Matt Wood Posted August 16, 2021 Share Posted August 16, 2021 Hi all, its been a while, hope you're all well! Long story short here, im helping a friend of mine with shifting issues on his C6 (1970) basically it really doesn't want to shift, it will hold gears for way too long and will only shift if you come off the throttle a hair, and then it jumps hard into the next gear (adjusting the modulator does NOTHING) We have done lots of investigating and testing and we're down to just the governor, the issue is we will be doing this on a farm in the middle of nowhere so tools won't be a problem but spare parts aren't an option on the day. I'm worried about seals and such. Any advice on the removal of the governor and what to look out for as to not need any new parts, or if I will need them, what am I likely to need so I can order them in before the end of the week Thanks Matt Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 17, 2021 Share Posted August 17, 2021 Hey, Matt! How's the UK? I'm reading that y'all are seeing a significant drop in COVID cases. Hope that's true and you are staying safe. On the tranny, I don't know as I've not pulled a governor apart on a C6. All I can suggest is that you read the factory shop manual section here: http://www.garysgaragemahal.com/c6.html And, I've tagged Bill/85lebaronT2 as I think he's rebuilt those transmissions. Let's see what he says. Link to comment Share on other sites More sharing options...
grumpin Posted August 17, 2021 Share Posted August 17, 2021 I would check for soft vacuum lines to the tranny. Can you swap in a good modulator? Link to comment Share on other sites More sharing options...
85lebaront2 Posted August 17, 2021 Share Posted August 17, 2021 Hey, Matt! How's the UK? I'm reading that y'all are seeing a significant drop in COVID cases. Hope that's true and you are staying safe. On the tranny, I don't know as I've not pulled a governor apart on a C6. All I can suggest is that you read the factory shop manual section here: http://www.garysgaragemahal.com/c6.html And, I've tagged Bill/85lebaronT2 as I think he's rebuilt those transmissions. Let's see what he says. To get to the governor, remove the driveshaft from the transmission. If you have a 4WD, then both driveshafts and the transfer case need to come out. After you have either the extension (tailshaft) housing or the transfer case adapter left on the transmission, you will need to remove the nuts from the bottom of the crossmember. Support the transmission, a floor jack with a piece of 1/2" (13mm) plywood big enough to spread the load on the pan will be needed to raise the back of the transmission off the crossmember. This is where a 4WD is a little easier. On a 2WD there are two gusset plates on each end of the crossmember, there are two bolts from the top of the frame through the gussets. These do not need to be removed, even the nuts do not nee to come off, just loosened to the point the gussets can be lifted off the crossmember. On a 4WD the driver's side comes up on the outside of the frame rail and has two through bolts, passenger side is the same as the 2WD. The passenger side bolts will be a pain due to the exhaust pipe(s). With the gussets free, there are two bolts, one on each end of the crossmember, with them removed, and everything clear (lifted off) the crossmember will either drop (4WD) or can be twisted back on one side so it drops clear (2WD). Now that you have an unobstructed view, lower the transmission for better access and if a 2WD remove the speedometer drive from the extension housing, take out the bolts holding the adapter or extension housing to the rear of the main case. You may need to remove the mount form the adapter or extension to reach one or more of the lower bolts. With the output shaft exposed, if there is a speedometer drive gear on the shaft, it will need to be removed by depressing the retainer clip and sliding the plastic gear off the shaft. Now, there are 4 bolts holding the governor to the parking lock gear, remove them and slide the governor off the shaft. There should be a small cone shaped strainer in the feed hole (a) don't lose it but (b) take it out and check for crap on the outside and clean it. FWIW, I agree with checking the soft vacuum lines and modulator. If the truck is using ATF and smoking, that is a sign of a bad modulator. