stuck caliper...

This came up a few months ago when I posted that I'd bought Raybestos pads with
a "lifetime warranty" a coupla years ago. I thought as you did: That normal wear
and tear doesn't count. But someone here at the newsgroup (Mike?) said he
thought it might be otherwise.

I asked about this in my brakes class recently. One of the guys works for a
Checker auto parts store and answered. He said that not long ago, Raybestos did
warranty its pads for life, including normal wear and tear. This has since
changed, according to him.

When my Raybestos pads wear, I'm going to take them and the warranty, receipt
etc. to a nearby Carquest and see what they say.

My impression for now is that lifetime warranties, even for normal wear and
tear, may still exist for brake pads.

 

AFAICT, "lifetime" pads are lifetime pads. they count on people to lose
the receipt, forget, or sell the car.

the only one ive ever seen got the caliper so hot the boot melted, and
all the fluid leaked out.

 

I've heard here that double-clutching means putting it in neutral
between shifts and letting the clutch out (i.e., releasing the pedal),
but wouldn't the point be to simply rev-match (approximately, after long
experience) before engaging at the lower gear, to reduce the wear on the
clutch?

 

Thanks again, that's exactly what I wanted to know. I already know
enough not to get it on the rotor!

Incidentally, would it be imprudent to dab a small amount of brake
caliper grease at the edges of the pad backing plate where it contacts
the caliper? My existing pads are pretty well stuck at that point with
rust. I'm assuming I'll wire-brush/sand the caliper at that point before
installing the new pads.

Sorry, I should've said something like "doubt I'll be messing with the
boot"--I don't want to stress it at all if the rubber is on the old
side. 'Spose I could examine it and decide on the spot.

If I understood you correctly, the piston is supposed to be able to
rotate--so there's no channel that prevents it from doing so? Or is it
that I have to eject the piston past such a channel?

 

I'll take a look at the warranty and file the receipt anyway. Far out.

The boot is fine. Maybe I'll be lucky...

 

Whew! Sure wish I could take a ride with you to learn how to do it
properly! Not that I've worn out a clutch yet, but the previous owner
had hers replaced at a mere 81K, I bought it at 112K, and have no
illusions that I'm an expert at shifting--I may be doing it right, might
be less-than-perfect. At least I don't ever smell that clutch-burning
smell... ;-) Anyway, I'm still working out the occasional kinks after 8
yeasr with an automatic.

 

Never mind, I just reread your FAQ comments on the topic.

 

I am in full agreement with you on what double-clutching is. In the good
old days, before fully synchronized transmissions, double-clutching was
a must.

Doing it on a car with a synchronized transmission does not reduce wear
on the clutch, but it reduces wear on the synchros. If your synchros are
already worn out, double-clutching will allow you to shift with less
clunking and grinding, particularly on down-shifts.

 

there's no real wear on the clutch from shifting, whether just relying
on synchros or double clutching. clutch wear comes from drive-away from
a standstill, holding it on the clutch on hills, "resting" a foot on the
clutch pedal on the freeway, etc. if you don't peel away from lights,
use the parking brake on hills & rest your foot on the floor, there's no
reason a clutch won't last like tegger's is doing. also don't under
rate a dealer's hunger for recommending unnecessary work.

yes, double clutching is putting into neutral and using engine revs to
spin/slow the ratios on the next gear so they engage cleanly. even with
synchros, many big rig drivers still do it to reduce synchro wear or
even get the thing into gear in the first place! it's less of an issue
these days, but when synchros first came in, some designs weren't too
good and they'd wear out quickly. expensive! with a good modern
synchro, once moving, you can change gear without using the clutch at
all. don't make a habit of it, but you can test that for yourself -
just do what you'd do normally to shift with shift lever & throttle, but
don't touch the clutch! honda synchros are very good and won't let you
fubar anything unless you try /real/ hard.

 

Abeness <> floridly penned in

Copper grease or M77 , not silicone, goes there. Check my Brake Service
pages again for photos of where to put the grease.
http://www.tegger.com/hondafaq/rustybrakes/brakes2.html
about 3/4 of the way down. One thing I noitce I don't show is putting a bit
of grease on the shim that rests against the piston. A little should go
there as well. You can even separately put some on the caliper hooks
themselves as well as the shims and pads.

Rubber should be fine. It lasts a long time. If it is aged and brittle,
you'll know the instant you try to pull it out of the groove.

