Transmission problems!

I've had my AOD transmission rebuilt three times already. when I get to 55mph and the transmission shifts, its like it goes to neutral. Then I need to completely stop the car to be able to drive it again but I need to go under 55mph. Can anyone let me kno whats going on? Ive had different shops rebuild the transmission.

-Fernando

Nando559 said:

I've had my AOD transmission rebuilt three times already. when I get to 55mph and the transmission shifts, its like it goes to neutral. Then I need to completely stop the car to be able to drive it again but I need to go under 55mph. Can anyone let me kno whats going on? Ive had different shops rebuild the transmission.

-Fernando

Click to expand...

The trans shop that did your rebuild(s) should be able to plug into the pressure ports and know exactly whats not right. Of course they should have done that and road tested it as well after they rebuilt it.

Heres some background. Gear 3 has the Forward & Direct clutches engaged and no bands applied. Just 2 clutches. The O/D gear has the O/D band applied, and the Direct Clutch engaged. 1 clutch and 1 band. On a 3-4 shift, the forward clutch is dropped and the O/D band applied.

This points to a problem with the O/D band or direct clutch. Presuming that you have a good 3rd gear, that would seem to indicate the direct clutch is working (but not necessarily) and the problem is with the O/D band or servo. More likely, its the O/D servo, or... servo incorrectly installed and not locked against the band (very easy mistake to make).

The O/D servo can be removed, serviced, and reinstalled correctly without removing the transmission.

Thanks!

What you said is EXACTLY what my transmission guy said!
He also said since the valve body is very old, that I should consider replacing it. Does that sound correct? He also suggested a shift kit.

-Fernando

Nando559 said:

What you said is EXACTLY what my transmission guy said!
He also said since the valve body is very old, that I should consider replacing it. Does that sound correct? He also suggested a shift kit.

-Fernando

Click to expand...

How bout that.

The VB can be inspected and some piece parts can be replaced (like the boost and TV valves), but for piece of mind, its easier to just replace it as well. Shift kit will help it out some, but honestly, the stock AOD shift isn't all that bad for 1-2, 2-3. However, 3-4 and 4-3 usually need help.. so if it fixes that I'd say it its worth it.