I tried topping off my swing brake fluid with ATF instead of the good stuff

Last month on a job in Mobile I ran out of the proper hydraulic fluid for my swing brake and figured transmission fluid was close enough. Next day the brake started grabbing unevenly and I nearly overspun the load into a steel beam. It cost me 6 hours of downtime and a $450 flush to fix what I caused. Anyone else ever try a dodgy substitute and get burned bad?

3 comments

3 Comments

riley_miller2523d agoMost Upvoted

Whoa, wait. You actually used ATF in a swing brake? That's wild man, I can't believe you even tried that. I mean I get being in a pinch but that stuff is totally different, it's got friction modifiers and crap that mess with the seals something fierce. You're lucky it was just a grabby brake and not a full lockup at the wrong moment, that could've been a real disaster. I've seen guys substitute cheap hydraulic oil for the good stuff but never transmission fluid, that's a whole new level of daring. Glad you got it flushed out but man, that's a hard $450 lesson right there.

bennett.mason23d ago

Jump right into what happens with those friction modifiers when they mix with brake fluid residues, it can create a weird sludge that clogs up the tiny passages in the valve body. Your mileage may vary but I've torn down a few brake systems that had ATF in them and the seals were all swollen and mushy, totally shot. Take this with a grain of salt but $450 sounds about right when you factor in the labor to chase down that kind of hydrolock issue.

susan13021d ago

Didn't you feel the pedal get all weird and spongy right before it started grabbing?