Can a hydraulic brake line have invisible damage?

[spokewrench]

Almost 3 years ago I bought an Abound with Tektro HD E350 brakes. The front lever would pull farther than the rear. In the past month I've unclamped brake levers twice to change handlebars. There was no sign of leakage, but now I can pull the front lever all the way to the grip. Without being squeezed, both levers are 55mm from the bar, so they are clamped the same. I haven't checked pad thickness because hydraulic brakes are supposed to adjust themselves.

If the bike arrived with a damaged brake line, maybe it could be expanding at one spot when I pull the lever. Does that happen? I've replaced mechanical brake cable housings, but not hydraulic lines.

There's a recent problem with the rear brake, too. As I pull the lever, I feel it pass through a point of friction. Sewing machine oil didn't cure it. The lever is riveted, so I won't try to take it apart. I've read that over tightening the clamp on a Tektro brake lever can distort the cylinder, causing friction with the piston. On mine, I don't see how clamping force could distort the cylinder.

 

[fooferdoggie]

Almost 3 years ago I bought an Abound with Tektro HD E350 brakes. The front lever would pull farther than the rear. In the past month I've unclamped brake levers twice to change handlebars. There was no sign of leakage, but now I can pull the front lever all the way to the grip. Without being squeezed, both levers are 55mm from the bar, so they are clamped the same. I haven't checked pad thickness because hydraulic brakes are supposed to adjust themselves.

If the bike arrived with a damaged brake line, maybe it could be expanding at one spot when I pull the lever. Does that happen? I've replaced mechanical brake cable housings, but not hydraulic lines.

There's a recent problem with the rear brake, too. As I pull the lever, I feel it pass through a point of friction. Sewing machine oil didn't cure it. The lever is riveted, so I won't try to take it apart. I've read that over tightening the clamp on a Tektro brake lever can distort the cylinder, causing friction with the piston. On mine, I don't see how clamping force could distort the cylinder.

Sounds like you need to bleed it. It’s not too hard to get a kit and mineral oil and try it. I would not try replacing the housing; it's a hassle. It takes an especial cutter and tools, and you still have to bleed them.

 

[PedalUma]

@spokewrench, I agree with @fooferdoggie. Get the calipers far away from the rotors when removing them. You do not want the brake specific oil anywhere near the rotors. Remove the pads. Insert a spacer. Use syringes on both ends to remove and replace the fluid. Remove all bubbles, that takes time, pumping the levers with suction. Then replace the pads with bronze sintered. If you are not confident take it to a pro. Sewing machine oil sounds like a disaster. It could destroy the seals and O-rings. You may need to replace the enticer thing. Stopping is more important than going.

 

[Gionnirocket]

Sounds like a bit of air at the handle end which is most common.
I'd do a lever bleed first before doing a full bleed
It's much easier, less chance of mistakes and many times all that is needed.
Just match the fluid type. Tektro I believe are mineral oil based.

 

[spokewrench]

@spokewrench, I agree with @fooferdoggie.

You may need to replace the enticer thing.

I hadn't heard of the enticer thing. I asked Amazon, and this is what they offered.

https://www.amazon.com/WERHY-Electric-Adults-Folding-Bicycles/dp/B0GFN4BM8F/

 

[Gionnirocket]

Here we go again.... To smart to have a lick of common sense

 

[spokewrench]

Sewing machine oil sounds like a disaster. It could destroy the seals and O-rings. You may need to replace the enticer thing. Stopping is more important than going.

I think sewing machine oil is mineral oil. This bottle has a zip code, so it's not from before 1963, but it may come from the 1960s - somewhere between Surfin USA and Sugar Sugar.

It's Singer oil, and I didn't want my brakes to sing. I took the lever off, inverted it, and squeezed it a couple of times to be sure I hadn't gotten oil on the rod going into the cylinder. When I clamped it back on the bar, the friction point had disappeared. Now the lever can be pulled all the way to the bar. I guess squeezing it while inverted got air in the line.

I'd better put Singer oil on my disks. That way, pedestrians will hear me coming up on them and jump out of my way. Stopping isn't important to those of us with singing brakes.

 

[PedalUma]

Surely you must be joking. Yes, a top bleed is normally al that is needed. But once contaminated other oil is introduced, a full bleed is required. Tektro is mineral oil. It says it on the lever. It happens when kids wanting to do wheelies swap their levers instead of hoses. They have brakes until suddenly they don't.

