stuck caliper...

They get worn and lose effectiveness, but still work.

Balk rings are just the female half of the synchro assembly. The male half
bears against this, with the oil film in between.

When the revs are mismatched, the balk ring is forced to turn slightly,
misaligning the pins/teeth/whatever system is used to prevent the synchro
hub from sliding. Once the two halves have been dragged down to the same
speed, the rotational force on the balk ring drops to zero, allowing the
balk mechanism to slide and for hand pressure to push the dog teeth
together, engaging the synchro hub to the chosen gear.

If the synchro friction surfaces wear, it will take longer to drag the two
halves to the same speed, so you will not be able to rev as high in a gear
and be able to just move the lever into the next gear as easily as you used
to.

If you use hypoid or other incorrect lubricant, it will have the same
effect as if your synchros were worn: It will be difficult or impossible to
engage a gear unless you double-clutch or shove the lever in really hard.
That's because the oil film is preventing the synchros from rubbing
together and matching their speed, so the balk rings will never be allowed
to move.

Some newer transmissions have double-cone synchros, which doubles the
sliding surface area, giving smoother shifts as well as longer life.

 

Matching your revs then releasing the clutch as quickly and smoothly as
possible will be benficial to clutch life, since you minimize sliding.

Shoving the shift lever from slot to slot quickly will accelerate wear on
shift forks, dog teeth, synchros, all kinds of parts.

 

the first intent of a clutch is to get used. so what if it wears out?
not using it for its intended purpose it like trying not to use brakes.
or not driving.

clutch life, like with brakes, is a function of the driver. there is
actually a strong argument for slipping the clutch more than might be
assumed from reading so far in this thread. the purpose of the clutch
is to allow both drive-away & smooth shifts. it's entirely feasible to
shift no clutch, but it's hard on the vehicle - motor mounts,
transmission, diff pinions, drive shafts, even the clutch plate torque
springs. harsh shifting causes much greater momentary spike loads in
all these components than does shifting smoothly & using a bit of
clutch. my experience is that stick shift vehicles often wear through
drive shafts much more quickly than than automatics of the same model,
for exactly this reason. there's absolutely no stigma in changing a
clutch at 100k.

it's just like doing a brake. satisfy your urge at a junk yard.
honestly, it's really nothing interesting unlike cams or injection.

you can see /all/ this in a good [bad] junk yard. you don't even have
to buy anything!
http://www.technolab.org/Hako/Katalog-e/Section10.htm

go to a lousy junk yard that has stuff lying about all over the place.
you'll see way more than a place that has everything neatly arranged &
ready for resale.

 

here's a pic of a porche synchro assembly:
http://www.hako-didactic.de/english/produkte/prod10/images/HAKO1104g.jpg

from:
http://www.hako-didactic.de/english/produkte/prod10/1102.html

ain't no cones in there!

there's two main types of synchro today; cone type & porsche. both use
something called a baulk ring, but they're utterly different in nature.
in the cone type, it's the part that prevents engagement until
synched. the the porsche, the baulk ring is also the friction surface &
it runs directly against the engagement dog. it won't prevent
engagement if you want to force it because the dog will just press right
over it.

 

jim beam <> floridly penned in

I wish I had a bigger picture; I'd love to study the construction more
closely. Looks a bit different from Toyota T-40 4-speed I pulled apart.

Either way, it's conceptually the same as any other synchro design: You
have two friction surfaces which are separated by a thin skin of oil that
is easily sheared under stress. When those friction surfaces wear, the
synchros cannot synchronize as quickly, and you will have difficulty
changing gear unless you double-clutch.

Double-clutching saves the synchros from some of their work.

 

true. they're both very interesting though. fwiu the cone type clutch
is fundamentally less prone to wear. the majority of the cone surfaces
are covered in oil & metal to metal sliding contact is minimal as i'm
told that there is a reasonable degree of friction within the oil shear
layer as they get close. the porsche type relies on direct metal to
contact - and has a rough sand-cast exterior for just this purpose. the
baulk ring locks by self-activating expansion against the inside of the
dog, much like a band clutch locks a ratio in a planetary automatic gearbox.

to be honest, i've not played with the cone type synchros as much as the
porsche type - basically because i've not had as many vehicles with that
type synchro fail like i have had the porsche type. as you say, second
gear [on that type of box] goes all the time.

indeed. it's the /only/ way to drive a car with a dud synchro!

 

You'd be surprised how tiny some of those "cones" really are, like a ring
1/4" wide.