It's hard to turn because it's so big and may be gummed up, but you CAN
turn it. Put silicone in first, work the piston in and out a few times to
loosen it up, then try to turn it. You need to eject it enough to pull the
dust boot off the groove in the piston. Make sure you don't scar up the
piston inboard of the boot groove.

 

Randolph <> floridly penned in

Double-clutching specifically does not reduce wear on the clutch, but the
throttle-press that is used in double-clutching is also used when rev-
matching the clutch, so that DOES reduce clutch wear.

 

Driving environment helps too. My driving is mostly highway, so the clutch
gets little use until I've left the highway.

jimbeam's tips are right-on, though; he says what I already do; the clutch
is NOT a hill-holder and it is NOT a brake pad.

What you're trying for when you do use the clutch is to use it sparingly
and with minimal slip. You want the quickest, smoothest engagement possible
with the least slip you can achieve. When you're stopped at a light, the
shifter is in neutral and your foot is OFF the pedal.

If you're timing your shifts right, there will be essentially zero wear on
the clutch when the car is moving. The only wear will occur when you're
actually getting the car started from rest. Keep that wear down and the
clutch will last ages.

I knew a guy who used to wear out his clutches every 90K miles or less. I
used to wonder why until I went for a ride with him once, then I saw
*exactly* why he wore them out: Everything jimbeam says NOT to do, he was
doing it! He was one of those people who used the clutch to hold the car
still on inclines, letting the car roll back, then blipping the clutch to
bring it forwards again, roll back, blip forwards, etc, etc, etc. Yeesh.

 

Before I saw Jim's post and mention of the "synchro," I was torn about

1. wear on clutches from shifting
2. the need to double-clutch

Speaking as someone who's never "DIY replaced" a clutch, the "synchro" piqued my
interest. The reports I am seeing say that modern synchros (about the last
twenty years or so?) preclude the need to double clutch (as many of you I'm sure
have heard). For example:

1.
"In modern cars double-clutching is replaced by a synchronizer."
http://www.angelfire.com/hiphop3/ppddaiddddyy/ManTrans.html

2.
"Manual transmissions in modern passenger cars use synchronizers to eliminate
the need for double-clutching." http://auto.howstuffworks.com/transmission6.htm

3.
"Today, all manual transmissions have 'synchros,' so double clutching is
completely unnecessary. And in fact, it DOES put extra wear and tear on the
clutch because you're using it twice for every shift instead of once."
http://www.cartalk.com/content/columns/Archive/1996/December/11.html

4.
" 'Synchronizers' in manual transmissions in modern passenger cars, eliminate
the need for double-clutching." http://www.automotiveforchicks.com/?page=tips

I did see some arguments (one?) about using double clutching to spare wear on
the synchro. OTOH, the synchro might be something that lasts the life of a car.
I didn't quite get resolution on this.

At the moment I am under the impression that the really big wear item in, say,
circa 1988-1995 Civics with manual transmissions (which seems to include my 91
Civic and possibly going back a few years more) may be the clutch release
bearing. It wears with every depress-and-release of the clutch pedal. Also
riding the clutch pedal between shifts or keeping it depressed at stops will
wear it.

I am still a little intrigued about the argument that 'the clutch is being used
as a brake pad when one downshifts.' Seems to me that engine inertia is being
used as a brake pad, and engines are iron horses that can take it for a design
life of say 15 years and 250k miles plus.. For now, I suppose the real argument
against downshifting as a means of slowing the car down is that many, when
downshifting from 5th gear to 1st to neutral, will use the clutch say five
times. Compare this to shifting from 5th to neutal and using the disc/drum
brakes on the wheels; the clutch is used once. Downshifting translates to using
the release bearing several times more each time the car comes to a stop.

And again, correct me if I'm wrong, but apart from downshifting, driving style
will have an impact on clutch life as well. E.g. shifting very quickly.

 

changing a clutch is a procedural pita because of access, but it's not
technically hard. the cam belt is technically much more involved even
though access is much easier.

hmm, automotiveforchicks propagating old lore about the 3000 mile oil
change & changing transmission fluid "every 100,000 kms or 32,500 miles"
has got to challenge their credibility.

generally, synchros do last the life of the car. some of the old types
of synchro, notably some of the early porsche designs, were great for
racing & fast forced shifts, but they wore quickly, particularly if
there were problems with insufficient clutch disengagement [clutch plate
not being sufficiently free to "float" on the drive pinion], then they'd
check out pretty darned quick. the current cone clutch design of
synchro just shrugs off bulk abuse.

