• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Fiesta ST Forum and Fiesta ST community dedicated to Fiesta ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Fiesta ST Forum today!

OEM clutch durability

Messages
476
Likes
175
Location
Kelso
#21
I've just had to replace mine at 66,000 miles. While I tend to drive the car hard sometimes, I'm never abusive. It had been clicking at idle for several thousand miles and finally let go. I've never worn out a clutch in car with less than 140,000 miles.

The symptoms were odd. (The streets had been full of water the day before I had problems. I tried not to go thru anything that would touch the bottom of the car, but I had to get home soooo... maybe it did. But I digress). The next day the clutch pedal was low, only about 1/2 way up. I noticed that it was slipping on some shifts. I limped it home without stopping (I only had to run two STOP signs). I tried starting and stopping the engine to make sure that I could disengage the clutch and that the car would still start. I came out the next morning and the pedal was to the floor. It had simply sunk down during the night!. I pulled it up with my hand, started the car and everything was fine. Odd. I assumed that the problem was in the slave cylinder and took the car to the local mechanic. (My local Ford dealer is a piece of crap to whom I will never again take a car. I have my servicing done an hour away in Portland). They told me the clutch needed to be replaced. In order to access the slave cylinder they have to take out the tranny and if you're going that far it's silly NOT to replace the clutch while you're there anyway. I agree.

The flywheel was slightly scored with definite burn marks and ----I don't know the name but it the facing loose on the flywheel. That was the rattling I've been hearing as the noise it gone at idle in neutral. This is probably what caused the clutch to wear prematurely. They replaced the slave of course but found no leakage indications., which seems odd given the symptoms. All good now.

My 2¢
 


Intuit

2000 Post Club
Messages
2,255
Likes
851
Location
South West Ohio
#22
Whatever was causing the clutch pedal to not fully return was likely responsible for the clutch scoring, damage. It not returning to full engage height is the proverbial equivalent to "riding the clutch".
The fact that it sunk down overnight means the hydraulics were loosing pressure. The clutch diaphragm springs are not intermittent... though they sometimes break off... which would be incredibly noisy I think.

Hydrualics can be intermittent because they rely on some form of silicon or rubber, sealing against the internal walls of a cylinder. While the slave can only leak externally, the clutch master can leak either way; externally or internally or even both. In most Ford passenger car designs, it draws its fluid from the brake reservoir. That reservoir for safety reasons is compartmentalized via spillway. So if the clutch portion of the reservoir goes empty (potentially causing the symptoms you mentioned) it won't necessarily be obvious when looking at that reservoir. If I hadn't already cut it off, I would've pulled my hair out trying to bleed the clutch on my prior vehicle because the reservoir always appeared 75% full when bleeding. Hours later it occurred to me to check for line obstruction or restriction between reservoir and master, only to find there wasn't any fluid in a tiny, tiny back corner of that reservoir; the only part that the clutch master was drawing fluid from.

The part you're referring to is call a "dual mass flywheel". A dual mass flywheel will not cause or contribute to clutch failure. You have a spring-loaded clutch disc... in our case, we have a spring-loaded flywheel. When that dual-mass flywheel part breaks, it basically spins freely. So the link between the engine and the transmission is effectively lost. It wouldn't surprise me if parts from an "exploded" DMF sometimes end up causing collateral damage though.

What I find interesting is, my prior car had a spring on the fulcrum of the clutch pedal; causing it to rise-up without strictly relying on return pressure generated by the clutch diaphragm's springs. That's mostly if not totally what created the "freeplay engage height" spec on my prior car. I'll take a peak under my FiST's dash and see whether my pedal is spring loaded... and/or also look for evidence that it might've been encorporated into the original design. But the fact that one can pull up on it to regain clutch engagement, suggests that it may be hard-linked to the master cylinder... which is also different from my prior car.
 


Messages
147
Likes
88
Location
Cranbrook, BC, Canada
#23
Does the OEM clutch in these cars have a sprung hub clutch or is it a solid hub clutch because of the dual mass flywheel?

If I'm replacing the clutch am I better off going to a solid flywheel and a sprung hub clutch or sticking with the Dual Mass Flywheel?
 


Last edited:

Intuit

2000 Post Club
Messages
2,255
Likes
851
Location
South West Ohio
#24
Clutch disc and flywheel are spring loaded. Better to stick with OEM design. There were some technical reasons for the addition of the DMF. Memory serving, one of them was to dampen (direct injection four cylinder) engine output. I got the impression that the only reason we're specced to allow part-synth transfluid, as opposed to full-synth, is because to that DMF. https://www.just-auto.com/interview...mx65-manual-transmission-family_id163132.aspx
 


Quisp

1000 Post Club
Messages
1,103
Likes
366
Location
Davenport
#28
The guy I e-mailed at Spec clutch said that the spring hub clutch won't work with the OEM flywheel????
Is this wrong??
No the flywheel has take up springs in the OEM , so no need for the clutch disc to .
 


Similar threads



Top