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Stiff clutch pedal on hot days

This is a problem I had last summer, and it is occurring again this summer. Stock clutch, assist spring installed last summer, deleted this summer. My car is garaged at night. When I start the car in the morning, the clutch feels fine. I drive to work (10 miles), then the car sits in a metal building garage at ambient temperature for about 4 hours. When I get in it again, the clutch is stiff and feels like it is binding. I then drive the afternoon in city conditions, with multiple stops (ignition off), and in town shifting. During this time, the clutch pedal is stiffer than normal, but doesn't feel like it's binding. By the end of the day, the ball of my clutch foot is sore and bruised feeling. I drive the car home and park it in the garage overnight. The next morning, the clutch feels fine again.

This condition only occurs when ambient temperatures are in the high 80's and above. It is not quite as bad with the clutch assist spring removed, but I don't believe that the clutch spring is/was part of the problem. The shifts feel a little notchier to me when this happens, and I wonder if the clutch is fully engaging. The friction point appears unchanged when the problem occurs, however. Has anyone experienced this issue, or does anyone have any thoughts as to the cause?
 
I've had similar experiences during the last two track events - between sessions. I'd come out of the track (after a cool down lap) and park the car. Once I was ready to go out for the next session, the pedal would feel very firm, but it would go back to "normal" after a few pumps of the clutch pedal while the car was idling. It almost felt like the clutch plate was sticking to the flywheel!

At this point I have no recommendations, other than maybe replace brake and clutch fluid. I'm having the transmission rebuilt along with a clutch replacement soon. So, if it's clutch assembly related issue, I may be able to chime in with more info once the shop has it apart.

I also want to mention that after I experienced the firm pedal when hot, my car would also occasionally "jolt" forwards or backwards, depending on gear selection, even though the clutch pedal would be fully depressed. So, it may even be a throw out bearing related issue :(. Have you experienced any "jolting"?
 
I replaced my brake fluid at the first of this month (Motul RBF 600). Same was in the car last year. No, I have not experienced any jolting while the clutch is depressed.
 

Justin

Save the dawn for your dishes!!!
I am willing to bet that it's binding due to swelling of metal in the pressure plate. Highly recommend getting a McLeod rst or rxt clutch and be done with you clutch problems


Sent from my iPhone using Tapatalk
 

Fred G

What Goes Around Comes Around
Just came back from the Mustang Alley where I met a driveline engineer at the test track event on Friday. We spoke about the mushy and sticking clutch problem and how by removing the assist spring appears to have solved (at least) my issue. I have to say, and please don't shoot the messenger, that he was pretty adamant that one has nothing to do with the other, and believed it was strictly a hydraulic issue, and recommended bleeding the system, which he said in theory, should self bleed by pumping the clutch pedal (however many times). He said an actual bleed with a vacuum pump would obviously be the better way to go. Again, I was thrilled to even be talking face to face with him, so I didn't want to become confrontational, because removing the spring did solve my problem, although I do not track my car, yet, so I don't know if I'd still have the problem with actual hot laps on a road course. For some serious street flogging and an occasional drag race, the problem was there and removing the spring worked for me. I then asked about the larger diameter clutch line and at the same time mentioned that a friend of mine, who does track his car regularly, somehow convinced a local dealer to replace the clutch pedal assembly with a GT500 set-up (under warranty) to solve the problem and it did. He stuck by his guns and commented that in order to replace the clutch pedal assembly. you'd have to bleed out the clutch line and that (the bleed) in his opinion, was what solved the problem, not the new pedal assembly. I might add that he was standing with several other engineers and they all concurred with him on this, however their major concern was how/why air was getting into the system in the first place. I did not follow-up with his thoughts on the larger diameter clutch line, but I'm sure he would have related any success with that to having to bleed the line after installation... BTW, most of these guys own Boss 302's and appear as passionate as we are about them.
Fred G
 
Fred, thanks for sharing that conversation. I agree with the engineer that changing the pedal assembly did not fix the problem unless there was a defect in the original. The Ford Racing SS clutch line is not larger and is only designed for heat protection when using headers. Installing it will not solve any issues.

Regarding the helper spring I disagree with the engineer. As you and others have found out removing the spring solves the problem although it may not be the cause. My experience is I had the pedal stick multiple times over a period of months. I was at a track day and had the pedal stick multiple times during two morning sessions. I removed the spring during the lunch break and have not had the clutch stick one single time since then. That afternoon the ambient temps rose a good 20 degrees and no more sticking. If members have their pedal stick remove the spring and don't look back. I'd be happy to discuss this with a Ford engineer anytime. ;)
 

TymeSlayer

Tramps like us, Baby we were born to run...
3,776
2,696
Exp. Type
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Brighton, Colorado
I know many have removed this clutch assist spring because of sticky pedals but not once in nearly three years have I had this issue. Normally I would just follow the leader on this because there's no cost nor is it difficult to remove, but this is one case of don't fix what ain't broken I paid heed to.
 

