replaced them under warranty anyways (which was nice since technically I violated the warranty) and I had to flush out the DOT5 and use DOT3 on the car, with success. I have also replaced a lip seal caliper in a car running DOT5, pressure bled, and no problems. My theory is that the rubber in the o-rings and lip seals are different. The o-rings are not compatible with DOT5. So, my policy has changed to I will no longer do conversions to DOT5. Cars that are already DOT5 stay that way but only lip seals will be used as replacements. I will use o-ring calipers at customer request but only for DOT3 or 4 systems.

[Joe L.]

Re: Dot 5 Fluid and CSSB Warning

That doesn't sound like a test reflecting real-world conditions. Wouldn't a more realistic test be cycling temperatures with complete cool down to ambient and repeat for some period of time?

I keep returning to the Google for information on this as new comments are made. I can't find anything concerning a chemistry change of DOT 5 fluids, either during the Obama admin or ever. Wouldn't that need to go through DOT testing if such a thing were to have occurred? It seems all the stuff I've come across are postings and enthusiast-oriented publications articles with little (no?) reference to testing.

I really don't want to beat a dead horse, but I don't think this nag is dead yet! What is the quality of the origins of the DOT 5 controversy? If it were detrimental to the safety of the system, wouldn't you have DOT or NHTSA or whomever pulling the product?

Owen------


The test I suggested approximates the test methodology that the US Department of Transportation specifies for testing brake system elastomeric materials. I've been thinking about doing it myself in order to test various seals and brake fluids and settle this once and for all.

[Patrick H.]

Re: Dot 5 Fluid and CSSB Warning

Owen------


The test I suggested approximates the test methodology that the US Department of Transportation specifies for testing brake system elastomeric materials. I've been thinking about doing it myself in order to test various seals and brake fluids and settle this once and for all.

I would be happy to spend you fresh DOT5 as well as several lip seals if you want to try it.

[Terry M.]

Re: Dot 5 Fluid and CSSB Warning

I believe there may have been a change in the elastomeric material as well as the DOT 5. The one car with DOT5 and no leaks Gary B referred to is mine. I made that change around 40 + or - years ago and I used GM lip seals on stainless sleeved calipers from LoneStar. The DOT 5 was from Dow Chemical, and of course it is similar age as the lip seals.

My guess is with current materials and DOT 5 this no longer works.

[Joe L.]

Re: Dot 5 Fluid and CSSB Warning

I would be happy to spend you fresh DOT5 as well as several lip seals if you want to try it.

Patrick------


Thanks. I'll keep your offer in mind if I go ahead with this test. I've been thinking about it for a long time. I'd like to get some of the "military grade" DOT 5, too.

[Mark E.]

Re: Dot 5 Fluid and CSSB Warning

I thought of this thread while visiting Duntov Motor Company's website today. Here's their take on brake fluid (from www.duntovmotors.com/tech-brake-fluid.php , including the "hydroscopic" typo):


Brake Fluid School

There is a lot of misinformation out there, so here is some information I have put together about brake fluid as it applies to your Corvette!
Brake Fluid Ratings, with BP (Boiling Point Standard) in degrees Fahrenheit:

DOT 2 - Forget about it, it is obsolete.
DOT 3 - Glycol based, Dry 401, Wet 284
DOT 4 - Glycol based, Dry 446, Wet 311
DOT 5 - Silicone Based, Dry 500, Wet 356

Dry refers to virgin fluid; wet to fluid that has been in use for a while.

For owners of 63-82 Corvettes, we can eliminate DOT 5 silicone fluid. First of all, it is non hydroscopic, meaning it doesn't mix with moisture. But in the course of normal driving, moisture is going to get into your brake system and cause havoc. By not mixing with the brake fluid, this trapped and highly compressible moisture becomes highly corrosive. Corrosion is one of the reasons every brake caliper on 65-82 Corvettes has either already been sleeved, or probably should be.

Unless you flush and bleed your fluid a couple of times a year, silicone fluid is not the answer. Even dry virgin silicone fluid is more compressible than glycol fluid, so it doesn't work for me, even right out of the box. You can't mix Dot 5 fluid with even a trace of glycol fluid, whereas you don't have to worry about compatibility when switching between glycol-based fluids.

So now we are down to deciding between DOT 3 and DOT 4 fluid. The key number is the wet boiling point, as that is where your car lives. Dry boiling point is only relevant for road race cars, as their fluid is normally changed before every event. The higher the wet boiling point, the longer the fluid will perform well in your car. DOT 3 fluid should be flushed and replaced every year. DOT 4 fluid might give you an extra year. Our Type 200 fluid has a wet boiling point of 396 degrees, the highest of any glycol-based fluid I considered. I concur with the manufacturer's recommendation of a three-year interval between changes.

One last consideration on brake fluid is packaging. The smaller the container the better, and a steel can is much better than a plastic bottle. Moisture penetrates plastic containers, so it is 'wet' by the time you open it.

[Patrick B.]

[Joe L.]

Re: Dot 5 Fluid and CSSB Warning

Mark —- You are not appreciating the full implication of the non-hydroscopic property of silicone brake fluid. Water gets into brake systems because the regular hydroscopic brake fluid draws water into the system through the rubber brake lines. If you start with a dry brake system and use silicone brake fluid you will never have water in your system and you will never have rust. My 70 Corvette was used in some silicone brake tests by NHTSA in the early 70’s before silicone brake fluid was approved and designated DOT-5. I did not touch the brakes until about 2000 after the fluid had been in the car for about 25 years. The lip seals had taken a set and started to weep. However there was zero rust in the original non-sleeved calipers. I am sure my car is the only 1970 Corvette with the original calipers without sleeves and without rust. Do dot dismiss silicone fluid as unsuitable for 63-82 Corvettes. It does have a slightly spongy petal because of its compressibility but it is the best fluid for these cars and it poses no risk to expensive paint jobs. I would use nothing else.

Patrick-----

I agree.