Dragging front drivers side brakes

[Ducked]

Originally Posted By: Tegger
Originally Posted By: Ducked
AFAIK there was no brake fluid ahead of the seal before I put it there, because the seal was still, like, sealing.

I think that doesn't say much for any alleged penetrative properties of brake fluid. If brake fluid had penetrative properties, would it not have been present on the outside of the hydraulic seal if rust were present? Or is this thought also too hypothetical?


No. Its thought to be too bloody silly.

OF COURSE brake fluid is penetrative. Unlike grease, its a liquid, which flows and is subject to capilliary forces.

Saying it isn't, because the seal keeps it in is like saying hot engine oil isn't penetrative, because seals keep IT in.

Or penetrating oil isn't penetrative, because if it was you'd never be able to keep it in the bottle.

(Most) bullets bounce off (most) tanks, but they penetrate uniforms with distressing ease.

Its a RELATIVE TERM.

Originally Posted By: Tegger


Originally Posted By: Ducked
Dunno if its done any good (the main resistance is probably rust behind the seal,

Rust on the piston itself. Rust on the bore will have little to no effect. THIS is what sticks-up a piston:

Sure. I didn't say different.

Originally Posted By: Tegger


You can go on a voyage of discovery for yourself and see if your piston is similarly decorated.



That's the plan, and thanks for the permission, though it does seem at odds with you not thinking I should work on my car.

Originally Posted By: Ducked
I can't see why it would do any harm.


Originally Posted By: Tegger

No harm, but it did make an ineffectual mess for you, which silicone grease (or red rubber-grease) would not have done.


I don't know if it was effective, though it was certainly easier, cheaper, and less messy than grease would have been. Perhaps optimally I'd have done both.

However, to justify your original "I don't think you should do mechanical work on your car" it'd have to be definitely damaging and/or dangerous. Phooey.

 

[Tegger]

So, have you managed to get the piston out?

 

[andyd]

I refresh the calipers as needed on my BMWs . I leave the caliper attached to the brake hose and slowly pump the pedal until the piston extends far enough to grab it with pliers. I clean up the piston with a wire brush, If it has rust, I use a small file to smooth it. I use silicon, but brake fluid will work too. Lube the piston and the cylinder bore. With the bleeder out, start the piston back in. I use a C Clamp and hammer taps to keep it straight as it goes into the bore past the dust seal, which I leave in place. Only purchase is silicon lube or brake fluid.

 

[Ducked]

Piston is out. When it was about half way, I eased the boot back over the piston, pushing it back with chopsticks (bit of local colour there).

After the first rather sudden "give" I tried to use...er..short strokes, to minimise the risk of master cylinder seal damage.

A lot of gritty, rusty sludge in the caliper cylinder, but it cleaned up quite well. There was quite a lot of barrel corrosion ahead of the seal, and some light pitting of the corresponding part of the piston, but not much corrosion behind the seal, suggesting the sludge came from elsewhere, presumably master cylinder and/or pipework.

The piston had some black "varnish" stuff adhering, which I'd guess was transferred seal material. I removed most of this, and I suppose it MIGHT have been contributing to the sealing, so maybe it'll leak when I put it back together.

I put silicon grease behind the dust boot, but found it impossible to get the piston back in with the boot in place.

I thought of cutting it and using superglue after assembly, (which I'd already used to patch a hole made when initially trying to remove it), but the silicon grease (which is effectively impossible to remove) would probably have stopped that working.

Having nothing to loose, I tried harder, and was eventually able to loosen the circlip from its bed of heavy corrosion and get the boot off, without causing it much more damage.

Scraped out the boot-groove, but have to do some work now so it'll probably be a while before I try putting it back together.

I'll post some pictures later.

 

[Ducked]

Caliper on first removal.



Back on car during piston removal with hydraulic pressure, after partial clean-up and failed attempts with compressed air.



Piston on first removal. Euew!



Bottom of piston on first removal. Euew again.



Sludgy Cylinder Base



Cylinder Rim Corrosion



Cleaned Piston



Dust Boot Out



Dust Boot Seat Corrosion



Partly Cleaned Dust Boot Groove (Bore looks rusty but its mostly rust from the seating groove sticking to silicone grease)

 

[Tegger]

It's interesting that your piston is not rusty, but instead was gummy. It makes me suspect that the original lubricant was not silicone, but some sort of petroleum-based grease.

Silicone is not any kind of barrier against water, and tends to allow rust to occur on the exposed portions of the piston (under the dust boot, but ahead of the hydraulic seal).

As for the rust on the dust-boot lip area, that is very common. I just scrape away as much as possible and live with the residual. That rust is OK so long as it doesn't cause binding or leakage.

 

[Ducked]

Originally Posted By: Tegger
It's interesting that your piston is not rusty, but instead was gummy. It makes me suspect that the original lubricant was not silicone, but some sort of petroleum-based grease.


Since it seems to be impossible to find special brake greases here, I'd strongly suspect that local mechanics usually just use general purpose (probably lithium base) grease, but perhaps modern cars use synthetic (eg viton) rubber for the seals so it doesn't matter.

