No reverse
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Instructor
Joined: Mar 2012
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From: MISSISSAUGA ONTARIO
No reverse
Hi guys, on the way home tonight go to park in my spot underground and crap no reverse gear ( TH400) all forward gears are good however when it's between park and reverse it's still in a forward gear....I'm thinking shifter cable it was perfect before this it's driven every day April to November about 6000 miles or more a year about 28000 miles on a completely rebuilt trany with shift kit and like I said until now 0 problems. If it matters at all its a small block.Thanks for any input.
Last edited by WHITE 1974; Nov 19, 2015 at 10:46 PM.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Hi guys, on the way home tonight go to park in my spot underground and crap no reverse gear ( TH400) all forward gears are good however when it's between park and reverse it's still in a forward gear....I'm thinking shifter cable it was perfect before this it's driven every day April to November about 6000 miles or more a year about 28000 miles on a completely rebuilt trany with shift kit and like I said until now 0 problems. If it matters at all its a small block.Thanks for any input.
If you can feel the individual detents (R, N, D, 2, 1) its not the shifter cable. The early TH700R4's had a carburetor type clip that connected the shift spool link to the detent plate and perhaps your TH400 has one of those clips too. I suggest dropping the oil pan and look the internal linkage over and also look in the bottom of the pan for signs of a tiny broken clip.
Melting Slicks
Joined: May 2004
Posts: 2,002
Likes: 17
From: Inlet Beach, FL
It could be that a Reverse Servo Accumulator seal has gone bad. When I had a TH400 in my car that was the problem when my reverse went out. All forward gears worked fine.
It is located on the valve body and has a round cover. You will have to drop the pan.
It is located on the valve body and has a round cover. You will have to drop the pan.
Last edited by Brass Pass; Nov 19, 2015 at 11:22 PM.
Thread Starter
Instructor
Joined: Mar 2012
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From: MISSISSAUGA ONTARIO
If you can feel the individual detents (R, N, D, 2, 1) its not the shifter cable. The early TH700R4's had a carburetor type clip that connected the shift spool link to the detent plate and perhaps your TH400 has one of those clips too. I suggest dropping the oil pan and look the internal linkage over and also look in the bottom of the pan for signs of a tiny broken clip.
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
The shift cable can be worn/damaged so that either REVERSE or LOW will not engage, but the other ranges will still feel like they have detent. Look at the shift cable where it attaches to the shift arm (on the left side of the transmission). Watch it as someone else shifts through ALL the ranges (with engine NOT running, of course) and look for any kinking of the cable between ranges and/or when reversing cable direction.
My bet is on a worn-out shift cable. Nothing lasts forever.....
My bet is on a worn-out shift cable. Nothing lasts forever.....
Last edited by 7T1vette; Nov 20, 2015 at 05:20 AM.
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Instructor
Joined: Mar 2012
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From: MISSISSAUGA ONTARIO
fixed
Thanks guys I got it up on the hoist everything looked fine externally was prepared for the worst when my buddy says " cable may be a bit loose won't hurt to snug it up it seems a little longer than I remember" Now I have reverse again I remembered stalling at a light in the way home as the air temp had dropped about 30 degrees and quickly slamming back to park to restart I guess in my panic at the lighat I was to rough at any rate thanks again for all the ideas and she's going into hybernation soon so in the spring I will probably replace the cable to be safe I agree nothing lasts forever
