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Old 05-20-2022, 10:03 AM   #1
Nima
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Pressure plate

How often a pressure plate goes bad? Or, how often a brand new pressure plate is defective?
I have swapped my clutch linkage with a hydraulic system (Hydromax from American powertrain) and my clutch doesn't engage. It seems everything is function as it should and throughout bearing is travelling about 0.5", so, Based on their tech advise (which by the way, their tech support could be a lot more helpful considering their product price tag), it could be the pressure plate which is brand new with the clutch kit.
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1953 GMC 3/4 ton: current project
1967 C20: 5.3 voretc with T5 conversion, 4 wheel 8 lug disc brake
1972 Nova: my 4 door sport sedan! 5.3 voretc + T5 conversion. drivable project, FUN!!
1979 Camaro Z28: 5.3 vortec conversion with build TH350: drivable project, Fun to drive
1992 Camaro RS convertible (Z28 clone): 5.3 conversion with build T5: on going project
2005 Silverado 2500, 4x4 Duramax, original owner
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Old 05-20-2022, 10:24 AM   #2
geezer#99
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Re: Pressure plate

What’s the clearance between the tob and the fingers on the pressure plate?
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Old 05-20-2022, 10:38 AM   #3
Nima
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Re: Pressure plate

It is about 0.15". Their recommendation is 0.15" to 0.2"
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1953 GMC 3/4 ton: current project
1967 C20: 5.3 voretc with T5 conversion, 4 wheel 8 lug disc brake
1972 Nova: my 4 door sport sedan! 5.3 voretc + T5 conversion. drivable project, FUN!!
1979 Camaro Z28: 5.3 vortec conversion with build TH350: drivable project, Fun to drive
1992 Camaro RS convertible (Z28 clone): 5.3 conversion with build T5: on going project
2005 Silverado 2500, 4x4 Duramax, original owner
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Old 05-20-2022, 10:48 AM   #4
geezer#99
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Re: Pressure plate

So if the tob is pushing on the fingers correctly then my thought is you have the disc installed backwards.
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Old 05-20-2022, 05:17 PM   #5
Nima
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Re: Pressure plate

I guess there is only one way to find out!
It seems all the roads are point toward me taking the tranny off, the last thing I wanted to do
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1953 GMC 3/4 ton: current project
1967 C20: 5.3 voretc with T5 conversion, 4 wheel 8 lug disc brake
1972 Nova: my 4 door sport sedan! 5.3 voretc + T5 conversion. drivable project, FUN!!
1979 Camaro Z28: 5.3 vortec conversion with build TH350: drivable project, Fun to drive
1992 Camaro RS convertible (Z28 clone): 5.3 conversion with build T5: on going project
2005 Silverado 2500, 4x4 Duramax, original owner
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Old 05-20-2022, 06:37 PM   #6
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Re: Pressure plate

Depending on pressure plate style sometimes you can see inside to the plate and see if you can see the disc’s springs pointing to the back.
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Old 05-21-2022, 10:53 AM   #7
Nima
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Re: Pressure plate

Thanks.
It seems I have to remove the tranny regardless since I have to check everything anyways, again!
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1953 GMC 3/4 ton: current project
1967 C20: 5.3 voretc with T5 conversion, 4 wheel 8 lug disc brake
1972 Nova: my 4 door sport sedan! 5.3 voretc + T5 conversion. drivable project, FUN!!
1979 Camaro Z28: 5.3 vortec conversion with build TH350: drivable project, Fun to drive
1992 Camaro RS convertible (Z28 clone): 5.3 conversion with build T5: on going project
2005 Silverado 2500, 4x4 Duramax, original owner
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Old 05-21-2022, 11:08 AM   #8
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Re: Pressure plate

Perfection takes time!
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Old 05-22-2022, 10:29 PM   #9
Nima
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Re: Pressure plate

Well, I removed the tranny. Before I took the clutch set off, I rechecked my bearing Clerance and it was at 0.17. What I don't see is any marking on the fingers of pressure plate where the throughout bearing touches them. I know it is a new clutch set and system, but I expect to see some marking where the throughout bearing touches the fingers since the bearing was moving about 0.5" when the pedal was pressed. I took the clutch set off, it was installed correctly so, I am still in dark. I guess I need to research what a defective pressure plate is and how to test it.
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1953 GMC 3/4 ton: current project
1967 C20: 5.3 voretc with T5 conversion, 4 wheel 8 lug disc brake
1972 Nova: my 4 door sport sedan! 5.3 voretc + T5 conversion. drivable project, FUN!!
1979 Camaro Z28: 5.3 vortec conversion with build TH350: drivable project, Fun to drive
1992 Camaro RS convertible (Z28 clone): 5.3 conversion with build T5: on going project
2005 Silverado 2500, 4x4 Duramax, original owner
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Old 05-22-2022, 11:08 PM   #10
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Re: Pressure plate

Pardon my ignorance but what does the tob bolt to?
The bellhousing or the trans?