if you want a conclusive demo on the value of synchros/double-clutching,
drive something like a cement truck. the transmissions on those things
are fully synchroed, but you need to be built like arnie to shift them
unless you double-clutch. so, yes, double-clutching spares some of the
spinning gear momentum the synchros would otherwise have to deal with,
but on something like a honda, with a light transmission, light
viscosity gear lube and pretty much "fool proof" design, i wouldn't
waste any bandwidth worrying about it.

the thrust bearing should last at least the life of the clutch. if a
clutch is badly adjusted or the driver "rides" the clutch pedal all the
time, it will wear more quickly, but i wouldn't worry about it. you've
got this far, so i doubt your driving habits are bad.

correct, it's the engine that does the braking, not the clutch.

shifting down through the gears is not that big a deal. consider the
principle of the relative loads; can you "chirp" the drive wheels
downshifting? no? then there's not as much load as chirping on the
up-shift.

you don't "need" to go 5-4-3-2-1 by the way. 5-3-1 is perfectly ok.
braking in neutral is potentially very dangerous. not only are you in
no position to apply power if required, you also have no engine braking.
again, going back to the cement truck, losing brakes on a fully loaded
vehicle because they've overheated on a big descent is no joke. trust
me on that. engine braking may not be "necessary" in all situations,
but to get out of the habit is a big no-no.

shifting fast has a positive effect on the clutch [if any] but negative
on the synchros.

 

"Caroline" <> floridly penned in

Synchros have changed relatively little since 1928, when they appeared for
the first time on a Cadillac. In operation, sychro components rub together
in an oil bath and drag the mainshaft and countershaft speeds so they match
each other before the dog teeth are allowed to mesh. Since synchros work by
abrasion, it stands to reason that they are a consumable; eventually they
will wear out no matter what.

Second gear is usually the first one to wear out. It gets the most use,
experiences the most rotational difference when used, so also experiences
the most frictional force.

When you double-clutch, you use the clutch to bring things into
synchronization (most of the way, anyway), and remove some of the
responsibility from the synchros. There *is* a tiny bit more wear on the
clutch when you do this, but is is a *tiny* bit. The mass being moved when
double-clutching is less than 0.1% of the mass of the car itself, so wear
is correspondingly less.

A clutch's greatest wear by far is experienced when starting up from a
standstill.

Release bearings wear from excessive use, not from normal use. Riding the
clutch, "blipping" at stop lights, and failure to maintain proper
adjustment is what does it.

Normal day-to-day up shifting and downshifting will not cause excessive
wear.

Not quite: The clutch CAN be used as a brake pad, but that is the WRONG way
to downshift. The right way does not use the clutch as a brake pad, but
matches clutch and countershaft rotational speeds before the clutch is
reengaged, so the engine becomes the brake pad.

See above.

 

I'm just figuring I'm going to need some kind of hoist to do it right. (Maybe
I'm wrong. I studied what you said before and the manual on this.) Not sure I'll
feel so inspired to go spend some serious bucks on something I think I will only
use once every say 15 years.

Aside: They called this a rule of thumb. In closing on this, the site says:
"Bottom line: Maintain the practice of changing engine oil at recommended
intervals."

I'm not saying any of the above sites are perfect. I am saying there does seem
to be a consensus re synchros greatly improving clutch life and performance
(probably performance was the bigger motivation, as far as I can tell). That's
why someone thought of the synchro, right?

My 1.5 liter, under two ton Civic is not a cement truck, so I see your point but
am not sure this would say anything terribly meaningful... Very different
engineering and needs being satisfied...

Aside: I'd like to see more reports from others here who have had clutch parts
replaced.

What is the meaning of the (I suspect highly technical) term "chirp"?

Yes, I do this often. Just depends on the situation. I think over the years I
have come to operate by what has perhaps become fortuitous feel. In general, I
avoid letting the engine spike high or low in RPMS all of a sudden.

Ha. Interesting point.

Plus, maybe here or somewhere else on the net I read recently it's illegal in
many areas to let the car coast (say to a stop) in neutral, for the reason you
give.

I should toss in at this point that Tom 'n' Ray, despite their comments above,
say not to downshift to brake unless one is on a very steep hill. Then use the
engine to brake to keep the brake fluid from boiling (in the extreme), etc.

I'm not sure they're fully up-to-date, for one. Or there's a lot of variation
from one car make to another re how well clutch parts are designed.

I'm not sure we mean the same thing when we say "shift fast."

