Sonnax installed - shift question
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Senior User
Joined: Dec 2003
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From: Union Grove, Wisconsin
Sonnax installed - shift question
I just completed my sonnax and tranny cooler install. After I warmed up the truck and took for a ride, it seemed like the shift from 3rd to O.D. dropped more RPM's than normal. Maybe I was just paying attention to it more. While accelerating with light (normal throttle) RPM's were at approx. 2200 then shifted into O.D. and dropped down to approx. 1400 RPM's. Does this seem like a large drop in RPM's? It seems larger than before I installed the sonnax and cooler.
Post Fiend
Joined: Jul 2005
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From: 21791
this is because the tricumulator springs firmed up the shift points. it doesnt alter the timing of them, just the firmness. another bad thing about the stock transmission is the fact that the torque converter lockup in OD and shift from 3 to OD happen at almost the same time, giving the effect of shifting from third gear to OD in a manual transmission. aftermarket programming can hold the lockup in OD to a little longer. i had the same symptoms as you had, and hated it. now i took the Juice off and am just running the evolution, it is alot better. however i am selling the evolution also, for a DP tuner chip. 
Senior User
Joined: Jan 2005
Posts: 345
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From: Monterey Park, California
You are increasing the line pressure with a shift kit. The line pressure applies on the clutches when you shift creating less slippage and faster shifts.
Before it was a gradual decrease when you went to OD. Now it's fast and you notice the rpm drop right away.
You can also program in more shift firmness if you didn't have a shift kit. That will also increase the line pressure. That's why a programmer will ask you if you already have a shift kit. Otherwise if you programed more shift firmness with a shift kit, your shifts will be really harsh.
Before it was a gradual decrease when you went to OD. Now it's fast and you notice the rpm drop right away.
You can also program in more shift firmness if you didn't have a shift kit. That will also increase the line pressure. That's why a programmer will ask you if you already have a shift kit. Otherwise if you programed more shift firmness with a shift kit, your shifts will be really harsh.
Last edited by Hello; Jan 2, 2006 at 02:17 AM.
Fleet Mechanic
Joined: Feb 2005
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From: Northern Colorado
Originally Posted by Hello
..........if you programed more shift firmness with a shift kit, your shifts will be really harsh.
Posting Guru
Joined: Dec 2004
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I just switched to a DP Tuner chip - that dreaded 3rd-to-OD-plus-TC-lockup is now gone (or rather, happens very rarely with only a certain throttle/load combo - and at a higher speed so the RPM drop is less problematic).
Using normal, light throttle, the tranny feels like a 5-speed - it shifts from 2nd to 3rd at about 28, TC lockup at about 35, 3rd to OD at about 42. Very nice. I always HATED the giant RPM drop when my truck would do the OD+TC lockup.
Using normal, light throttle, the tranny feels like a 5-speed - it shifts from 2nd to 3rd at about 28, TC lockup at about 35, 3rd to OD at about 42. Very nice. I always HATED the giant RPM drop when my truck would do the OD+TC lockup.
Posting Guru
Joined: Sep 2003
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is there any way to hook the transmission up to some kind of manual switch so you can manually shift 3-4 and with or without lockup like say if you are cruising with a full load of hay in od and you come to a slight hill and want to keep it in od but unlock the converter and climb the hill instead of a harsh downshift followed by a harsh lockup... that pisses me off, sometimes if i turn my flashers on, i can make the t.c. stay unlocked for a while... i think the locup is hooked up to the brake lights somehow i dunno...but it still likes to downshift when it really needs to let the t.c. work like its supposed to instead of downshifting. do ya'll agree?
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Junior User
Joined: Dec 2005
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I thought it was just my truck that does that, now it makes sense. This site is great. My truck makes a whirring noise when going from 3rd to o.d at tc lockup.
Is that just boost pushing back down the intake from the rapid rpm drop? Or is it the TC getting ready to grenade? Its not overly loud just really noticable with a load.
Is that just boost pushing back down the intake from the rapid rpm drop? Or is it the TC getting ready to grenade? Its not overly loud just really noticable with a load.
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Post Fiend
Joined: Jul 2005
Posts: 14,582
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From: 21791
do you have an open-element air intake, such as the AFE or Kwik filter? the open element design really lets the sounds come out, unlike the stock system or the Ford AIS.
no sound=restriction IMHO.
the whooshing noise is just the boost coming back out past the turbo and out of the filter. much more noticeable if you are on it hard and suddenly let off. awesome indeed
no sound=restriction IMHO.
the whooshing noise is just the boost coming back out past the turbo and out of the filter. much more noticeable if you are on it hard and suddenly let off. awesome indeed
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1997, booster, f350, firm, instalation, install, kit, line, powerstroe, powerstroke, pressure, quicker, shift, shifts, sonnax, tricumulator
