T-400 tranny swap

1200 Views 5 Replies 3 Participants Last post by ericnova72, Sep 16, 2009

1964_442

Discussion Starter · Sep 14, 2009

Chazmac said:
Short tail 350 and short tail 400 are the same length, only requires slip yoke change. If you go to two piece driveshaft, use a bolt-on yoke 400 if possible.
Short tail is ~6" long

I want to put a TH400 w/4'' tail in my 64 olds cutlass (same a body as the chevelle) that already has a TH350 w/6'' tail.....

what do I have to change besides moving back the Crossmember??

sorry to wake up old thread but its very on my question

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redsdad

· #2 · Sep 15, 2009

I show a 6" tail 350 at 27-11/16" while the 400 is 28-3/8". That is 11/16" difference. Depending on how long your driveshaft is now, you may bottom the yoke unless you shorten the shaft.

You will also need a 400 yoke as the diameter and splines are different.

The 350 has a cable for the downshift. The 400 requires an electric switch on the carb or gas pedal.

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1964_442

Discussion Starter · #3 · Sep 15, 2009

redsdad said:
I show a 6" tail 350 at 27-11/16" while the 400 is 28-3/8". That is 11/16" difference. Depending on how long your driveshaft is now, you may bottom the yoke unless you shorten the shaft.

You will also need a 400 yoke as the diameter and splines are different.

The 350 has a cable for the downshift. The 400 requires an electric switch on the carb or gas pedal.

sorry , but can you explain me this? bottom the yoke

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ericnova72

· #4 · Sep 15, 2009

1964_442 said:
sorry , but can you explain me this? bottom the yoke

If the driveshaft is too long, the slip yoke at the trans will "bottom out" on the output shaft when the rearend is compressed(like going over a bump). This pushes the driveshaft forward, if there isn't enough travel it will try to force the output shaft into the transmission, damaging the trans.

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1964_442

Discussion Starter · #5 · Sep 16, 2009

ericnova72 said:
If the driveshaft is too long, the slip yoke at the trans will "bottom out" on the output shaft when the rearend is compressed(like going over a bump). This pushes the driveshaft forward, if there isn't enough travel it will try to force the output shaft into the transmission, damaging the trans.

now I understand hehehe and how much travel es safe enough? its a 64 A-bodied Cutlass

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ericnova72

· #6 · Sep 16, 2009

5/8" to 1" is the recommended distance.

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