new component, soft clutch, wont go into gear

Giro

Registered User
So I did some searching, but could not find anything that applies to my situation.....I replaced the clutch master cylinder, pushrod, and slave cylinder and bled the system. Pedal still feels soft, goes into gear fine while moving, but from dead stop, it won't go into gear. The grommet on the pushrod is still good, as far as I know, no leaks, but I will check tomorrow to see if it does leak.

What can be the cause? Pushrods (old and new) are the same length, so I'm at a loss. Parts were bought from rockauto (rhinopac brand). Thanks for your time.
 
Thats what I'm kinda hoping for....since the master and slave are new, maybe there's air somewhere in the middle (from the master). I've read about pumping fluid up the bleeder screw, but what would be the best way to go about ensuring all air is out? I think I mentioned it, but I get a good stream out of the bleeder right now, so I thought it was bled thoroughly.
 
The system is supposed to be self bleeding. Pumping the pedal a bunch of times (like 50 or so) usually works.
 
I just re-bled the system...put some clear hose on the bleeder and routed it back up to the reservoir, got a lot more air out, but upon test driving the car, its still doesn't seem to want to go into gear from a dead stop. It will go in fine if rolling/moving, and when car is off, but not when driving.
 
The last time I did a clutch job on a customers truck I purchased a brand new aftermarket master cylinder .. turned out to be defective. But yeah make sure you bleed this one first .. Ive had to pump them well over 50 times and wait a few minutes in between each session for the air to bleed up to the resivoir before the pedal was stiff.


- Dan
 
i remember reading something about prying the slave cylinder/throwout bearing one way....cant find it now, but does that sound like something i need to do?
 
No prying necessary. Its a self bleeding clutch system .. if its not bleeding properly it could be a bad master or slave.


- Dan
 
Great, both parts that are "brand new". Hopefully its not the slave, I don't want to drop the tranny again.
 
Reviving this thread because I have now replaced all cluch components: new dorman slave and master cylinders, new centric hose, new o rings, and I even shimmed the slve because previous owner resurfaced the flywheel. I literally sat in my car for 20 minutes and must have pumped that clutch pedal about 1000 times (at least it felt like it) and I got some resistance to the pedal, but I'm still having issues.

Apparently, I have SCP headers (if it makes a difference because of how close the clutch hose passes to it), and I've noticed that the car shifts fine cold. After about 15-20 minutes of the engine running is when I'm having issues. Like I said, I pumped the clutch pedal for 20 minutes, and still having this issue. If it truly is self bleeding, then there's something going on. I tried gravity bleeding; no success. Conventional bleeder screw method shoots out solid stream of fluid.

The only thing I have not done is pressure bleeding backwards through the bleeder screw, and this is because I don't have the tool. I did find a TSB however that states that this is the only correct efficient bleeding method for concentric slave cylinders. Can anyone please shed some light on this subject? Its very frustrating. Thanks.
 
What kind of heat shield do you have on the line? It could be the brake fluid in the line boiling due to heat from the headers.

RwP
 
I knew I forgot to mention someting. I have a heat sleeve on the hose, and I'm using motul rbf600 brake fluid. Could it still be boiling over despite the sleeve and high temp brake fluid?
 
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How many miles on the tranny, has it been rebuilt? Mine started doing that when I'd stop, go to neutral, let up on the clutch then depress the pedal and it wouldn't go into gear unless I let the car roll. I later found metal in the oil and part off a syncro spring that came out the drain. That was at 106K on the odo.
MikeH
 
When you press on the clutch pedal it must be a firm pedal at some point and provide resistance 2 to 2.5" below the end of it's travel. Your foot moving on the pedal pushes on the hydraulic fluid which then presses on the slave cylinder. When the slave cylinder contacts the pressure plate, that is when the extra force should be felt. If you don't feel that or you feel it late in the stroke of the pedal, you probably have air in the system. In particular if it is an issue when hot, not cold.

Yes, it is supposed to automatically bleed.... but that doesn't mean it will. My fool proof method of bleeding is to open the bleeder, and let the fluid drip out while keeping the clutch master cylinder full. Don't let the master cylinder run dry or you will have to refill it and start again. I let it run and kept filling until I had run through a 1/2 quart of fluid, then stopped the bleeder and quit adding fluid.

Once you have a solid pedal all the time, if you still have trouble shifting into gear, then you may not have the correct shim needed for your combination installed. The slave cylinder can only move so far, and once it hits that limit the pressure plate fingers need to be fully depressed. If not, you need additional shim. But make sure things are bled fully first.
 
How many miles on the tranny, has it been rebuilt? Mine started doing that when I'd stop, go to neutral, let up on the clutch then depress the pedal and it wouldn't go into gear unless I let the car roll. I later found metal in the oil and part off a syncro spring that came out the drain. That was at 106K on the odo.
MikeH

i have no clue on the tranny's history, except that the previous owner replaced the original tranny (i believe it was auto) and put in a 94/95 5 speed.

My fool proof method of bleeding is to open the bleeder, and let the fluid drip out while keeping the clutch master cylinder full. Don't let the master cylinder run dry or you will have to refill it and start again. I let it run and kept filling until I had run through a 1/2 quart of fluid, then stopped the bleeder and quit adding fluid.

so basically gravity bleed it? ill have to go to the store and get more brake fluid.....and a case of patience.
 
so basically gravity bleed it? ill have to go to the store and get more brake fluid.....and a case of patience.

Yes, gravity bleed. The issue with pushing the pedal back and forth to bleed it is it can aerate the fluid making it impossible to bleed. That is why they make vacuum bench bleeders for clutch master and slave cylinders, they are such a pain to bleed once installed.

The gravity bleed will force the small little bubbles to bump into each other and reform the larger bubbles, being pulled out with the fluid carefully through the passages rather than violently. After you run about double the fluid through the system, it should be clear. Use a clear tube on the outlet of the bleeder so you can watch the migration out. Use a clear catch can and you can see all the little bubbles in the fluid after it drains out. Eventually you will see bigger bubbles in the bleeder tube, and then clear.
 
what i did

i replaced master slave and hose too on my sc i used a small screwdriver on the hose end that fit the slave while someone was pumping the clutch when i got fluid there i installed it on the slave and bled it like brake and it was pretty easy to get full pedal! but i still think that with a bigger fluid tank or a better hose to slave system the clutch system would be a lot better when im hard with it seem to get some air in system and fluid become black :confused:
 
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