2004R 2-3 shuttle

[GNeric]

I have only experienced this when using the TransGo kits. Never had it with Art Carr or B&M (when I used to use them). I have used CK's kit for customers and don't have the shuttle and those are all dual fed units. I developed the "kit" I personally use in my transmissions in early 90's and don't have that problem...yet. (may have jinxed it now)

 

[matt69olds]

I had the trans-go kit before the CK shift kit, I cant recall if the trans-go kit had the 2-3 shuttle shift. I know Chris's kit is far better that any other I have used. It doesn't do it all the time, I just live with it. It is annoying when I happens, I would like a fix but it isn't a priority. My trans isn't dual feed, I have never tried the dual feed mod on a 2004r trans. Next time I'm into my trans I would like to try it.

 

[TurboBuRick]

I have a ck valve body that does the exact same thing. I have to speed up then let off the gas so it will shift. Once it shifts I have to keep the speed up or it will go back and fourth between gears. Very irritating. I have adjusted my driving around the problem and leaned to live with it but would be nice to get a fix.

It definitely not as bad if the tv cable is loosened up but I worry about line pressure.

The geometry of the throttle linkage is something that can be improved on.
The problem with the tb's, you need full line pressure by half throttle. Hard to have the best of both worlds.

Thoughts?

 

[TurboDave]

I wish Don Wang would join this discussion!!!! My 87 has the light throttle 2-3 stutter, but not my 86.

 

[jakeshoe]

On the big power units I started going to fixed line pressure.

 

[chris718]

Anyone having this type of issue can contact me off the forum.I have something I believe will help.Email me.

 

[TurboBuRick]

Anyone having this type of issue can contact me off the forum.I have something I believe will help.Email me.

Chris,

I'll be calling you soon. Thanks.

RL

 

[quickt]

After spending way too much time on this here are my findings. Testing 4 different VBs BR/CZ/OG/CT. All 4 had the same issue with the BR being the absolute worst. With practice you can reproduce the 2-3 busy shifting I am going to call it. The problem seems to happen at light throttle very little acceleration right about the time the car starts to level out trans will shift to 3rd and then right back to 2nd and back to 3rd. Let off it stays in 3rd. Accelerate and she stays in 2nd. After looking at my mods and the others that I know of the one thing in common is they remove the TV up shift valve spring. I reinstalled the TV up shift spring and problem is gone. At least in two of the VBs tested the BR and CT. I could not reproduce the problem so I stamped it busted. I was satisfied it would produce the same result in the other two. The one thing I did notice is that the trans definitely shifts earlier at light throttle the one thing Buick turbo guys don’t like. Hope this helps.

 

[TurboBob]

what about using an extremely light MTV Up spring?

Doesn't the BRF have this spring missing from the factory?

Bob

 

[jakeshoe]

what about using an extremely light MTV Up spring?

Doesn't the BRF have this spring missing from the factory?

Bob

Correct,
BRF doesn't have it.

 

[TurboBuRick]

Chris is saying to install a 3/16 shim between tv plunger and spring.

 

[Mike T]

Any updates on this subject? Mine is dual feed and does this at very light throttle.

 

[77 cruiser]

My CQ still does it after shimming the TV limit, then changing the MTV up & down springs. After doing all that just does it at a slightly different speed. It's the nature of the beast I think.

 

[TexasT]

I found that when you open the feed hole in the spacer plate that feeds the direct clutch the problem arises especially on dual feed units. I have played with different T.V. settings and adding 1-2 grams of weight to the primary weight on the governor. It reduces the problem but it never completely went away. Went back to a plate with stock size feed hole to the direct clutch and problem completely went away. My take on it it's caused by a sudden line pressure drop when the direct clutch is engaged. Since line pressure is controlled by pump volume I think we are overtaxing the volume demand at low throttle angles when the direct clutch engages.

I see you went back to the stock plate(what, seven yrs ago, haha) Attached is a pic of a plate, is the hole you are referring to #14? How big did you go? Do you know how big the stock hole is? Thanks


Mine is an AA and has the shift business. I was going to see about the spring in the mtv down next time I drop the pan. Might also put a shim in the 3-2 downshift to raise it a little. I don't think it will do much as I want a lot of throttle to cause the down shift.

I guess with the higher line pressure is is just too close as stated several times above. I cant imagine the time and effort hydramatic put into these to get the calibrations for so many different applications.

 

[INEEDAGN]

See, to me the "increased line pressure" theory makes the least sense. We are talking governor pressure vs tv pressure and neither of those should be heavily affected by increased line pressure especially at very light throttle where the problem is occurring.

 

[Mike T]

Mine is not constant and actually hadn't happened at all in the first1500 miles after the rebuild. It started about a week ago and was at a low throttle angle as everyone has said. I have tried to duplicate the condition for a week now and can't.

Shift quality in general was a little off while it was happening so it leads me to believe something in the valve body or governor is on the verge of hanging up.

 

[TexasT]

My pressure jumps pretty much as soon as the throttle is opened. This to me sez the elevated pressure could be a cause. The pressure for the 2-3 shift and the 3-2 shift being too close is also a logical theory to me. Just having it shift and your foot moving on the pedal causing the tv pressure to change might be a cause as well . The pressure in the vb on those shift valves affects the shift along with the governor. The pressure rise isn't really linear, it jumps a lot in mine and the seven vane pump makes the pressure pulse so that could affect the shift also.

Again, these are only theories in my head. No specific test data to show any of them.

 

[INEEDAGN]

MTV up oil is cut off to the valve as the shift is made and the mtv down oil is opened. Playing with MTV up oil can change the dynamics of when the shift happens and possibly mask the issue but can't possibly be the root cause of it backshifting. You either have residual pressure in MTV down or detent passage when it's not supposed to be there or you have a drop in governor pressure during the shift. Drop in governor pressure is obviously the most likely. Whether the area X stroke of the valve is exceeding the volume available through the governor orifices or the drive 4 oil feeding those orifices is dropping because of the volume needed to apply the clutch and release the servo, or combination of the two, that is the million dollar question. Either way I'd love to see the effects of opening up the governor feed orifices in the plate/gasket and resultant shift timing.

The other (crackpot) option is trying to limit the stroke of the valve to reduce its volume demand on governor oil. Which might be impossible, I haven't looked into that.

 

[Mike T]

It has to be correctable. Just going by what I'm experiencing now it has shifted flawless for about a week until this morning. Made half a dozen start stop shifts that were all perfect and then (at low throttle) it jumped between 1-2 at least 5 times. It seems as if it would have continued to do so if not for a very slight throttle increase.

I know it has never done this before and my driving habits haven't changed so something is moving at a different rate in the valving. Like others have said two forces are trying to overcome each other. Temperature seems to have no effect.

 

[Mike T]

Should have read back and forth between 2-3