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Mechanical Linkage Installation

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Old 07-30-2018, 01:28 PM
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Mechanical Linkage Installation

Hi all! I’ll try not to make this too long; My main question is how exactly is/are the spring/s supposed to be setup on the z-bar going to the clutch fork? I’ve rebuilt the T5 a couple weeks after researching and watching videos for hours and hours. Everything turned out great (for only the first day), now I have that dreaded cricket/metallic/scratching noise coming from right around the TOB. Although I know it isn’t the bearing cause it’s brand new and also tested cause I know they can come sometimes a little wacky. So after researching and tinkering the sound goes away and everything works great if the clutch fork is just a hair tilted up or down. But where the springs are now it has the tiny chirping noise when the pedal is resting. So my theory is the last owner just either had wrong springs installed or had not enough/too many. **I’ll add now that i’ve put lithium grease on the fork pivot ball, quadruple checked with a borescope that the bearing is seated properly, and the bearing is good** But when it comes to finding 1983 clutch return springs I haven’t found any replacements or even pics of the whole thing set up on a car for reference.

Thanks in advance for any help.
Old 07-30-2018, 01:35 PM
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Re: Mechanical Linkage Installation

There is no return spring.

The only spring there is, just keeps the fork and Z-bar tight on the adjuster.
Old 07-30-2018, 01:47 PM
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Re: Mechanical Linkage Installation

Ah then he did put too many. He had 1 spring like you said but the other going to the control arm bushing for some reason.
How would the pedal return then if no tension is pulling back on it?
Old 07-30-2018, 02:05 PM
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Re: Mechanical Linkage Installation

The clutch pressure plate is the "return spring" for the pedal
Old 07-30-2018, 03:30 PM
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Re: Mechanical Linkage Installation

Interesting, so it pretty much makes continuous contact with the pressure plate? Wouldn’t that wear it out? ***Not disagreeing with ya i’m just curious***
Old 07-30-2018, 05:08 PM
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Re: Mechanical Linkage Installation

No, it just kinda lays there. no real pressure at all.
Old 07-30-2018, 06:36 PM
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Re: Mechanical Linkage Installation

Thanks guys, i’ll have to order a new spring due to the correct one being bent and stretched. When it comes in i’ll get everything set up and let you know how it goes.
Old 07-31-2018, 10:40 AM
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Re: Mechanical Linkage Installation

Originally Posted by CyrusSaurusRex
Interesting, so it pretty much makes continuous contact with the pressure plate? Wouldn’t that wear it out? ***Not disagreeing with ya i’m just curious***
That's kind of an old wives tale. Almost all clutch systems are designed to have the throw out in contact (not full pressure, just no slack) with the pressure plate at all times. Some of the high performance stuff we work on has pull clutches where the throw out is physically snapped into a retainer clip on the pressure plate springs and it pulls the pressure plate away from the engine instead of pushing on it. You can imagine that there is no way to unload the throw out bearing or prevent it from touching the pressure plate.

GD
Old 07-31-2018, 11:27 AM
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Re: Mechanical Linkage Installation

Originally Posted by GeneralDisorder
That's kind of an old wives tale. Almost all clutch systems are designed to have the throw out in contact (not full pressure, just no slack) with the pressure plate at all times.
Old is right. The systems with mechanical linkage and return spring *had* a specification of a small air gap between bearing and pressure plate. You might hear 50 thousandths as a recommendation when the guys with 60s and older cars talk. In theory, it prevents bearing wear. But when the disc wears, the PP fingers rise and the gap goes away. The solution was better bearings.

A light pressure against a robust bearing and long life sn't an engineering challenge. The late model concentric slave cylinders (98-02 F) with attached bearing have a light coil spring holding the bearing against the PP fingers, and they generally have good service life.

Not a wive's tale. Just more stuff we don't have to do anymore, but the guys who did can still tell you about doing it on the vehicles in their era. Pre-third gen.
Old 07-31-2018, 12:39 PM
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Re: Mechanical Linkage Installation

Originally Posted by jmd
Old is right. The systems with mechanical linkage and return spring *had* a specification of a small air gap between bearing and pressure plate. You might hear 50 thousandths as a recommendation when the guys with 60s and older cars talk. In theory, it prevents bearing wear. But when the disc wears, the PP fingers rise and the gap goes away. The solution was better bearings.

