First real Garage Post so be kind....

Have 2 issues with a clutch on a 96 Sentra

1) The clutch will stick to the floor when fully engaged. It doesn't stick hard (just have to take your toe and flick it up to get it back, but its aggravating). In order to drive it you have to master the art of pressing it in just enough to disengage the transmission (85-90%) but not enough to stick. I can drive it fine but anyone without intimate knowledge of the thing, good luck. Its my beater car so I don't want to sink a lot into it. Is this fixable short of replacing the clutch?

2) Other issue is the stiffness of the clutch seems to fluctuate. It will start out soft, and as you drive it, it will get stiffer and stiffer. on my drive from Raleigh to RTP it starts out, the weight of my foot can depress it, and by the time I get off 40 (especially after stop and go traffic) I have to literally stand up on it sometimes (and I'm not a light guy). Any advice for this one?

Thanks for any help I get.

8/28/2007 3:03:02 PM

Sounds like you got some clutch hydraulic issues, maybe the master cylinder. When it's soft, the clutch DOES operate like it's supposed to, right? Or does it grind when you try to shove it in gear?

If the inner seals are swollen (usually due to petroleum contamination), you might have a binding issue where the piston sticks in the bore of the master cylinder. I honestly don't know what else could be the problem, unless you've got air in the system (the pedal will stick to the floor then as well).

That whole getting stiffer as you go along puzzles the shit out of me.

I've seen clutches get stiff as they age, but that's over a period of years and tons of pedal action. The diaphragm spring gets fatigued, and the spring action gets harder and more linear, even though clamping force diminishes greatly.

8/28/2007 3:18:11 PM

Thx for the reply.

Issue 1 is constant. Doesn't matter if the clutch is soft or stiff.

I rarely, grind gears when shifting (every once in a while If I'm not paying attention and misjudge my 85-90% clutch action). sometimes it will not want to go into the lower gears but I also attribute that to trying to avoid sticking the clutch and not depressing it enough to open up the trans.

8/28/2007 3:22:53 PM

oh yea, on the possibility of air being in the hydraulics system, that sounds like a easy/cheap thing to check or do. Any recommendation on a place/person to do that?

8/28/2007 3:24:59 PM

sounds like a bad master cylinder to me, but have you checked to see if the fluid level is right?

8/28/2007 6:04:58 PM

Sounds like there may be air in the line or a bad master or slave.

First I'd bleed it since its the cheapest to do
slave is cheaper than master so you could replace that
if that doesn't fix it it sounds like the master cyl.

And if that still doesnt fix it it could be the pp.

The 'getting stiffer' is kinda wierd, although perhaps it could be from the fluid expanding as it heats up so there is more pressure in the line?

[Edited on August 28, 2007 at 7:12 PM. Reason : add]

8/28/2007 7:11:13 PM

^ first of all the slave cylinder either works or leaks, theres no gray area, second its a self bleeding system, the air would work its way out, third, the sticking and varying feedback is due to soft/swollen cups on the master cylinder piston

8/28/2007 7:35:09 PM

Having dealt with it in the past I just figured I would throw out my experience. My car had a similar problem and I managed to fix it.

8/28/2007 7:46:47 PM

whatever floats your boat, i usually like to diagnose by symptoms, not by whats cheapest to replace until its fixed

8/28/2007 7:56:36 PM

Quote :

"sounds like a bad master cylinder to me, but have you checked to see if the fluid level is right?"

Honestly didn't know there was "clutch fluid" I've got a Haynes manual for the car so I will look there to see how to check it and get back to you on that one later. I guess I need to get the answer to this question before I address the other posts.

Thanks

8/28/2007 8:35:33 PM

Quote :

"first of all the slave cylinder either works or leaks, theres no gray area, second its a self bleeding system, the air would work its way out, third, the sticking and varying feedback is due to soft/swollen cups on the master cylinder piston"

That sounds about right. I've dealt with petroleum contamination in systems before, as I'm sure Keith has as well.

8/29/2007 8:24:17 AM

My 240sx did the same thing and ZXAppeal told me the same thing. Turns out he was right: the clutch master cylinder was kaput. I didn't think it'd be the slave cylinder since it wasn't leaking, etc.

I bought both master and slave cylinders just in case (not that expensive)


[Edited on August 29, 2007 at 8:31 AM. Reason : fyi clutch fluid = brake fluid]

8/29/2007 8:30:00 AM

Quote :

"fyi clutch fluid = brake fluid"

whew! was starting to think I had missed a whole system to try to keep maintained. I thought all the cylinder stuff sounded brake system ish. I didn't check the "clutch fluid", lol, last night, but I will do it over my lunch and get back with you guys. All and all it sounds like I should price getting the brake cylinders replaced (at least the master, but easier to just get them both I would assume) and I should then be good. By the way, If I just said something stupid please correct me. Only way I will learn this stuff.

Thanks for the help guys. I'll let you know what I find out.

8/29/2007 11:40:18 AM

same thing on the vette ended up being a bad slave cylinder... but also had the same happen on a dodge stealth that was the master. So, one of those.

[Edited on August 29, 2007 at 11:48 AM. Reason : ^not brake cylinders, clutch master/slave..]

8/29/2007 11:48:09 AM

You seem to be confused.. the clutch and brake systems are entirely separate. But you use brake fluid to fill up the clutch system, get it? That's why you don't see bottles of "clutch fluid" on the shelves.

Just like I use automatic transmission fluid to fill up my power steering system

8/29/2007 11:52:46 AM

DOH!

ok, so the Clutch has a separate hydraulic system (was going to ask why the brakes worked fine if the cylinders and stuff were going, glad I didn't). Where would I look to check the fluid levels for the clutch ? when I thumbed through my manual last night, it talked about checking and topping off transaxle fluid (for a manual transmission) and such, but it seemed like you had to get into it and remove major stuff to check/fill that.

Its funny, I understand the basics of how a car works, and I try to do as much of my own maintenance as I feel comfortable with (oil, drain and fill radiator, rotate tires, change filters, etc) but as a general rule of thumb, once a pile of parts starts to stack up on the bench I take it to the professionals. This is sounding more and more like a pile of parts.

8/29/2007 12:44:25 PM

it should be a resevoir right beside of the brake fluid resevoir. will be smaller though

8/29/2007 12:50:22 PM

Ok, after much research, I don't think my clutch is hydraulic at all. I can't find any extra reservoirs under the hood, and my manual only talks about a clutch cable and associated hardware (leading me to think the system is all mechanical). I've found what I believe to be the end points to the cable so it seems the manual is on the correct path. Could a worn clutch cable be causing these issues? And if so, how difficult is it to replace it on a scale of 1-5?

8/31/2007 10:17:37 PM

What's the difference between clutch fluid and transmission fluid? I thought they're both the same.

8/31/2007 10:32:05 PM

wait, i thought all sentras had hydraulic clutches, now i am truly confused

9/1/2007 8:05:51 AM

Earlier models I KNOW are cable (B11 through at least B12, maybe B13).

9/1/2007 9:15:55 AM

Quote :

"wait, i thought all sentras had hydraulic clutches, now i am truly confused"

Join the club. I've learned a lot messing with this though

Quote :

"Earlier models I KNOW are cable (B11 through at least B12, maybe B13)."

This is a '96 4 cyl. is that considered 'earlier'?

9/1/2007 11:04:34 AM

Quote :

"What's the difference between clutch fluid and transmission fluid? I thought they're both the same."

clutch fluid = brake fluid

transmission fluid is more of a oil than brake fluid

9/1/2007 11:10:40 AM