HOW TO DO AN ADVANCED SEARCH.
Mon Jul 08, 2013 3:56 pm by Admin
For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.
When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).
After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …
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Clutch Issues - HELP!!!
+3
docwyte
sharkey
jHo
7 posters
Page 1 of 1
Clutch Issues - HELP!!!
So my car's been running for a little over a year now, and it seems that the nagging problem is with the clutch. I've already replaced the the throwout bearing once, and a few months later it feels like the clutch is slow to release from the floor again. At startup after sitting for a week or so, it legitimately stayed on the floor until I kicked the pedal to release it, then as I drove it, it did not stick, but felt like it released slowly off the floor. So I bled it, and it felt a bit better, but still doesn't seem right. Seems like there is a hesitation off the floor, so I don't think that "fixed" the problem.
My car is an 86 n/a with turbo trans, LS3 crate, Ford Hydroboost, stock 944 clutch master (not the original, but a stock one that was replaced years before the swap), GM flywheel, pressure plate, throwout bearing, and TPC clutch.
Any ideas what is wrong?
I went the LS3 crate for reliability reasons, so I really want to get the problems sorted, even if it means new parts and more $$$.
Thanks in advance.
My car is an 86 n/a with turbo trans, LS3 crate, Ford Hydroboost, stock 944 clutch master (not the original, but a stock one that was replaced years before the swap), GM flywheel, pressure plate, throwout bearing, and TPC clutch.
Any ideas what is wrong?
I went the LS3 crate for reliability reasons, so I really want to get the problems sorted, even if it means new parts and more $$$.
Thanks in advance.
jHo- Posts : 42
Join date : 2014-11-21
Location : Grand Junction, CO
Re: Clutch Issues - HELP!!!
did you remove the clutch assist spring from the clutch pedal when you did the swap? if not i would recommend doing that and see how it feels.
sharkey- Posts : 713
Join date : 2014-11-21
Age : 39
Location : Abbotsford BC
Re: Clutch Issues - HELP!!!
I put my clutch spring back in. I hated the way it felt without it. I feel there are no benefits for removing the spring, if you're having a clutch issue, its not due to the spring.
docwyte- Posts : 1393
Join date : 2010-07-18
Re: Clutch Issues - HELP!!!
Differing opinions! I love the internet!
Seriously though, I appreciate both opinions, and I don't remember removing that assist spring, so I believe mine is still there. Plus, the clutch feels fine when it's moving, it's just the hesitation (or worst case sticking) as it comes off the floor. So I might be leaning toward's docwyte's opinion there.
Any thoughts on the clutch master? Are guys using Porsche 944 ones, or going with different ones that are a different size? Pro's and Con's?
Thanks!
Seriously though, I appreciate both opinions, and I don't remember removing that assist spring, so I believe mine is still there. Plus, the clutch feels fine when it's moving, it's just the hesitation (or worst case sticking) as it comes off the floor. So I might be leaning toward's docwyte's opinion there.
Any thoughts on the clutch master? Are guys using Porsche 944 ones, or going with different ones that are a different size? Pro's and Con's?
Thanks!
jHo- Posts : 42
Join date : 2014-11-21
Location : Grand Junction, CO
Re: Clutch Issues - HELP!!!
there is some debate on master cylinder size. some run stock, others go with a larger 13/16" or 7/8" bore. size is generally increased if the clutch is releasing/grabbing real close to the floor.
the clutch assist spring is designed to make the stock clutch smoother and more linear pressure feel. in the first bit of the travel you are actually pushing against the spring, making the pedal firmer, and once you get down part way the spring overcenters and it helps push the clutch pedal down, making the bottom part of the travel softer. the spring is set up for the stock pressure plate, and any changes in the clutch system can cause issues with it.
when i did my swap my clutch pedal would go down real easy, and would come up slow, i had to almost take my foot right off the pedal to get it to come up, and it would get a ways up and then pop up the rest of the way. i removed the spring and never looked back.
i would try it without the spring, or at least adjust it as weak as possible.
the clutch assist spring is designed to make the stock clutch smoother and more linear pressure feel. in the first bit of the travel you are actually pushing against the spring, making the pedal firmer, and once you get down part way the spring overcenters and it helps push the clutch pedal down, making the bottom part of the travel softer. the spring is set up for the stock pressure plate, and any changes in the clutch system can cause issues with it.
when i did my swap my clutch pedal would go down real easy, and would come up slow, i had to almost take my foot right off the pedal to get it to come up, and it would get a ways up and then pop up the rest of the way. i removed the spring and never looked back.
i would try it without the spring, or at least adjust it as weak as possible.
sharkey- Posts : 713
Join date : 2014-11-21
Age : 39
Location : Abbotsford BC
Re: Clutch Issues - HELP!!!
