Is there anything in the hydraulics on the '04/'05 Sports that would make them incompatible with DOT 4? I noticed that the '06s have reverted to DOT 4. I have always felt that I feel somewhat 'removed' from the braking by using DOT 5...I had tried it on other bikes only to give up and return to DOT 4...primarily because of 'feel'. Would like to do so on the Sport after warranty expires.

Kim

Brake parts companies tell me there's no problem in terms of seals and hard parts, but rather that the problem is in the difficulty of purging the system of DOT5, something about how you shouldn't mix DOT5 with anything else... uniquely silicone based... getting foggy.

Assuming that's true, I would think that if you diassembled and fully cleaned everything, calipers, pistons, etc, you'd be OK.

The big question is why would you want to?
DOt 4 is a water soluble oil, it is cheaper, but is also soaks up water like a sponge, and that is what corrodes your brake components. It also has a much lower boiling point, thous the bakes will wash out at a much lower temperature.

Bottom line, it is a bad Idea IMHO.

The big question is why would you want to?
DOt 4 is a water soluble oil, it is cheaper, but is also soaks up water like a sponge, and that is what corrodes your brake components. It also has a much lower boiling point, thous the bakes will wash out at a much lower temperature.

Bottom line, it is a bad Idea IMHO.


Plus it can damage your paint if it is spilled on it...

Kim,

If you want to convert, go for it. But be sure to clean out the system REAL well. Might be a good idea to rebuild your calipers at this point, that way you can be sure that there isn't any old DOT 5 hanging around anywhere in the system.

If you do this, go with DOT 5.1, it has the same wet & dry minimum boiling point as DOT 5.

DOT 5: silicone-based.

DOT 3, 4, and 5.1: glycol-based.

DON'T DO IT!!! Dot 5 brake fluid is some real tenacious stuff and getting it completely flushed is not going to happen. When you pour that Dot 4 brake fluid in there you'll ruin the brake system. I prefer Dot 5 brake fluid anyways. Harley-Davidson and the US Military (the military may have switched though) are about the only two organizations that use it. Yes, it causes spongy brake feel, but it's synthetic and won't ruin paint when spilled, won't absorb water, and has a very high boiling point (higher than Dot 4). It really helps with keeping corrosion out of the brake system.

My guess is the MOCO is going back to DOT 4 to save a few bucks. Sure sounds to me like we DOT 5 users have a better fluid in our braking system. If you want more "feel" I would suggest a switch to braided brake lines instead.

Sure sounds to me like we DOT 5 users have a better fluid in our braking system. If you want more "feel" I would suggest a switch to braided brake lines instead.

If I didn't screw up my history here, then the moco originally switched to DOT 5 for one really big reason; hamfisted mechanics were ruining very expensive paint jobs and guess who had to pick up the bill.

As for DOT 5 being better that's really up in the air. The two places DOT 5 really suffers is that it can't be used with ABS and the so called spongy "feel" (that makes racers discriminate against it). However, (not 100% sure here) it does give you quicker response at the brakes as the fluid flows quicker; they just feel spongy.

I have heard that steel braided lines will fix or vastly improve the spongy feel. I have never tried it out and at this point I will consider it a rumor as I haven't seen it mentioned often.

Oh ya, and for those that care; DOT 5 is a synthetic brake fluid while the others are not. Technically, the other ones can be synthetic but tend not to be while DOT 5 is synthetic.

I added a braided stainless steel front brake line, and the front brake is noticeably stiffer. For the trouble of having to clean everything thoroughly and having a chance to ruin your paint, I would pay the 45 bucks, and get a braided stainless line.

my .02

Cory

Thanks, all, for the insight. I know that DOT 5 is the only readily available brake fluid that is not hydroscopic and that it is less likely to attack painted surfaces...I just didn't care for the spongy feel. My brakes work fine, so I expect braided lines will be in my future. I really like the black versions, but don't think I have seen them in anything other than 'roll-your-own' versions...which I don't mind doing. Hopefully, banjos to fit the '04 and up bikes will hit the distributors soon.

Kim

*ahem* we can make you a set of black-coated braided stainless lines with swaged fittings. Galfer will make us custom lines to your spec at the factory. $59.95 per line. They also come in a couple of different standard configs for the dual-disc bikes, with the proper (10x1.25mm and 12x1.25mm) fittings for the '04s.

Best regards,