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Dot 5 vs. everything else

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I thought of this thread the other night when my Son and I were refilling the master cylinder on his rpu. When we pulled the body off to remove the motor and transmission he had to disconnect the brake lines, his mc is one of those Kugel Komponents sideways ones under the dash. Anyway, as we were refilling it with a funnel a drop splashed onto the paint on his cowl. Since it was Dot 5 it wiped right off, if it had been regular fluid it would have ruined the paint job.

As 2old2 fast said, no matter how careful you think you are, sooner or later....................................:oops:

Don

Don, that's why I have always had a bottle of water whenever I'm filling the resovoir or mastercylinder. It[water] is the only thing that I know of that will stop it from eating paint.
​
 
Here's an interesting question... If you lived in So Cal. and have the ability to drive the car, lets say 9 outta 12 months. And you have the old 50's f-1oo style brakes in both front and rear without a booster. What DOT fluid would you choose in this application?
 
Either Dot 3 or 5 would work fine. Like I mentioned, my only reason for running Dot 5 is I don't want the paint on any suspension or body parts messed up with Dot 3 when bleeding or if I get a leak.

Don
 
I think that you are referring to DOT 3 about paint damage, Don, not DOT 5.

Jim
 
I ran 5 in the bucket for over 180,000 miles and the brakes seemed ok, (thought the same thing paint)but when H-D switched to 4 because of anti lock brakes I decided to try it too (been wrenching H-D for over forty years). Yes there is a difference, firmer pedal and less pedal travel for the same amount of braking. With the m/c being lower than the calipers or cylinders on most buckets the air most always will collect at the wheel. I haven't tried everything but this was the one thing that I changed that generated the biggest improvement.
 
EX JUNK said:
I think that you are referring to DOT 3 about paint damage, Don, not DOT 5.

Jim
Click to expand...

Yeah, I hit the 5 instead of the 3 key, and by the time I went back to edit it my 10 minutes had elapsed so I had to leave it. You are right Jim, I meant Dot 3 would damage the paint.

Don
 
Rogers23T: Sure I'll try and explain. Pedal pressure did not change but pedal travel did approx.1/2" - 1" higher and that is most noticable after being on the road for a couple hours without using the brakes. I'm using a pair of H-D fixed 4 piston calipers with .250x11 rotors up front and 4 Vette non parking brake floating single piston calipers with .875x11 rotors on the rear with a 3/4" aluminum dual m/c 7-1 pedal ratio, 10lb. line valves front and rear no proportioning valve. Flushed the 5 out with the cheaper 3 and then added the H-D 4 and changed nothing else in the system. The rubber parts will work with either one, H-D did it twice and it's still working for them. My m/c to caliper to tire size ratio is such that if need be all four can be locked up evenly on dry pavement. The vette caliper is approx. twice the size of the H-D up front and there are two of them on each wheel, but those 31-18.5x15's are 4times bigger than the 165x15 up front. It takes between 800 - 1000 lbs to lock up on dry. That's my story and I'm sticking to it.
 
I talked with wilwood guys over the weekend I explained my brakes and usage along with concerns. They suggested I use DOT 4 and flush the system every few years to keep water and dirt contanimation down to a minimum. Also told me to never use a bottle that has sat around for like a more than 3 months. Possible water issues... Something I just wanted to share with you guys
 
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