I still have the spring installed, 12 years with no issues....
The topic of sinking/non-returning clutch pedal has been a popular one over the years. If your pedal is going to the floor and staying there, and the clutch is still engaged, then there is some failure in the hydraulic/mechanical circuit.....obviously.
If the hydraulic circuit is all liquid, no air, then it is considered incompressible....motion at the pedal should directly translate to movement at the clutch pressure plate and vice versa.
This could be a failed MC, air in the system, SC, or excessive gap between SC and clutch fingers. Since your system worked before, and sort of works after manual actuation, I would say that it is one of the first 2.
Cheap/failed MCs can leak fluid internally causing this type of problem, getting better once you cycle some additional brake fluid back in.
Air - this I think is the most common issue and most difficult to eliminate. The air can be there from the beginning in a small amount then once heat cycling begins - expansion of air and brake fluid - the brake fluid can be forced back in to the reservoir up top, then once cooled create a sort of negative pressure that allows the pedal to come down. Also, I have read about boiling of the fluid, creating a similar situation with the pedal going to the floor.
If it were me - I would replace the MC with the OEM ATE brand, inspect the SC checking for leaks and correct shim gap, and then fully bleed the system.....fully. Tick performance's speed bleeder works very well, just submerge the one end in the brake fluid reservoir and bleed away. There is a check valve allowing you to just cycle the pedal up and down. Also, you leave the speed bleader attached to the SC, keeping the end up high, and you can then burp air out in the future
The topic of sinking/non-returning clutch pedal has been a popular one over the years. If your pedal is going to the floor and staying there, and the clutch is still engaged, then there is some failure in the hydraulic/mechanical circuit.....obviously.
If the hydraulic circuit is all liquid, no air, then it is considered incompressible....motion at the pedal should directly translate to movement at the clutch pressure plate and vice versa.
This could be a failed MC, air in the system, SC, or excessive gap between SC and clutch fingers. Since your system worked before, and sort of works after manual actuation, I would say that it is one of the first 2.
Cheap/failed MCs can leak fluid internally causing this type of problem, getting better once you cycle some additional brake fluid back in.
Air - this I think is the most common issue and most difficult to eliminate. The air can be there from the beginning in a small amount then once heat cycling begins - expansion of air and brake fluid - the brake fluid can be forced back in to the reservoir up top, then once cooled create a sort of negative pressure that allows the pedal to come down. Also, I have read about boiling of the fluid, creating a similar situation with the pedal going to the floor.
If it were me - I would replace the MC with the OEM ATE brand, inspect the SC checking for leaks and correct shim gap, and then fully bleed the system.....fully. Tick performance's speed bleeder works very well, just submerge the one end in the brake fluid reservoir and bleed away. There is a check valve allowing you to just cycle the pedal up and down. Also, you leave the speed bleader attached to the SC, keeping the end up high, and you can then burp air out in the future
948- Moderator
- Posts : 571
Join date : 2009-06-09
Age : 108
Location : East PA
Re: Clutch Issues - HELP!!!
I bought a Tilton 7/8" bore MC from our site sponsor (TPC). I wanted to have all the parts for a no-brainer swap out. I'm installing it today. I'll let you know how it works.
FWIW-everyone seems to complain about problems getting all the air out of the system. I'm going to try to install the MC with brake fluid already filled before I connect the hoses. It might be a little messy but worth the problems you may avoid. Once I install the MC I will replace the fluid in the entire system in the traditional way (pump the pedals). If I need a power bleeder I can get one from Advance Auto on their tool loaner program.
Wish me luck!
Fubar
FWIW-everyone seems to complain about problems getting all the air out of the system. I'm going to try to install the MC with brake fluid already filled before I connect the hoses. It might be a little messy but worth the problems you may avoid. Once I install the MC I will replace the fluid in the entire system in the traditional way (pump the pedals). If I need a power bleeder I can get one from Advance Auto on their tool loaner program.