I would think if you took the pressure plate to a machine shop they could put it in a press to see how it’s working.

You got any pics.
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Old 05-23-2022, 12:31 AM   #11
kwmech
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Re: Pressure plate

I think the bearing has to move than 1/2''. Looking at my 68 (although mechanical linkage) it moves at least an inch or more. I'd recheck for air in the system
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Old 05-23-2022, 09:52 AM   #12
Nima
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Re: Pressure plate

Quote:
Originally Posted by geezer#99 View Post
Pardon my ignorance but what does the tob bolt to?
The bellhousing or the trans?

I would think if you took the pressure plate to a machine shop they could put it in a press to see how it’s working.

You got any pics.
The TOB just slides over the input shaft. It doesn't bolt to anything. It just has a guide and suppose to slide back and forth based on the hydraulic (brake) fluid pressure.
I do have a small press and I can see the pressure plate's disc moves up and down when I press it even 3/8" or less.
In the picture below, you can see the TOB (blue) was moving forward (the silver area between the blue TOB and darker silver area which are the spacers over the input shaft). I just don't know if it was putting enough pressure over the pressure plate fingers since I don't see any marking on the fingers. You think there would be some scratch marks when two metals push on eavh others. I am confused!

Quote:
Originally Posted by kwmech View Post
I think the bearing has to move than 1/2''. Looking at my 68 (although mechanical linkage) it moves at least an inch or more. I'd recheck for air in the system
When the guy at American powertrain emailed me finally last week, he told me the TOB is suppose to move only about 0.4" to engage.
I am going to call them again, although I've never been able tog et hold of anybody!
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1953 GMC 3/4 ton: current project
1967 C20: 5.3 voretc with T5 conversion, 4 wheel 8 lug disc brake
1972 Nova: my 4 door sport sedan! 5.3 voretc + T5 conversion. drivable project, FUN!!
1979 Camaro Z28: 5.3 vortec conversion with build TH350: drivable project, Fun to drive
1992 Camaro RS convertible (Z28 clone): 5.3 conversion with build T5: on going project
2005 Silverado 2500, 4x4 Duramax, original owner
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Old 06-04-2022, 02:35 PM   #13
geezer#99
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Re: Pressure plate

Did you get this figured out?
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Old 06-04-2022, 10:42 PM   #14
Nima
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Re: Pressure plate

Still working on it.
I have taken the tranny and clutch out to be be sure I have not installed anything wrong, which I didn't (sometimes you wish you did, that would make it easier!). I tested the pressure plate on my basic press. It seems the fingers are moving within 0.3 to 0.5 inches. I am thinking the Hydraumax bearing is not travelling far enough (it seems it suppose to travel 0.4") to press the fingers.
I ordered a ram hydraulice bearing which has up to 0.8" travel time. We'll see!
I guess the short answer is "no"!
__________________
1953 GMC 3/4 ton: current project
1967 C20: 5.3 voretc with T5 conversion, 4 wheel 8 lug disc brake
1972 Nova: my 4 door sport sedan! 5.3 voretc + T5 conversion. drivable project, FUN!!
1979 Camaro Z28: 5.3 vortec conversion with build TH350: drivable project, Fun to drive
1992 Camaro RS convertible (Z28 clone): 5.3 conversion with build T5: on going project
2005 Silverado 2500, 4x4 Duramax, original owner
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Old 06-16-2022, 01:31 AM   #15
Nima
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Join Date: Apr 2004
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Re: Pressure plate

So, I have taken this transmission off 3 times so far. I replaced the TOB with a Ram brand which has more travel. Finally, after many bleedings, my clutch engages well, but now, I have a leak inside the bellhousing which I don't know where it comes from. I am assuming it is leaking from the bearing. I am keeping eye on the fluid to see if it is going down. I used teflon tapes (per Ram instruction) to seal the fittings.
At least I can drive the truck for now.
__________________
1953 GMC 3/4 ton: current project
1967 C20: 5.3 voretc with T5 conversion, 4 wheel 8 lug disc brake
1972 Nova: my 4 door sport sedan! 5.3 voretc + T5 conversion. drivable project, FUN!!
1979 Camaro Z28: 5.3 vortec conversion with build TH350: drivable project, Fun to drive
1992 Camaro RS convertible (Z28 clone): 5.3 conversion with build T5: on going project
2005 Silverado 2500, 4x4 Duramax, original owner
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