how do i adjust shift points?

[69oiler]

on my new truck, the trans shifts funny. on light accelleration it will shift into 2nd at 25mph and 3rd at 40mph. it also shifts hard. if i floor it, it shifts thru the gears how i would expect. also, when cruising, if i fall below 38 mph it kicks down to 2nd. i.e. i cant drive 35 mph in 3rd gear.

how do i adjust this? is it that thing on the drivers side of the IP? i turned that a little today and it didn't make any difference. maybe i didnt move it far enough. what should i be looking for?

FWIW i get about 22 inches of vacuum on my guage and the system holds vacuum when i shut the engine off.



Rob

 

[tractorman86]

get a manual and shift it wherever you want. sounds like you are on the right track but i've never had an a/t on one of these.

 

[funnyman06]

Could be a vaccum leak, when i broke one of my hoses it shifted funny.

 

[6 Nebraska IDIs]

Yea, its most likely a vacuum leak, or someone's built that trans to shift there, and put a shift kit in to make it shift hard.

 

[dieselutheran2]

the modulator valve on the back of the C6 has an adjusment screw inside it. take the vacuum line off and there is a screw there, clockwise increases speed b4 shift, counter-clockwise should reduce it. If i'm wrong someone will be along shortly to correct me. if when you take the vacuum line off some transmission fluid dribbles out, the modulator is bad and must be replaced.

the black assy on the side of the ip is the vacuum regulator valve (VRV) and needs to be set by using a vacuum gauge. I wouldn't turn that at all unless you are going to go through the process to set it properly.

make sure your fluid level is right, that will cause problems too.

 

[h2odrx]

the modulator valve on the back of the C6 has an adjusment screw inside it. take the vacuum line off and there is a screw there, clockwise increases speed b4 shift, counter-clockwise should reduce it. If i'm wrong someone will be along shortly to correct me. if when you take the vacuum line off some transmission fluid dribbles out, the modulator is bad and must be replaced.

the black assy on the side of the ip is the vacuum regulator valve (VRV) and needs to be set by using a vacuum gauge. I wouldn't turn that at all unless you are going to go through the process to set it properly.

make sure your fluid level is right, that will cause problems too.

I'd start with the VRV There is a tech write up here some where.

 

[LCAM-01XA]

the modulator valve on the back of the C6 has an adjusment screw inside it. take the vacuum line off and there is a screw there, clockwise increases speed b4 shift, counter-clockwise should reduce it. If i'm wrong someone will be along shortly to correct me. if when you take the vacuum line off some transmission fluid dribbles out, the modulator is bad and must be replaced.

That is all very correct - a small screwdriver is all that's needed for adjusting the modulator, tho it has to be fairly short as the T-case mount is right behind the modulator.

 

[69oiler]

i looked in the tech articles and searched and didnt find anything on the VRV. i guess trial and error it is.

 

[Agnem]

Rob,
I'd definitely start with the VRV. Here are the instructions courtesy of a post by good ol' Cnrdsguy (Pete)

You may only need to reset the VRV.....

How to adjust VRV by James

You don't have the engine running for the test, you need to apply 20" vacuum (Hg) 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" vacuum (Hg) 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 (Hg). 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.
Good Luck
James

Note..... 20" vacuum Hg is equal to MINUS 65 Kpa..........

 

[Ford428CJ]

I'll find a link for ya on the VRV! That to needs to be adjusted right. Here is a link and it should be near the bottom of the page. Enjoy!~

http://www.intellidog.com/dieselmann/idi2.htm

 

[69oiler]

thanks guys i'll monkey with it tonight.

 

[69oiler]

well i guess i need a new VRV. i monkeyed with it and now with i maxed out in one direction i can get like 5 inches of vac.. though i'm not sure how accurately i'm doing the test, getting .515" from wide open throttle proves to be a hit or miss type of affair. i have a spacer the right size but there's not a lot of room to use it between the linkage and the stopper.

at any rate it still doesn't shift right but it's better than it was. maybe it will be a rally clinic if i don't get it right before then.

 

[HammerDown]

When my VRV went bad the symptoms where...very high 1'st-2'nd shift point and I usually had to lift off the throttle a tad to get that shift then BANG into second it went. I tested the VRF and sure enough it was bad. Installed a new one, set it up and ahhhhhh no more neck snapping shifts or knocking the life outta the u-jounts.

 

[slideordie]

where do you get a vrf if you need one? mine is doing the exact same thing.

 

[HammerDown]

where do you get a vrf if you need one? mine is doing the exact same thing.

Got mine at my local Ford dealer...he had to order it of course.
(like they stock anything for a 20 yeard old truck)