Fred G

What Goes Around Comes Around
NFSBOSS said:
Fred, thanks for sharing that conversation. I agree with the engineer that changing the pedal assembly did not fix the problem unless there was a defect in the original. The Ford Racing SS clutch line is not larger and is only designed for heat protection when using headers. Installing it will not solve any issues.

Regarding the helper spring I disagree with the engineer. As you and others have found out removing the spring solves the problem although it may not be the cause. My experience is I had the pedal stick multiple times over a period of months. I was at a track day and had the pedal stick multiple times during two morning sessions. I removed the spring during the lunch break and have not had the clutch stick one single time since then. That afternoon the ambient temps rose a good 20 degrees and no more sticking. If members have their pedal stick remove the spring and don't look back. I'd be happy to discuss this with a Ford engineer anytime. ;)

Well as I said, the spring removal definitely worked for me, but going along with Tymeslayer's comment about not having the problem, I went out on three hot lap sessions in two different '13 Bosses and one of the new 2015's. All three of the guys that were driving were engineers from product development and all owned Bosses (12's and 13's). I specifically asked each if they ever encountered the sticking clutch problem and they claimed they did not. I didn't have a whole lot of time to talk to each as our conversations took place during hot laps, but these guys were wearing their own personal helmets and from the way they were flogging these cars around the track, it was obvious they were also into it on a personal level. I have to say that I was really impressed by witnessing first hand the continual abuse these cars, which outwardly appeared bone stock, were taking without so much as a hiccup, stopping briefly only for re-fueling. So all in all it was a great weekend and I learned the following about my car as a result of the 1500 mile round trip drive from Long Island to Dearborn:
1. My car will not melt in the rain and the Expel clear-bra on the front cover was well worth the money.
2. The Boss 302 truly is a fantastically well balanced and comfortable car to drive over almost any road conditions (read George Washington Bridge and Cross Bronx Expressway!).
3. Apparently these cars can take having the snot beat out of them and keep coming back for more.
4. Driving 10 hours straight, twice within four days, mostly at 80 to 90 MPH was absolutely effortless for the me and the car.
5. I'm selling myself short if I don't get to more track events.
Fred
PS: Using 5W-50 full synthetic Mobil 1 and did not burn one drop.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
438
Southeast
NFSBOSS said:
Fred, thanks for sharing that conversation. I agree with the engineer that changing the pedal assembly did not fix the problem unless there was a defect in the original. The Ford Racing SS clutch line is not larger and is only designed for heat protection when using headers. Installing it will not solve any issues.

NFSBoss:

Actually it is larger. I compared the two lines side by side and the plastic line has aluminum sleeves pressed in each end that have small holes, the I.D. of the FRPP stainless line is larger, (2X minimum).

I totally agree with you about the helper spring as I too had the clutch stick to the floor in race conditions, (7300 RPM 2-3 shift). Once helper spring was removed, no issues afterwards. I would never expect a Ford Employee would tell the public anything other than what was reported. My follow up question would be, why did you remove the clutch line bleeder valve in 2011? (Cost).

It is hard to say this works, or this doesn't work because each Driver is different and operates the vehicle differently. Then, each owner is doing different fixes at different times.

For me I had the following done that fixed my shifter issues:

- Installed MGW shifter
- Removed helper spring
- Warranty clutch replacement, flywheel, pressure plate, disc and T/O Brg.
- FRPP stainless line
- Trans fluid change per TSB

All of the above have fixed my shifting issues, up shift, down shift grind or lock out. The other variable for me with the up shift smoothing out is mileage. I now have over 12,000 miles on my car and maybe it took a few thousand miles to break-in? Don't know but all of these things together fixed my troubles, it was not one specific item.

I like the MT-82 Transmission and the gear ratios Ford selected, but like all things it has a life expectancy and when the time comes, I'll send it out for an overhaul with improved and updated parts, synchronizers, fork blocks, etc.

Just one Boss owners experiences, still think she's the best outhere!
302 HP
 
I have a 2012 Boss, #2541 (2451?) - I took delivery in Dec. 2012-I have run track days at Sonoma, Thill and Laguna beginning in March 2013. Shifting was never smooth/easy from day one --not near as smooth as my 2004 CTS-V that I never had problems with. Clutch was getting stickier and stickier, especially after 2-3 sessions. Shifting more and more difficult ---especially from 2nd to 3rd and 3rd to 4th. It all came to a head at Thill, running the long course on a hot day in July, 2014. Could not downshift 4th to 3rd without a lot of trouble, could not upshift 3rd to 4th and 4th to 5th (on the straight). I ended up not even trying to upshift to 5th on the straight at Thill. I have 13 K miles on car. Took it in to selling dealer - Frontier Ford. They replaced entire clutch, disc, pressure plate --and flywheel (so they said). All under warranty. I just ran a track day at Sonoma and no issues with shifting--still not a great tranny but at least now it works. Another, and new, problem cropped up with my check engine light blinking and reducing my power. I will address that in another comment at the appropriate location.
 

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