Auto trans slipping
Thread Starter
Instructor
Joined: May 2012
Posts: 243
Likes: 2
From: North Georgia
Auto trans slipping
1974 with a 454 ran great........until I drove it today for first time in 45 days
Goes into 1st and reverse firm....but will not shift into second......it free wheels up to say 5k runs then if you let off gas it will go into second but will not shift into 3rd
What gives?
Plenty of clean trans fluid........never any prob before
Orig 35,000 mile car
Goes into 1st and reverse firm....but will not shift into second......it free wheels up to say 5k runs then if you let off gas it will go into second but will not shift into 3rd
What gives?
Plenty of clean trans fluid........never any prob before
Orig 35,000 mile car
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
I assume it is a TH400??? It may be the rubber hose(s) that go form the intake manifold to the transmission valve on the side. The hose could have fallen off or split and it is not able to get vacuum.
You description is 'misleading'...because I have to assume that you have the shifter in DRIVE or '3'...and it is not working. Have you manually tired to shift it...meaning start in FIRST GEAR...and then shift to SECOND....then shift to THIRD??? IF it works...and you are sure your fluid is fine...which is should be because you wrote that REVERSE works well and shifts FIRM. I would be looking at your modulator line and hoses. The modulator should be on the passenger side of the transmission just above the pan gasket surface.
IF you disconnect the rubber hose form the modulator and you get transmission fluid...replace the modulator.
Also....there should be a steel line for the modulator...that allows small short sections of hose to connect it to the vacuum fitting on the intake and also the modulator itself. I WOULD NOT ( personally/professionally) run a rubber hose from the intake fitting to the modulator.
DUB
You description is 'misleading'...because I have to assume that you have the shifter in DRIVE or '3'...and it is not working. Have you manually tired to shift it...meaning start in FIRST GEAR...and then shift to SECOND....then shift to THIRD??? IF it works...and you are sure your fluid is fine...which is should be because you wrote that REVERSE works well and shifts FIRM. I would be looking at your modulator line and hoses. The modulator should be on the passenger side of the transmission just above the pan gasket surface.
IF you disconnect the rubber hose form the modulator and you get transmission fluid...replace the modulator.
Also....there should be a steel line for the modulator...that allows small short sections of hose to connect it to the vacuum fitting on the intake and also the modulator itself. I WOULD NOT ( personally/professionally) run a rubber hose from the intake fitting to the modulator.
DUB