"Fast shifting will place greater strain on synchronizers as will marginal
lubrication and the presence of dirt or particulate in the transmission fluid."
http://www3.bc.sympatico.ca/Volvo_Books/trans1.html

But like I said, this is just google stuff that is not all entirely in
agreement, and I haven't put my hands on the guts of the parts about which we're
talking. So I'm all eyes if people have more to say on this.

 

Something's changed, else I wouldn't see so many reports of how better modern
clutches are. My take is double-clutching was strongly recommended before
something like 1985.

Depends on what you mean by "eventually." Before the engine needs a ring job?

snip

Yes, it's used excessively, arguably, when downshifting.

Though I saw some commentary on how practically all new cars have a clutch
self-adjusting feature that may obviate your point on adjustment...

Seems like you're talking about some totally crazed way of using (abusing) the
clutch that would fail the intuitive sense test as well as the common sense
test... Now I'm sure there are some young drivers who do this, but I suspect
there's a whole repertoire of other abuse that accompanies and even overshadows
this.

In any event, you clarified your original position. I suspect we're all
practically on the same page...

 

but caroline, you're an engineer. example of extreme is meant to
illustrate the principle. braking in neutral is pretty generally
inconsequential in a car, but very very dangerous in a truck. the value
of synchros in a car, especially to a driver that may never have tried
anything without them, is, imo, not appreciated until a different kind
of vehicle is experienced. a big truck, where synchros merely assist,
not override the gear change procedure, is easier/better experience to
get than finding some old stick-shifting banger with straight cut gears.

most shops just replace everything - clutch, pressure plate, thrust
bearing, pilot bearing, and often skim the flywheel too. personally,
i'm happy just replacing the clutch plate if everything else is ok. if
the flywheel is skimmed, the bolt mounting surface needs to be skimmed
also to maintain the same degree if differential with the friction
surface that it had when new. frequently, that's not done so people
wonder why the clutch goes again so soon again after... insufficient
pressure can be brought by the pressure plate.

on the change up from 1-2, [& 2-3 if you have a powerful motor], floor
the gas, then slam the clutch into the gear. it'll "chirp" the wheels
as they spin momentarily with the engine's momentum. it's an immaturity
thing.

you can get away with all kinds of bad behavior in modern cars. the
reason i gave the cement truck analogy is because heavy equipment like
this is not abuse tolerant. riding the clutch, bad shifting, no engine
braking - all get you stuck at the side of a road with a rapidly
hardening cargo in no time at all. repairing the vehicle is one thing.
crawling inside the hopper with an air hammer to remove all that
concrete is something else.

yes, but modern synchros won't let you abuse them, unlike some of the
older designs. you /can't/ shift until it's synched. the old porsche
design [had kind of a baulk ring that ran directly against the dog] was
great if you really needed to shift asap because you could just force
it, but was just not abuse/bad driver tolerant.

hopefully your car maint class will allow you to get your hands on the
workings of a gearbox. alternatively, visit a junk yard some time -
great places to learn.

 

Synchros were always meant to be used, and always meant to be used without
double-clutching. Their very reason for existence was to eliminate the need
for double-clutching. Earl Thompson sold the idea to Cadillac in 1924 on
that very point.

Also, keep in mind that almost everything on or in a car lasts far longer
now than it used to. Synchros in a 1955 Pontiac might have lasted less than
100K, but the engine didn't last much past 100K before needing a rebuild.

Synchros in a modern Civic may last over 250K, but then so does the engine.

Not at all; you're not on it long enough. Riding the pedal and incorrect
adjustment means the bearing is constantly loaded, several hundred
(thousand?) percent more load-time than if properly used. That's abuse.

Like the old saying goes, common sense isn't too common.

People will move the lever down to the next gear, then simply let the
clutch out, letting the car drag the engine up to speed. Very common. This
guy that wore his clutches out in 90K did that.

 

I agree it illustrates a principle. But, techies that both you and I are, I
trust you agree that practically speaking not double clutching on a 91 Civic may
have negligible effect on it compared to the life of its other parts.

Not so for the cement truck, it would seem.

Okay. I appreciate the "art of the synchro" here. Seriously!

Ya but when, and how come someone else with a 91 Civic may have been through a
clutch after only 100k miles?

We've certainly touched on this. Looking for still more empirical data. I did
google the archives a bit and it seems it does happen to Hondas of this vintage.

I gotta do this sometime... I don't want to hit age 70 without having taken
apart a clutch and having put it back together...

Yes, I was going to take the manual transmission course but stuff happened.

Yes, I was thinking of seeing what I could pick up for five bucks at my favorite
import junkyard...