th-350c to 200R4, couple questions....

[Yedi]

I want to swap my th-350c w/ a 200R4, I have a G-Force dual hump crossmember, will this work w/ the 200R4? I have read about moving the crossmember 6" back? MY car is an 83 and doesnt have the extra holes.
What about my driveshaft, will it hook right up?

Any info would be great, I'm thinking about either going through Bruce or BowTie overdrives (anyone ever heard of them?)


thanks.

 

[INEEDAGN]

I've been planning on doing this also. I "think" the driveshaft will work. I don't know anything about what has to be done to the stock crossmember but here is a TTT for you.

 

[Yedi]

Thanks INEEDAGN, there has to be someone that has done this, or knows what it takes, anyone???

 

[Yedi]

nobody knows? I'm the first one to do this I guess

 

[INEEDAGN]

Well here's what I know about the driveshaft. When we put an 8.5 rear in a buddies car with the stock 8.5 driveshaft, it fit fine. The rear and shaft were out of an 84 hurst olds with 200-4r, they went in an 80 cutlass (same frame) with a factory 350 and fit perfect. This leads me to believe there's no length difference in the 350 to 200-4r. I don't remember if his car had a short or long tail 350 though. Do a search on people wanting to go the other way. Many more go to 350 from the 200 and I think you'd find your info there.

 

[87moonroof]

th 350

I have done it the driveshaft will work and you can make a plate from the mount to the cross member or you can make a plate on the drivers side just to move that side only then you have to rig a set up for the shifter because the cables are different also you should put a one way check valve to the module so it shifts on its own for normal driving you prob. know but be sure to put a good stall in it if you have anymore questions let me know

 

[Yedi]

ok so my driveshaft will work. I forgot to mention that I have a B&M MEgashifter so the cable thing wont be a problem.

87moonroof, what is this plate you are talking about? is what your saying is I can leave my crossmember where it is and just make a plate to extend out the mount? Thanks for the help everyone I appreciate, keep the tips comin.

Oh, I've done searches for 200 to 350 and didnt find much about that either.

 

[Yedi]

If it matters, I have a 7.5 rear end not a 8.5 like you turbo guys, drive shaft should still work though, right?

 

[Turbo Loyd]

TH 350 - Overall Length 27 5/8” Face to mount distance 20 3/8”, Ratios: 1st 2.52, 2nd 1.52, 3rd 1.00

TH 200 R4 Overall length 27 3/4”, Face to mount distance 26 7/8”, Ratios: 1st 2.74, 2nd 1.57, 3rd 1.00, 4th .67 It is the same overall length and output spline as the short tail turbo 350.

The G Force crossmember for the TH 350 is different than their product for the TH 200 R4

G Force Procducts

Note from G Force Web site

GM altered the common frame configuration to accommodate the longer 200R4. Because the 200R4 crossmember mounting pad is further back than the TH350, a new design, stock crossmember was installed also. This stock crossmember mounts in a new set of holes in the frame on the driver side. The new holes in the frame can be identified as 14 inches rearward of the first set on the driver side frame rail. For reference, the TH350 factory crossmember mounts diagonally across the frame rails while the 200R4 (4spd automatic) crossmember mounts straight across. Therefore, pre 1984 vehicles will require the frame extension kit to install a 200R4 or a TH400 transmission. The TH400 mounts the same as the 200R4. Requires installer to drill two ½” holes with the provided template.

FE100 Frame Extension (above) is for 1978 thru 1983 G-Body cars that will retrofit a 200R4 or TH400 trans. It adds the second set of crossmember mounting holes to the driver side frame rail in the same location as the 1984 thru 1988 G-Body cars.

If you have a 1978 thru 1983 G-Body and want to put in a 200R4, TH400, T-56, 4L60E (1997 and up trans), or 4L80E transmission, this part is required. If you have a 1984 thru 1988 G-Body the FE100 is not required for any transmission……$59.00

Another thing you will have to install is the TV cable. This will require modifications to the throttle cable bracket and a place on the throttle to pull the cable.

Interesting reading on installing TV cable

The drive shaft lenghts for the 7 1/2 differential and 8 1/2 differential are different, but as long as you are not changing differentials it will not matter. You may want to consider upgrading to an 8 1/2 at some point if you are making serious power.

Hope this helps

 

[Yedi]

Almost there now!

Turbo Loyd, very helpful details. I contacted G-force before I read your post and they told me the same thing, I need the different crossmember and the extension bracket as you posted to make the install correct. So I will be selling my dual hump G-force crossmember for my th-350 and getting one for the 200r4. All I need to do now is get in touch w/ Bruce and figure out the tranny details (stall size, T.V cable, and speedo gears) Thanks again Turbo Loyd and everyone else that chipped in some help.