Th400 Tailahaft/output shaft length
02-28-2005, 09:22 PM
#1
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Th400 Long/Short output shaft strength I've heard that the 3" output shaft is much stronger that the 9". Due to the fact that the 9" is longer, thinner and doesn't have as many splines. Is the shorter shaft actually any stronger? Has anyone has problems breaking the 9" shafts?
Last edited by LSmokin1; 02-28-2005 at 11:37 PM.
03-01-2005, 12:38 PM
#3
There are several different shaft sizes and lengths.
The th375 was only used a few years in the 70's. They had small shafts and longer tailhousings with 375 cast into them. These transmissions were weaker because they used fewer clutches inside.
Now in the 80's this same shaft diameter and housing length was used on th400's, even HD th400's (3L80HD). Same thing but it was no longer called a 375. And the mount is in a different location.
This length is also available in the larger 32 spline output shaft.
In fact the 32 spline comes in 13" versions.
I've heard different opinions on the lengths. Some people think the short one is weak because it doesn't allow flex like the longer shafts.
I have seen a 4L80E output broken off at the bushing journal.
The th375 was only used a few years in the 70's. They had small shafts and longer tailhousings with 375 cast into them. These transmissions were weaker because they used fewer clutches inside.
Now in the 80's this same shaft diameter and housing length was used on th400's, even HD th400's (3L80HD). Same thing but it was no longer called a 375. And the mount is in a different location.
This length is also available in the larger 32 spline output shaft.
In fact the 32 spline comes in 13" versions.
I've heard different opinions on the lengths. Some people think the short one is weak because it doesn't allow flex like the longer shafts.
I have seen a 4L80E output broken off at the bushing journal.