 

[spokewrench]

Surely you must be joking. Yes, a top bleed is normally al that is needed. But once contaminated other oil is introduced, a full bleed is required. Tektro is mineral oil. It says it on the lever. It happens when kids wanting to do wheelies swap their levers instead of hoses. They have brakes until suddenly they don't.

The sewing machine oil was for the lever of the rear brake, which until now worked fine but had friction. It didn't get into the cylinder.

 

[Gionnirocket]

Surely you must be joking.

Anything is possible with invisible damage and please don't call me Shirley

 

[stompandgo]

If "damage" includes an improperly installed barb and olive, yes. I would not just bleed the brakes. I would remove the nut and inspect the end of the brake hose. The barb should be flush, The olive should be square on the hose, and the hose should have no creases near the olive. Reinstall and do a full bleed, as the fluid is 3 years old.

 

[PedalUma]

I like my olives pitted. Don't call me Barb. And I do not like getting hosed.

 

[Gionnirocket]

Ohhh that's just great!
Go looking for trouble and fix what ain't broke... smh...
And #1 why my bike will never see the inside of an LBS.

 

[stompandgo]

And I do not like getting hosed.

Something tells me that you do.

 

[stompandgo]

Ohhh that's just great!
Go looking for trouble and fix what ain't broke... smh...
And #1 why my bike will never see the inside of an LBS.

What's wrong with disconnecting the hose when you're going to bleed it anyway?

 

[Gionnirocket]

What's wrong with disconnecting the hose when you're going to bleed it anyway?

Well like I said I wouldn't do a full bleed or fluid change... I would just top it off with the lever bleed which only requires removing the lever bleed screw.
He said the problem developed after swapping handlebars a few times. To me this information points to air at the lever.. Which also happens to be one of the most common brake issues.
Then add with all the issues he has with bike repairs and tools he probably only has less than 1000mi on the bike so I would K I S S

ymmv

 

[spokewrench]

Surely you must be joking.

I got in trouble for a similar joke Saturday. The 65-year-old guy across the street asked if I would help him load the box with his Adventure 3 on his truck so he could take it 20 miles to a dealer, where it would wait 3 weeks to be assembled for $100. He was reluctant to believe it was easy enough for me.

I brought a tube of grease for the pedal threads, but I soon realized he'd insist that I open the 1ml foil pack that came with the bike because it was labeled "bike grease." After it was assembled, he asked what the remaining grease was for. I said the brake disks. He asked what they were. I pointed. When I realized he didn't know it was a joke, I confessed. I said contaminating a disk with grease or anything else would cause regret.

Now it was the time for him to adjust the saddle to his liking. He insisted that I be the one to ride around and adjust the saddle according to what I thought would fit him. That left tire pressure, which was 27 front and 17 rear. The sidewalls said 30 max and 5-15 recommended. I said I'd brought a pump but nothing to bleed off pressure. He said I didn't need to let air out. He wanted both pumped up to 30 because he weighed 232. I said it would be better to try it in the recommended range. In the end, he agreed that I could leave the front at 27 if I would pump up the back to 20.

Then he came back to greasing the brakes. He'd forgotten that I was joking. Now every week he'll be after me to grease his brakes.

 

[PCeBiker]

Just match the fluid type. Tektro I believe are mineral oil based.

Yeah, they're labeled,..

@spokewrench
Just an FYI,..

Mineral oil for brakes isn't the same as regular mineral oil.
Brake oil is refined to be as thin as possible but still have a high boiling point.

Regular mineral oil is thicker (more viscous) and the brakes would feel sluggish and less responsive.
It does work though, and you can use it in a pinch.
You can also use baby oil if you want your brakes to smell like a fresh diaper.

Calipers That Will Not Adjust Straight

I checked my brakes again and took some pictures,.. It turns out that the caliper spacer is countersunk, so there is actually a flat surface that could do some sealing and accommodate an o-ring,.. I don't think that's it? The spacer hole is only a smidgen bigger than the bolt. The...

forums.electricbikereview.com

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[Gionnirocket]

I assumed so as my TRP/Tektro are mineral oil... but I didn't want to make a blanket statement for all models and/or past products.

 

[PCeBiker]

I assumed so as my TRP/Tektro are mineral oil... but I didn't want to make a blanket statement for all models and/or past products.

Do you know of any hydraulic brakes for bicycles or ebikes that Don't use mineral oil?

I've never heard of DOT 3 oil on a bike.
My motorcycle was DOT 3 (or 4?) though.