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 17, 2021 Share Posted August 17, 2021 To get to the governor, remove the driveshaft from the transmission. If you have a 4WD, then both driveshafts and the transfer case need to come out. After you have either the extension (tailshaft) housing or the transfer case adapter left on the transmission, you will need to remove the nuts from the bottom of the crossmember. Support the transmission, a floor jack with a piece of 1/2" (13mm) plywood big enough to spread the load on the pan will be needed to raise the back of the transmission off the crossmember. This is where a 4WD is a little easier. On a 2WD there are two gusset plates on each end of the crossmember, there are two bolts from the top of the frame through the gussets. These do not need to be removed, even the nuts do not nee to come off, just loosened to the point the gussets can be lifted off the crossmember. On a 4WD the driver's side comes up on the outside of the frame rail and has two through bolts, passenger side is the same as the 2WD. The passenger side bolts will be a pain due to the exhaust pipe(s). With the gussets free, there are two bolts, one on each end of the crossmember, with them removed, and everything clear (lifted off) the crossmember will either drop (4WD) or can be twisted back on one side so it drops clear (2WD). Now that you have an unobstructed view, lower the transmission for better access and if a 2WD remove the speedometer drive from the extension housing, take out the bolts holding the adapter or extension housing to the rear of the main case. You may need to remove the mount form the adapter or extension to reach one or more of the lower bolts. With the output shaft exposed, if there is a speedometer drive gear on the shaft, it will need to be removed by depressing the retainer clip and sliding the plastic gear off the shaft. Now, there are 4 bolts holding the governor to the parking lock gear, remove them and slide the governor off the shaft. There should be a small cone shaped strainer in the feed hole (a) don't lose it but (b) take it out and check for crap on the outside and clean it. FWIW, I agree with checking the soft vacuum lines and modulator. If the truck is using ATF and smoking, that is a sign of a bad modulator. Thanks, Bill. Link to comment Share on other sites More sharing options...
Matt Wood Posted August 24, 2021 Author Share Posted August 24, 2021 To get to the governor, remove the driveshaft from the transmission. If you have a 4WD, then both driveshafts and the transfer case need to come out. After you have either the extension (tailshaft) housing or the transfer case adapter left on the transmission, you will need to remove the nuts from the bottom of the crossmember. Support the transmission, a floor jack with a piece of 1/2" (13mm) plywood big enough to spread the load on the pan will be needed to raise the back of the transmission off the crossmember. This is where a 4WD is a little easier. On a 2WD there are two gusset plates on each end of the crossmember, there are two bolts from the top of the frame through the gussets. These do not need to be removed, even the nuts do not nee to come off, just loosened to the point the gussets can be lifted off the crossmember. On a 4WD the driver's side comes up on the outside of the frame rail and has two through bolts, passenger side is the same as the 2WD. The passenger side bolts will be a pain due to the exhaust pipe(s). With the gussets free, there are two bolts, one on each end of the crossmember, with them removed, and everything clear (lifted off) the crossmember will either drop (4WD) or can be twisted back on one side so it drops clear (2WD). Now that you have an unobstructed view, lower the transmission for better access and if a 2WD remove the speedometer drive from the extension housing, take out the bolts holding the adapter or extension housing to the rear of the main case. You may need to remove the mount form the adapter or extension to reach one or more of the lower bolts. With the output shaft exposed, if there is a speedometer drive gear on the shaft, it will need to be removed by depressing the retainer clip and sliding the plastic gear off the shaft. Now, there are 4 bolts holding the governor to the parking lock gear, remove them and slide the governor off the shaft. There should be a small cone shaped strainer in the feed hole (a) don't lose it but (b) take it out and check for crap on the outside and clean it. FWIW, I agree with checking the soft vacuum lines and modulator. If the truck is using ATF and smoking, that is a sign of a bad modulator. So sorry it took me ages to reply, I didnt get an email saying there was activity on this thread! (Probably my fault for not checking the box) Gary, the uk is going back to 'normal' no more restrictions and masks are now optional, most have now had their jabs! (I know that can be a sore subject your side of the pond!) And most importantly car shows and events are now able to go ahead!! Been to goodwood festival of speed and 'the classics' at silverstone so far since re opening, its nice to see everyone's work throughout the last year worth of lockdowns! How was your overlanding adventure? Looked amazing from the photos! Bill, thank you for the really detailed instructions! Its a 2wd which seems like more work unfortunately lol, we never got a chance to tackle it last weekend so will be having a go in mid September when we're back down there, it doesn't sound like there are any seals to look out for and (maybe a stupid question) am I going to take anything off thats going to drain the fluid? I've already checked for rubber lines and tried multiple modulators, no smoke or anything like that so the govenor is the last resort really, failing this we'll be buying a new trans to make it easier Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 24, 2021 Share Posted August 24, 2021 So sorry it took me ages to reply, I didnt get an email saying there was activity on this thread! (Probably my fault for not checking the box) Gary, the uk is going back to 'normal' no more restrictions and masks are now optional, most have now had their jabs! (I know that can be a sore subject your side of the pond!) And most importantly car shows and events are now able to go ahead!! Been to goodwood festival of speed and 'the classics' at silverstone so far since re opening, its nice to see everyone's work throughout the last year worth of lockdowns! How was your overlanding adventure? Looked amazing from the photos! Bill, thank you for the really detailed instructions! Its a 2wd which seems like more work unfortunately lol, we never got a chance to tackle it last weekend so will be having a go in mid September when we're back down there, it doesn't sound like there are any seals to look out for and (maybe a stupid question) am I going to take anything off thats going to drain the fluid? I've already checked for rubber lines and tried multiple modulators, no smoke or anything like that so the govenor is the last resort really, failing this we'll be buying a new trans to make it easier Matt - Glad to see that things are getting back to normal. And those events sound like a whole lot of fun! Link to comment Share on other sites More sharing options...
Ken Blythen Posted August 26, 2021 Share Posted August 26, 2021 Matt Just before you open up the transmission........C6 governors can get sticky & problematic due to a lack of lubrication in the rear housing. An easy fix (if nothing else is wrong) is to either lift the rear of the truck off the ground, or find an empty stretch of road, then have a couple of minutes drive in reverse. In reverse, oil is flushed into the rear housing & floods the governor in oil. I've had two C6's & both benefited from this at times. Another symptom can be that as you coast to a stop (or to low speed), the transmission doesn't consistently downshift to take off again. Well worth a try....although I didn't get the hard shifting problem. As suggested, I would also check that you are getting good vacuum at the modulator. Good luck Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 26, 2021 Share Posted August 26, 2021 Matt Just before you open up the transmission........C6 governors can get sticky & problematic due to a lack of lubrication in the rear housing. An easy fix (if nothing else is wrong) is to either lift the rear of the truck off the ground, or find an empty stretch of road, then have a couple of minutes drive in reverse. In reverse, oil is flushed into the rear housing & floods the governor in oil. I've had two C6's & both benefited from this at times. Another symptom can be that as you coast to a stop (or to low speed), the transmission doesn't consistently downshift to take off again. Well worth a try....although I didn't get the hard shifting problem. As suggested, I would also check that you are getting good vacuum at the modulator & that the modulator diaphragm is ok (holding vacuum). Good luck And there, friends, is the beauty of this forum. We have a guy in New Zealand helping a guy in England. Link to comment Share on other sites More sharing options...
Ken Blythen Posted August 30, 2021 Share Posted August 30, 2021 Matt Just before you open up the transmission........C6 governors can get sticky & problematic due to a lack of lubrication in the rear housing. An easy fix (if nothing else is wrong) is to either lift the rear of the truck off the ground, or find an empty stretch of road, then have a couple of minutes drive in reverse. In reverse, oil is flushed into the rear housing & floods the governor in oil. I've had two C6's & both benefited from this at times. Another symptom can be that as you coast to a stop (or to low speed), the transmission doesn't consistently downshift to take off again. Well worth a try....although I didn't get the hard shifting problem. As suggested, I would also check that you are getting good vacuum at the modulator & that the modulator diaphragm is ok (holding vacuum). Good luck And there, friends, is the beauty of this forum. We have a guy in New Zealand helping a guy in England. Hi Gary, I still appreciate your guidance de-smogging my truck back in the day......I removed the last remnant of that Ca. system two weeks ago (long story) & installed a new Holley! Feels like a 20% power bump....don't know about mpg yet Link to comment Share on other sites More sharing options...
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