Best type of brake fluid

[Houndawg76]

Greetings-

I am going to flush the brakes in my 1982 GS850L, and I was wondering what the best recommended type of brake fluid to replace the old fluid with.

 

[hillsy]

DOT4. Doesn't really matter what brand as long as you flush all the old fluid out.

 

[Brendan W]

Fresh fluid is the best. Everyone knows about the boiling point thing but at least as important in my book is flushing all the wear debris from the bottom of the system where it collects and contributes to piston pitting and seal damage.

 

[Nessism]

DOT 4 is fine.

Sorry to preach but many people don't realize how much crud accumulates inside the brake system. The old fluid coagulates and chunks form and once that happens the only way to clean it out is to tear down the system. Pop out the caliper pistons and inspect everything carefully. And replace those 40 year old rubber brake lines.

 

[SVSooke]

DOT 4 is fine.

Sorry to preach but many people don't realize how much crud accumulates inside the brake system. The old fluid coagulates and chunks form and once that happens the only way to clean it out is to tear down the system. Pop out the caliper pistons and inspect everything carefully. And replace those 40 year old rubber brake lines.

Yes all the brake systems need to cleaned,found that out the hard way.

 

[Houndawg76]

After reading everybody's responses and now that the weather decided to act more like November, I'm going to rebuild the brakes. Can someone tell me what the size of the banjo fittings are so I can order the correct size, or is it a universal size for most bikes of this vintage? I'm probably going to rebuild the calipers also.

 

[Nessism]

I'm not sure about the banjo size, but I do know there are a LOT of different brake line threads in the archives so the info is out there...

Regarding rebuilding the system, that's a very good idea. Pop out the caliper pistons and inspect the pistons for pitting before ordering any parts. The OEM Suzuki parts are still available and are vastly superior to aftermarket brake system parts like K&L. Parts Outlaw is one of the favorite Suzuki OEM parts sources.

 

[bwringer]

One note: don't pay extra for "synthetic" brake fluid -- all brake fluid is synthetic. And don't pay the nosebleed prices found in a motorcycle shoppe, unless you're feeling charitable. You will pay a little extra for DOT 4 as opposed to the more common DOT 3. The brand I usually find on the auto parts store shelves around here is Valvoline, but any brand will be fine.


Brake banjo fittings are 10mm diameter, which is pretty universal.

The banjo bolt threads on an old Suzuki, however, are 10mm diameter by 1.0mm thread pitch, so you do have to be careful if you buy new banjo bolts. (Most modern bikes use 10mm X 1.25mm thread pitch.)

Personally, I think the original banjo bolts are much higher quality than any aftermarket pieces I've seen, so I usually clean them up and re-use them.

And don't forget to order up a bunch of crush washers. I prefer the aluminum ones.


Lastly, you didn't ask, but do NOT buy the crappy incomplete imitation overpriced aftermarket brake rebuild kits. K&L is Krap. Visit your favorite online source for Suzuki parts and you'll be pleasantly surprised to find that OEM parts are correct, complete, and usually cheaper. The caliper piston set (part number 59301-45822), for example, is only $22.96 each at my usual supplier and includes a new piston and seals. The aftermarket set only includes shonky imitation seals and no piston for about the same.

http://www.onlinecycleparts.com/oemparts/a/suz/50d40200f8700230d8b4e633/front-calipers

 

[DohcBikes]

Surprised to see nobody mention DOT5.1, not to be confused with DOT5

There absolutely is a difference between synthetic and conventional brake fluid. While both begin life as a polyethylene glycol based fluid, synthetic manufacturers then add, regroup, and lengthen the molecules to change the performance characteristics and enhance longevity.

Hmmm, wasn't aware of the banjo thread pitch. I was thinking 10x1.25

 

[Houndawg76]

Thanks for all the info! The banjo bolts look OK, so I will go ahead and reuse them, unless they look corroded on the inside. My next question, how long are the brake line I need to order? I measured the originals, and they're 23 inches long from end to end. The replacement fittings I have looked at online seem to be 1 1/2 inches long, so do I order brake lines about 20-21 inches long?