Wish me luck!
Fubar
Fubar- Posts : 9
Join date : 2015-03-09
Location : Leesburg, VA
Re: Clutch Issues - HELP!!!
UPDATE!!!!
So I was ready to buy a new clutch master from Kent at TPC and he showed me two other links from the forum, that sounded like very similar issues to mine. And they both pointed at the assist spring. So Kent suggested I check that before buying anything (what kind of a sales guy does that?).
I was able to access it from under the fuse panel, although I couldn't figure out how to remove the spring, I was able to loosen the nut almost all the way backing it off the spring.
And one days worth of driving it to work, out at lunch, back to work, and home again...all successful. I don't have any issues with pedal feel, and it seems to be working so far.
Shout out to Kent and everyone else on the forum for chiming in, and keeping this place as a priceless collection of knowledge.
So I was ready to buy a new clutch master from Kent at TPC and he showed me two other links from the forum, that sounded like very similar issues to mine. And they both pointed at the assist spring. So Kent suggested I check that before buying anything (what kind of a sales guy does that?).
I was able to access it from under the fuse panel, although I couldn't figure out how to remove the spring, I was able to loosen the nut almost all the way backing it off the spring.
And one days worth of driving it to work, out at lunch, back to work, and home again...all successful. I don't have any issues with pedal feel, and it seems to be working so far.
Shout out to Kent and everyone else on the forum for chiming in, and keeping this place as a priceless collection of knowledge.
jHo- Posts : 42
Join date : 2014-11-21
Location : Grand Junction, CO
Re: Clutch Issues - HELP!!!
jHo wrote:I was able to access it from under the fuse panel, although I couldn't figure out how to remove the spring, I was able to loosen the nut almost all the way backing it off the spring.
to remove the spring you partially press the clutch down until the spring is collapsed as far as it goes before it starts opening, and there is a little hole in the rod, stick something like a drill bit in there, then lift the clutch pedal all the way up and it will all off the one side. unhook the clip and slide it off the rod and it will come out.
[You must be registered and logged in to see this image.]
you can see the one here has a clip in it.
sharkey- Posts : 713
Join date : 2014-11-21
Age : 39
Location : Abbotsford BC
Re: Clutch Issues - HELP!!!
Thanks for posting this. Just off a fresh build and having the exact same issue. Bleeding this clutch line to death and it has been randomly sticking to the floor regardless of how much new fluid is bled through. Going to loosen the spring as suggested and see how it fares. Being use to a really stiff clutch this may or may not fare well as long as it don't stick down like it did in downtown Trenton traffic. Nothing like pulling up the clutch with your handfoot while shifting I thought it was a good idea to have a cane like an old man strapped to my leg to make it stinking work. The other emergency option is to tie your shoelace to the clutch pedal. In case of engine fire, remove shoe to get to fire extinguisher. Anyone keep brake fluid/power bleeder in the hatch with wrenches next to the cv joint tightening tool? As the cv bolts back out, the clutch sticks to the floor.. lol .. at least I solved cv bolt backout with stage 8's!
Plucky948- Posts : 49
Join date : 2017-06-21
Location : Southern NJ
Re: Clutch Issues - HELP!!!
I backed the spring assist off completely (adjust to make the spring longer) but left the spring in place. That gave a weird “two stage” feel to the pedal, where it was too light for the first half, then too heavy for the second half of the pedal travel and it would only return halfway up to the top of the heavy portion of the pedal travel. I then made small adjustments adding back in spring assist (making the spring shorter) until the pedal felt completely smooth and normal along its full travel (it took very little spring assist to make this happen).
*Note: I have a 7/8 clutch master from TPC, not the stock 951 master.
*Note: I have a 7/8 clutch master from TPC, not the stock 951 master.
chrenan- Posts : 203
Join date : 2011-11-20
Re: Clutch Issues - HELP!!!
Posting an update.. this weekend I installed a brand new clutch master, and took 80% of the spring pressure off the clutch pedal. Bled system 12 times to purge air and pedal has never felt better. Hopefully this fixes the issue and I can finally drive the vehicle again to find out I need to do something drastic to the brakes... New brake master cylinder.. electric, hydroboost, dually.. decisions, decisions!
Plucky948- Posts : 49
Join date : 2017-06-21
Location : Southern NJ
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