A light pressure against a robust bearing and long life sn't an engineering challenge. The late model concentric slave cylinders (98-02 F) with attached bearing have a light coil spring holding the bearing against the PP fingers, and they generally have good service life.

Not a wive's tale. Just more stuff we don't have to do anymore, but the guys who did can still tell you about doing it on the vehicles in their era. Pre-third gen.
Very interesting. Sounds like a giant pain in the A$$ to adjust and maintain. I guess when the entire service life of the vehicle is 100k miles and you'll probably do a few clutches in that period - what's the difference? I'm sure there must be upgraded parts available for most of those applications that no longer require this gap?
Old 07-31-2018, 01:58 PM
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Re: Mechanical Linkage Installation

Originally Posted by GeneralDisorder
Very interesting. Sounds like a giant pain in the A$$ to adjust and maintain. I guess when the entire service life of the vehicle is 100k miles and you'll probably do a few clutches in that period - what's the difference? I'm sure there must be upgraded parts available for most of those applications that no longer require this gap?
I’m sure there are some kind of upgrades available from some company but as far as I know people opt to just change from mech—>hyd. Also quick question; My fork spring is bent and stretched for about 4 coils. I’m looking around for another but thinking about it now i’m not even sure this is the correct spring. (Also there seems to not be ANY fork springs for the years ‘82 and ‘83) The closest I found is ‘81, did 81, 82 and 83 share the same style spring?
Mine currently looks like this one:
http://www.firebirdcentral.com/mobil...uctCode=CLU-25
But the ‘81 style looks like this:
http://www.firebirdcentral.com/mobil...uctCode=CLU-27

Old 08-01-2018, 01:14 PM
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Re: Mechanical Linkage Installation

Originally Posted by GeneralDisorder
Very interesting. Sounds like a giant pain in the A$$ to adjust and maintain. I guess when the entire service life of the vehicle is 100k miles and you'll probably do a few clutches in that period - what's the difference? I'm sure there must be upgraded parts available for most of those applications that no longer require this gap?
Most engineering changes like this have a heavy push from new car assembly ease. One less adjustment when building a new car or truck meant saved money for the OEM, and ease of repair later too. Upgraded clutches are available for third through current gen Camaros; not sure I get that question,
Old 08-01-2018, 01:23 PM
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Re: Mechanical Linkage Installation

Originally Posted by CyrusSaurusRex
My fork spring is bent and stretched for about 4 coils. I’m looking around for another
I just hit the Dorman HELP section, and find one that will slide over the lower linkage pushrod, and reach from the Z-bar to the fork. The second one you linked is probably correct, and is a retaining spring, but incorrectly labeled a return spring.
Old 08-02-2018, 08:59 AM
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Re: Mechanical Linkage Installation

Originally Posted by jmd

I just hit the Dorman HELP section, and find one that will slide over the lower linkage pushrod, and reach from the Z-bar to the fork. The second one you linked is probably correct, and is a retaining spring, but incorrectly labeled a return spring.
Thank you kindly, also UPDATE! So I ordered the spring linked above and while i’m waiting I tried getting the bent one straight again, being stretched doesn’t matter due to the correct spring being longer anyway. I put it on and adjusted til about 3/4” of play and the whining sound was still there but DEFINITELY way less. I have a feeling the new spring will do the trick, i’ll let you guys know how it goes.
Old 08-02-2018, 11:26 AM
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Re: Mechanical Linkage Installation

PROBLEM SOLVED!!!

So a family friend who works on old Chevy’s gave me a spare spring he had (should’ve asked him before) and the sound now had ceased when the car is on. I wanted to really know exactly what was up so i kept playing with the old springs and found out the slight screeching sound was actually the clutch fork clip! That said it’s the double ended clip on the bottom side of the fork that holds the bearing and clips onto the ball-pin. That clip was slightly loose and the scraping sound was the clip rubbing against the ball-pin when the car was idling (little shaky and since no pressure on it when clutch is engaged the clip would just wriggle all around the ball and make the sound. Thank you guys very much for the help.
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