A few questions for experienced transmission gurus.

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
kickerfox
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A few questions for experienced transmission gurus.

Postby kickerfox » Mon Oct 06, 2014 9:26 pm

Long story short... I'm doing an engine swap involving an Isuzu v6 engine, Isuzu Trooper v6 bell housing, modified Isuzu v6 flywheel, 3.4L Camaro clutch disc, 3.8L Camaro pressure plate, Miata pilot bearing, an '08 Colorado concentric slave cylinder being pushed by a '80 Jeep CL7 clutch master, and an '08 Solstice MA5 5 speed trans.

This all bolts together but I have two questions that are sort of general and should apply to any manual setup.

First question - My transmission shifter binds when moving left and right (neutral). I opened the trans and noticed the 3-4 shift rail is .020" offset from the others. The detent balls are centered in the grooves on the shift rails so this seems to be a manufacturing defect. Has anyone come across this problem before? This trans is "new" from a GM auction years ago. I'm wondering if I can just grind one side of the detent's V groove so the rail moves over .020".

Second question - Using a brake system as an example, when the brake pedal is up, a caliper piston can be pushed in easily as the fluid flows back to the brake master reservoir. Is a clutch system similar? The problem I'm having is when the clutch is bled and pumped up, it's imposable to push in the slave cylinder. I'm concerned that as the disc wears the pressure plate fingers will move towards the throw-out bearing. If the throw-out bearing can not move (due to the slave cylinder not moving) the clutch will slip. I'm also concerned about the load on the throw-out bearing.

Any ideas would be appreciated.

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Re: A few questions for experienced transmission gurus.

Postby Rope-Pusher » Mon Oct 06, 2014 10:51 pm

kickerfox wrote:Long story short... I'm doing an engine swap involving an Isuzu v6 engine, Isuzu Trooper v6 bell housing, modified Isuzu v6 flywheel, 3.4L Camaro clutch disc, 3.8L Camaro pressure plate, Miata pilot bearing, an '08 Colorado concentric slave cylinder being pushed by a '80 Jeep CL7 clutch master, and an '08 Solstice MA5 5 speed trans.

This all bolts together but I have two questions that are sort of general and should apply to any manual setup.

First question - My transmission shifter binds when moving left and right (neutral). I opened the trans and noticed the 3-4 shift rail is .020" offset from the others. The detent balls are centered in the grooves on the shift rails so this seems to be a manufacturing defect. Has anyone come across this problem before? This trans is "new" from a GM auction years ago. I'm wondering if I can just grind one side of the detent's V groove so the rail moves over .020".

Second question - Using a brake system as an example, when the brake pedal is up, a caliper piston can be pushed in easily as the fluid flows back to the brake master reservoir. Is a clutch system similar? The problem I'm having is when the clutch is bled and pumped up, it's imposable to push in the slave cylinder. I'm concerned that as the disc wears the pressure plate fingers will move towards the throw-out bearing. If the throw-out bearing can not move (due to the slave cylinder not moving) the clutch will slip. I'm also concerned about the load on the throw-out bearing.

Any ideas would be appreciated.

Yes, when the disk wears the diaphragm spring finger tips need to push the bearing further toward the transmission or the pressure plate will not be able to press the clutch disk against the flywheel with the full force intended.

Start with the last part - when the clutch master cylinder is in it's "Home" position (with pedal "up"), the piston should be far enough back that it uncovers the port to the fluid reservoir and there is no fluid pressure in the line going down to the slave cylinder. If this isn't the case, then maybe the master cylinder piston is being held forward too far and the forward side of the piston is not being vented to the reservoir. Can you pull up on the clutch pedal and get it to vent? Can you shorten the rod that connects to the pedal so the master cylinder comes back further? Unhook this rod from the pedal - does the end of the rod come back past were it would attach to the pedal when the pedal is full up?

About the shift rails...the "Lugs" that the shift finger engages should all line up evenly when the trans is in Neutral. Is your 3/4 rail just nudged out of position, or is it really being centered by the detent at an offset to the other shift rails? Is something bent? Is there a sheared roll-pin? Does it come back to this same offset position when you come out of 3rd or 4th, or is it only offset coming from one way? I think if the detent ball is truly centered in the v-groove on the rail, then opening up one side of the V-groove will make the centering vague. I'm thinking there is something else going on - bent shift fork? - that is fighting the detent spring.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

kickerfox
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Re: A few questions for experienced transmission gurus.

Postby kickerfox » Mon Oct 06, 2014 11:11 pm

About the trans - As far as I can tell, the collars(?) (the things the forks move) are centered, so the forks must be ok. The slots in the ends of the rail are forged into the rail and the shift forks are bolted on. No pins to bend. Nothing seems bent. I think it's a machining issue. I would need another 3-4 rail to compare. I don't think I'd have to remove too much material from the detent groove. It would alter the detent spacing where neutral-third would be slightly shorter then neutral-fourth but I don't think I'd even notice.

This carmageddon of parts is going into an RX8. I had to make the clutch push rod but I'm 100% sure it's not pushing on the piston when the pedal is up. The fluid doesn't enter through a hole on the side of the cylinder. It enters in the center of the cylinder at the back (opposite the push rod.) It has what looks like a spring loaded check valve on the end of the piston that covers the hole. Look up a 1980 Jeep CJ7 6 cylinder to see the master or even find a pic of a rebuild kit showing the piston. I can't imagine how fluid would ever get back into the reservoir with that check valve closed. All parts are new by the way.

