Random clutch pressure

[militant_x]

ok, so im driving home from the engineering campus, ive been having fun this morning (alot of hard 1-2 2-3 shifts, fast turns, etc). When i realise my clutch pedal is feeling a bit weird, what i noticed was:

first there was a bit more play than normal before i felt any pressure on it. So i wanted to see exactly how much play....

I press the clutch down slowly and it goes all the way to the floor.. no pressure.

I was able to get the car home by mashing the hell out of the pedal to shift. Starting off in first was a bit hard also because the pedal seemed to have very little back tension.

anyway, i get home and check the resevoir, its almost full. But there are signs of some fluid ontop of the cap and around that area.. as if it were splashing out somehow. So i top if off again but leave the cap off.. pump it a few times, no change in the pedal feel... Now though the resevoir is half full, and the area around the resevoir wet with fluid.

My fluid is a brownish color as of right now.

what is going on... i have to get to school this week.

also what type of clutch fluid should i be using.

man i love this car, but it seems like everyweek there is another problem. Last month the clutch line started leaking.. so i replaced that... i dont think i bled it correctly though cause the pedal had some travel or play when i finished..

another thing, the new clutch line is about half a centemeter over the catalytic.... do they sell some form of heat shield or insulation or is this the way its supposed to be.

please help,

-chris

 

[militant_x]

ok, the car made it to school today... i did some research. Could this be a bad master cylinder? Also would i need a new slave cylinder?

*bump*

-chris

 

[Ken]

... the new clutch line is about half a centemeter over the catalytic.

Hmmm... Not a good thing. Move the line away from the heat or get a shield to prevent radiant heat from impinging on the line. If the heat gets to the fluid, you'll definitely have a spongy feel to the pedal.

 

[tnovot]

spongy clutch

You should be using a good quality high temp brake fluid with DOT 3 rating.
You said you were driving hard so the cat could have really been heated up. If the line is not protected from excessive heat, the fluid will tend to become less dense and then change state to a gas. As an engineering student, you already know that a gas (unlike a liquid) is much more compressable. That could be giving you the spongy feel.
Also. the heated fluid/gas mixture would expand to the point where it would try to overflow the resevoir.
I'd try to bleed the system again and reroute the line or fabricate some type of heat shield before doing the more involved stuff.
If you still think you want to replace the master cyl, I'd advise to do both at the same time. You could same lots of $ by getting rebuild kits thru a local parts store or www.parts.com.

 

[Ken]

Re: spongy clutch

... you want to replace (both) ... at the same time.

Yes, that is definitely good advice. Thank you for pointing that out.

_ken

 

[tnovot]

Yep, just trying to help the young lad out. I guess that's what it's all about - helping each other - giving our opinion and advice when we can.
Terry

 

[militant_x]

and I appreciate it,

thank you,

-chris

 

[vettedoc]

Chris-

I had a similar problem last year. I replaced both master and slave and she shifts like a new car. You can rebuild and save some money if you have the time and mechanical ability. I would definitely do both.

Doc

 

[militant_x]

Alright, so ive decided to rebuild the units. Im taking off the mastery cyl right now. I dont like to force things so here it goes.

The pushrod that attatches to the stud on the clutch pedal... does that just slide off? I have the clip and washer off... but it seems like i would have to really move the pushrod to one side to slip it off. Is this how its done.. or do i need to take the clutch pedal partially off?


actually, im thinking once the two bolts that hold the cyl in place come off i can slide it over. However getting that second bold the one closer to the passanger side is gonna be some fun.

Also, anything i should know when it comes to actually rebuilding the unit?

thanks,

chris

 

[tnovot]

Rebuilding hyd clutch cyls

The rebuild kits should have come with instructions.
If it’s anything like rebuilding the wheel cyls on the old style drum brakes, use very fine emery cloth to break the glaze in the cyl bores and clean several times with alcohol. I'm sure there is someone out there who has done this and can provide more useful info.
Cleanliness of the interior surfaces is very important. Try to use something like a coffee filter or dryer sheet that won't leave lint. Sometimes a finger works best. Don’t clean using anything containing water. Brake fluid has an extremely strong affinity for water.
Also, when filling and bleeding, keep the container and master cyl closed whenever possible because again, brake fluid will absorb water right out of the air.
Len in previous reply had good advice on bleeding the system.
Take your time and work carefully. Give us a little feedback after you're done to let us know how you did and if there are any little tricks the rest of us should know about.
Terry

 

[militant_x]

Alright, so the master cyl is back in and rebuilt. One of the center seals was toast.

I havent tested it yet though, tomorrow i do the slave.

The hardest part was getting that second bolt out. I took off the cruise control thing, and with a help of a friend wedged the battery out.

After the bolt putting the pushrod back on the pedal was hard for me, took a while of fighting it. It might have been funny to watch, at times my head was resting on the brake pedal and my feet were way in the air.

hopefully it all works out, i cleaned best i could. Im using the valvoline synthetic fluid.. this alright? It says it exceedes dot 3 and 4. The rebuilding kit said to use atleast dot 4.

thanks guys,

-chris

 

[militant_x]

Well its all almost done. Both the slave and master are rebuilt and back in place. They are bled and ready to go. I havent driven the car yet because now the clutch line is touching the catalytic, im going to bend the line slightly.

Removing the slave was a bit hard for me. I hadnt jacked up the car ever before and was a little lost on how to do so. I ended up rigging up a piece of wood and jacking it from the center of one side as this c4 corvette book i have recomends (but doesnt go into specifics). I put jackstands on the front and back and proceded to unbolt the slave.

Removing it is pretty easy, the bolts might be tight and you wont have room under the car to get a good pull, but they come off. My friend advised me not to remove the clutch line from the cylinder, so i rebuilt from the side of the car (with the slave under the car).. hanging. I felt a little dumb, the seal seemed pretty much brand new or perfect, I kept telling myself "its old".

Cleaned it all up and bolted it back in. The higher of the two bolts is tricky to reinstall because the catalytic blocks your hand should you try to start the bolt with your hand.

I cant wait to drive it, i could feel when bleeding it, its much stiffer now. It still has a littleeee bit of play at the top. This is my first standard shift car and I dont know how it should be. Next thing to tackle.. u joints.

thanks again,

-chris

 

[tnovot]

rebuild finished

Chris -
Glad to hear you again have a dependable set of wheels to get you to and from school.
Don't worry too much about the amount of free pedal movement. You should have a little bit of free play in the clutch. Not sure how much for your car but usually around 1/2" to 3/4" is OK. Maybe someone out there has the specs on this?
My final advice is to keep up with the studies and work on the car only when you have extra time. I'm sure you already know this.
Thanx for the good feedback on a job well done.
Terry