Does anyone know what alterations have to be made in order to use a th400 when there was a th350?
I was so worried about getting pontiac bolt pattern I neglected to think of all modifications Id have to make to fit a 400. Does anyone know whether i'll have to modify...
1) mount
2) cross member
3) driveline
4) is there a kickdown for the 400?
Its lookin like I'll have to shorten the driveline and I know I need a different yoke. Do they make a ujoint that will accomodate the swap or will I have to modify it myself?
Oh guess you need to know what its goin in too lol
1981 trans am with a bb 400 (no its not stock) was a pos 301 in it with turbo 350.
Why not stick with the 350? Your car is light and the 350 should get that car haulin ass in no time. The 400 is heavy and you may also need to enlarge the trans tunnel more than it has already been enlarged. If the 350 you have is toast then just replace it with a beefed up 350 and you are good to go! I think you can get a conversion set up for the 400 that will work with the yoke you have if you must have a 400. The cross member is different. Good luck with the project.
They make a u-joint for the switch to run the 400 yoke. Your also going to have to cut like 4 inches out of your driveshaft since the 400 is longer. Also modifying your crossmember inless you want to buy a new one. If I remember right they make one for the t-400 but I could be wrong. Before you install it put a shift kit in it to eliminate the auto upshift (when you hold it in first gear it will shift up without you shifting it) but that may just be a chevy thing. If it was me I would just get a good t-350 since I know they can handle good power if there taken care of and I believe they are the better trans of the two. Plus you dont have to go thru all this bs just to swap in the boat anchor. Just my 2 cents.
thanks guys...the turbo 350 that was in it was toast the guy I bought it from lied to me. the tailshaft was so sloppy i took it to a transmission shop and they just said OHHH ( i thought it needed a new bushing lol)
so then started callin wreckin yards as I already have $6000 invested in a car that doesnt even move lol. The wreckin yards had a hard time finding me the 400 with pontiac bolt pattern. They were unsuccessful in finding me a 350. So its not like I wanted the 400 its kinda what I ended up with. I figured I could atleast get the motor broke in with the 400. The motor wants to lean against the distributor without any transmission in so breakin it in without a tranny is not an option.
I'm kinda new at this. I'm a paint & body girl. I just decided if I was gonna own a muscle car then I needed to learn how to work on it too. Unfortunately I learn things the hard way lol. I just assumed the 400 would be a better tranny for me since there was a sb 301 in it (nonrunning)and I put a 400 bb in it. Im not sure of the hp rating on it but brittco racing who rebuilt the motor told me I have 500 ft lbs of tork.
To be quite honest I was happy to find any transmission with the right bolt pattern for $125.
Sounds like a nice car you have there.... As for breaking it in, if you wanted to run the car you can put a block of wood on a floorjack and lift the engine from the oil pan enough to level it out and it will run fine. Careful with reving it up with the lack of transmission it will rev up super fast, kinda kool actually. Or you can put a 2x4 across the fenders and run a chain over it to bolt on the back intake bolts to hold the engine lever but you risk scratching the fenders if done wrong
the turbo 400 tranny is nice and strong. but it built more for trucks. and cars not so much. the turbo 400 is bigger and heavier also it robbs more power then the 350. again the 400 is a strong tranny. but i wouldnt put it in the car. but as for the 350 it is a bullet proof tranny. built for the street and the strip. i would stick with that and wouldnt want to go with a 400 for the car. but thats my opinion. but stick witht the turbo 350.
yes transmission will bolt up, as long as its a buick ,olds or cadillac transmission. move cross member back holes should already be in that frame,if not drill out holes as needed drive shaft is the same lenth if you use short tail 400 change u- joint and yoke if you have a good parts store old part number precision u joint 372 might be inter change with other u joint manufacter number need to change fill tube and dipstick,relocate vaccume line to mogulator
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