Sorry in advance! What makes the hurst valve body special and what is the best way to get your tcc to unlock on the factory trans set up
200r4
- Thread starter 90hurst/oldsguy
- Start date
on the 2004r VB in the HO they had a factory shift kit, the governor also was different with different springs and weights. when building them if i wanted to eliminate the lock up i would remove the TCC valve and swap the springs from the front of the valve to the back of the valve so it would stay engaged thus giving it a full-time lube, because with no L/U it has little lube to the planets, but doing that you also have to use a dummy converter with no clutch,,,,,,,,,,,,,,,,,,,,
There's a few more parts that VIN 9 Olds cars have that are slightly different than regular 200-4Rs. Mostly it was spring calibrations for controls and used different pressures. 83-85 OZ transmission had a tremendously stiff 1-2 shift. So much so, some people complained about it when new. Seriously. They were very hard shifting transmissions. So for 1986, they "softened" the shifts. They were still firm, but not bone-jarring. The OZ's settled down as the miles went up and parts would wear some, but still maintained a firm shift.
Interestingly, if you were to go back in time, if GM had to supply an 83-85 OZ or 86 KZF transmission as a remanufactured unit, you got p/n 8639966. (8639967 for 1987).
If you bought a brand new transmission for 1983-85 OZ, it was p/n 8652078.
What's confusing is that the 85 OZ pump cover says it's the same p/n as an 86 KZF, which either one is specific to VIN 9 Olds. Eh, not to sure about that. EDIT: What I mean is I'm not sure the 85 OZ doesn't share the pump cover of the KZF. Otherwise the transmission part number would have to change. They essentially carried over 84 VIN 9 specs to 85 VIN 9.
Interestingly, if you were to go back in time, if GM had to supply an 83-85 OZ or 86 KZF transmission as a remanufactured unit, you got p/n 8639966. (8639967 for 1987).
If you bought a brand new transmission for 1983-85 OZ, it was p/n 8652078.
What's confusing is that the 85 OZ pump cover says it's the same p/n as an 86 KZF, which either one is specific to VIN 9 Olds. Eh, not to sure about that. EDIT: What I mean is I'm not sure the 85 OZ doesn't share the pump cover of the KZF. Otherwise the transmission part number would have to change. They essentially carried over 84 VIN 9 specs to 85 VIN 9.
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A lot.
I spent some time a few years ago trying to reverse engineer what makes a 'performance' 2004r valve body different than a run of the mill 2004r valve body.
I had a 305 SBC 2004r core and was putting it behind a turbo buick. Everyone says how much different a GN trans or Hurst/MCSS is than a normal passenger car spec trans but nobody says what or how. My trans rebuilder took my valve body in as a core for a few springs but otherwise he put a BRF GN valve body together for me. Many 2004r specialists also don't like the aftermarket transgo type shift kits.
This example is for a BQ buick version but it's similar in scope of changes to a 442/HO or MCSS
I was in denial that 2004r valve bodies matter because with TH400's or whatever, nobody cares if the trans comes out of a 70 Chevelle SS 454, a 78 caprice, or a 88 C30 camper chassis. All people care about in TH400 world is that it's a TH400, 2004r people get all worked up about the calibration. I was certain you can make a peformance 2004r valve body out of a run of the mill one with maybe some tweaks, but the differences are thorough and throughout.
These are notes from a post Jake Shoemaker (of Jakes performance transmissions) put somewhere online 15yrs ago. I tried to mark all the stuff that is different.
According to Husek who built my trans the valve body casting between any standard unit is also different than a performance unit (any turbo buick, 442/HO, or MCSS unit), so even if you have some of the shift spools from a performance unit or could somehow modify the stock shift valves from a non performance unit, the sleeves they ride in, and the springs also are different.
I spent some time a few years ago trying to reverse engineer what makes a 'performance' 2004r valve body different than a run of the mill 2004r valve body.
I had a 305 SBC 2004r core and was putting it behind a turbo buick. Everyone says how much different a GN trans or Hurst/MCSS is than a normal passenger car spec trans but nobody says what or how. My trans rebuilder took my valve body in as a core for a few springs but otherwise he put a BRF GN valve body together for me. Many 2004r specialists also don't like the aftermarket transgo type shift kits.
This example is for a BQ buick version but it's similar in scope of changes to a 442/HO or MCSS
I was in denial that 2004r valve bodies matter because with TH400's or whatever, nobody cares if the trans comes out of a 70 Chevelle SS 454, a 78 caprice, or a 88 C30 camper chassis. All people care about in TH400 world is that it's a TH400, 2004r people get all worked up about the calibration. I was certain you can make a peformance 2004r valve body out of a run of the mill one with maybe some tweaks, but the differences are thorough and throughout.
These are notes from a post Jake Shoemaker (of Jakes performance transmissions) put somewhere online 15yrs ago. I tried to mark all the stuff that is different.
According to Husek who built my trans the valve body casting between any standard unit is also different than a performance unit (any turbo buick, 442/HO, or MCSS unit), so even if you have some of the shift spools from a performance unit or could somehow modify the stock shift valves from a non performance unit, the sleeves they ride in, and the springs also are different.
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I don't keep up with what's different or not very much, but those GN transmissions are also some differences between the H/O and MCSS versions. I think each has their own separate calibrations. Some parts may be the same, but some are different. How they get there for each verison I do not believe has been researched 100%. But you are 100% correct in that you can't just build any old 200-4R and turn it into a GN or H/O or MCSS transmission.
i was a professional transmission rebuilder for 45 years, retired about 5 years ago. it has been a few years since i built a G/N or HO 2004R. if i remember right the cases is also different in the oil passages for the VB on the G/N H/O from the standard 2004R, the separator plate is also different, so the VB alone does not do it all.
