Impala Forums banner

1 - 12 of 12 Posts
C

·
Guest
Joined
·
0 Posts
Discussion Starter #1
do I do to the crossmember? I have heard slide it back, turn it over or just leave it the way it is.
 
C

·
Guest
Joined
·
0 Posts
Discussion Starter #2
You will need to buy a new one if your old one wont fit right. I suggest buying one from goodmark.
 

·
Super Moderator
Joined
·
7,057 Posts
It should fit, but until you put the tranny up there you won't know. If it does not fit as is ask a transmission shop what they do to fit the TH400 into this car. The 77-79 had the option of a bigger tranny being installed. You might check the salvage yards to find one that had it and buy the cross memeber.
 

·
Registered
Joined
·
27 Posts
i believe the holes are 6 or 4 inches backwards. you also need the flex plate, all the cables/wiring from the 400, the slip yoke, and shift linkage. you might need to shorten your driveshaft, depending on the tail shaft length
 

·
Registered
Joined
·
624 Posts
hmmm i thought the 400 wherer more used with big block and 350 for the mouse motors,you ll need i would think the correct one for the proper pinion angles,i dont remember too if these have a kick down cable (av cable) or if its a vacuum type,if u used a 700r4 (non electronic) would still need to research but u get a better 1st gear ratio and od
 

·
Registered
Joined
·
11 Posts
why would you want to put a th400 in there? i wouldn't count on anything fitting. i would be surprised if it would even fit in the existing tranny hump.
a 200-4r will bolt right in place of the th350. it has a desirable gear ratio as well as overdrive. some came with only a buick-olds-pontiac bolt pattern only, but most had a universal bellhousing bolt pattern to fit all gm vehicles.
 

·
Registered
Joined
·
303 Posts
Makes sure that you really have enough engine to justify the THM400. The internals are heavy. The extra rotational inertia is hard to overcome without a lot of torque. In many cases, you are better off with a good built THM350 (or convert to a THM700R4/4L60 with overdrive and really low first gear and run a better rear gear)

IIRC, the THM200 in the b-body was mainly used with V6's and the diesel 350 (though the THM200 can be built really tough thanks to GM putting it in the Buick Grand Nationals).
 

·
Registered
Joined
·
11 Posts
my '87 caprice with a 305 had a 200-4r, as does my '87 wagon with a 307 olds. they also came in g-bodies. from what i have researched, there isn't much difference in strength between a stock 200-4r and a 700r4. they are both plentiful. i'm almost certain the 200-4r has a better 1st gear, but it's been a while since i've researched this stuff. the thm200 was a cheaper 3 speed used in place of the th350 in the late 70's and early 80's...and that one sucked. the 200-4r is based on that transmission i believe, but with stronger internals and overdrive.
if being used behind a more powerful engine, i know a weakness of the 200-4r is its small diameter input shaft.
 

·
Registered
Joined
·
16 Posts
If youre going to change out the tranny - put in a 200-4R. Its pretty much a drop in and you don't have to cut the driveshaft. Steeper 1st gear than a TH400 so you can launch off the line and OD is .68 ! So you'll rev at 2G instead of 3 G on the highway. Way better fuel economy !!!
 

·
Registered
Joined
·
9 Posts
I've got a 200r4 from an '86 cap. for sale if anyone is interested... since were talking about O/D trannies
 

·
Registered
Joined
·
13 Posts
No U Don't Need A Diff Cross Member 200r4-th350-th400 Same Cross Member, And Same Pitch For The Tail Shaft. Don't Worry!!!! Same Thing!!!!
 
1 - 12 of 12 Posts
Top