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About to reassemble one brake caliper on rf of my '68 coupe. It is an frame-off and VERY slow moving project. Read where I can fill caliper with brake fluid (I am planning on using DOT 5) and til it flows out the bleeder. Finish date is several years down the road. Should I fill caliper or no? TIA
I would definitely fill it. In fact, I would bleed the system if you have enough parts installed to do that. The fluid will keep moisture out and help prevent seals and metal parts from oxidizing or drying out.
Are you intending to also work on the three remaining calipers? No sense bleeding one only to turn around and have to bleed three more.
Yes, planning to rebuild all three. They have been setting for about 22-23 years and the last thing I want is to take it out on it's maiden voyage and have the brakes fail! So SLOWLY but surely I will get them all gone through and then really start advancing on the project.
Yes, planning to rebuild all three. They have been setting for about 22-23 years and the last thing I want is to take it out on it's maiden voyage and have the brakes fail! So SLOWLY but surely I will get them all gone through and then really start advancing on the project.
In that case, I agree with the previous member who said not to install and bleed them one at a time. As you rebuild each one, coat the internal parts with DOT5, then pour a little fluid in and seal the hole until you're ready to finish the job. Good luck with everything!
If your set on DOT 5, I recommend DOT 5.1 so that it is compatible with DOT 3 and 4. Plain ole DOT 5 is not compatible with anything else. (glycol vs. silicone based). Unless your auto crossing, DOT 5 is an overkill anyway.
Two reasons; first it is not compatible with conventional brake fluid (meaning no DOT3/4 in a pinch). It's nearly impossible to remove it all from a system without excessive flushing later. Secondly it's also compressible meaning that under load it won't provide the same tactical feel.
It's only real benefit is that it does not eat paint. Which is great...I get that. And yes a lot of folks do like it. But aside from a show car/bike I'd not suggest it.
This is a frame off total replacement all new system, never had fluid in it before, so I am not anticipating any problems, but I may check into the 5.1. Thanks guys!
Just so you understand, the only difference between DOT 3, 4 & 5.1 brake fluid is the boiling point. They are ALL glycol-based brake fluids. Glycol based fluids are hygroscopic, which simply means that they attract and hold water molecules from the surrounding environment.
Most all DOT 3, 4 & 5.1 fluid sold these days is labeled "synthetic". This doesn't change the fact that they are glycol based and consequently hygroscopic.
DOT 5 brake fluid is silicone based fluid, not to be confused with "synthetic" brake fluid. Silicone brake fluid is non-hygroscopic, it does not attract water. This is the major advantage of silicone (DOT 5) brake fluid. It is particularly suited for hydraulic brake systems that do not see regular use. The Department of Defense switched much of it's rolling stock with hydraulic brakes to DOT 5 (they purchase it in 55 gal drums) back in the '80's primarily to reduce recurring maintenance, for which it has proven very effective.
There are some significant differences between glycol based brake fluid and silicone brake fluid. Depending on how you use your vehicle, one or the other may well be much better suited for your particular use
Brake fluid in caliper?
Should I fill caliper or no? TIA 
and the last thing I want is to take it out on it's maiden voyage and have the brakes fail! 
