Slow 3-2 downshift/kickdown - why?
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Launching!
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From: Jacksonville, Florida
Slow 3-2 downshift/kickdown - why? After rebuilding my trans I have developed a SLOW 3-2 downshift/kickdown. This happens if I punch it in 3rd and it automatically kicks down to 2nd and also if I manually drop it into 2nd. Its a slow 1.5-2 second delay or so - it feels like a slight bogg. All of my upshifts are instant - its just mt 3-2 downshift.
Any ideas? It worked fine before the rebuild.
Thanks for the help!
David
Any ideas? It worked fine before the rebuild.
Thanks for the help!
David
Thread Starter
Launching!
iTrader: (18)
Joined: Mar 2003
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From: Jacksonville, Florida
Originally Posted by Ratchthed
Well in order to form an opinion it would be useful to know the build specs., what components were used in the build, etc...
A few things come to mind, but we could be way off base.
g
A few things come to mind, but we could be way off base.
g
j/kHere are the parts that were replaced/upgraded:
-HD rear 5 pinion planetary
-vette 2nd gear servo
-sonnax super 4th
-alto kolene steels
-alto red eagle clutches
-alto wide band
-transgo **** kit
-10 vane pump rotor gear, guides, and vanes
-beast sun shell
-sonnax 1-2 and 3-4 "pinless" billet accumulators
-TCI deep pan
Thread Starter
Launching!
iTrader: (18)
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From: Jacksonville, Florida
No sir - I did not modify the pin length. The servos are vette servos with the 4th gear super hold. I notched 4 oil vents in one of the 'covers' (not sure of the technical term) but the instructions advised that.
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FormerVendor
Joined: Oct 2006
Posts: 3,123
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From: D-F/W
Sounds good so far... thanks for being patient. I know it can be frustrating answering question after question but having a good understanding of the components is important. Initally John and I assumed you had installed a TG HD -2 kit, turns out that was a bad assumption.......
Based on the good up shift and based on the components used, I would take a long hard look at the servo seals myself. It is possible that one is bypassing. Hydraulically speaking allot has to happen for a 3/2 downshift to happen... pressure is being released on one side of the servo while pressure is being applied on the other side. A fair amount of fluid under pressure has to be exhausted very quickly during a 3/2 downshift.
Now, that being said you could also have a sticking 3-2 downshift valve or 3-2 control valve sticking. The only way to know is to remove the valve body and check to see that they are free.
Was the tune modified in any way?
g
Based on the good up shift and based on the components used, I would take a long hard look at the servo seals myself. It is possible that one is bypassing. Hydraulically speaking allot has to happen for a 3/2 downshift to happen... pressure is being released on one side of the servo while pressure is being applied on the other side. A fair amount of fluid under pressure has to be exhausted very quickly during a 3/2 downshift.
Now, that being said you could also have a sticking 3-2 downshift valve or 3-2 control valve sticking. The only way to know is to remove the valve body and check to see that they are free.
Was the tune modified in any way?
g
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Launching!
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From: Jacksonville, Florida
Thanks for your help! Pulling the VB was my next step - I just wanted to be sure what I was looking for. Do you know where to drill the VB plate to exhaust the 3-2? I heard there is a port that needs to be drilled? Should I check the servo seals? If a seal was bad - would it affect my upshift? My solenoids appear fine. I can control them with EFI live and can hear them clicking on and off. (with the car off of course)
Thanks again,
David
Thanks again,
David
FormerVendor
Joined: Oct 2006
Posts: 3,123
Likes: 3
From: D-F/W
Sorry for just getting back to you.....
After discussing this at length with my builder John over coffee this morning, we are concerned that you have not got the 3-4 clutch return springs offered in the HD-2 (reprogramming) kit. Those springs are very important to the longevity of this transmission in a H/P environment. Because you have improved the hydraulic components at the servo and in the accumulation, you have effectively decreased the time it takes to apply the band. Therefore you should also decrease the time it takes to release the 3-4 clutches. It is highly possible that your 3-4 clutches are staying applied momentarily when the downshift occurs. The springs I referenced not only help to release the 3-4 piston but also keep it from applying during a high RPM event in 1st and 2nd gears, say 6000 RPM's and up.
Also, did you remove the factory original load release springs at the 3-4 clutch pack... if so that will aggravate the centrifical condition.
As far as the hole you referenced, not sure at all what you have been told. The feed holes are modified sometimes depending on the application, but that is not what you are talking about... right?
Now, all that being said... another component to consider that would be relatively easy to deal with would be the 3-2 Control Solenoid. It could be defective, the spring behind the valve could be defective or the valve itself could be sticking as I mentioned previously.
That's a bunch to absorb, but automatics can be very difficult to diagnose on the bench or in the car with all of the technical support a modern shop has at its' disposal... and much more so on the internet!
Good Luck.
g
After discussing this at length with my builder John over coffee this morning, we are concerned that you have not got the 3-4 clutch return springs offered in the HD-2 (reprogramming) kit. Those springs are very important to the longevity of this transmission in a H/P environment. Because you have improved the hydraulic components at the servo and in the accumulation, you have effectively decreased the time it takes to apply the band. Therefore you should also decrease the time it takes to release the 3-4 clutches. It is highly possible that your 3-4 clutches are staying applied momentarily when the downshift occurs. The springs I referenced not only help to release the 3-4 piston but also keep it from applying during a high RPM event in 1st and 2nd gears, say 6000 RPM's and up.
Also, did you remove the factory original load release springs at the 3-4 clutch pack... if so that will aggravate the centrifical condition.
As far as the hole you referenced, not sure at all what you have been told. The feed holes are modified sometimes depending on the application, but that is not what you are talking about... right?
Now, all that being said... another component to consider that would be relatively easy to deal with would be the 3-2 Control Solenoid. It could be defective, the spring behind the valve could be defective or the valve itself could be sticking as I mentioned previously.
That's a bunch to absorb, but automatics can be very difficult to diagnose on the bench or in the car with all of the technical support a modern shop has at its' disposal... and much more so on the internet!
Good Luck.
g
Last edited by Gilbert@Ace Racing; Jun 19, 2007 at 10:06 AM.