This car is over 30 years old, so I'd guess its seals might be more vulnerable, though I'd use general purpose grease if I knew it was OK.

The closest Daihatsu manual I have (for the G100) says "rubber grease".

I believe the trad "Red Rubber Grease" that Castrol make/made is/was castor oil base. This wont be completely stable, so if that had been used I'd expect it would eventually set hard. This could explain the black "varnish" on the piston, which might be eroded seal material bound by polymerised castor oil.

When I take the other side apart I might use Canola oil as a disassembly lubricant (backing up the brake fluid) to help the seal over the piston. This wouldn't be good long term, since it'd gum things up, but its not locally scarce/irreplacable like the brake greases are, and unlike silicone, it should be possible to clean it off, especially important if I have to glue anything.

Originally Posted By: Tegger


Silicone is not any kind of barrier against water, and tends to allow rust to occur on the exposed portions of the piston (under the dust boot, but ahead of the hydraulic seal).



That's unfortunate, because I've got more silicone stuff than "rubber grease". I suppose I should use the latter when I re-assemble, but I intend to maintain it better in future, so it may not be critical.

 

[asand1]

TL-DR
I stopped at PTFE tape. Unless you have tapered pipe threads, Teflon tape does not belong on brake parts.

The first step with a sticking caliper should be opening the bleeder to check for a bad hose trapping fluid pressure.

Second would be sliders, not likely to case that much drag though.

Third would be replace or rebuild if you're in a mild climate.

 

[Ducked]

Originally Posted By: asand1
TL-DR
I stopped at PTFE tape. Unless you have tapered pipe threads, Teflon tape does not belong on brake parts.


And yet its a common complaint that brake bleeders seize up from corrosion, which Teflon tape helps to prevent.

Greasing them would of course help too, but (apart from earwax) I didn't have (and could not locally get) any rubber compatible grease when I did this.

One of the interesting (from my perspective) things to emerge from this thread is the possibility that the advice to use rubber-compatible grease may be obsolete, but I'm not sure that this applies to my car (itself also obsolete)

Now I have some rubber-compatible grease I may not apply PTFE when I re-assemble the system, due to the slight risk some of it could cause a blockage, which you do have to guard against.

 

[Tegger]

Originally Posted By: Ducked
Originally Posted By: asand1
TL-DR
I stopped at PTFE tape. Unless you have tapered pipe threads, Teflon tape does not belong on brake parts.

And yet its a common complaint that brake bleeders seize up from corrosion, which Teflon tape helps to prevent.

Teflon tape is just fine on bleeders. Not a thing wrong with it. The only things you need to do are:
1) avoid overtorquing the bleeder screw; Teflon tape can act as a lubricant;
2) keep the tape away from the taper at the end of the bleeder screw, so that the taper can seal properly against its mating surface on the caliper.
Both points are very easy to do.

If "asand1" thinks your posts are "TL", then he has some problems of his own. Your posts are reasonably well-written and quite a lot easier to read than some others that have been posted to BITOG recently. You have also provided significant amounts of valid and usable information in your posts.

Originally Posted By: Ducked
One of the interesting (from my perspective) things to emerge from this thread is the possibility that the advice to use rubber-compatible grease may be obsolete

Such advice would only be valid if the composition of your brake components were to have changed. I don't think that has happened. If rubber grease was originally specified, then chances are excellent that rubber grease is still indicated.

That gummy deposit on your pistons is FAR preferable to rust. Therefore it is preferable that Daihatsu use rubber grease rather than silicone grease, which they appear to have done. From what I have read, lithium-soap grease can be considered as a rubber-compatible grease in situations where rubber grease is indicated.

 

[Ducked]

Thanks. I didn't take 'TL" as a criticism, though it may have been meant as one.

I don't always read the whole of a thread before posting in it myself, and maybe I should add "DR" to such posts, in case (as here) I'm saying something that has already been covered.

Afraid I put it back together with silicone grease, since I couldn't find my rubber grease (generally disorganised, and in the middle of a house-move). I'll probably use it when I do the other side, sort of an accidental experiment.

Brakes seem much better, but there's rubbing (mostly on corners) from the other side, where I'd removed the pads to strip the caliper but then ran out of time so just put them back. Maybe I swapped them over and they are just re-bedding, but I don't see why that would be sensitive to cornering.I'll have another look at it at the weekend.

Don't seem to be any leaks, but the engine is now cutting out a lot so it hasn't had a very long test drive yet.

I'll probably have to try and understand the late 80's carburretor. Last time I tried that I got a headache, and my choke stopped working.

 

[neo3]

Originally Posted By: Ducked

In general in Taiwan, most parts (apart from consumables like oil filters) are impossible to source yourself, since there is no DIY, and the trade is a closed shop.


Just curious, why is there no DIY? That is surprising to me... when I need good quality mechanic tools I always look for "made in Taiwan".

 

[Ducked]

Originally Posted By: neo3
Originally Posted By: Ducked

In general in Taiwan, most parts (apart from consumables like oil filters) are impossible to source yourself, since there is no DIY, and the trade is a closed shop.


