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Discussion Starter · #1 ·
I have a 1984 Buick Grand National with a replacement 200r4 tranny. The transmission is not an original GN – BRF transmission but it was rebuilt by a reputable builder to shift like a BRF, however it doesn’t shift like it should. I took it out and sent it back to the builder once and he made some improvements, but it is still not right.

I’d like to understand if my problems are just in the valve body, and it might be an easy fix, or do I have internal issues which require dropping the trans again. I don't have a lift, so I'd like to avoid dropping the trans. I really don't have time for that.

First let me say the following things work fine, with no issues:

- Overdrive/Converter lockup

- 3 – 4 Shift

- Full Throttle shifts

My problem is really with part throttle shifts on the 2-3 shift. At part throttle, the 2-3 shift always occurs at 22 MPH. It doesn’t matter if I am at 5% throttle or 40% this shift always wants to happen at 22. So, at 5% throttle where it shifted into 2nd at 13 MPH or something like that, then a 22 MPH shift to third might be OK, but at a higher throttle where it holds 1st gear until 20 mph, then it is almost immediately shifting from 2 to 3, when it should have held the gear longer. Once the throttle goes up over 50-60 %, then it will hold 2nd gear until a lot more RPMs, like it should.

The 1-2 shift isn’t perfect. Often it will hold first gear too long, holding first gear until 3000+ RPM’s at very light throttle and then due to the problem described above it will shift straight to 3rd gear without ever going into 2nd. Though that doesn’t happen all the time.

If I manually shift from 1 to 2 to D, it will generally shift OK.

So does this seem like a Valve body issue or something more serious. And if it is the VB, what should I inspect/replace to fix this?
Thanks for any insights.
 

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I am not a trans guy in any form, but I have swapped a 200r4 in an 77 olds.
The one thing I learned was TV cable set up is very critical to these transmissions.

My 1st question is: are you using all stock linkage for this transmission, focusing on the TV valve, all oem at throttle body and cable mounting brackets?

2nd have you made sure cable is properly adjusted.

I am guessing that the answer is yes on both.

then my next step would be to get a long high pressure hose with a high pressure gage. There is a pressure test port on passenger side of transmission. Attach hose and gage, have some ride with you and recorded readings off gage to make sure pressure are correct during shift points.
From here I would talk to Tran builder to review facts.
 

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Hates: Liver. Loves: Diesel
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Not that this will cause your issues, but keep in mind that the Z-trans versions (the ones in 442s, GN, GNX, etc) are not just built differently, they're a different case and valve body. The case is cast with different passages to match the Z valve body, so it kind of makes them two different transmissions. I only mention it because your "normal" 200-4r might not like the power you give it with the GN.

First things first, reset the TV cable. Squeeze the connector at the throttle bracket and pull the cable housing out. Then go through a couple throttle WOT cycles. It will pull the housing back in to the right spot. If that doesn't fix it, it needs internal help.
 

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Discussion Starter · #4 ·
Hi Guys, Thanks for the responses. Though I don't suspect my TV cable or adjustment. My shifts are good at WOT. My understanding was that the TV adjustment would be most critical there at WOT. My problem is the opposite....only an issue at part throttle and only on 1-2 and 2-3 shift. I wouldn't have a complaint if I spent most of the time at the track, :) but my car is all stock and I mostly just drive around town on the weekends.
 

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To make it work like a BRF trans you need valve body,governor,servo and spacer plate to work together.
Shift valve springs,governor springs and spacer plate hole sizes. The way you describe the way it’s working sounds like a TV problem.If your rebuilder is local,take the car to him,he should be fixing this not you.
 

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Hates: Liver. Loves: Diesel
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To make it work like a BRF trans you need valve body,governor,servo and spacer plate to work together.
Shift valve springs,governor springs and spacer plate hole sizes. The way you describe the way it’s working sounds like a TV problem.If your rebuilder is local,take the car to him,he should be fixing this not you.
I agree with the last part, but I don't think the first part is correct. It's not just a different valve body, the casting of the case is different to match the different valve body on the Z and BRF units. They have different "mazes" and I don't think the two are mix and match.
 

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I’ve never heard of a different case casting.I’ve rebuilt a few BRF units,but never actually compared the channels against another model.They only give you 1 set of valve body gaskets in the kits,which makes me think the cases are the same. CK performance used to sell BRF valve bodies with matching governor to make any model work like the grand national unit and he doesn’t mention a case change.You would have to have the 2 models side by side to confirm.
 

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afaik the only differences in cases are the different bell housing pattern. the bop pattern and the multicase pattern.
The vb/gov are different setups for different units. There is also a diesel setup with hydraulic lockup for the torque converter but those are pretty early in the production.

Sounds like you might have a sticky tv valve.
 
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