SRAM brake fluid & bleed question

My Force brakes are due for a bleed - the left/front feels fine, but the right lever goes right to the bars. I bled them when I installed everything maybe 2 years ago, but I need new fluid so just wanted to consult the experts.

  • SRAM states you don’t have to use their branded brake fluid as long as it’s DOT 5.1. Has anyone used fluid from the auto parts store? Seems to be a quarter of the price.

  • How much do you think I’d need for a full bleed of both front/rear? If I go with the SRAM fluid from my LBS, it seems to come in a 4 oz container. Not sure if that’s enough but I don’t want to buy too much.

Thanks!

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autoparts brake fluid is fine, even dot 4 will work IME.

4oz is more than enough, typically the smallest container at the auto store is 12oz.

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Following. I’m in the exact same situation - left/front is fine, right/rear lever pulls to the bar.

What brake bleed kit do you have?

Also, any idea why / how / where the brake fluid went? I haven’t noticed any leakage from the caliper, connections, or brake lever. Hope the hose doesn’t have a pin hole leak and my frame isn’t full of DOT fluid!

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I wish I knew where it went! :melting_face: I’ve never seen a leak. This bike spent most of the winter in my basement on the trainer and the brakes were fine last fall!

I have this kit. It was pretty easy to bleed when I build the bike up ~2 years ago.

As your pads get thinner, pistons extend more, more fluid is pulled into the calipers, that’s one possibility. So, if you’re going through the trouble to do the work, I would start with fresh pads too.

Brake fluid should be replaced periodically anyways, it absorbs water and starts to become less effective. This is an argument for using the smallest you can find, because if it’s been sitting around for too long after opening, you’re probably better off buying a new bottle just to be safe

(Lost my rear brakes coming down Columbine at Leadville on a training ride last year - not a lot of places you’ll run into that on the east coast though)

FWIW, DOT 3, 4, and 5.1 are compatible. The higher the number the higher the temperature range. Sram fluid is 5.1 though they say you can use DOT 4. (DOT 5 synthetic is not compatible.)

In a pinch, I’ve used DOT 3 on my Sram Force brakes and it worked fine. It was what I could buy on the spot at my local store.

It definitely doesn’t seem worth it to buy 4 ounces of Sram fluid for $10-20.

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Same here!

New pads were installed in the fall. I’ll double check them, though.

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Thanks @Pottery @AJS914 ! Found a 250ml/8.4 oz bottle of DOT5.1 at my local auto parts store for $9 vs $14 for 4oz of Sram.

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You may not need to replace the fluid, it’ll depend on the condition. If it looks milky/discolored or has particles, dump it and pump new in, otherwise remove all air properly and you’re good to go. I just bled both my brakes after two years (gravel/CX bike) and the fluid was fine.

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image

screw the lid on tight after this bleed, and keep the bottle in a climate controlled place (inside the house, not in the garage for example) and it should be good to use for a second bleed in the coming years :slight_smile:

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I just use dot 5.1 for cars. You only need a very small amount, maybe 50-60 ml in total, and only a small fraction of that stays in the system (you need a bit more to flush it through).

Dot fluid is hygroscopic, and will draw water over time, so they don’t recommend using an open bottle again after a few months (I may or may not follow that recommendation :zipper_mouth_face: ) Basically, don’t buy a big bottle of it, unless you do several bikes.

The fluid in the system also draws water, which will make it less temperature/fade resistant over time.

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Don’t forget to push the pistons back before you do the bled. Take the pads out and put a bled block in whilst you do the bled to prevent contamination. You may of course already know this…

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Just did the front lever for my cx bike on saturday. I had washed it after sitting all winter and found even with the handle at the bars the pads barely moved.

I just used one of the sram channel brake bleed videos to guide through the process, Make sure to secure the bleed block… you don’t want to blast the piston out of the caliper. And dot fluid is a bit nasty on your hands, so do wear the gloves and have lots of shop towels on hand. Go a bit slow with the dot fluid degassing as the plunger seal can fail and actually introduce more air (although I’ve heard people say you don’t really need to do this, which would speed things up a bunch).

Also, In case this does anyone else some good, I’ve had this annoying loose jiggle in the lever for a while. It’s apparently due to friction in the master cylinder that the spring can’t always overcome. It can be fixed per this video put out by a local shop. This looked a bit intimidating but was almost easier than bleeding. In my case, I first bled the brakes but they still didn’t really work. I did this procedure and found my master cylinder was actually stuck. I had to pressurized it from a bleed port to pop it out once I was inside the lever.

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My bleed kit should arrive today. I plan to flush my brakes and replace all of the fluid. About how fluid is needed for the rear brake system (eg piston, hose, and calper)? I ordered a second 4 oz bottle of DOT 5.1 fluid in case it takes several flushes.

Should only have to flush it once, unless you mess it up and have to redo. Doesn’t take a lot of fluid. I would estimate you can get 2 full bleeds (front+rear x2) out of the 4oz sram bottle. I bought some dot4 fluid just in case I ran out, but still have some in my original sram bleedkit bottle.

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About 25mL with a bit more when bleeding.

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Success! Thanks for all the help answering my questions. Below was my makeshift setup. We’re camping with our homeschool group so I brought the bleed kit and a bunch of tools to work on the bike while the kids played after breakfast. Bled the rear brake (front is fine), and adjusted my cockpit setup by rotating the bars forward to make the drops more comfortable, slide the levers up to keep them in the same relative position, and angled then inward for comfort. Even got a 50-min Z1 ride in with my 13 year old to test it all out.

What do you do / how do you store the plungers and tubes that had DOT fluid in them? Do you clean them in any way?

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I drain all the fluid from the syringes, and give everything a wipedown with dry paper towel before storing in a locking/gasketed plastic storage container.

If you’re using them very sporadically, it may be good to remove the plunger from the syringes so that the o-ring is not compressed. However, replacement o-rings are usually included with the sram kits.

No need to wash the pieces imo, avoiding water is best and they are a pain to fully dry out etc anyway.

image

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From experience, don’t leave the fluid in the syringes. Because that means you have the clamps locked. And year or 2 clamped will put a very permanent kink in the hose.

In a completely unrelated question, anyone know what kind of tubing is needed to replace them? :stuck_out_tongue_winking_eye:

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SRAM suggests rinsing with alcohol, so I do that. Works well enough.

And yeah, don’t leave them clamped … did that too :grimacing:

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