DOT 5

[bill440rt]

I run Valvoline synthetic DOT3/4 in my '69 with the Wilwood's, as they specified not to use DOT5 for some reason.
I'll be running the same stuff in my '68 (formerly stock drums now Master Power front discs), as Master Power also stated DOT5 would void any warranties. I may switch back to DOT5 once the warranty period is over as long as there are no compatibility or safety issues.

I would listen to the manufacturer's recommendation of what fluid to use if you are running an aftermarket brake system.

I was just thinking about your quote today, especially regarding Wilwood. Last I heard Wilwood says their brakes are for race application only but it's common knowledge that many people use them on classic cars out on the streets. IMO Wilwood classifies their brakes as race-only to avoid liability should they fail due to quality issues or if someone installs them wrong, etc. That way when someone plows into a tree or a minivan full of kids they can pull the "race-only" card. I understand this is just speculation on my part but if I'm right I can't help but think they're doing the same thing on the DOT 5 issue. This is one reason I probably won't be using any Wilwood products if I can help it. If they don't believe in their products it doesn't really give me much confidence in them either.

Curtis, I have to respectfully disagree. Are you saying they don't believe in their products based on your speculation? With ANY aftermarket brake supplier, the liability they have is enormous. They make BRAKES.
Yes, Wilwood does have a race-specific brake line. They also have a street line. They are a supplier for race, STREET, and OE applications. Says so right on their home page.
http://www.wilwood.com/

I'm certainly no poster child for Wilwood, and the thread originally wasn't about which aftermarket brake system to use, but what brake fluid to use. All I can say is with those applications, it was stated by the manufacturer (plastered on little paper flyers in each package, and confirmed verbally with tech support) not to use DOT 5. It's also stated in the manual (and I confirmed verbally) with tech support at MP.

Is DOT 5 compatible it those systems? I dunno. Would it work? Maybe. Perhaps. It might. I just didn't want to take the chance.
It's been working fine in my '70 (stock system) for about 15 years now. 

[FLG]

Exactaly,

Unless they weren't just a supplier and had people installing them, they simply can't take peoples word because bubba down the block decides to use a toothpick instead of a bolt and well gosh darnet it dun didn't work.

[John_Kunkel]

It's possible the Wilwood dust boots are made if silicone in which case silicone fluid will eat them.

[bull]

Curtis, I have to respectfully disagree. Are you saying they don't believe in their products based on your speculation? With ANY aftermarket brake supplier, the liability they have is enormous. They make BRAKES.
Yes, Wilwood does have a race-specific brake line. They also have a street line. They are a supplier for race, STREET, and OE applications. Says so right on their home page.
http://www.wilwood.com/

I'm certainly no poster child for Wilwood, and the thread originally wasn't about which aftermarket brake system to use, but what brake fluid to use. All I can say is with those applications, it was stated by the manufacturer (plastered on little paper flyers in each package, and confirmed verbally with tech support) not to use DOT 5. It's also stated in the manual (and I confirmed verbally) with tech support at MP.

Is DOT 5 compatible it those systems? I dunno. Would it work? Maybe. Perhaps. It might. I just didn't want to take the chance.
It's been working fine in my '70 (stock system) for about 15 years now. 

Lots of companies make brake parts and lots of them don't say anything about Dot 5 being unsafe.

[elacruze]

My specific example here is my '68 pickup, which had all original brake components. It also has a hydraulic clutch. I flushed the clutch and filled with DOT 5. 2 weeks later the clutch got spongy and didn't return cleanly. 3 days after that the clutch master went to the floor and stuck there. I kicked it loose, and the next time I pushed it the main cup blew out and left me driving home in second gear.
I had already flushed the old brake fluid and put in DOT 5 synthetic. 2 weeks later my master cylinder started leaking. 3 weeks later, my left front wheel cylinder stopped returning and heated up the shoes. I rebuilt all 4 wheels and installed a new master cylinder.
So in the course of 6 weeks every part of my original '68 rubber brake bits were eaten alive.

I tentatively used DOT 5 in the Charger, which has all new components except for the rear wheel cylinders which are circa 1984. I inspected the cup in the master before installing, and rebuilt the front calipers myself; they all appear to be shiny synthetic so I ASSUME and hope that they are compatible. It was a gamble.

Guess what's leaking right now?

My right rear wheel cylinder.

Out.

[Plumcrazy]

I tentatively used DOT 5 in the Charger, which has all new components except for the rear wheel cylinders which are circa 1984. I inspected the cup in the master before installing, and rebuilt the front calipers myself; they all appear to be shiny synthetic so I ASSUME and hope that they are compatible. It was a gamble.

Guess what's leaking right now?

My right rear wheel cylinder.

Out.

I'm not trying to be a smart a$$,  but do you think maybe the fact that the wheel cylinder was over a quarter of a century old might be the reason it's leaking?

[The70RT]

I put silicone in mine a couple years ago and have all new componets. I noticed my propotioning valve is leaking....i havent got the car together yet, it is leaking just setting there. I don't remember seeing anything with the paper work stating I could or couldn't use it. All I know is it cost me a lot of money and if I have to get a new one again   

[elacruze]

I tentatively used DOT 5 in the Charger, which has all new components except for the rear wheel cylinders which are circa 1984. I inspected the cup in the master before installing, and rebuilt the front calipers myself; they all appear to be shiny synthetic so I ASSUME and hope that they are compatible. It was a gamble.

Guess what's leaking right now?

My right rear wheel cylinder.

Out.

I'm not trying to be a smart a$$,  but do you think maybe the fact that the wheel cylinder was over a quarter of a century old might be the reason it's leaking?

No. The fluid was changed every 5 years or so and they had less than 1500 miles on them. I will verify when it comes apart whether there is any corrosion or if this is the result of the DOT 5. It's obvious that old rubber (probably natural rubber) deteriorates in DOT 5.

[John_Kunkel]

My specific example here is my '68 pickup, which had all original brake components. It also has a hydraulic clutch. I flushed the clutch and filled with DOT 5. 2 weeks later the clutch got spongy and didn't return cleanly. 3 days after that the clutch master went to the floor and stuck there. I kicked it loose, and the next time I pushed it the main cup blew out and left me driving home in second gear.

This is a well known phenomenon; the failure wasn't because of what you changed TO but rather that you CHANGED, period. Same thing often occurs when changing from dino oil to synthetic or from P/S fluid to ATF and the new fluid gets the blame but it's actually just a case of the old seals rebelling against the change.