C6 problems up shifting
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C6 problems up shifting
Hi all. First timer here. Picked up an 87 f250 extra cab, long bed, 6.9, c6, ford 10.25, a couple months. It runs strong so I have been ironing out the wrinkles.
Since purchase it will only hit 2nd gear above 25mph and only if i completely let off the gas, and 3rd gear above 45mph again only completely off the gas. I since have installed a new modulator on the trans. Have also played with the set screw position and the best I can get is, with the set screw completely removed it shifts same as it always has. If I run the set screw all the way in I have to be above 30 to get 2nd and can even get 3rd.
I seem to be getting good vacuum at the modulator though I don't have a gauge to really know. Is the vacuum supposed to increase with the RMPs? What should the vac be?
So now i'm thinking the VRV on the IP. I dont see any obvious adjustment. Is it just an R&R? There must be some sort of adjustment.
Thanks,
Since purchase it will only hit 2nd gear above 25mph and only if i completely let off the gas, and 3rd gear above 45mph again only completely off the gas. I since have installed a new modulator on the trans. Have also played with the set screw position and the best I can get is, with the set screw completely removed it shifts same as it always has. If I run the set screw all the way in I have to be above 30 to get 2nd and can even get 3rd.
I seem to be getting good vacuum at the modulator though I don't have a gauge to really know. Is the vacuum supposed to increase with the RMPs? What should the vac be?
So now i'm thinking the VRV on the IP. I dont see any obvious adjustment. Is it just an R&R? There must be some sort of adjustment.
Thanks,
i ain't rite
Joined: Mar 2005
Posts: 65,445
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From: Marlboro Mental Hospital.
welcome to FTE.
you need to set the VRV, or maybe replace it.
your problem is that you are not getting vacuum to the modulator .
here is the instruction for setting the VRV.
https://www.ford-trucks.com/forums/s...6&postcount=12
you need to set the VRV, or maybe replace it.
your problem is that you are not getting vacuum to the modulator .
here is the instruction for setting the VRV.
https://www.ford-trucks.com/forums/s...6&postcount=12
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http://www.thedieselfiles.com/Ford/C...c%20tranny.pdf
The adjustment is in that file .
It doesn't take much to get the shift points where they need to be .
On my injection pump I took the phillips screws out and put hex head bolts in so the VRV is easier to adjust .
The adjustment is in that file .
It doesn't take much to get the shift points where they need to be .
On my injection pump I took the phillips screws out and put hex head bolts in so the VRV is easier to adjust .
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thanks guys. its the vrv. with it adjusted to max, i get about 8". took it for a drive after maxing it out and at least now I can get to 3rd at 35 if i let off the gas. Much better then taking it to 45 before shifting. If there is any hill or load though it will almost immediately down shift until i get to 45 and then it will keep 3rd. On that run the set screw in the tany modulator is completely backed out. That was the only way i could get it to shift up.
If im understanding this correctly I need more vacuum to make it shift sooner and to turn in the set screw on the trany modulator to keep it from downshifting on me??
Thanks again!
If im understanding this correctly I need more vacuum to make it shift sooner and to turn in the set screw on the trany modulator to keep it from downshifting on me??
Thanks again!
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thanks guys. its the vrv. with it adjusted to max, i get about 8". took it for a drive after maxing it out and at least now I can get to 3rd at 35 if i let off the gas. Much better then taking it to 45 before shifting. If there is any hill or load though it will almost immediately down shift until i get to 45 and then it will keep 3rd. On that run the set screw in the tany modulator is completely backed out. That was the only way i could get it to shift up.
If im understanding this correctly I need more vacuum to make it shift sooner and to turn in the set screw on the trany modulator to keep it from downshifting on me??
Thanks again!
If im understanding this correctly I need more vacuum to make it shift sooner and to turn in the set screw on the trany modulator to keep it from downshifting on me??
Thanks again!
i ain't rite
Joined: Mar 2005
Posts: 65,445
Likes: 5,517
From: Marlboro Mental Hospital.
thanks guys. its the vrv. with it adjusted to max, i get about 8". took it for a drive after maxing it out and at least now I can get to 3rd at 35 if i let off the gas. Much better then taking it to 45 before shifting. If there is any hill or load though it will almost immediately down shift until i get to 45 and then it will keep 3rd. On that run the set screw in the tany modulator is completely backed out. That was the only way i could get it to shift up.
If im understanding this correctly I need more vacuum to make it shift sooner and to turn in the set screw on the trany modulator to keep it from downshifting on me??
Thanks again!
If im understanding this correctly I need more vacuum to make it shift sooner and to turn in the set screw on the trany modulator to keep it from downshifting on me??
Thanks again!
correct.
also, if memory serves correct, you need a green stripe modulator for the diesel C-6
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I shouldn't need to turn down my vacuum should I? All the spec say 20". I'm getting 25 at the VRV. Could that be hurting the valve?
Sorry for all the questions. This is my first Auto trans Ever.
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You want 18" or so at the VRV , as you open the throttle the vacuum should drop , full throttle should show about 3-0" .
On the vacuum modulator put the screw in 3 turns .
I'm saying 18" going to the vacuum modulator from the VRV
On the vacuum modulator put the screw in 3 turns .
I'm saying 18" going to the vacuum modulator from the VRV
i ain't rite
Joined: Mar 2005
Posts: 65,445
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From: Marlboro Mental Hospital.
at least 20 inches vacuum. over is fine, because you will compensate with the VRV.
25 sounds like a new pump.
minimum vacuum needed at the VRV is 17 inches.
green stripe is on the modulator. there are green, black, white, and i believe purple. the black, white, and purple stripes designate different sea levels for gas engines, and the green is for diesels.
at least this is the way i remember it from the last time i messed with one 10 years ago.
my 88 would not shift worth a damn when i first got the trans. an old time trans guy gave me the heads up on the different modulators. i popped a green stripe in and reset the VRV and it has been golden since.
25 sounds like a new pump.
minimum vacuum needed at the VRV is 17 inches.
green stripe is on the modulator. there are green, black, white, and i believe purple. the black, white, and purple stripes designate different sea levels for gas engines, and the green is for diesels.
at least this is the way i remember it from the last time i messed with one 10 years ago.
my 88 would not shift worth a damn when i first got the trans. an old time trans guy gave me the heads up on the different modulators. i popped a green stripe in and reset the VRV and it has been golden since.
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So i picked on up from an injection shop near me. Don't know why i didnt think of them sooner. they gave me a known good used one for half what a new on would of cost me.
Works like a champ now! I ended up setting the vac to 16" at idle and two turns in on the trans modulator. So it shifts early and wont downshift unless you really get into it.
Thanks for the Help Guys!!
Works like a champ now! I ended up setting the vac to 16" at idle and two turns in on the trans modulator. So it shifts early and wont downshift unless you really get into it.
Thanks for the Help Guys!!
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