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DOT 5 fluid in aftermarket metering/proportioning valves

Grady Cain

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Anyone having issues with leaks after using DOT 5 silicone-based brake fluid in these aftermarket valves from Inline Tube? I just had a PM conversation with an FEBO member regarding this issue so I went to the source; a Support Tech. at Inline Tube and got some interesting answers to several questions I had:

I just got off the phone with Greg in Technical Support at Inline Tube and he told me NOT to use DOT 5 fluid in their metering/proportioning valves.

TAKE ALL OF THIS FOR WHAT IT'S WORTH - WHETHER OR NOT TO BELIEVE ANY OF THIS IS UP TO YOU. I AM ONLY REPORTING WHAT I HEARD DIRECTLY FROM HIM.

I asked him why this information was not on their website and he stated that this was something they have only discovered "...within the last 2 weeks" and that the common link to the leaks from each plaintiff was DOT 5 fluid.

I asked him if this was something the company was looking in to and he told me that they would be looking to their supplier/manufacturer of the parts to see if they are supposed to be or will be updated to be compliant with DOT 5.

I asked him if this only applied to recently manufactured parts (I told him I purchased mine in 2015 but haven't filled the system yet) to which he stated that he would still NOT use the older parts. He said he had one that was purchased 6 months ago being the oldest one reported to fail.

I asked if the leak(s) appeared right away. He said, "No, they appear some time after being in service. The seals swell due to the silicone causing the leak(s)..."

I asked how Inline Tube was handling this issue regarding replacing parts that have leaked. He stated that they are shipping out replacements to anyone that had an issue.

I did not ask him how many people have had this problem but he did tell me that he had at least 5 persons calls this week with this issue.

Now be advised that if you go the DOT 5 route and have a leak in one of the valves and get a replacement part(s), you would have to completely flush out the entire brake system and go back to DOT 3/4 which is an incredible task to make sure there is no silicone left in any the components.

I would like to know if other manufacturers are having the same issues with their aftermarket metering/proportioning valves or if any other members have experienced this.
 
I have heard if you mix fluid types it will cause a problem. I have never heard of it swelling seals when used with new parts.
I believe it is generally safer to use DOT3 or 4.
I had a Harley Davidson and it specified on the master cylinder lid DOT5 so they must be OK with it.
 
All of my rockauto wheel cylinders, M/C, and hoses are OK so far after 1.5 years with DOT 5.
 
Must be that just their manufacturer is supplying them with junk? Out of the thousands of metering/proportioning valves that Inline Tube sells, I have to imagine that a fairly decent percentage of those installed have DOT 5 put in them. I can't imagine that all of them leak. The FEBO member I was discussing this with called Inline Tube today and spoke with someone different than I did. When asked why they are not telling people about their valves leaking if you use DOT 5 (ie: via their website), he was told that "...DOT 5 has only been out on the market for a few years and they haven't had time to update their literature yet..." Seriously? Silicone brake fluid has been around for 40+ years in military applications and has been in passenger cars and trucks for many, many years.

I guess what I'm trying to get at here is does anyone seriously think that it is the DOT 5 fluid causing these few reported leaks? Or is it more likely just a small batch of defectively manufactured parts that got out there and now every one Inline Tube has sold is getting condemned?

Yes, I guess I'm looking for opinions here. I used DOT 5 in my '68 Bee which had a completely original brake system without any issues. My A12 car has all the original brake components in it but my T/A has an Inline Tube metering/proportioning valve set and I was planning to run DOT 5 in it. Now I'm not so sure.

I appreciate those of you who responded and am curious to hear from as many people out there who use DOT 5 in their brake systems that have aftermarket valves...
 
I have had Silicone brake fluid in my '59 Imperial for 30 plus years. The comment above about the brake parts supplier tells me the rubber components are not Silicone compatible thus making them prone to leaking and failure. The best example of what I mean is the brake light switches on the master cylinder. I was going thru one every 2 or so years. The would not work at all. Finally someone suggested I use a Harley Davidson brake light switch. I went to that and never replaced (eight years ago). The only difference is the threads are metric and I had to get a short adaptor. They look exactly the same.
 
Yeah, this has always been a debate. I have a hot rod shop here that only uses DOT5. Only comment I heard from them is that after a few days they'll have to snug up a couple lines when using stainless lines. Never any issues.

I've used White Post restorations a couple times now on rebuilding MC's and WC's. They make it very known that they do not want you to use DOT5 in anything they rebuilt. Voids the warranty. Loud and clear on the documents that come with your rebuilt brake part. Never asked they why but they seem stern about it.
 
I had some wheel cylinders sleeved years ago and a red label inside said "Do Not used DOT4.
 
Different "O" rings for specific applications, engine oils, hudraulic oils, kerosene, gasoline, air, Silicone, etc...Chemicals added to rubber for very specific applications.Most chinese **** will leak with Silicone, it melts it over time. I run Dot 5 in all my rides, no issues with North American made rubbers.

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I'm a DOT5 guy. We like the Cartel DOT5 brake fluid made in Michigan. I have heard of a few DOT5 failures in cars that were not driven and stored in non-climate controlled areas. Typically the fluid was reported to have sort of crystallized where you would normally find water/rust in the wheel cylinder. Personally I think main reason that DOT5 gets a bad rap in street/track applications is variance in manufacturer quality. I HATE the stuff in the green or purple bottle that most chain stores (napa, Autozone, etc.) carry. It seems to get aerated very easily. The Cartel fluid does not have that issue. I think we have five cars currently running DOT five.
 
Curious why one would choose to run DOT5 fluid other than it being the 'latest & greatest'? All the other glycol based brake fluids should far surpass any conditions the old brake designed systems will ever encounter in these cars.
 
M/C stays painted and doesn't rust and you don't risk a spill or leak ruining your paint.
 
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