Hey all,
Can someone point me to how to adjust shift points on. C6 transmission. I've checked fluid levels and all seem fine. it is a rebuilt transmission from a shop but they adjust it and a week later seems to go back to when it first left the shop.

The transmission doesn't seem to downshift once in 3rd. only will downshift when come to a full stop.
Not sure what needs done there.
Thanks for the help.

 

I would NOT do anything to it at all, except take it back to the trans shop (again) and tell them it is still not shifting correctly. The second you take the pan off I bet you will void any warranty. Did it use to downshift more than once when in third, before the rebuild? Maybe is doesn't "seem" to down shift because it is happening so smooth? Did you visually insp everything that is suppose to be connected to it, like the vacuum modulator line?

 

Totally agree with 77&79F250. The shop that did the work owns it until you are satisfied.. Get them to fix it!

 

What happens here is the modulator regulates pressure, it boosts pressure toomuch, the pressure overcomes the governor and the governor can't return by spring since the fluid pressure boosted up by modulator holds governor against spring, making your transmissions brain think you are traveling over 40 mph then when coming to a stop, rpm drops, fluid flow drops, vacuum comes up and no centrifugal force to move governer over means governor is able to return atleast part way and allow downshift. but once rpm/speed/pressure comes up and vacuum drops you get an upshift causing high gear all the time, likely needs modulator adjusted softer, meaning turning screw counterclockwise and/or a rod change in the boost valve. Likely a shorter rod. Is it a screw in modulator or push in? What color modulator is in it? green? purple, black? Was the modulator changed? If so was the Overall length checked of the modulator and rod to the original? Was the valve body dismantled? I agree that the builder/installer needs to be held accountable, but if he doesn't understand the anatomy of this and the affects there in you might as well put in a mail box for the thing down there because it will never leave. He will change modulators, governors, fluid and filter and never gain at all. I tune mine how I want because the guy driving it may have diferent expectations than you or I.

 

Wow that is a full on mouth full.
They did a full rebuild. the body was dismantled. Sorry for getting back so late. I have no idea the color of the regulator.
The color of the transmission housing did change so i am not sure if they did a rebuild or just sent if off and got another shipped in that was already rebuilt.

 

there is a screw that adjusts this as well as a rod that is internal. it all has to be tuned in by someone. there could be a vacuum supply issue or a hand ful of other issues

 

It could also just be the kickdown rod adjustment. That's what its for.