Clutch questions....

[badtlc]

I'm not new to driving a stick, but I'm new to owning a stick and drivig it every day. After owning one for 6 months I have some questions:

1) Does brake/clutch fluid have any effect on clutch performance? Is having brakes/clutch share fluid harder on the fluid?

2) I have had this happen a couple of times lately, like maybe 2 or 3 times total. After a cold start, during one of the first 2 or 3 starts from a stop, I have felt what i can only describe as the clutch "hopping" during takeoff. I think the clutch pedal has been completely released during this event, but it only happens when i'm accelerating firmly (not fast or hard). If I release the clutch fairly slow, it never happens. Could this be from a cold clutch or maybe from condensation getting on a clutch? I'm not familiar with the design of a clutch.

 

[AandPDan]

In 30 something years of driving, only 5 were spent in an automatic, so I'm somewhat used to a manual and it's quirks.

Yes on the "hop." I only notice it more when it's been very humid out and for the first couple of starts. After that it's gone. I do think that some surface rust or condensation on the flywheel/clutch disc is the factor here. I consider it normal.

I don't see why sharing fluid would be harder on it. My truck has a separate master cylinder for the clutch and if anything it's cleaner looking than the brake fluid - both Dot 3.

 

[onemig]

Same here. My clutch chatters/hops especially on a rainy/humid day for a couple of starts.

 

[Dave Sherman]

I doubt your clutch and brakes share the same fluid, unless you're driving some old British sports cars. They may use the same type, they don't share it. Don't forget to change the clutch fluid though, it still attracts moisture and promotes corrosion when it does. Do it when you change your brake fluid.

 

[d00df00d]

My car has a shared reservoir for brake and clutch fluid.

I can't imagine it hurts the fluid. Brake fluid doesn't "wear down" from use; what gets it is moisture, and there's nothing about a shared reservoir that should increase exposure to moisture.

 

[badtlc]

Originally Posted By: Dave Sherman
I doubt your clutch and brakes share the same fluid, unless you're driving some old British sports cars. They may use the same type, they don't share it. Don't forget to change the clutch fluid though, it still attracts moisture and promotes corrosion when it does. Do it when you change your brake fluid.


My car has only one resvoir. It states quite clearly brake/clutch fluid.

Quote:
I can't imagine it hurts the fluid. Brake fluid doesn't "wear down" from use; what gets it is moisture, and there's nothing about a shared reservoir that should increase exposure to moisture.


I realize the fluid doesn't wear down. I just didn't know if a clutch introduces water faster than just a brake system. I tend to do brake fluid every 3 years, but I was considering every 2 years if the clutch made a difference in the water absorption rate.

And thanks everyone. It sounds like it is normal. It has been VERY humid here fora few weeks now due to the storms and flooding.

 

[Dave Sherman]

Ah, learn a new thing each day then. Didn't know shared clutch/brake reservoirs were still in use, the last couple stick shifts I had used separate reservoirs. The AH Sprite my MG evolved from used a shared reservoir, but they eventually used separate ones.

 

[Whimsey]

My 2002 F-150 has a separate clutch reservoir where as my 1996 Ford Contour uses the brakes reservoir.

Whimsey

 

[UNC017]

Originally Posted By: Dave Sherman
I doubt your clutch and brakes share the same fluid, unless you're driving some old British sports cars. They may use the same type, they don't share it.


Actually, its not that uncommon for the brakes and clutch to share a reservoir. My SRT-8 has a typical large partially-divided brake reservoir, but the clutch has no reservoir. A hose from a nipple on the side of the brake reservoir provides the clutch master cylinder with its fluid supply.


Frankly I prefer that setup to the separate (tiny!) reservoir for the clutch on my daughter's 99 Cherokee. The clutch fluid gets freshened whenever the brake fluid is flushed.

 

[KrisZ]

The slight shuddering when cold and damp is normal and it happened on my 95 Accord and is now happening occasionally in my 03 Focus.
The shared brake fluid is not a big deal at all since the clutch slave cylinder is usually far away from the clutch friction plates or is much further from the plates than brake pistons are from brake pads.

 

[TallPaul]

Never happens to me. Suggests to me a slight warping of the disk or possibly an uneven wear pattern on the flywheel. Think they used to call it clutch chatter and in the old days I heard they would put the bumper against a tree and then slip the clutch a bit to try smoothing it out. That is not recommended for the tree as it may damage it, and probably not best for the clutch disk either.

Perhaps this may have some info on it (several items on clutch diagnosics near the bottom of the page):
http://www.rsgear.com/technical.aspx

 

[badtlc]

If it were uneven clutch wear/warping, I would think it would be more noticeable when letting the clutch slip/releasing it slowly. When the clutch is in contact and slipping, there are no discernable vibrations, bumps, hiccups, hopping or the likes.

 

[KrisZ]

Originally Posted By: badtlc
If it were uneven clutch wear/warping, I would think it would be more noticeable when letting the clutch slip/releasing it slowly. When the clutch is in contact and slipping, there are no discernable vibrations, bumps, hiccups, hopping or the likes.


Actually I would double check if the clutch pedal is fully released when this "hop" happens.
The slight clutch shudder in my case happens during clutch release, not after the clutch was fully released.

Also, I think that if it was uneven clutch wear or deposits the problem would get worse as the clutch warmed up, sort of like with brakes. Brakes with uneven pad deposit issues always seem to be very smooth when cold but start to vibrate when warmed up.

 

[surfstar]

I've had it occasionally on all my clutches. Although we don't have damp weather here very often, it just would happen randomly in the mornings. My '93 Mazda still had the original clutch when junked last fall at over 340k miles.

 

[badtlc]

Originally Posted By: KrisZ
Originally Posted By: badtlc
If it were uneven clutch wear/warping, I would think it would be more noticeable when letting the clutch slip/releasing it slowly. When the clutch is in contact and slipping, there are no discernable vibrations, bumps, hiccups, hopping or the likes.


Actually I would double check if the clutch pedal is fully released when this "hop" happens.
The slight clutch shudder in my case happens during clutch release, not after the clutch was fully released.

Also, I think that if it was uneven clutch wear or deposits the problem would get worse as the clutch warmed up, sort of like with brakes. Brakes with uneven pad deposit issues always seem to be very smooth when cold but start to vibrate when warmed up.


It was probably at about 90% release on the clutch pedal when it happened but the pedal has no feeling at that point. So I asume the clutch to be completely engaged at that point, maybe it wasn't.