DOT 5 in trailer surge brakes

[armytruck63]

Guys,
My brother gave me an old single axle car trailer with surge brakes. I opened up the master cylinder and found it was full of rusty goo. I will obviously need a new master cylinder and probably wheel cylinders as well.

My question is, can I use DOT 5 silicone brake fluid when I rebuild the surge brake system? I'm sure it was designed for DOT 3.

Should I just forget about the surge brakes and switch everything over to electric brakes? I will be towing this trailer with both my M1009 and my M35A2.

Thanks,
Matt

 

[Nonotagain]

I purchased a couple of the M105a3 trailers from GL a couple of months back that have surge brakes.

The brake system uses Dot 5 silicone.

Unless you can convert your trucks to use an electronic brake controller why not just flush the trailer brake system out and refill with Dot 5 and call it a day.

The only issue that I have with surge brakes is that its a bear to back up into my driveway since the apron has a two inch rise from street level and the surge controller activates the brakes.

A single axle car trailer can't possibly tow that much weight unless you have a mighty axle underneath.

 

[armytruck63]

I am leaning towrds the DOT 5 conversion. The trailer will be either used to carry a Mule or a Mighty-Mite, nothing heavier.

The real reason I got this trailer is because my wife saw me loading the Mule in the back of the deuce on two large planks. She freaked out and made me promise not to do that again.

Thanks.

 

[Jake0147]

First off, I can't see any compatibility issues, dot 5 will do just fine in that respect.

I offer for consideration though my opinion. Just an opinion, not fact or statistically proven data... Dot 5 will NOT absorb water, but it can not prevent water from getting in. Dot 3 or 4 will absorb water. When water gets in, damage begins. With dot 3, water stays in the fluid and therefore comes out with the old fluid. With dot 5, you have to push the fluid through fast enough to lift the settled pools of water from the bottom of the lowest spots, including the wheel cylinders/calipers depending on which you have. Either way, that's a lot of lifting for the amount of flow you are able to create when flushing out a brake system.

Like I said, just food for thought. I'm not knocking silicone brake fluid in any way, I just sometimes question it's practicality in something that isn't used much and/or has questionable ventilation control to it's master cylinder resivoir.

 

[papercu]

IMO the military only went to DOT-5 for certain military reasons and none would apply to normal civilian use.
As bad as you say your system is, you may need to replace everything. Would you want a rusted steel line blowing out? While if it does you may never notice it, the car behind you might.
If you do decide to go with DOT-5 the parts house should be able to tell you if the parts are rated for it. Wayne

 

[trog]

DOT 5 is usually about 98% silicone fluid with a little tricresyl phosphate added to give it the same rubber compatibility as DOT 3. So, DOT 5 is compatible with the same parts, but does not absorb moisture like DOT 3. If you buy a quantity of DOT 5 from someone who has a large quantity of surplus, you can get a good price and use it for every vehicle worth preserving. I have rebuilt many rusty brake cylinders and I LOVE DOT 5.

 

[Brock Steel]

I have 5 dot in all my toys and cars