Yep. The Integra's second synchro is on its way out right now. I can't rev
any higher than 4K RPM anymore unless I want to let the revs drop to 3,000
before the lever will move. Shifting at 3,500 seems to be about right for
second now.

The second gear hub on this car *also* carries the reverse gear hub. The
extra mass of that combined with the 1,500 RPM spread between 1st and 2nd
is, I'm sure, the reason second is relatively weak in these cars.

 

yes, i've taken them apart before - just not had the opportunity of
testing the results of my having messed with them!

that's possible, but second is always the first to go on any car,
regardless of make. 1-2 has the biggest ratio difference and is much
more frequently rushed. it also gets the effects of the first shift on
the coldest oil!

 

jim beam wrote:

AND if the engine just happens to cough and die, there you are
with no vacuum for the breaks and no power for the steering
either!

 

Couldn't find copper grease. I wound up just using a dab of the CRC
brake caliper grease on the edges of the pad backing plate, where it
sits in the stainless mounting clips, and around the edge of the piston
where it hits the shim.

The rubber is indeed fine. Aging, yes, but still supple enough that I
was able to pull it back and apply a bit of brake fluid in the pinch--I
couldn't find silicone grease by the time I had to do the job, ad it
appears that my pistons are starting to rust in the boot groove. I
scraped out a bit of it, but I'll either have to pull the pistons out,
sand, and replace, applying silicone grease then, or replace the
calipers when they seize. I did not see rust further in than the groove,
but that's of course only a matter of time unless I stop it.

At the moment I can't decide which would be easier--probably just doing
the piston, unless the bore is rusted, too, so maybe wholesale
replacement is in order. Probably no way to know how long I can wait,
but perhaps it will be a project for next summer. Suppose I could check
the fluid in the spring to see how dirty it is, and just change it more
frequently if necessary, for a while.

In fact I was able to turn it by grabbing the edge firmly with a pliers
and turning it. Did take a good deal of effort, but I was able to turn
it about halfway around to get at the groove rust I mentioned.

The upshot is... the piston wasn't stuck, and the pins are fine (I did
apply more grease while there). Must have been rust sticking the pad
edges in place--it was pretty firmly stuck there, I did have to use a
screwdriver to pry it out. The rear pins are starting to bind a tad on
the left (only one I had time to check), and since the pins are fine I
assume it has to be the bore. See below.

I took a bunch of rust out, but foolishly didn't think to apply grease
between the stainless clips and the caliper tabs they abut--i.e., on the
other side of the stainless lip from the pad backing plate edge. Ahh
well. I'll keep an eye on it. I do need a better way to sand down those
tabs. Perhaps a wire brush drill attachment next time.

Anyhow, got the pads replaced and the fluid changed. Boy, was it a nice
coffee color--after pushing the problem caliper piston in with the
clamp, the reservoir was swirling with rust, and the other lines were
similar. Lord knows the last time it was changed, and I have to assume
there's rust in the bore that will be a problem at some point.

I also checked the left rear caliper, where the p-brake isn't working.
Tried screwing the piston all the way in, and was also able to screw it
out (not all the way, of coures). Applying the main brake pushed the
piston out, and releasing the main brake allowed it to retract.

Applying the p-brake did nothing, however--no piston movement, whether
the piston was completely screwed in, or screwed out somewhat. I did not
have time at that point to compare the action on the right side, but I
presume it's supposed to push the piston out.

What bothers me about this failure is that the rear calipers were
supposedly replaced at 111,494. The local dealer noted that the p-brake
"needed attention" when I had the car inspected prior to purchase at
113K, and there's no way a caliper should fail within 1600 miles. Damn.
Why the bore would be rusted so fast, too, I dunno. I've contacted the
previous owner to see if it's possible to pursue it, but it may not be,
or be worth it--especially since she threw out the receipts when I
bought it!! More and more I'm finding out why that was a terrible
thing... hope there's no more. Sheesh.

Many thanks for everyone's help here, especially you, Tegger. I've now
done my first brake job, and am invincible!! <vbg> (actually wasn't hard
at all; now, a timing belt I might leave to a shop)

 

And from dropping into a lower gear at high speed without rev-matching.
If I'm going, say, 40 and drop into second gear, the revs are going to
shoot up to 4K or more. If the engine is at ~1K or 1.5K after
disengaging the clutch, there will be clutch wear during engagement in
second.