Found some pics for you. https://www.carpartsdiscount.com/clutch ... ?3594=2115

kickerfox
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Re: A few questions for experienced transmission gurus.

Postby kickerfox » Tue Oct 07, 2014 4:14 am

YES!

Found the clutch problem. It actually IS a defective (new) master cylinder. The push rod is held in the master cylinder using a washer with a snap ring on top of it. When the washer and snap ring are in place, it holds the piston down just little bit causing the rear check-valve to close. I ground down the ball on the slave side of the rod. Works great now.

I feel sorry for R&R guys who would have no idea why they keep burning up throw-out bearing or why the clutch slips at 10k miles.

kickerfox
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Re: A few questions for experienced transmission gurus.

Postby kickerfox » Mon Oct 13, 2014 3:32 am

I wound up grinding down one side of the detent grove in the shift rail and now my shifter moves side to side in neutral without hanging up.

Does anyone have access to a service manual for this trans? It's from a 2008 Pontiac Solstice.

I'm trying to find out of the counter shaft is supposed to slide in and out of the bearing in the center housing or if someone left out a spacer. I can't imagine it would rely on the clip on the front countershaft bearing to prevent the counter shaft from moving.

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Re: A few questions for experienced transmission gurus.

Postby Rope-Pusher » Mon Oct 13, 2014 9:04 pm

kickerfox wrote:I wound up grinding down one side of the detent grove in the shift rail and now my shifter moves side to side in neutral without hanging up.

Does anyone have access to a service manual for this trans? It's from a 2008 Pontiac Solstice.

I'm trying to find out of the counter shaft is supposed to slide in and out of the bearing in the center housing or if someone left out a spacer. I can't imagine it would rely on the clip on the front countershaft bearing to prevent the counter shaft from moving.

Sometimes they will use a snap-ring in a groove on the shaft to hold something in place, like to limit the position of a washer that pushes up against a thrust bearing.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

kickerfox
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Re: A few questions for experienced transmission gurus.

Postby kickerfox » Mon Oct 13, 2014 9:41 pm

Rope-Pusher wrote:
kickerfox wrote:I wound up grinding down one side of the detent grove in the shift rail and now my shifter moves side to side in neutral without hanging up.

Does anyone have access to a service manual for this trans? It's from a 2008 Pontiac Solstice.

I'm trying to find out of the counter shaft is supposed to slide in and out of the bearing in the center housing or if someone left out a spacer. I can't imagine it would rely on the clip on the front countershaft bearing to prevent the counter shaft from moving.

Sometimes they will use a snap-ring in a groove on the shaft to hold something in place, like to limit the position of a washer that pushes up against a thrust bearing.


With the front cover in place it will hold the shaft from moving back and forth but then all the thrust (from the helical gears) is put on the clips and the countershaft's smaller front bearing. That's my concern.

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Re: A few questions for experienced transmission gurus.

Postby Rope-Pusher » Mon Oct 13, 2014 10:13 pm

Rope-Pusher wrote:Does anyone have access to a service manual for this trans? It's from a 2008 Pontiac Solstice.


From a Parts website:
http://parts.nalleygmc.com/showAssembly ... bly=436179

http://www.tonkinonlineparts.com/showAs ... bly=812396
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

kickerfox
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Re: A few questions for experienced transmission gurus.

Postby kickerfox » Mon Oct 13, 2014 11:11 pm

Looks like a roller bearing on the rear of the tail shaft. Probably can't handle anything other then rolling so maybe they do rely on the front bearing.

None of the 10 national transmission rebuilders I called could tell me. They all said they never worked on one before. I guess that says something for this trans.

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Re: A few questions for experienced transmission gurus.

Postby Rope-Pusher » Mon Oct 13, 2014 11:25 pm

kickerfox wrote:Looks like a roller bearing on the rear of the tail shaft. Probably can't handle anything other then rolling so maybe they do rely on the front bearing.

None of the 10 national transmission rebuilders I called could tell me. They all said they never worked on one before. I guess that says something for this trans.

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kickerfox
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Re: A few questions for experienced transmission gurus.

Postby kickerfox » Mon Oct 13, 2014 11:35 pm

Not sure where your going with that.

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Re: A few questions for experienced transmission gurus.

Postby Squint » Tue Oct 14, 2014 9:28 am

kickerfox wrote:Not sure where your going with that.

You'll get used to Rope-Pusher if you hang around here long enough. He certainly knows what he is talking about car-wise, though.
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Re: A few questions for experienced transmission gurus.

Postby theholycow » Tue Oct 14, 2014 11:49 am

1980 Buick LeSabre 4.1L 5MT

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kickerfox
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Re: A few questions for experienced transmission gurus.

Postby kickerfox » Tue Oct 14, 2014 5:55 pm

They do actually. There's a note about having to lift up the countershaft to get the clip in the front. That would infer the countershaft is flopping around until the clip goes on. Couldn't find anything clearly stating it though.

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Re: A few questions for experienced transmission gurus.

Postby Rope-Pusher » Thu Oct 16, 2014 7:58 pm

kickerfox wrote:Not sure where your going with that.

If repair shops don't have experience with repairing them, it could mean they never go bad or that they disintegrate and you're better off just to replace them.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"


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