alright so this wednesday i will be dropping in the 455 out of a 442 into my buddies cutlass, its got a 400 trans for it i already have the 307 motor mounts picked them up earlier. i need to know if the 400 trans will bolt up to the 200r4 transmission cross member. any help is appreciated, ill post up picks for you guys once i get started.
455/400 trans swap.
- Thread starter WASTEDTALENT
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i found this for you real quick
TH400 or 2004R
At first, I thought this was an easy swap. I read an article that said you can get the crossmember from any g-body equipped with a 2004R and it will bolt right up to the TH400. Well, that is partially true. IF you have a 84 OR LATER G-body, it will work. But, the 78-83 G-bodies never came with the 2004R. The frame rail crossmember mounts are different from the latter year models. The latter year G-bodies frame mount locations that extend further back (toward the rear of the car). Since the 78-83 models do not have these, you will not be able to use the factory crossmember (unless you make the frame extension piece). Other options are to either get a crossmember from G-Force Performance, get a "universal" crossmember, modify/fabricate your own, or make a frame extension piece and use the stock TH350 crossmember. I modified mine by removing the mount pad from the front side of the crossmember, then using 1/4" thick steel plate, welding it to the back side of the crossmember. I then drilled an elongated hole for the transmission mount bolt to go through. Not too difficult to do yourself if you have access to a welder. Otherwise, you will need to get someone to do this. The TH350 driveshaft will either need to be shortened, or you can use a stock one from a later model G-body that had a 2004R transmission. Remember, you will have to use the yoke from the TH400 on the new driveshaft.
TH400 or 2004R
At first, I thought this was an easy swap. I read an article that said you can get the crossmember from any g-body equipped with a 2004R and it will bolt right up to the TH400. Well, that is partially true. IF you have a 84 OR LATER G-body, it will work. But, the 78-83 G-bodies never came with the 2004R. The frame rail crossmember mounts are different from the latter year models. The latter year G-bodies frame mount locations that extend further back (toward the rear of the car). Since the 78-83 models do not have these, you will not be able to use the factory crossmember (unless you make the frame extension piece). Other options are to either get a crossmember from G-Force Performance, get a "universal" crossmember, modify/fabricate your own, or make a frame extension piece and use the stock TH350 crossmember. I modified mine by removing the mount pad from the front side of the crossmember, then using 1/4" thick steel plate, welding it to the back side of the crossmember. I then drilled an elongated hole for the transmission mount bolt to go through. Not too difficult to do yourself if you have access to a welder. Otherwise, you will need to get someone to do this. The TH350 driveshaft will either need to be shortened, or you can use a stock one from a later model G-body that had a 2004R transmission. Remember, you will have to use the yoke from the TH400 on the new driveshaft.
youngdeezy said:
thanks for the info, i didn't even think about cross member mounts on the chasis
, either way i can make this work im pretty good at fabricating i could make my own but i was hoping for a short cut. thanks for the info
WASTEDTALENT said:thanks for the info, i didn't even think about cross member mounts on the chasis
Summit and Jegs both sell a simple bolt-in bracket to use the 200-4R crossmember in a pre-84 G-body.
Gforce is easy and really make the car stiffer ( i have T-tops i noticed in a big way). Just need to know the kind of trans and the year of the car. Before i had that all i did was cut the mounting plate off and weld it to the other side of course member. (TH400 is shorter)
WASTEDTALENT said:
TH-400 and 200-4R use the same crossmember. Direct swap.
You will need the proper driveshaft yolk, and you will need to have the driveshaft shortened approx. 1/2" - 3/4".
joe_padavano said:WASTEDTALENT said:thanks for the info, i didn't even think about cross member mounts on the chasis
Summit and Jegs both sell a simple bolt-in bracket to use the 200-4R crossmember in a pre-84 G-body.
what are they called? cant seem to find them on the website
dr78442 said:
so that's all it is a piece of metal with 4 holes in it, i can make that with a quickness. is something like that strong enough?
WASTEDTALENT said:
That's it . I made the same part for my 78 . I made it about 12 years ago and I have had no problems with my 502/400 combo. Good luck
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