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Brake fluid debate is OVER!!

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healeyboz

healeyboz

Jedi Knight
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I finally did it! I was going to change from dot 3 to dot 5 this winter for all of the reasons we have discussed in the past. I was touching up a few spots in the engine compartment before she goes in to get painted this weekend and noticed a bit of red fluid on one of the front wheels. The old fluid has eaten the seals out of the calipers as well as the master. All is dismantled and striping the paint. Flushed the lines with dot 5 and soon to rebuild everything! /bcforum/images/%%GRAEMLIN_URL%%/mad.gif
 
I agree. I do think that the only way to be successful is to completely rebuild or replace all the cylinders, flush the lines with solvent, and then <u>replace</u> the flexible lines. The seals supplied in the new cylinders and rebuild kits are not made from the same rubber orignally that was not compatible with DOT5. The new rubber seems to hold up fine. I converted my Sprite 4 years ago with no problems. I will do my MGB soon because I am beginning to see the old DOT3 problems with it. The very thing that makes DOT3 safe (water absorption) is what causes rust inside the cylinders. Four years with silicone and it is still clear. I am over due to flush it. You should flush DOT5 every couple of years beacuse it can collect a water bubble. That's my opinion, I hope it does not spark another debate.
 
I am glad to hear that you have not had any problems. I did leave the slave cylinder in place. And all of my flexible lines are braided. I believe all is flushed thoroughly with dot 5. Dunno? I guess I will find out!
 
And may I ask how you flushed it? And how much fluid you used?
 
Even the braided lines have rubber in them. I would just feel better knowing that all the rubber was new so that it had not absorbed the DOT3. But it will most likely be fine. The two are not compatible, so I would flush with something that would mix with the DOT3 and evaporate when air was blown through it like, dare I say lacquer thinner. My favorite all purpose solvent. Others have recommended alcohol. The DOT5 is too expensive to be wasting it to flush lines.IMO
 
Aren't some of the braided lines lined with some type of teflon?

I agree about the cost of DOT5.
 
I agree with the cost as well. It cost me about $14 to flush the lines. I thought about flushing with alcohol, but I think I got it all flushed. The final time I flushed everything I left the new Dot 5, which is purple, in the pneumatic container. If there was any left it should separate and cause some worry.
 
I started using DOT 5 11 years ago. And in that car the only hydraulic failure I had was the slave cyl.
All the brakes are still fine 11 years later.
I have DOT 5 in my 58 and 59 Sprites too.
I had it in the Rally Midget too. Everything!
And no more peeled paint, no more leaky cylinders.
Alcohol at about a buck a pint is a lot cheaper to use when flushing the lines but I still recommend a complete hydraulic replacement including the lines, hoses, and cylinders before making the switch.
Also DOT 5 eats pressure operated brake light switches, they last about 2 months max if you use the car. I already replaced 2 in the 58 Sprite which I finished last Feb. I have since installed a pedal operated brake light switch on that car.
The Austin is more of a challenge, I just keep replacing the pressure switch every few months. My 59 has the later pedal box with a contact switch.
But it's easy to make up a contact switch for the early pedal boxes.
 
I was considering doing the change, but after reading about the problems with the brake light switch, I may need to rethink it. Although, coming up with a switch that is pedal actuated should not be that difficult. I currently have the pedal box out, and could rig a bracket to hold a small switch, and then just run the wiring to the box.

Something to consider.
 
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