Clutch master cylinder rebuild kits?



Simple rule of thumb: When upshifting, your revs drop to match the new gear. When downshifting, your revs rise to meet the new gear.
Basic process: I've got an upshift coming up. Pull the tranny out of gear. Allow engine to wind down to approximately the right range (and this is almost always a "practice until you figure it out for this particular car" concept). Revs are about right? OK, try for the gear I'm wanting. Maybe need to play with the throttle a little to match up more closely. Once I'm in the new gear, mash or release the throttle as needed to achieve desired ground speed. Done.
Downshifting is exactly the reverse: Pull it out of the gear you're in, wind the engine up to the right revs (again, a "learn by practice" thing) for the ground speed you're doing, then try for the gear you're looking for, playing with the throttle as needed to get it to fall in.
The key concept involved is this: At any given speed, in a specific gear, there is an engine RPM that exactly matches the speed the input shaft of the transmission is turning. You're looking for that engine speed. Once you find it on a given vehicle, that's your shift point in and out of that gear. As long as the ground speed and engine RPMs match, you'll be able to shift into or out of that gear with either no grind at all, or only the tiniest bit of grind.
A real-world example... My '82 Mazda 626 is rolling along at 25 MPH according to the speedo. What gear I'm currently in is irrelevant - I might even be in neutral. Because I know this car well, I know that if I wind the engine up to *ABOUT* 3500 RPM, I'll be able to slip into first without too much, if any, trouble or grind. If I want second gear, I need to dump RPMs until I hit roughly 2K on the tach. If I want third, then I'm going to have to drop the RPMs to about 1300. For fourth, I need my revs at about 900. (which is right up against the limit of practical for this car) For fifth, I can just plain forget it at 25MPH. Nothing I can do from the driver's seat can get the engine slowed down enough to match the speed of the input shaft. In theory, about 400-500 RPM should let me do it, but since this engine idles at 650-750 RPM depending on whether the AC is on or not, it's simply not going to happen without a lot of grinding and cussing, and even with a liberal amount of both, still probably won't happen.
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Excellent discourse, one of the only ones I've ever seen. It also explains the concept behind double clutching unless I'm mistaken.
Thanks.
Jim
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Gunner wrote:

A prime example of why I wouldn't touch anything made by Ford, and haven't since 1965...
Bob
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Gunner
Try to locate a brake cylinder repair kit with the corect cup size. many of the older parts stores had the individual cups available.
JRW

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On 11 Aug 2004 09:01:08 -0700, snipped-for-privacy@hal-pc.org (J.R. Williams) wrote:
||Gunner || ||Try to locate a brake cylinder repair kit with the corect cup size. ||many of the older parts stores had the individual cups available.
I have a whole assortment of them. What size? Texas Parts Guy
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snipped-for-privacy@hal-pc.org (J.R. Williams) wrote:

That was my move when I was having clutch MC trouble a while back. Darn thing was eating cups. Went through three rebuild kits in 3 months. Finally gave up on the Autozone/Kragen's BS and went to a *REAL* auto-parts store (not Autozone, not Kragens, not anything similar - I'm talking about the kind of place where you walk in and the smell of machine oil gives you a friendly slap upside the head as a welcome, there are stools at the counter so you can cop a squat and jawbone with the guy behind the counter (who probably has grease-stains on his coveralls, and maybe a streak of grease on his nose as he comes out of the back wiping Go-Jo off his hands 'cause he just came in from helping a customer put a newly bought part on his vehicle out in the parking lot) about what it is you need, and so on - a *REAL* auto-parts store.) and got myself half a dozen cups that were aimed at brake-slaves for a buck and a half out the door. Been using those ever since.
In my case, they need to be cut down just slightly (the lip was a hair - maybe two millimeters, if that - too "tall", so it completely blocked the inlet port in the cylinder, although the diameter was right) by brushing the open end across the wheel of the bench grinder a couple of times, but otherwise, they were perfect. I'm running on the second one of them now, in fact - the first one I cut down too far, so it died the same way the (much lighter) "intended for the clutch MC" cups were going. The slightly longer and heavier lip on the brake cups never encounters the bad spot in the cylinder (A razor-edge on the forward part of the inlet port that, with the edge of the piston, forms a shear), so it doesn't get pushed up into the inlet port by the piston and "clipped off". The one in there now has been going strong for... <thinks> Gotta be close to 7 months now, with no sign at all of trouble.
I hear the nanny-state folks already... "What if it fails 'cause you used the wrong parts!?!? You could kill somebody!" Hardly... It's a clutch, not brakes or steering. A clutch is, at least to anyone I consider to be a minimally skilled driver of a stick, nothing more than a convenience item for everything but starting from a dead stop. Other than that specific situation, there is no actual "gotta have it to make things work" need for a clutch. (Yes, I know, slap-shifting isn't always fun and easy, but it *IS* doable in *EVERY* vehicle with a manual transmission, whether it's a stick or "on the tree", that I've ever gotten behind the wheel of) So the clutch fails. Big fat hairy deal. Worst case scenario: I find out I've got no clutch "the hard way", by stepping on it and getting no response. Oooh!!!! Panic situation! We're all gonna die!!!! NOT!
How hard is it to slap the shifter into neutral and coast to the side of the road? Or, more likely, just keep on driving, shifting clutchless if needed, until I find someplace to either turn around and go home to the toolkit, or if I've got my usual travelling kit with me, sit there and do the 20 minute cup-swap? Never mind the fact that I have yet to meet a vehicle that can't be stopped by mashing the brakes, regardless of the gear it might be "stuck" in. Sure, it'll probably stall out in the process, but so what?
Nah... safety considerations on this substitution are nil, so save the lecture for someone who actually needs it.
Of course, there's another plus: the rebuild kit for my MC is (or was - probably closer to $25 now, what with inflation) $19.68 plus tax. It consists of a new (or perhaps salvaged? No way to be certain, really) aluminum piston, a spring, and a new rubber cup. Other than the first time, I've never replaced the piston or spring - They simply don't wear out. Why should I buy a $20 kit when all I actually need is a 25 cent rubber and 20 minutes to put it in?
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I've got two used ones, with hoses. 1 from my kids 93 and 1 from my 94. You just need to come to Florida to get them. gary

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I've got two used ones, from a 93 and 94 ranger, with hoses, but I'm in Florida. gary

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wrote:

Got any of the smog stuff? 3.0 v6 on the 94 should be the same as mine. With 387,000 on the original smog stuff..it needs changing out, including the O2 sensors
Gunner

"In my humble opinion, the petty carping levied against Bush by the Democrats proves again, it is better to have your eye plucked out by an eagle than to be nibbled to death by ducks." - Norman Liebmann
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