Hey Fellas, changed the IP on my 1986 6.9, 4X4 with C6 auto, last week. Must have got the VRV out of adjustment. Was shifting very hard and late (assume lack of or low vacuum).

Any way played with the VRV and got it shifting at these points 1-2nd at 15mph, 2-3rd at 35mph on a light throttle. With a firm but acceptable shift and no flareing. But for the life of me I cant remember what speeds it had shifted before.

Do those shift points sound about right to you all? Thanks for your help and advice.

Andy

 

VRV adjustment.....

How to adjust VRV

You don't have the engine running for the test, you need to apply 20" vacuum to upper VRV port and attach vacuum gauge to lower VRV port. The lower port is the one that goes to tranny, the upper to vacuum pump.
You have to maintain 20" througout this test. If it drops off you need to pump it back up.
Remove throttle return spring, cycle throttle lever 5 times from idle to WOT. Make sure 20" vacuum is maintained on upper port side.
Move throttle so it is 0.515" (33/64") from wide open (they make a tool for this). Vacuum gauge should read from 6-8" of vacuum. If incorrect adjust VRV to 7".
Again apply 20" vacuum, cycle throttle from idle to WOT 5 times. Return to idle. Gauge should read at least 13".

It says if you can't get the 7" or the 13" to replace the VRV. If VRV checks out maybe the diaphragm (modulator), line from VRV goes to the vacuum diaphragm I believe. Can't find any adjustment for the diaphragm but I think there is a little.

Basically all you need for the test is a vacuum pump (handheld type), vacuum gauge and a ruler to measure 1/2" or a 33/64" drill bit in lieu of the .515" tool. And a screwdriver for any adjustment needed.

 

Specified shift points depend upon the axle gear ratio (See Table Below). My truck has 3:55 gears and shifted at the same speeds as you just stated which I would be happy with but they were quick, harsh (hard hitting) shifts. After trying to correct that I think the VRV is shot- I can't get any setting to work.

The image is not very clear but I think the first 3 vertical columns are for the E series and right half is for the F series

 

the last post in this thread was 10 years ago, and the poster has not logged on in 10 years.

 

I'm glad you mentioned it, Tom, I understand your point. I was very aware of that but the original poster doesn't matter, the readers of the thread matter and most of all the quality of content matters (which wasn't much in this thread). Consider: Lot's of people currently (and in the future will) want to know the answer to this question, relating to shift points, adjustments, vrv, etc.. When they do a search (which I did for the same reasons) this thread will come up because the title of the topic is very clear and precise. They will click on it. Now instead of wasting their time reading a thread that had no useful answer, they will find a table to use as a good reference point. I think the table came from a service bulletin.

That was my logic for answering this old thread.

I also considered posting a brand new topic only to show this table which would have been the better choice because I could have made the title very specific, to the effect; 'This is the C6 1-2-D shift table in MPH.' I didn't do that because I was very tired and the quality of the image is poor even after I worked on it in a photo editing program It started from a small thumbnail negative (reversed black and white) of this one. Finally, the title of the thread is precise enough for people to find the table.

I would have preferred a new post with a quality image and if I find one I'll do that, but that being said, I don't think this will hurt anything.

There are SOME good reasons for reviving a very old discussion (good content is just one) but it might be better to lock and archive old discussions, (still searchable), so newer discussions are more up to date and new people can have fun and provide input.

Thanks,
Fxnstuff