A904 issue with stock converter

[mattr927]

Been driving my 70 318 swinger with a 1973 a904, tf2 shift kit, fresh ati super f fluid, lokar cable, and a fresh 90's pan/filter/gasket. Twice now while I've been holding at about 45 mph it gives me a feeling like the brakes are being applied(4 wheel manual drum.) 99% sure its transmission related, 1st time it happened I thought the engine was bogging down but it almost seems like 3rd gear holding tighter. I pumped the brakes a bit then I pushed throttle just enough to jump to 2nd and it still has the feeling, after accelerating a bit and letting off the throttle it went away. I turned towards home and now its not shifting to 3rd. The cable is adjusted just tight at full throttle. Anyone have an idea? Something internal? I also changed the 741 for a 489 since it happens last.

 

[Locomotion]

Only thing that comes to my mind is I've had a similar "feelings" when a sprag was going away in my race cars. It felt like the brakes were applied to the point of wanting to lock up. Don't know if the kickdown adjustment or something else could be involved. Regardless of the problem, for more clues, drop the pan and look for debris and see if the rear tires rotate freely by hand when off the ground and in neutral. Disconnect the driveshaft just to be sure it's not something in the rear.

 

[mattr927]

Thank for the reply. I just put in a new 489 case that was supposedly rebuilt, everything looked new. It did it once with the old rear end and it seems to be intermittent. I replaced the filter and put the shift kit in after it sat for 20 years. Maybe the filter is gummed up, but the fluid looks very good. I'm thinking ill just tear it down and go through it since the condition is unknown.