Oldsmobility85

iTrader: (1)

I am looking into converting my 4th gen sbc car from 700r4 to a th400. Everything is in the stock location and I am just wondering how much if any had to be removed from other peoples drive shafts. Any help would be appreciated.

dnkynrbk

iTrader: (34)

I would just have a new driveshaft built for the car. That what we ended up doing.

Oldsmobility85

iTrader: (1)

Thanks for the input. Also are the output shafts on a 400 the same as a 700? Spline wise I mean. Can I use the same yoke I have or do I have to purchase another?

Dustytrix

iTrader: (4)

The yokes are way different, you will need the 400 yoke. Also I cut my driveshaft about 5 inches so if you are going to have one made take your old one and let them cut it. That way your supplying the material, save a few coins.

Jays_SSZ28

iTrader: (2)

No it depends on the th400.
The short tail th400's have big 32 spline output shafts.
The long tail th400's have the common 27 spline size.

And to go off topic there are some old 70's cadillac th400's with real long 32 spline outputs.
Around 1976 there was a weak version of the th400 called the th375 that was a long tail 27 spline.
I've seen at least 12 different th400 output shaft sizes.

Oldsmobility85

iTrader: (1)

The trans a am looking at has a short shaft 32 spline output. I wonder if I could get a u joint that would convert from the stock steel driveshaft to the 400 yoke. I have seen this done with trucks that used metric u joints who install 14 bolt heavy half running gear. Then I could just have it shortened. 5 inch's seems like a lot. 700r4's are pretty long them self's.

Jays_SSZ28

iTrader: (2)

Your driveshaft is too short for that swap.

Dustytrix

iTrader: (4)

His question was are the yokes different between a 400 and 700. So are you saying. He can use a 27 spline 400 to fit a 700r? Or a 32 spline 400 to fit 700r?

Jays_SSZ28

iTrader: (2)

First he asked if the outputs are the same between the 400 and 700. The answer to that depends on which output his th400 has. If it had a 27 spline, then yes he could use the same 27 spline yoke in both thransmissions.

Now he got back with more information and says he has a 32 spline output, so he needs a 32 spline yoke.

Obviously no one can use a 32 spline yoke on a 700.

The problem the OP has is he has a driveshaft for a 700 and wants to use it with a short th400. The driveshaft is too short. At this point it's not even a question about yokes.

Oldsmobility85

iTrader: (1)

Thanks guys. I will probably try to find another driveshaft and have it cut down to fit my car. I appreciate the help.