Author Topic: Adding mineral oil to Shimano hydraulic brakes for the first time.  (Read 418 times)

Tomorrow I will be cutting some hydraulic hose to length, and fitting to brake levers and calipers for a new recumbent build I'm doing.  My question is about adding mineral oil to the system (Shimano) for the first time. I've bleed the hydraulics on my mtn bike a few times but that's usually just adding a little oil / removing air.

I've found this Park Tool guide

https://www.parktool.com/blog/repair-help/shimano-hydraulic-brake-service-and-adjustment

Is this also a recommended procedure when starting with a hydraulic system that only contains air?

Re: Adding mineral oil to Shimano hydraulic brakes for the first time.
« Reply #1 on: November 11, 2019, 07:03:53 pm »
Inject it through the calliper and into the additional reservoir tank you’ve mounted on the lever. Let it settle. Then bleed back as usual.

I use this kit, and their website has good guides.

https://www.epicbleedsolutions.com/products/bleed-kits/universal/
We are making a New World (Paul Nash, 1918)

Re: Adding mineral oil to Shimano hydraulic brakes for the first time.
« Reply #2 on: November 11, 2019, 08:29:57 pm »
Thanks, now found that technique buried in a Shimano manual on hydraulics. Yes, got a bleed kit in readiness.

Re: Adding mineral oil to Shimano hydraulic brakes for the first time.
« Reply #3 on: November 13, 2019, 08:55:10 am »
I did a hose installation alongside a professional mechanic yesterday - new but partially drained components on an upright road bike.

We did:

0) Check lever adjustment is set to max, and calliper pistons are appropriately positioned. (We did this part way through.)
1) Bike angled so the hole in the hoods is horizontal, with a slightly-filled reservoir fitted.
2) Feed from a syringe at the calliper, until bubbles mostly stop arriving at the reservoir.
3) Swap out syringe for a drainage bottle (remember to bung and tighten the relevant orifices!).
4) Make sure there's enough oil in the reservoir and allow system to drain into the bottle until no bubbles.
5) Tip bike back so hoods at 45 degrees, frob levers and open and close bleed port (if we're thinking of the same Shimono doc, I think it's detailed here), keep going until you get pressure on the levers and bubbles have gone. Repeat with bike tipped forward 45 degrees.
6) Repeat for back brake. (We tipped the bike up loads to get a downhill run on the hose, then rotated the bars to get the right angle at the hoods. Have fun doing the equivalent with a bent!

The mechanic was also saying they'd ideally then leave the bike hanging up for a bit to allow any remaining bubbles time to work up through the system.

Isopropyl alcohol spray and lots of tissue and jay cloths!

All the best with it.

LMT

Re: Adding mineral oil to Shimano hydraulic brakes for the first time.
« Reply #4 on: November 13, 2019, 09:38:17 am »
What I done regarding putting hydros on my recumbent.

Does not matter ime if the hood is horizontal or not.

Remove brake pads and wheel, unscrew caliper from the frame.

Undo resevoir bolt on the hood and screw in the plastic container. Make sure it is tight but not overly tight so as to damage the seal.

Attach a 6 inch plastic hose (which you can buy from CRC) to the bleed hole. Attached at the other end of the hose is a sandwich bag tapped to the end with duck tape.

Fill container with mineral oil, reset the pistons with a plastic tyre lever if needed and insert the bleed block.

Pull the brake lever a few times to draw oil into the system Then undo the bolt next to the bleed port (depending the caliper you may have to undo a nut on the bleed port with a small spanner). Continue pulling the brake lever. After a few pulls you should see a steady stream of oil come through the hose. The lever should have some feel to it as well. Tighten bleed bolt and now there should be little to no give in the lever.

Remove plastic hose. Take off plastic container but let some oil drip into the port hole on the hood covering it. Reinsert port sctew in the hood. Remove bleed block and throughly clean the hood, caliper with a degreaser to remove any oil.

Let dry, reinsert brake pads, reattach caliper and wheel and you are good to go.

Re: Adding mineral oil to Shimano hydraulic brakes for the first time.
« Reply #5 on: November 13, 2019, 10:16:15 am »
I use this kit, and their website has good guides.

https://www.epicbleedsolutions.com/products/bleed-kits/universal/
+1
Recently fitted new caliper, shortened hose and bled using the kit and guides from Epic, very clear and easier than I was expecting.

Re: Adding mineral oil to Shimano hydraulic brakes for the first time.
« Reply #6 on: November 13, 2019, 12:41:16 pm »
Thanks all.

I injected the mineral oil from the brake caliper. I had an initial duh moment when injecting the front caliper and it was getting harder and harder and realised I had the reservoir tank attached to the left hand lever I.e. Rear brake. That'd be why no oil had appeared in the reservoir tank.  Once the right brake lever had the brake bleed nut removed and reservoir attached it was fairly straight forward.

The rear took longer to remove the bubbles as no easy way of getting the hose vertical. So I just slowly pushed and pulled the caliper syringe, with the odd brake lever pull, and tapped the hose, caliper and lever with the handle end of a screw driver.

Both brake levers now have a good firm bite and there is no leakage from anywhere. I've wiped down the caliper and lever but will give them a proper wipe down with soapy water later.

Tomorrow I'll probably get round to putting the pads back in and put the rotors back on the wheels. They were kept well out of the way of any oil.

It was approx 20ml of oil per brake.  Since I have a little under litre of mineral oil from my mountain biking hey days I think I'm set for life for annual oil replacement!