cold temp or CDV reason for brief dead clutch?

twofast2s · 01-24-2011, 08:27 AM

hi guys,

I had CDV mod done and clutch line bled not too long ago, and I feel like CDV mod helped w/ the 1 to 2 gear shift, but the shifter felt little clicky as far as shifting into gears, where i can feel other "clicks" b/f going into gears (not a smooth transition like i've experienced w/ my previous cars).

I also felt that the clutch pedal felt just tad bit soft, but I thought this was just placebo effect cuz i get paranoid sometimes when i bleed brakes or clutch.

This morning, the outside temp was -2F and when i started the car and put in first gear, it went in, and when i again try to shift to 2nd, the clutch felt really soft and i couldn't put in gear.

I was basically parked in middle of the street for few min, but finally was able to shift into 1st again, but w/ great hesitation and little bit of griding sound as i went into 1st gear.

so the question is:
is this incident due to perhaps a tiny amount of air that may have been trapped in the clutch line

or from change in viscosity of the clutch/brake fluid due to temperature?

thanks for your input.

Tzu · 01-24-2011, 03:58 PM

I couldnt find a chart of viscosity vs. temperature of Dot4 fluid, but brake fluid is ensured to have very consistent viscosity under all user encountered temperatures.

I assume since you had just started the car, the car was cold. My tranny is clicky when its cold as the tranny fluid takes time to warm up.

As far as the gear grinding, it sounds like the clutch isnt fully disengaging. You may have had a bad bleed when you did the CDV.

Does everything operate normally when the car is warm?

twofast2s · 01-24-2011, 09:19 PM

The car at operating temp shifts fine. When the car is cold, I can feel mushyness of the clutch pedal and engagement point closer to the floor. as the car gets warmer, the clutch gradually returns to normal operation.

If there is a little bit of air, will it produce symptoms that I'm experiencing?

Tzu · 01-24-2011, 10:37 PM

If there is a bubble in there, it will always feel mushy. Mine is "mushy" and "clicky" for only the first 5 minutes in or so in negative temperatures (Celsius) when everything is cold. I would expect this from a car that sits overnight (temperature has had time to equalize).

Does the pedal return back to the top after being depressed? Maybe pull it up to check if theres any more room. If so, rebleed. You can always rebleed to be safe.

twofast2s · 01-25-2011, 04:03 AM

Thanks for the advice.
everything returns to normal when the car is on for few min.

i guess i need to rebleed when the weather gets warmer outside.

01-24-2011, 08:27 AM	#1
twofast2s Private 5 Rep 95 Posts Drives: 2007 328i Join Date: Sep 2010 Location: Boston, MA iTrader: (0)	cold temp or CDV reason for brief dead clutch? hi guys, I had CDV mod done and clutch line bled not too long ago, and I feel like CDV mod helped w/ the 1 to 2 gear shift, but the shifter felt little clicky as far as shifting into gears, where i can feel other "clicks" b/f going into gears (not a smooth transition like i've experienced w/ my previous cars). I also felt that the clutch pedal felt just tad bit soft, but I thought this was just placebo effect cuz i get paranoid sometimes when i bleed brakes or clutch. This morning, the outside temp was -2F and when i started the car and put in first gear, it went in, and when i again try to shift to 2nd, the clutch felt really soft and i couldn't put in gear. I was basically parked in middle of the street for few min, but finally was able to shift into 1st again, but w/ great hesitation and little bit of griding sound as i went into 1st gear. so the question is: is this incident due to perhaps a tiny amount of air that may have been trapped in the clutch line or from change in viscosity of the clutch/brake fluid due to temperature? thanks for your input.
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01-24-2011, 03:58 PM	#2
Tzu Lieutenant Colonel 29 Rep 1,551 Posts Drives: 335i Join Date: Jun 2010 Location: Toronto iTrader: (1)	I couldnt find a chart of viscosity vs. temperature of Dot4 fluid, but brake fluid is ensured to have very consistent viscosity under all user encountered temperatures. I assume since you had just started the car, the car was cold. My tranny is clicky when its cold as the tranny fluid takes time to warm up. As far as the gear grinding, it sounds like the clutch isnt fully disengaging. You may have had a bad bleed when you did the CDV. Does everything operate normally when the car is warm?
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01-24-2011, 09:19 PM	#3
twofast2s Private 5 Rep 95 Posts Drives: 2007 328i Join Date: Sep 2010 Location: Boston, MA iTrader: (0)	The car at operating temp shifts fine. When the car is cold, I can feel mushyness of the clutch pedal and engagement point closer to the floor. as the car gets warmer, the clutch gradually returns to normal operation. If there is a little bit of air, will it produce symptoms that I'm experiencing?
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01-24-2011, 10:37 PM	#4
Tzu Lieutenant Colonel 29 Rep 1,551 Posts Drives: 335i Join Date: Jun 2010 Location: Toronto iTrader: (1)	If there is a bubble in there, it will always feel mushy. Mine is "mushy" and "clicky" for only the first 5 minutes in or so in negative temperatures (Celsius) when everything is cold. I would expect this from a car that sits overnight (temperature has had time to equalize). Does the pedal return back to the top after being depressed? Maybe pull it up to check if theres any more room. If so, rebleed. You can always rebleed to be safe.
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01-25-2011, 04:03 AM	#5
twofast2s Private 5 Rep 95 Posts Drives: 2007 328i Join Date: Sep 2010 Location: Boston, MA iTrader: (0)	Thanks for the advice. everything returns to normal when the car is on for few min. i guess i need to rebleed when the weather gets warmer outside.
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