hi everybody again. i have a 81 bu that has about a 250 hp 350 with a turbo 350 trans. i was planning to put one of my drag race 350 trans. in ,but came across a 200r4 from a 85 mc. that has about 5000 miles on it. it came from a very reliable source and has the stock lock up conv. later on this summer i will put in my 375 hp 350. i would like some input from the 200r4 guys as to the extent of modifications to help this trans. survive under these mild engines. the rear is 3:73. i have been buliding turbo 350's trans. performance and race for about 15 years, so i have a little exp. on some trans funtions. but not the 200r4. from what i have read so far i was going with the hardened stator support, better accumulators,betrter rings for the pump,bigger fluid drain back holes, and i would like some opinions on the constant pressure modification thats done to the vb and case. also a good shift kit. as always thank you very much for your input.200r4 mods
- Thread starter dwelch
- Start date
hi everybody again. i have a 81 bu that has about a 250 hp 350 with a turbo 350 trans. i was planning to put one of my drag race 350 trans. in ,but came across a 200r4 from a 85 mc. that has about 5000 miles on it. it came from a very reliable source and has the stock lock up conv. later on this summer i will put in my 375 hp 350. i would like some input from the 200r4 guys as to the extent of modifications to help this trans. survive under these mild engines. the rear is 3:73. i have been buliding turbo 350's trans. performance and race for about 15 years, so i have a little exp. on some trans funtions. but not the 200r4. from what i have read so far i was going with the hardened stator support, better accumulators,betrter rings for the pump,bigger fluid drain back holes, and i would like some opinions on the constant pressure modification thats done to the vb and case. also a good shift kit. as always thank you very much for your input.
I am in the middle of a diy assemble, with the help of several very knowledgeable individuals.
What I am doing includes the things you mentioned along with:
Hardened sun shell
Some valve body/governor mods as I don't have a cz like you
.500 boost valve
Larger rev boost valve
Boost Spring
Some mods to the line bias and accumulator valve
Springs for the accumulators
Some drilling to vb separator plate
Red clutches for the direct, tans for the rest.
Many of these things will come in a "shift kit" your call where you spend the money
A 10vane pump kit with hard rings(i just bought the hard rings and a stiffer spring for the slide, again your call)
If you plan on hard shifts or dual feeding the directs a billet shaft forward drum is a good investment
The book from CK performance is full of info, and a shop manual or area manual with specs is needed to set the clearances.
Lots of stuff inside that case.
What I am doing includes the things you mentioned along with:
Hardened sun shell
Some valve body/governor mods as I don't have a cz like you
.500 boost valve
Larger rev boost valve
Boost Spring
Some mods to the line bias and accumulator valve
Springs for the accumulators
Some drilling to vb separator plate
Red clutches for the direct, tans for the rest.
Many of these things will come in a "shift kit" your call where you spend the money
A 10vane pump kit with hard rings(i just bought the hard rings and a stiffer spring for the slide, again your call)
If you plan on hard shifts or dual feeding the directs a billet shaft forward drum is a good investment
The book from CK performance is full of info, and a shop manual or area manual with specs is needed to set the clearances.
Lots of stuff inside that case.
X2^^, on above Info.
Just increasing Pr. Regulator spring & Slide spring strength and TV + Low/Rev boost valve sizes helps a great deal on power handling, opening up the Orifices in the Seprator Plate is also needed.
Good Info on Dual Feeding / Extra Frictions / Boost Valves:
When swapping from TH350 to TH2004R you need to make sure you have the correct TV cable Bracket + TV geometry corrector bracket if you're using an Aftermarket Carb, Holley, Eddy etc.. If using a Q-Jet it must also have the correct Linkage for TV cable use. If not it will burn the Clutches quick.
From GM Manual:
"The TV cable used with the 2004R transmission should not be thought of an automatic downshift cable. The TV cable used on the 2004R controls line pressure, shift points, shift feel, part throttle downshifts and the detent downshifts. The function of the cable is similar to the combined functions of a vacuum modulator and a detent cable."
Just increasing Pr. Regulator spring & Slide spring strength and TV + Low/Rev boost valve sizes helps a great deal on power handling, opening up the Orifices in the Seprator Plate is also needed.
Good Info on Dual Feeding / Extra Frictions / Boost Valves:
When swapping from TH350 to TH2004R you need to make sure you have the correct TV cable Bracket + TV geometry corrector bracket if you're using an Aftermarket Carb, Holley, Eddy etc.. If using a Q-Jet it must also have the correct Linkage for TV cable use. If not it will burn the Clutches quick.
From GM Manual:
"The TV cable used with the 2004R transmission should not be thought of an automatic downshift cable. The TV cable used on the 2004R controls line pressure, shift points, shift feel, part throttle downshifts and the detent downshifts. The function of the cable is similar to the combined functions of a vacuum modulator and a detent cable."
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thanks very much for your replies. i'm sure i will have more questions once i get into this trans.
