TH400 bad at 80k?
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Instructor
Joined: Nov 2005
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TH400 bad at 80k?
I'm thinking my tranny is going away. 
When I was driving the car the other day, it wouldn't shift into 3rd and seemed to hesitate when I put it in drive/neutral before it would engage. It also slipped out of gear twice while driving.
As I've said in other threads, it basically just sat for +-8 years before I got ahold of it... is there any chance that something as simple as a tranny flush may solve my problems? Or should I just save that extra $40 towards a rebuild? I didn't expect something like the th400 to be dying at a medium-low amount of miles like that.
When I was driving the car the other day, it wouldn't shift into 3rd and seemed to hesitate when I put it in drive/neutral before it would engage. It also slipped out of gear twice while driving.
As I've said in other threads, it basically just sat for +-8 years before I got ahold of it... is there any chance that something as simple as a tranny flush may solve my problems? Or should I just save that extra $40 towards a rebuild? I didn't expect something like the th400 to be dying at a medium-low amount of miles like that.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Used trans fluid will lose it's viscocity from sitting. That is why the manuel recommends 3 years or 30,000 miles. I would have it flushed and then drop the pan and change the filter and top with new fluid. I had this happen before and topped it up with Amsoil trans fluid after the flush and filter change. IT WORKED PERFECT WHEN I WAS DONE!!! Cost me about $150 but it was way better than changing the trans. IF YOU DRIVE IT MUCH AT ALL LIKE THAT YOU WILL SMOKE THE TRANS CLUTCHES!!!! Then you will be rebuilding it for sure!
Last edited by 63mako; Feb 8, 2006 at 08:04 PM.
Pro
Joined: Aug 2003
Posts: 530
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From: Victoria Texas
I am redoing a 73 now that has 68,000 orignal miles on it, it also sat for several years without being driven.
The trans shifted ok for the age, it is a t-400 also.
I am putting a 383 in the car and decided to pull the trans out to rebuild it at the same time, I am glad that I did, when I pulled the clutch packs down several of the clutch linings were down to the steel or so thin that you can see the steel face .
It would not have lasted long with the new engine that I am putting in it.
The car was driven several hundred miles after removed from storage over the last year, I suspect that the linings were dry from age and once I started to drive the car they wore out rather fast.
I have pulled down transmissions with many more miles on them than this and the clutches were in better shape.
Best bet is to rebuilt it now and save the trouble , the seals that are internal dry out also.
Thanks, Mark G
The trans shifted ok for the age, it is a t-400 also.
I am putting a 383 in the car and decided to pull the trans out to rebuild it at the same time, I am glad that I did, when I pulled the clutch packs down several of the clutch linings were down to the steel or so thin that you can see the steel face .
It would not have lasted long with the new engine that I am putting in it.
The car was driven several hundred miles after removed from storage over the last year, I suspect that the linings were dry from age and once I started to drive the car they wore out rather fast.
I have pulled down transmissions with many more miles on them than this and the clutches were in better shape.
Best bet is to rebuilt it now and save the trouble , the seals that are internal dry out also.
Thanks, Mark G