I don't do such extreme shifts very frequently, but perhaps I'll pay
more attention to rev matching and doing things more smoothly. I just
don't especially like the idea of revving to high rpms during
downshifting, as I'm so used to letting my foot off the gas during a shift.

 

Adjusting the clutch is just a matter of adjusting it at the pedal as
described in the Helm manual, right? I'm due to do that shortly, when I
replace the clutch master cylinder.

An excellent tidbit, thanks. Lord knows what was done on my car when the
previous owner had the clutch replaced. Here's to hoping they were a
savvy shop...

LOL!!

 

An excellent reminder of the reason for a clutch. I've always believed
in moderation--it helps both the body and the machinery last longer.
Balance is key to longevity.

 

Ahh. I live in NYC, and on a hill to boot. While most of my driving is
outside of the city, there's a fair bit of time spent getting out or
back in. I don't expect my clutch to last as long as yours, for sure,
even if I had had it from the beginning.

That is precisely what I do.

Ahh, parallel parking on a hill--that may be my clutch's downfall. But I
do my best to get it right the first time.

Yeah, what an idiot. World is full of people who don't have any idea how
equipment works and a sense of making it last.

I do a fair bit of computer consulting. Recently did a job for a client
out in NJ, and noticed on my way out at about 10 p.m. that her neighbor,
who was running a computer learning center for kids, had a whole bunch
of nice flat panel displays on full, no screen saver. So I suggested to
my client that she might mention to her neighbor that if she wanted to
make them last she should enable the power saving mode.

Got a call from the neighbor and she wanted to know if she really had to
do that given that she was just going to get new ones in 30 months...
some people...

 

drive a big rig. there, high revs are your friend - you'll /never/
succeed in getting a downshift without them. 4krpm is on a honda is
nothing. if you need comparision, f1 car's don't even idle below 3k.

 

if it's hydraulic, it's self adjusting at the slave end, and all the
pedal end does is adjust the gap between the pedal rest stop and the
cylinder engagement point. yes, adjust per the manual, if required.
unless stuff's worn & has been messed with, there's little if anything
you'll need to adjust.

 

more likely, all the goop got squeezed all the way up from the caliper.
whenever pushing a piston back in, /always/ open the bleed nipple and
disgard what gets squeezed out. it's always contaminated.

i recommend re-bleeding using full pedal travel to make sure you move as
much of that stuff back out of there as possible. full travel ensures
you really do press it out, not leave the cruddy stuff at the bottom of
the cylinder.

when you bleed, you may want to bleed at the caliper banjo bolt too.
avoid getting the muck back into the caliper!

yes, it is suposed to push the piston out. the arm moves, right? if
not, check the brake cables. if it does, disconnect the brake cable and
see if it moves by hand. if it's all loose and bottoms out, sounds like
you may have a problem.

if they were replaced, they should be peachy. if not, make sure you
familarize yourself with the parts drawings & tegger's removal
instructions. maybe yours got reassembled wrong, or the adjusting
screw's in need of a little encouragement to start doing its job.

 

Yeah, I suppose you're right--the tach is marked with red only at above
~7K rpm. I just get worried about that high-pitched engine buzz, bot
something I'm used to. But then I'm coming from a V8-350 (5.0 liter) on
a station wagon. That sucker probably never revved over 3K... And if it
did, the deep throaty roar just sounded normal. ;-)

 

I doubt I need to rebleed--I went through perhaps 3/4 of a quart of new
fluid, and with full pedal travel, in the course of changing the
fluid--that is, pumping the pedal until the fluid was clean on all four
calipers. The front pistons were pushed in all the way. The fluid should
be pretty clean now, and I'm sure I can live with whatever traces remain
till the next fluid change.

Thanks for the tip on opening the bleed screw when pishing a piston back
in, I'll remember that.

Unfortunately, the arm moves totally freely and bottoms out at the stop,
like the shaft has sheared.

I'd think they should be peachy, which is what bother me and makes me
wonder if the gal got scammed. Sounds like you're suggesting I
disassemble the sucker and figure it out. Ordinarily I'd enjoy the
puzzle (and of course the opportunity to acquire a pair of snap-ring
pliers), but I don't really have a place to leave it out of commission.
Perhaps if I could cap the brake line securely while the caliper is off,
such that I could drive it a few feet. Does such a cap exist?

Anyway, the caliper is close to $200, no reman listed at Majestic, so I
have greater incentive to puzzle it out.

 

It's hydraulic. I definitely need to adjust the pedal, though, it
disengages *very* close to the top of travel. Much closer, and the
clutch will be slipping.