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Pressure Plate Issue???

 
Old 07-09-2010, 12:56 AM
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Pak_37
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Default Pressure Plate Issue???

We have a 1990 C4 with 140,000 miles - to our knowledge the clutch was replaced at around 90,000 miles. The transmission appears to shift smoothly with no noises. Since we have had the car (125,000 miles), the clutch pedal seems to have always had a very strong return feel (not easy to hold the clutch pedal to the floor for a long time at a traffic light). Recently it is getting more difficult to put the car in first gear. Would be interested in other people's experience with issues like this and suggestions on what I should investigate.
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Old 07-09-2010, 08:17 AM
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newsboy
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Have you ever changed the gear oil? Many have helped there shifting into 1st gear by using either Swepco or Redline 75/90.
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Old 07-09-2010, 08:19 AM
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When is the last time you bled the clutch slave cylinder?
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Old 07-09-2010, 08:26 AM
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Sorry for off topic but......Hey there Rocket!

Saw your name pop up....how ya been? Been back to the Glen? How's the driving season going?
R\
Scott
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Old 07-09-2010, 09:51 AM
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Originally Posted by Country911 View Post
Sorry for off topic but......Hey there Rocket!

Saw your name pop up....how ya been? Been back to the Glen? How's the driving season going?
R\
Scott
PM sent.
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Old 07-09-2010, 10:40 AM
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Originally Posted by Rocket Rob View Post
When is the last time you bled the clutch slave cylinder?
Originally Posted by Rocket Rob View Post
PM sent.
Thanks to both Rocket Rob and Newsboy for such prompt responses. We have changed the fluid about a year ago - we used a Mobil product when we changed the gear oil. We've been using ATE blue and gold on the brake system.

We have just noticed a hydraulic hose that goes to the slave cylinder is looking "tired" so we will be changing that directly and bleeding the system again. When we change this line can we just bleed the slave cylinder only and leave the brake system?
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Old 07-09-2010, 10:52 AM
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Yes, you can bleed just the clutch slave by itself.

If bleeding and changing the hose is not sufficient, then it may be time to change the slave cylinder itself.
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Old 07-09-2010, 11:55 AM
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I don't really understand why, but many here report the clutch getting heavy when it is on its way out. Of course, slave cylinder checks are wise to do first.
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Old 07-09-2010, 08:29 PM
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When we're putting it into first gear - it seems to engage better when you consciously ensure that the clutch pedal is fully depressed. We've never driven another 964 and I'm wondering if it's common to be able to shift all other gears other than into 1st with about 90% of the pedal depressed but 1st gear the clutch pedal has to be fully depressed. I'd be curious to know if there is any type of switch, or whether bleeding the slave cylinder may help with this symptom. Curious as to other's experience - is this a sign that there could be air or that the slave cylinder is wearing out?
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Old 07-10-2010, 12:18 AM
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I've had the experience of difficulty getting into first gear. Did the slave, hoses, bleeds, and new clutches.

In the end it was discovered that the pressure plate was flat; where it is supposed to be dished. It is likely that after three document clutch changes (26k, 36k and 55k) that the plate was never changed. It was finally change at 84k and has solved the problem.

It seems that a "clutch kit" does not include a new pressure plate in ever case (despite costing $1k more!!)
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Old 07-10-2010, 03:10 AM
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Originally Posted by dfinnegan View Post
I've had the experience of difficulty getting into first gear. Did the slave, hoses, bleeds, and new clutches.

In the end it was discovered that the pressure plate was flat; where it is supposed to be dished. It is likely that after three document clutch changes (26k, 36k and 55k) that the plate was never changed. It was finally change at 84k and has solved the problem.

It seems that a "clutch kit" does not include a new pressure plate in ever case (despite costing $1k more!!)
Thanks dfinnegan

1) How severe was the problem before you changed the pressure plate?
2) How was the car behaving before you felt you absolutely needed to remedy the problem?
3) Did you do the work yourself? If you did the work yourself did you drop the engine to do the work, or utilize the technique where you disconnect the front differential to create room to get the transmission out without dropping the engine.
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Old 07-10-2010, 12:53 PM
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Originally Posted by Pak_37 View Post
Thanks dfinnegan

1) How severe was the problem before you changed the pressure plate?
2) How was the car behaving before you felt you absolutely needed to remedy the problem?
3) Did you do the work yourself? If you did the work yourself did you drop the engine to do the work, or utilize the technique where you disconnect the front differential to create room to get the transmission out without dropping the engine.
1) How severe - It varied. When cold (as in winter) it was much worse. Sometimes just a nuisance and other times a down right pita.

2) Behaviour - Again, it varied. On rare occassions I would drive it with little difficulty. Other times I didn't want to drive it at all. It was nearly always difficult to engage first gear at a stop light. I started shifting into second before first when at a light, or stop. This helped, but second was sometimes still a bit of a "push" to engage.

3) DIY - I do most of the work on the car myself, but have not (yet) dropped the engine, nor done a clutch change. All of the clutch changes were done by pros.



In the end, I had replaced the clutch slave, done numerous bleeds, inspected the clutch pedal roll pin (new parts purchased, but not installed), inspected the clutch pedal bushings (new parts purchased, but not installed), and had new clutches installed.

Finally, I adjusted the clutch pedal travel as I had determined that there was less travel than specified in the shop manual. I really thought I had it this time! With the correct, measured travel I discovered that pushing the clutch to the floor would a) help the situation somewhat, and b) caused an awful clatter; like a card in bicycle spokes; only *much* worse! It turned out that the "fingers" of the plate were making contact with the fork trying, in vain, to fully release the clutch.

I learned to push the clutch pedal nearly to the floor and practiced my heel-n-toe down shifting a lot as I approached stops!

I still have the old plate as I was trying to determine its age based upon the serial/part nos. I was thinking of approaching the previous clutch installers, but, in the end, I was unable to determine the plates age (I believe it is original) and was never quite certain if the plate was "supposed" to be part of the clutch kit. I can say that the last clutch change was $1k cheaper than the one done previously and this time the plate was changed out.

I've been to some of the best, and most respected indys in the north east and have determined that, as with most businesses, there are very few that truly take pride in their work and treat the car as if it were their own. Because of this, I try to do as much of the work on the car myself as time and talent allow.
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Old 07-10-2010, 03:12 PM
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Originally Posted by dfinnegan View Post
I was unable to determine the plates age (I believe it is original) and was never quite certain if the plate was "supposed" to be part of the clutch kit. I can say that the last clutch change was $1k cheaper than the one done previously and this time the plate was changed out.
While I cannot speak for other shops, a properly done clutch change on ANY car includes a new clutch disc, pressure plate, release bearing, and sometimes a pilot bearing. Further, the release fork and its bearings/bushings should be lubricated or replaced, based on inspection. I also replace the slave cylinder in cars with hydraulically-actuated clutches as these are rarely maintainly properly. In short, its not a "slam-bam" operation if one expects longevity and reliability.

I've been to some of the best, and most respected indys in the north east and have determined that, as with most businesses, there are very few that truly take pride in their work and treat the car as if it were their own. Because of this, I try to do as much of the work on the car myself as time and talent allow.
Repair shops are owned and staffed by humans and as such, they vary widely. Like all people, some are bad, some are average, and some are outstanding in their attention to detail. Its worth taking time to find the best ones and solicit their services to make certain they are around when you need that level of expertise and professionalism.
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