Stiff clutch when cold

[ZAKU]

It is -22 here and I am having the exact same issues. 99% sure the issue is the clutch slave cylinder and the fluid inside it getting too cold.

I've noticed it especially when driving on the highway, the pedal will become rock hard. Meanwhile it will go from stiff to soft and back again when I'm running errands in the city and it has a chance to sit and warm up.

Check this out: http://www.dixcel.co.jp/en/subconten...erature02.html

DOT3 Viscosity (－40℃) under 1500cst
Dot 5.1 Viscosity (－40℃) under 900cst

I've ordered some DOT 5.1 fluid but it is taking FOREVER to get here.

Originally Posted by Exiwolfman

Use synthetic gear oil and u wont have any problems....or just let the car warm up a bit.

Originally Posted by thebarber

Not brake fluid, tranny fluid is cold. Happens to most cars. A switch to a good synthetic fluid can help. I like redline or amsoil

I'm running Amsoil as well and have the exact same issue. Think about it, how would transmission fluid affect the engagement of the clutch?