On Mon, 16 May 2005 13:30:47 -0000, (Gudmundur)
wrote:

In article ,
says...

On Mon, 16 May 2005 02:12:13 GMT, "Rob V" wrote:

Quick question.
I have a new Dorsey trailer w/ surge brakes.
I checked the fluid level today when we got back from the lake and it looks
low.

What kind of fluid should I use to fill it - brake fluid or hydraulic fluid?

My FIL says hydraulic - but I think brake. I dont have the manual and I
cant find it online any where.

Your father in law is right in one respect - brake fluid is a type of
hydraulic fluid. However, you need to use brake fluid and I suspect
that Dorsey recommends DOT-5. DOT-3 isn't recommended for immersion
in water.

As Dorsey is no longer in business, play it safe - use DOT-5.

Later,

Tom

It is very important to know if the system is a DOT 3, or DOT 5 system.
DOT 5 fluid is silicone based, and will within about 3 days time, attack
and destroy all the rubber cups used in the brake system if they are also
a silicone rubber molding. MANY ARE!! Several folks here have added
DOT 5 to their DOT 3 system, and the mess is expensive to repair. DOT 5
has a distictive purple color, and to an experienced eye, it is easy to
tell if it is a 3, or a 5 system. SS is correct that DOT 3 is a stupid
choice around water, but about 80% of the surge brake systems I have ever
repaired were in fact DOT 3. The rubber cups must be rated for a silicone
type fluid, otherwise the cups just simply dissolve into a black gooey mess.

Well I'll be damned - I didn't know that - I thought they were forward
compatible.

http://www.bobbyarchermotorsports.com/pdf_2848_2.pdf

My bad - should have looked first. Thanks for the correction.

Later,

Tom