Just curious, why is there no DIY? That is surprising to me... when I need good quality mechanic tools I always look for "made in Taiwan".
o

I suppose its a cultural thing. plus mechanics are cheap, plus cars must be new and shiny to give "face" (Cultural thing again) and new and shiny cars suck for DIY. Also, space is limited, so few people have garages. I have to work in the street, which isn't ideal, but not so bad for me since I'm used to doing that in Scotland, where its a lot worse.

Part of it is probably that DIY is associated with blue-collar employment, which is looked down on and not well supported by the education system (though that attitude is not limited to Taiwan)

This produces a culture of kack-handedness. I tagged along to a woodwork class my GF went to a couple of years ago. Made myself a spoon. 30 Taiwanese using edge tools, perhaps for the first time. It was absolutely terrifying. Somehow nobody got hurt, but I had to signal the instructor to take a chisel off the woman opposite me because I didn't want arterial spray in my eyes.

Estate cars (station wagon in American) are very rare here, apparently because they are associated with commercial vehicles, which again are blue collar. If you want to buy an oldish car your choice will be mostly be limited to 3-box saloons (sedans in American?) which gave their original purchasers more face.

Taiwanese are baffled by the fact that my car is still (sometimes) running, and I'm now starting to get a certain amount of flak from the school about parking it on campus. Bad for the corporate image, but hey, if the want me to have a flashier car, they should consider paying me above minimum wage for foreigners.

Then I might be able to buy something older

 

[Tegger]

Originally Posted By: Ducked
cars must be new and shiny to give "face" (Cultural thing again)

This prompts an uneducated (and off-topic) question from me, a North American: How is it seen to a Taiwanese if someone from outside of the Taiwanese culture mistakes him for a Chinese? Would that be considered a great insult?

 

[Ducked]

Originally Posted By: Tegger
Originally Posted By: Ducked
cars must be new and shiny to give "face" (Cultural thing again)

This prompts an uneducated (and off-topic) question from me, a North American: How is it seen to a Taiwanese if someone from outside of the Taiwanese culture mistakes him for a Chinese? Would that be considered a great insult?


I'd think as a foreigner they'd cut you some slack. Most people would recognize that the culture is basically Chinese, though perhaps the Japanese colonial period took some of the sharper edges off.

People do get angry about it though. I've done some proof reading for a rather elderly Physics Professor who was required to declare himself Chinese to get a paper published/attend a conference (can't remember which now) and I thought he was going to give himself a stroke. It was fun helping him draft his [censored]-you letter though.

Whether they consider themselves Chinese will often depend on family history. If the family was part of the large Kuomintang influx when the Nationalists lost the civil war on the mainland, they are likely to speak Mandarin in the home, may regard themselves as Chinese, and vote for the KMT.

If the family have been here for more generations, they are more likely to speak Taiwanese in the home, may regard themselves as Taiwanese (even if ethnically and genetically they are han Chinese, though there has been interbreeding with the aboriginals, who are a separate Polynesian tribal culture) and vote for the DPP.

There's a north-south divide as well, with the north KMT/han, the south DPP/Taiwanese.

But of course its much more complicated, and much less clear, than that.

 

[Tegger]

Originally Posted By: Ducked
People do get angry about it though... Whether they consider themselves Chinese will often depend on family history... There's a north-south divide as well, with the north KMT/han, the south DPP/Taiwanese...

This may then explain the reaction of one of my co-workers when I made that very mistake. Given his family name, his accent, and his physical appearance, I made an assumption that turned out to be extremely incorrect: He was actually Taiwanese, and he did not like being identified as Chinese, not one little bit.

My co-worker was upset enough to complain emphatically to our boss. The boss (white, like me) wasn't angry, but directed me to apologize to my co-worker in order to keep the peace. This I did, and the situation was eventually defused.

My mistake was an honest one, and there was no intent to cause offense. I guessed later that it must be a cultural thing, which you now seem to have confirmed.

 

[Ducked]

"Chinese" can be interpreted as (a) ethnically Chinese and/or (b) a citizen of China.

"China" can be interpreted as ROC (Republic of China, i.e. (sort of) Taiwan, and/or PRC (Peoples Republic of China).

It was the last (political)interpretation that angered the prof. This sort of thing sometimes happens when third-party international organisations, probably due to pressure from the PRC (or possibly simple ignorance), don't recognize the de facto independence of Taiwan, so, at its simplest, there's "only one box on the form".

The (British) Royal Yachting Association is one irritating example, but there are lots.

 

[Ducked]

So, having put the carb back together and got the car running., I was able to take it for an extended test drive. Brakes seem OK, but there's still a scraping sound from the other side (non-rebuilt caliper) on cornering.

I have the front hubs covered in aluminium foil (to stop the wheels sticking on) and I use PTFE (or latterly, polythene) on the studs as an anti-seize, so I took all that off and wire brushed everything, in case it was stopping the wheel seating properly. No change.

I probably swapped the pads and the noise is them rubbing-in, but I don't see why that would be sensitive to side loads.

Perhaps I've got excess play in the bearing? Seems OK pulling on top/bottom of the wheel though.