2004R 2-3 shuttle

mikestertwo

Well-Known Member
#4
It happens at the 2-3 shift under light throttle.
Well, it's a top of the line trans, $$$.
I spoke with the builder today, he thinks it's the governor.
I'll keep you posted.
If the trans is dual fed on the direct clutch that is a common problem. Let us know what the builder comes up with for a solution. There are a couple of things to do to eliminate it.
 

TurboBob

Resident mad scientist
Staff member
#6
the GN transmissions seem to do that once they are heavily built.

I'm not an expert, or a 'builder', but I went thru the hydraulic diagrams and think that the answer is related to the low hysteresis in the 2-3 shift valve (valve land sizes) and the overlap/bind-up in the 2-3 shift.

at light throttle, the upshift MPH and the downshift MPH are too close, and when it shifts there is a dip in the governor pressure from the overlap which causes it to downshift again. The cycle repeats until you speed up or slow down.

As far as I have been able to tell, there is no way to fix it with the GN valve body, as you can't change the valve land sizes. Reportedly, using a different base valve body (like from a monte SS, or olds 442) will fix the problem.

But I would love to be wrong.... as my tranny does this once in a while, and an easier fix would help out a lot of people.

Bob
 
#8
I also have this on KZ valve body

After lightly accelerating and then letting off the throttle, wants to go back and forth. Only time I notice it is when I'm stuck in freeway traffic. Not a big issue but I would welcome any suggestions.
 

TurboBob

Resident mad scientist
Staff member
#9
the light throttle 2-3 shift happens at about 25 mph.

Could yours be the TCC or the 3-4 shift?

Bob
 

Black3

Fargan sneaky bastages!
#10
Mine does the same also. Didn't do it stock, only after trans kit was installed. I've gotten at least 5 different explanations.
 

Steve V

Steve V's Automotive 757 560 2782
#11
I have all of mine doing it also. Does not stock as soon as shift kit installed yup its there forever. My guess it the line pressure and gov pressure are almost equal at that point and the shift valve is moving both ways causing this? Trans pumps pulse, this could cause the pressure to fluctuate a bit and hence 2-3 shift business...just my opinion.
 

chris718

Active Member
#14
The main cause of that is when valve body, governor, and axle ratio arent matched set.I dont know who your builder is but I will say this,our kit does little or nothing to change the point in the rpm range or throttle position that your shifts take place.It only affects the way the shift feels and how long it takes from start to finish.I am certain there is a slight ,possibly immesuarable difference that raisingline pressure has on shift timing. However because tv limit controls plunger feed and the resultant mtv up oil to a fixed pressure it is nothing here .Although governor feed is off of the forward clutch or drive oil,a direct reult of line pressure in its varying pressure direct from the manual valve, ,the orificing into the governor feed portion of the circuit makes it less sensitive to increased line pressure.Malfunctions or leaks in valve body casting may be the cause when this is experienced in matched combinations .Increased line can result into crossleaks if valve body isnt torqued down or if increased pressure cause leaks into adjoining passages .I have seen many leaky casting cup plugs caused all different types of issues as well.I believe that I have the best finctioning 2004r recalibration kit availablee for the 2004r and sales of more than 200 a year are a testament to the absolute success of the product that wouldnt be worth anything without the use of the new seperator plate.Most builders have adapted our methods of hydraulic alibrations for a reason,they work.
 

Steve V

Steve V's Automotive 757 560 2782
#16
The main cause of that is when valve body, governor, and axle ratio arent matched set.I dont know who your builder is but I will say this,our kit does little or nothing to change the point in the rpm range or throttle position that your shifts take place.It only affects the way the shift feels and how long it takes from start to finish.I am certain there is a slight ,possibly immesuarable difference that raisingline pressure has on shift timing. However because tv limit controls plunger feed and the resultant mtv up oil to a fixed pressure it is nothing here .Although governor feed is off of the forward clutch or drive oil,a direct reult of line pressure in its varying pressure direct from the manual valve, ,the orificing into the governor feed portion of the circuit makes it less sensitive to increased line pressure.Malfunctions or leaks in valve body casting may be the cause when this is experienced in matched combinations .Increased line can result into crossleaks if valve body isnt torqued down or if increased pressure cause leaks into adjoining passages .I have seen many leaky casting cup plugs caused all different types of issues as well.I believe that I have the best finctioning 2004r recalibration kit availablee for the 2004r and sales of more than 200 a year are a testament to the absolute success of the product that wouldnt be worth anything without the use of the new seperator plate.Most builders have adapted our methods of hydraulic alibrations for a reason,they work.
Your kit does it.......and no it did not do it before it was installed in a bonestock GN,Art Carr does it also....only happens a very light throttle. If you speed up shifts just fine or slow down a bit holds 2nd.

As far as your kit I have used every version through 2009,holes drilled in plate ,new plate 1st design,new plate 2nd design.
 
#17
What happens with a TV adjustment?

Interesting. I've never experienced it but I don't use a packaged valve body kit, however most of the units I have done are dual fed.
 

Steve V

Steve V's Automotive 757 560 2782
#18
What happens with a TV adjustment?

Interesting. I've never experienced it but I don't use a packaged valve body kit, however most of the units I have done are dual fed.
I have not messed with Tv trying to cure it. I accept is a nature of the beast.

My dual feed unit does it as well as my single feed unit too. Calibration is very similar to the one you posted a while back in this section.
 

mikestertwo

Well-Known Member
#19
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.
 

chris718

Active Member
#20
If this is a result of installing a kit,regardless of supplier than the first step to look at is what do they have in common and what is different.The only thing that comes to mind that would affect this is they are all using a higher rate pr spring.During a 2/3 shift there is very little volume of oil needed ,even with dual fed drums ,to apply the clutch and retract the intermediate servo.This includes the end to end core plugged tube passage on the backside of the valve body that carries 3rd oil to band retract diameter on the inside of the servo.Shuttle shifting has to be an issue associated with a point in which tv upshift oil pressure ,shift tv spring tension, and valve land diameter generated opposing force are equal to and or slightly highly or lower for a momentary period to the governor pressure and valve diameter opposing force.This would cause the valve to become "CONFUSED "as to where it should be.This is very similar to the buzzing of the spool valve when the power steering system on your Buick isnt completely full.This eventually stops as road speed is gained generating a higher governor oil upshift force upshifting the valve and keeping it there.Because of the general road speed and throttle position this takes place at I would surmise the point in which the primary governor weight is fully extended centrifugically and the secondary starts to extend is associated with this "phenomenon".Remember governor oil is fed line off the forward clutch or d4d3d2d1 circuit.A small price to pay for the dividends good kits provide in my opinion.