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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Odd Engagement Problem

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Odd Engagement Problem

Post by v8carreragts on Fri Sep 16, 2016 7:16 pm

OK, I finely got my garage set up here in Tucson, we are basically settled and I have a decent job. So I started working on the car again. I had a problem with the engine and FI system that I was able to fix with a custom ground Crane cam. Now the car runs good so I can start driving it.

Originally I had a Speedway Motors pressure plate and had engagement problems so I called there tech line. They told me that the way this pressure plate engages it would probably be a problem on the street. So I bought a stock replacement Camaro pressure plate so I could get the car on the road and start working out the bugs.

Now for the problem. The clutch pedal feel is perfect without the engine running, smooth to the floor and back up. With the engine running it is smooth to the floor but binds on the way up like the pedal bushing is chattering, so it is very difficult to start from a stop because this causes chattering. It doesn't matter if it is in neutral or in gear. So It looks like there was no problem with the Speedway motors pressure plate. Being it has such a strong spring it didn't feel like this. But now with the OEM pressure plate that has a relatively weak spring it shows up big time. I can't figure out why it only does it with the engine running. It doesn't make sense.

Any Ideas?
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Re: Odd Engagement Problem

Post by sharkey on Sat Sep 17, 2016 1:30 am

does it do it if you only press the clutch about half way down then release it? if so, maybe play around and see how far down it goes before it starts happening. my thought here is the pressure plate is going over center

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Re: Odd Engagement Problem

Post by v8carreragts on Sat Sep 17, 2016 5:53 pm

I just started playing around with it. You may have identified it. It looks like The pedal has about 2" too much travel. I need to make up an adjustable stop. It seems as though about 1/2 of the total travel opens up the clutch enough to shift into reverse (not synchronized) without grinding.
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Re: Odd Engagement Problem

Post by v8carreragts on Sat Sep 17, 2016 7:39 pm

That was it! I made an adjustable pedal stop, It stops the pedal about 2 1/2" from the floor. So when I get some more time I can put the Speedway Motors pressure plate back in. I don't think the stock Camaro pressure plate will last long.

Thanks for the idea, sharkey.
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Re: Odd Engagement Problem

Post by matt889 on Fri Sep 23, 2016 8:46 pm

are you using stock TPC clutch disk ? stock camaro flywheel ?

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Re: Odd Engagement Problem

Post by v8carreragts on Fri Sep 23, 2016 8:55 pm

I have a 153 tooth steel SFI approved flywheel (19#) a stock 70's Camaro high perf pressure plate (10.4"), a HP MOPAR disk, a 1300 McCleod hydraulic T/O bearing, the stock clutch master cylinder and pedal.
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Re: Odd Engagement Problem

Post by sharkey on Sat Sep 24, 2016 12:49 am

is that 70s camaro pressure plate a 3 finger style?

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Re: Odd Engagement Problem

Post by v8carreragts on Sat Sep 24, 2016 12:58 am

No, it's a diaphragm.
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Re: Odd Engagement Problem

Post by sharkey on Sat Sep 24, 2016 12:01 pm

its possible that slave cylinder needs less fluid volume to release the clutch than the corvette/camaro one everyone uses, and thats what caused it to travel too far. you could counter this by going with a smaller bore master cylinder, stock is 3/4, could maybe go down to a 7/10 or even a 5/8". this would give you a softer clutch as well.

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Re: Odd Engagement Problem

Post by v8carreragts on Sat Sep 24, 2016 12:23 pm

McCleod says that 3/4" is optimum for the hydraulic T/O bearing. They also say that the optimum for pedal ratio is more that the stock 944 is. They say 6:1 and the stock 944 is 5:1. 6:1 would have more travel I.E. push the Pressure Plate further.
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Re: Odd Engagement Problem

Post by v8carreragts on Sat Sep 24, 2016 12:42 pm

That's backwards. 5:1 gives more travel. So maybe this is it. For 6" of pedal travel I would get 1.2" of master cylinder travel VS 1" for 6:1. That's 16% more volume for the same pedal travel.
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Re: Odd Engagement Problem

Post by matty89 on Mon Dec 26, 2016 2:19 am

solved ? im getting weird engagement also .. it has a fast engage at 1 inch from the floor ... no grinding just almost like a pedal drop .. weird im using stock porsche master and the tpc kit for throwout , camaro PP and ls1 flywheel.

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Re: Odd Engagement Problem

Post by v8carreragts on Mon Dec 26, 2016 11:00 am

I am not certain yet. I thought I had it fixed when i put a stop on the pedal but is came back. Then i found that the diaphragm was not flat. So i swapped pressure plates. I haven't driven it yet as I am still converting it to a carb. The FI system i have will not work with long duration cams.

Originally, I used a hydraulic T/O bearing from Speedway Motors but one of the o-rings kept pushing out. I swapped to a McCleod hydraulic T/O bearing. Then after a few miles this problem came up. This is when i found that I was engaging it to far. I added an adjustable pedal stop and the problem went away. I swapped the cam to a milder cam trying to get the FI to work. I drove to one cruise night and almost didn't make it home because the FI was not working well and the sticky clutch come back.

Then I found that the diaphragm was warped.

I swapped the pressure plate and found that the cam I swapped destroyed a lobe. (flat tappet) I swapped the roller back and then began removing the FI and replacing it with a carb. I need to get the engine running well enough to figure out the clutch. At this point I won't be able to see if the problem was the pressure plate until I get it running again.

I a bunch of things to do to finish up yet. My wife had surgery 3 weeks ago so i haven't been able to get back to it. I am going to work on it today. I sometimes feel like I am never going to get it derivable. I know that i will eventually get this figured out.

Right now I have the stock 944 clutch master, a McCleod hydraulic T/O bearing, the Speedway Motors HP diaphragm pressure plate, a Chrysler disc (organic) and a 19# steel flywheel. I have my pedal stop adjusted so that the clutch just disengages enough to change gears.

At this time, all I can think of that could be causing the clutch problem is the hydraulic T/O bearing. I don't remember having the problem when I had the Speedway Motors bearing but that one squeaked when the clutch was engaged. The bearing was just touching the diaphragm enough to squeak. I am sure that the o-ring popping out was the fact that there was too much pedal travel.
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Re: Odd Engagement Problem

Post by matt889 on Mon Dec 26, 2016 1:43 pm

What o ring are you talking about?

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Re: Odd Engagement Problem

Post by v8carreragts on Mon Dec 26, 2016 2:21 pm

It's an o-ring inside of the T/O bearing. When it pushes out it dumps the fluid out. It is one of the o-rings that seals the piston.
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Re: Odd Engagement Problem

Post by sharkey on Mon Dec 26, 2016 6:18 pm

they shouldnt be an o-ring, should be a square cut seal.

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Re: Odd Engagement Problem

Post by v8carreragts on Mon Dec 26, 2016 6:43 pm

they shouldnt be an o-ring, should be a square cut seal.

Yes, I agree, but Speedway Motors uses o-rings on their's. (actually, it should be a quad-ring which is like an o-ring but has 4 distinct sealing edges) McCleod uses quad-rings.
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Re: Odd Engagement Problem

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