AP Organic clutch: Anyone had this stupid problem!!!!
30 March 2004, 09:48 PM
#1
AP Organic clutch: Anyone had this stupid problem!!!!
Driving me mad:
Fitted a new AP organic to my Stiv3. Now have the clutch pedal sometimes sticking down by 40 mm or so from the top.
I think it is the fit of the thrust bearing (original Sti) into the cover spring 'ring' where it all clips together with the thrust bearing.
Only occures during hard accelleration, does not happen when cruising and changing gear.
Clutch does not slip at all, and gears easy to change etc.
Any ideas? Lot of you have fitted them, but the sticking pedal 'syndrome' is quite common!
Really need some advice. Tried all the 'external' to the gearbox tweeks I and others can think of.
911
Fitted a new AP organic to my Stiv3. Now have the clutch pedal sometimes sticking down by 40 mm or so from the top.
I think it is the fit of the thrust bearing (original Sti) into the cover spring 'ring' where it all clips together with the thrust bearing.
Only occures during hard accelleration, does not happen when cruising and changing gear.
Clutch does not slip at all, and gears easy to change etc.
Any ideas? Lot of you have fitted them, but the sticking pedal 'syndrome' is quite common!
Really need some advice. Tried all the 'external' to the gearbox tweeks I and others can think of.
911
01 April 2004, 09:54 PM
#4
Had a conversation with AP tech services today, found out the problem. The clip (farty wire C clip) that retains the thrust to the diaphram spring is moving at high revs, and the pedal travels with it. this is why the pedal prob only occures at high revs and HARD accelleration, and all is well at moderate driving.
Removing the 'valve spring' off the pedal assembly tonight ensures the pedal always comes to the top (thanks to Roger Clark Motorsport for the tip).
I will strip it all soon and fit a new STi thrust and clip and all will be well then (I hope)
What a game!
Thanks to you all for your responses, been a great help.
911
Removing the 'valve spring' off the pedal assembly tonight ensures the pedal always comes to the top (thanks to Roger Clark Motorsport for the tip).
I will strip it all soon and fit a new STi thrust and clip and all will be well then (I hope)
What a game!
Thanks to you all for your responses, been a great help.
911
01 April 2004, 11:04 PM
#5
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911...
This is a new one to me, what exactly happens to the C clip??
Where is the Clip moving to?
Not tryin to be funny, just think you may be wasting your time taking it back out again..
Rob
Just to confirm
is the spring on the clutch arm? is there suitable tension in it to return the pedal?, as i said i'm just trying to save you some time, i might be completely wrong but i have solved the same prob about 5 times now. 4 times was missing spring and once was for poor tension spring.
This is a new one to me, what exactly happens to the C clip??
Where is the Clip moving to?
Not tryin to be funny, just think you may be wasting your time taking it back out again..
Rob
Just to confirm
is the spring on the clutch arm? is there suitable tension in it to return the pedal?, as i said i'm just trying to save you some time, i might be completely wrong but i have solved the same prob about 5 times now. 4 times was missing spring and once was for poor tension spring.
Last edited by tweenierob; 01 April 2004 at 11:11 PM.
02 April 2004, 06:37 AM
#6
Rob, thanks for your interest. This is the failure sequence as explained to me by AP:
1 AP Organic with my original Sti thrust bearing and retaining clip re-fitted by me.
2 Normal driving in traffic, clutch is perfect, smooth pedal always works.
3 Open road, and accellerate at max effort, 4500 to 8000 rpm, change gear no problem, pedal stays down by 40/50mm. Change again, all works with the pedal still down (repeat etc). Get to cruising speed, say 4500rpm (its an RA box!) the pedal still down will pop back up after 30 seconds or so. Why?
4 The thrust bearing snaps into the cover diaphram centre ring exactly as the original Sti design. The thrust has a flimsy 'c' ring clip made of spring steel wire to give an easy snap fit when re fitting the box. To make this action easy, Subaru (not AP) provide 2 steps of different diameter. The design is to allow the clip to come to position on one of the diameters. And stay there! Normally this is perfect. My stock clutch had no issues before the change except it slipped at one race.
5 During easy use the clip stays put.
6 During hard accelleration the high revs opens up the 'c' ring due to centrifugal force.
7 The thrust then slides forward about 3 mm as the ring displaces onto the 2nd diameter, The hydraulics of the pedal system follows the movement due to the tension spring on the clutch arm above the bell housing. This movement 'looks' like the clutch is partly depressed, as the 3mm movement is amplified due to the clutch arm pivot/fulcrum ratio(!)
8 If you are in 4th say, gun the car, the pedal will actually sink by 50mm OF ITS OWN ACCORD as this 'slide' takes place.
Whew!
Solution is to fit a new Sti clip which is only available with a £80 thrust bearing!
I can only think the old clip/bearing was worn, weakened etc and had lost it's tension.
At the moment the problem is fudged as I removed the huge pedal assist spring last night, and the pedal always returns to the top, BUT the thrust does still move.
I also have an old drum brake shoe return spring on the clutch arm/bell housing, so there is pleanty of tension there!
At least I go racing this weekend and next, then I have 3 weeks to strip, examin and put it all back together. What a game.
Regards, Graham.
1 AP Organic with my original Sti thrust bearing and retaining clip re-fitted by me.
2 Normal driving in traffic, clutch is perfect, smooth pedal always works.
3 Open road, and accellerate at max effort, 4500 to 8000 rpm, change gear no problem, pedal stays down by 40/50mm. Change again, all works with the pedal still down (repeat etc). Get to cruising speed, say 4500rpm (its an RA box!) the pedal still down will pop back up after 30 seconds or so. Why?
4 The thrust bearing snaps into the cover diaphram centre ring exactly as the original Sti design. The thrust has a flimsy 'c' ring clip made of spring steel wire to give an easy snap fit when re fitting the box. To make this action easy, Subaru (not AP) provide 2 steps of different diameter. The design is to allow the clip to come to position on one of the diameters. And stay there! Normally this is perfect. My stock clutch had no issues before the change except it slipped at one race.
5 During easy use the clip stays put.
6 During hard accelleration the high revs opens up the 'c' ring due to centrifugal force.
7 The thrust then slides forward about 3 mm as the ring displaces onto the 2nd diameter, The hydraulics of the pedal system follows the movement due to the tension spring on the clutch arm above the bell housing. This movement 'looks' like the clutch is partly depressed, as the 3mm movement is amplified due to the clutch arm pivot/fulcrum ratio(!)
8 If you are in 4th say, gun the car, the pedal will actually sink by 50mm OF ITS OWN ACCORD as this 'slide' takes place.
Whew!
Solution is to fit a new Sti clip which is only available with a £80 thrust bearing!
I can only think the old clip/bearing was worn, weakened etc and had lost it's tension.
At the moment the problem is fudged as I removed the huge pedal assist spring last night, and the pedal always returns to the top, BUT the thrust does still move.
I also have an old drum brake shoe return spring on the clutch arm/bell housing, so there is pleanty of tension there!
At least I go racing this weekend and next, then I have 3 weeks to strip, examin and put it all back together. What a game.
Regards, Graham.
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