Down shift problem

[DCGN]

Does anyone on this board know what might cause a 200-4R tranny to not downshift to 1st gear when coming to a stop? It takes off in 2nd gear, but if I shift to neutral or park then back to drive it takes off in 1st gear and shifts properly. Whats up with that?

If anyone on this board knows, or has had any experience with this problem, please respond.

Thanks,

Dan

 

[78oldscutlass]

I am having a simillar experience with mine. But for the past two weeks, It hasnt done it. Im thinking a piece of debris was hanging up the 1-2 shift valve.

Or it could be my POS KCF valve body.

 

[DCGN]

This transmission was just recently redone with all new parts. I am taking it back to the builder this Saturday to figure out what the problem is.... but I was just wondering if anyone else has had this kind of problem.

Thanks, Dan

 

[77 cruiser]

I had the same prob a while back. Check the line press first , on mine I had the boost valve together wrong & was getting full line all the time.

Read this also

http://www.turbobuick.com/forums/showthread.php?s=&threadid=25247&highlight=no+downshift

Just thought of it this morning.

Jim

 

[DCGN]

Thanks 77 cruiser, that's the link I needed. There is some good info in that thread. Now maybe we can get it fixed.

Dan

 

[chris718]

this has been addressed here several times .the answer is :too high a pressure in the governor circuit caused by a transgo shift kit that makes you reduce governor orificing and doesnt allow upshift oil to exhaust out the governor fast enough when stopping ,or a cross leak into the governor circuit not allowing oil to exhaust resulting in enough residual pressure to allow the shift valvetrain to remain open .by putting in in neutral or park you allow governor oil to exhaust at the manual valve downshifting the shift valve so that when you put it back in gear its now in first because the governor upshift oil is peeing out the governor balls with no driveshaft rpm present .a heavy crossleak may allow this even when exhausting oil in p or n and then again placing the trans in gear. change the spacer plate with a new unmodified part number 8657309 gm and double gasket the plate on both sides or you can get the plate at www.ckperformance.com

 

[bird]

hey dcgn im having the same problem but it only seems to do it when the trans heats up after some hard driving, is this the case with your trans as well? the trans shop ive been dealing with has had the valve body out 3 times. im geting annoyed. once they fix this i will never go back there. im up here in the great whie north(canada) and the weather wont get better for another month but i will be sure to pass on the info from youre posting to the trans shop ( especially chris k,s info). keep us posted on youre situation. thanks.

 

[DCGN]

More info

Here is a list of parts installed in this transmission:
New clutches and bands.
Art Carr pressure valve.
TC solenoid, switches and valve.
Hardened stator shaft.
13 vane pump.
modified accumulator spring.
.500 line rise control valve.
Small spring in line bias valve.
Spring in throttle valve. (return)
Oversize servo assembly.

Line pressure in park: Minimum TV = 110, Max TV = 275

According to my tranny builder, the separator plate is stock GM.

From this info, can you see any reason this tranny will not down shift to 1st when coming to a stop.

I agree with you Chris, I think the pressure to the governor is not being exhausted....... but why?

And Bird, it doesn't make any difference whether the fluid is hot or cold.

Thanks for your help.

Dan

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[DCGN]

Will a stock separator plate work with these elevated line pressures? Could that be the reason my transmission will not downshift to first when coming to a stop? Bruce? Mark? Chris? It is my understanding that if you are running stock pressures, you should use a stock, unmodified separator plate. But what if your pressures are considerably higher than stock... should you still use the stock plate?

Thanks for your help.

Dan

 

[chris718]

it shouldnt be affected by those pressures because thats roughly what we run and have not had a complaint of this nature when used with a bone stock 8657309 plate .checkfor crossleaks by reading the footprint on the gasket ,check plate for transgo mod ,and if the new plate dont fix it call us .

 

[DCGN]

Fixed.

Got my transmission fixed today.

One of the balls was stuck in the governor and would not let it exhaust the pressure. My tranny builder took the governor out, freed it up and put it back together. It now shifts perfectly. It appears there are several things that could cause this kind of problem. Mine happened to be a stuck ball in the governor.

Thanks to everyone for your help.

Dan