Th400 trans problems!!

SCOTT SST2871 · 11-23-2009, 11:43 AM

Anyone have suggestions on a fix (other that switching to a glide)i cant keep a trans in my car more than 70-80 passes.i've been told its a sprag issue..when it goes bad it wont shift into 2nd gear under power,but you can shift it into 3rd. I have 2 transmissions with 2 different valve body manufacturers and they both do the same thing.its a s/st car ,has about 450 hp,weighs 3025 lbs and the stop goes on and back off in 1st gear
thanks
scott fifield

rmcgill · 11-24-2009, 09:58 PM

Not an expert in 400s but I have a T 350 shelled out the $350 for the TCI sprag upgrade and have never had a problem. Its in a 3200 lbs 1969 Camaro 475 hp on motor 600 on N2O.

I got around 40 passes plus a good bit of street driving before I messed up the motor with the nitrous.

Ron Finney · 11-24-2009, 10:12 PM

You need the early model drum (69-72) that will accept the 34 element sprag to solve your problem. The 400 is much stronger than a glide if done right. I found a good drum on e-bay for about $50.00. You can also contact WIT Transmission...they are based out of Louisville, Ky and ask for Robert.....he can tell you where to get one if he doesn't have one in stock. 800-940-0197

Ron

Tom Goldman · 11-24-2009, 11:19 PM

You definitly need the early smooth race direct drum and the 34 element dogbone sprag [not the roller clutch found in later 400's]...........You may also be experiancing a lube problem that is helping the roller clutch fail earlier than it normally would......If you are doing your own trans pay carefull attention to the lube feeds to the sprag from the center support........ATI makes a modified center support with a support bearing between the ring lands to support the weight of the direct drum. ......If you are experianced in building 400's they also sell the smooth race seperately, so you can install it on your existing direct drum. ......You should be able to run a 400 for several seasons before it needs to be freshend. .....I have several customers who reguarly put 3 to 400 runs on them before freshining .........If tou have any questions you can PM me .....Tom

11-23-2009, 11:43 AM	#1
SCOTT SST2871 Member Join Date: Oct 2008 Location: PORT ST JOHN FLORIDA Posts: 226 Likes: 0 Liked 0 Times in 0 Posts	Th400 trans problems!! Anyone have suggestions on a fix (other that switching to a glide)i cant keep a trans in my car more than 70-80 passes.i've been told its a sprag issue..when it goes bad it wont shift into 2nd gear under power,but you can shift it into 3rd. I have 2 transmissions with 2 different valve body manufacturers and they both do the same thing.its a s/st car ,has about 450 hp,weighs 3025 lbs and the stop goes on and back off in 1st gear thanks scott fifield

11-24-2009, 09:58 PM	#2
rmcgill Junior Member Join Date: Nov 2009 Posts: 4 Likes: 0 Liked 0 Times in 0 Posts	Re: Th400 trans problems!! Not an expert in 400s but I have a T 350 shelled out the $350 for the TCI sprag upgrade and have never had a problem. Its in a 3200 lbs 1969 Camaro 475 hp on motor 600 on N2O. I got around 40 passes plus a good bit of street driving before I messed up the motor with the nitrous.

11-24-2009, 10:12 PM	#3
Ron Finney Member Join Date: Jul 2008 Location: Greenwood, IN Posts: 168 Likes: 0 Liked 0 Times in 0 Posts	Re: Th400 trans problems!! You need the early model drum (69-72) that will accept the 34 element sprag to solve your problem. The 400 is much stronger than a glide if done right. I found a good drum on e-bay for about $50.00. You can also contact WIT Transmission...they are based out of Louisville, Ky and ask for Robert.....he can tell you where to get one if he doesn't have one in stock. 800-940-0197 Ron __________________ Ron Finney 396V S/C

11-24-2009, 11:19 PM	#4
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,451 Likes: 810 Liked 754 Times in 219 Posts	Re: Th400 trans problems!! You definitly need the early smooth race direct drum and the 34 element dogbone sprag [not the roller clutch found in later 400's]...........You may also be experiancing a lube problem that is helping the roller clutch fail earlier than it normally would......If you are doing your own trans pay carefull attention to the lube feeds to the sprag from the center support........ATI makes a modified center support with a support bearing between the ring lands to support the weight of the direct drum. ......If you are experianced in building 400's they also sell the smooth race seperately, so you can install it on your existing direct drum. ......You should be able to run a 400 for several seasons before it needs to be freshend. .....I have several customers who reguarly put 3 to 400 runs on them before freshining .........If tou have any questions you can PM me .....Tom __________________ Tom Goldman 1500 SG , 1506 STK