silver93rx7r1

iTrader: (2)

I can feel and see my clutch pedal moving back towards the floor under hard accelerations. So far no slipping, but it seems odd to me that it does this. It also seems to happen more in 1st and 2nd gears. I have an ACT street/strip that was installed 11 years ago and has 22,615 miles on it. My rx7 is single turbo with 389rwhp so it's not like I've exceeded what that clutch should be capable of holding. Is it a pressure plate issue or any other ideas?

DaleClark

iTrader: (55)

That is an odd one. Have you noticed any loss of clutch fluid?

It might be worth replacing the clutch hydraulics if they haven't been done in recent memory. Sinking pedal many times means a failing clutch master. Even if you aren't getting a leak the internal pressure could be bypassing.

New clutch master and slave and a braided stainless clutch line, even if that doesn't fix the problem it's worth doing.

Dale

silver93rx7r1

iTrader: (2)

I've not noticed any loss of fluid. I did bleed the clutch system last winter. I think I will change the master cyl and line to the slave. I have to look through my maintenance records, but I know I did the slave cylinder years ago (but I'll prob just change it again).

Banzai-Racing

iTrader: (11)

So you are saying that the pedal starts to drop under hard acceleration, this is when there is no pressure being applied by the clutch hydraulic system. When you are not accelerating, is the pedal at normal height?

silver93rx7r1

iTrader: (2)

Ok, so I tried to get a better grasp of what it was doing today on my way home from work. The clutch pedal feels softer than I am used to it being (at all times). The confusing part is that it is not consistent. It varies from soft to much softer at times. I tried to watch the pedal a bit while accelerating (not easy to do safely!). I will say the pedal seems to stay in place, but it gets softer with higher RPM's. If I jump on it and wind it out when I go to shift the pedal is considerably softer then when I am driving like a "normal person." The pedal is very mushy and I finally get some pressure when the pedal is closer to the floor.

I am going to replace the master & slave cylinders along with adding a stainless steel line between the two as suggested by DaleClark. The part that confuses me is that I've lost hydraulic pressure in other cars' clutch systems, but they've never felt like this one.

I'm also going to pop the inspection plate off the transmission and take a peak to see if I see anything obvious going on inside.

Banzai-Racing

iTrader: (11)

A bad master cylinder is evident when you lose pedal pressure while it is depressed, not when the clutch is engaged. There is no pressure to lose, when driving. I can't see how replacing the hydraulics will fix your problem, however it is worth a shot since the parts are inexpensive.

Clutch Hydraulics (93+ RX-7)

What you are describing is the pressure plate losing clamping force with centrifugal force, which I have never seen

silver93rx7r1

iTrader: (2)

Leave it to me to have an odd issue! I'm going to change the hydraulics and see what happens as a starting point. Maybe I get lucky and I'm just a moron that isn't accurately describing what's happening 🤞🏻