 

[Nessism]

If you are handy with tools get yourself some Earl's components and make your own brake lines. No guessing on length, just cut to size. There is a long thread about making your own lines in the popular tech articles forum. It's great fun and cheaper than purchasing premade lines. All parts are made in usa too if you are so inclined to like that vs. China made parts.

Edit: here is the thread link. Tutorial photos on the last few pages of the thread...http://www.thegsresources.com/_forum/showthread.php?114521-Homemade-Stainless-Brake-Lines-Video

 

[bobgroger]

If you are handy with tools get yourself some Earl's components and make your own brake lines. No guessing on length, just cut to size. There is a long thread about making your own lines in the popular tech articles forum. It's great fun and cheaper than purchasing premade lines. All parts are made in usa too if you are so inclined to like that vs. China made parts.

Edit: here is the thread link. Tutorial photos on the last few pages of the thread...http://www.thegsresources.com/_forum/showthread.php?114521-Homemade-Stainless-Brake-Lines-Video

Many of us have had good results with Apex lines from Ebay. Here is a link to a 4-line auction. Ignore the brand, just include the fittings, length, orientation, and color. Good stuff, you will have it in 2-3 days. http://www.ebay.com/itm/BMW-MOTORCY...AKE-LINES-HOSES-HOSE-LINE-KIT-M-/401228791055

 

[bwringer]

All glycol-based brake fluids (DOT 3, 4, 5.1) are synthetic, no matter whether it has the word on the package or not. Glycols are synthesized, not refined like oil and gasoline.

That said, there certainly are differences in formulations between different brands and different grades of brake fluid, and the manufacturers certainly do adjust the formulations as you describe for different uses. And there are many different ways to synthesize glycols. In any case, the DOT specs do require brake fluids to be compatible with other brands when mixed, but overall it's best to try and stick with the same brand and grade to ensure that the additives and such are fully compatible.


But this is all nitpicking -- use any decent brand of DOT 4 fluid in your GS, change it every two years, use the same brand each time, and you'll be peachy-keen for decades to come. It's far more important to keep the fluid fresh and clean by flushing it every year or two than it is to quibble and dither about exactly which elixir is the best or whether the word "synthetic" means what you think it means.

Surprised to see nobody mention DOT5.1, not to be confused with DOT5

There absolutely is a difference between synthetic and conventional brake fluid. While both begin life as a polyethylene glycol based fluid, synthetic manufacturers then add, regroup, and lengthen the molecules to change the performance characteristics and enhance longevity.

Hmmm, wasn't aware of the banjo thread pitch. I was thinking 10x1.25

 

[hannibal]

I got my lines from this guy on Ebay: http://stores.ebay.com/Rennsport-Auto-Parts

Best prices I found and everything was delivered as ordered.

 

[bobgroger]

I got my lines from this guy on Ebay: http://stores.ebay.com/Rennsport-Auto-Parts

Best prices I found and everything was delivered as ordered.

Yep, that's the Apex guy.

 

[Houndawg76]

Got an update for everybody- I read Mr. Nessium's post on building brake lines, and I have ordered bakes line and fittings from ANfittings.com. I also got everything else locally (brake fluid, 1/4 in. vinyl tubing). I'll update when the goodies arrive.

 

[Houndawg76]

Got another question- should I go ahead and get new bleeder valves? The ones are original, and on the outside they look clean, but I wonder how clean they are on the inside. They have the rubber caps still on them.

 

[Nessism]

You should be able to remove them and shoot them clean with brake cleaner. Or replace them with new if that better suits your sensibilities.

Did you pop out the pistons and clean out the calipers? Cleaning out the bleeders doesn't add much value if the calipers haven't been cleaned out first.

 

[Houndawg76]

I haven't taken anything apart yet. We went from 70 degree weather right before Thanksgiving (got the bike out at that time) to the highs in the low 20's. I am waiting on crush washers, should be in this week. Forgot them in the initial order. I'm planning on cleaning and polishing the bores and pistons in the calipers while I had them apart- any suggestions on what to use for this?

 

[Nessism]

A gray scotchbrite should do fine. A soft stainless steel wire wheel on a dremel turning at low speed would work nicely to clean the caliper groove if there is corrosion that's hard to remove.