Rough park or neutral to drive engagement on 904

[azaustin]

My '65 Dart GT has the 904 Torqueflite with the 235hp 273 engine. The engagement is rough when shifting from Park to Drive, or Neutral to Drive. The lowest I can get the idle adjusted to is around 650-700rpm. I have seen some specifications that show the idle should be as low as 475-500 rpm for the V8 automatic combination. I don't think the car should "jump" like it does even with my higher idle setting. The transmission works perfectly otherwise. I don't know a lot about this transmission, so I'd appreciate any suggestions.

 

[TrailBeast]

First thing is to check your U joints for play in them, as this can cause harsh engagement.
(especially like going from forward into reverse or vise versa)

 

[azaustin]

U-joints are good. It feels like engaging at too much rpm, I don't think the rpm are the problem.

Thanks!

 

[fishy68]

650 idle rpm shouldn't be a problem. I wonder if someone blocked the accumulator in the trans? Does it shift real firm into 2nd gear like it has a shift improver kit installed? Blocking the accumulator in the trans is a popular 1-2 shift firmness improvement but if you have a stock converter it's not a good idea cause there's not enough cushion. I do it on transmissions that are using a high stall converter cause the converter slips enough to cushion things. If the 1-2 shift seems like a stock trans my other guess would be a problem within the torque converter.

 

[azaustin]

650 idle rpm shouldn't be a problem. I wonder if someone blocked the accumulator in the trans? Does it shift real firm into 2nd gear like it has a shift improver kit installed? Blocking the accumulator in the trans is a popular 1-2 shift firmness improvement but if you have a stock converter it's not a good idea cause there's not enough cushion. I do it on transmissions that are using a high stall converter cause the converter slips enough to cushion things. If the 1-2 shift seems like a stock trans my other guess would be a problem within the torque converter.

The transmission seems to shift well and work normally once it is in gear. Thanks for your response.

 

[oldkimmer]

If ur 200 Revs above idle that's likely ur problem. Maybe the 235 hp cars has a higher stall from factory. Kim

 

[Bad Sport]

I don't think the car should "jump" like it does even with my higher idle setting.

What rear end? Some old, partly worn out 7 1/4 rears have the dreaded clunk when going into gear, especially when going into reverse. That would be accentuated with a slightly higher RPM.

 

[azaustin]

What rear end? Some old, partly worn out 7 1/4 rears have the dreaded clunk when going into gear, especially when going into reverse. That would be accentuated with a slightly higher RPM.

The rear end is original, however it clunks going either way, from Park into gear, or neutral into gear. Not so much a "clunk" as a "jump" much as if the rpm were too high, but I don't think a couple of hundred rpm should make that much difference, and I'm not sure the specs are necessarily correct for the 235hp engine. 500 rpm is a low idle for any engine, and the 235hp has a hotter cam and much higher compression than the two-barrel engine. Once the car is in gear it runs, drives, and shifts smoothly.