Slow or hard to engage in reverse or drive

[rick1062]

Hi folks,

I am working on a 1965 Barracuda with a 273 engine and a 904 trans, all basically stock.

I have posted other questions about this car and received great help from this forum. One thing is the car was missing some of the throttle pressure linkage. I was able to find some linkage, installed and adjusted it as the manual says. So, I think that problem is put to bed.

Now that we have it running pretty well, we find when accelerating, the car shudders some and feels to me like the trans is slipping. If I ease off on the throttle, the shuddering stops or at least lessens by a lot. A second problem with the trans is that from park, the trans won't always engage in reverse, or sometimes forward. When it won't engage in reverse, and I move the shifter back into drive, then into reverse, it will usually engage. When it won't engage in forward and I move the shifter up to reverse then back to drive, it usually engage. This doesn't happen every time, but often.

I don't know if the shuddering and the non engagement into gear are related, or not. But if any of you have ideas, I would greatly appreciate any advice on these issues.

Thanks as always,
Rick

 

[oldkimmer]

.............Have u checked the fluid in neutral with the car running?.......is the radiator known to be good as the cooler in it may be restricting flow..another thing could be is u installed the wrong filter, cause there is a change up somewhere there as the old trannys had a rear pump...kim.......

 

[rick1062]

.............Have u checked the fluid in neutral with the car running?.......is the radiator known to be good as the cooler in it may be restricting flow..another thing could be is u installed the wrong filter, cause there is a change up somewhere there as the old trannys had a rear pump...kim.......

All good points Kim. I have checked the fluid in neutral with the trans warmed up and running. The engine coolant part of the rad seems clear and working fine. I really don't know about the trans cooler portion. The problems occur when cold or warmed up. Wrong filter??? possible, I can look into that, but i feel pretty confident it is correct.

Thanks for all of those great check points,

Rick

 

[RustyRatRod]

Sounds like a possible converter problem. But....if you pull it, might as well build it.

 

[AJ/FormS]

The high drum is not working right.
It is part of the reverse engagement process. It is also 3rd gear. The clutches are slipping.All your shifter fudging is proving that.Further more, when engaging reverse the line pressure regulator goes to maximum pressure. So if its slipping in reverse, and 3rd, the high drum is the go-to guy. Had you not mentioned a 3rd gear shudder, I would have pointed to the L/R band.
Now as to the slippage. There are 3 possiblities; 1) low fluid, 2) wrong fluid 3)mechanical failure inside the trans. The first is out as you have checked it.In NEUTRAL on flat ground. Right?
The 2nd is trickier. That tranny is designed to run with Dextron II. Not the modern Dextron fits all stuff.
So if its full of Dextron II and slipping, then we go to 3, mechanical. Theres no cure for this other than parts replacement. Well theres a slim chance that its a lip seal gone hard. Some folks have had success with a treatment package.
Since the 904s are so simple to overhaul, I just yank em.Its gonna have to get done sooner or later. Better now while its home, than 2 states over. At night. In the rain. Fifty miles from nowhere.

 

[rick1062]

The high drum is not working right.
It is part of the reverse engagement process. It is also 3rd gear. The clutches are slipping.All your shifter fudging is proving that.Further more, when engaging reverse the line pressure regulator goes to maximum pressure. So if its slipping in reverse, and 3rd, the high drum is the go-to guy. Had you not mentioned a 3rd gear shudder, I would have pointed to the L/R band.
Now as to the slippage. There are 3 possiblities; 1) low fluid, 2) wrong fluid 3)mechanical failure inside the trans. The first is out as you have checked it.In NEUTRAL on flat ground. Right?
The 2nd is trickier. That tranny is designed to run with Dextron II. Not the modern Dextron fits all stuff.
So if its full of Dextron II and slipping, then we go to 3, mechanical. Theres no cure for this other than parts replacement. Well theres a slim chance that its a lip seal gone hard. Some folks have had success with a treatment package.
Since the 904s are so simple to overhaul, I just yank em.Its gonna have to get done sooner or later. Better now while its home, than 2 states over. At night. In the rain. Fifty miles from nowhere.

AJ/FormS/

Great stuff and thanks for the ideas. But let me clear up a bit. I didn't mention that it was shuddering in 3rd. In fact, 3rd is probably the best. So, if it is not shuddering or slipping in 3rd, does that change your ideas about the high drum?

Another thing happened today that may point in a different direction. The battery was dead becaue a light was left on. I put it in neutral so we could coast it down the hill to a place where my batt charger was. We could not get the car to roll. No matter where I put the shifter, it would not move, like it was still in park. I took the batt out and charged it up. Then it started and was at least back to where it had been. Maybe this not being able to push it after taking it out of park is a clue.

Next from what you said, I have the wrong fluid in it. I did install the modern fits all Dexron. Hopefully I can find Dex 2 around here somewhere.


Thanks to all for your replies.

Rick

 

[fishy68]

AJ/FormS/

Great stuff and thanks for the ideas. But let me clear up a bit. I didn't mention that it was shuddering in 3rd. In fact, 3rd is probably the best. So, if it is not shuddering or slipping in 3rd, does that change your ideas about the high drum?

Another thing happened today that may point in a different direction. The battery was dead becaue a light was left on. I put it in neutral so we could coast it down the hill to a place where my batt charger was. We could not get the car to roll. No matter where I put the shifter, it would not move, like it was still in park. I took the batt out and charged it up. Then it started and was at least back to where it had been. Maybe this not being able to push it after taking it out of park is a clue.

Next from what you said, I have the wrong fluid in it. I did install the modern fits all Dexron. Hopefully I can find Dex 2 around here somewhere.


Thanks to all for your replies.

Rick

The shuddering is a sign the clutch plates are slipping. Since you said that only happens in 1st and 2nd that indicates it's the rear clutch slipping either because it's toasted or the seals are dried up and not applying it good. The rear band is possibly slipping due to wear or the servo seals are dried out so much it doesn't actuate the rear band to cause slow or erratic reverse. If it was ran with no throttle pressure linkage for a while (doesn't take long) it probably toasted the trans. The fluid you used is ok. Plain Dexron was what they originally used but now it's not even available so you have to use what ever Dexron is available and it'll work fine. Even type F will work fine. As for not being able to push it, it's possible the brakes are adjusted too tight.

 

[AJ/FormS]

Ok, thats a lot of new info.
Firstly; Fishy is giving good info. I think he is on the money.However, I have an issue with the oil. As long as the tranny is in good working condition that new slippery oil is ok. But the second the tranny is in trouble, that slippery stuff just aggravates it. Thats been my experience, allbeit limited.
Second, from your post#1, I assumed you got it into third gear from the accelerating statement.
Third , if the car wont roll with engine off, the brakes are most definitely dragging. And may be affecting the tranny as well.Fix that first.
Fourth, no where do you mention taking off in Low, so Im assuming you never tried shifting any of the gears manually.
Fifth when in reverse,the tranny oil pressure rises to its maximum, and that pressure is sent directly to the front clutch and the L/R servo.As a rule I use this fact as reason enough to pull a tranny that shudders or slips or acts as you describe.Or at least drop the pan and check the L/R band adjustment.
Now the front clutch is also used to engage 3rd gear. But you never got to 3rd, so we cant cross check it.Also now, the L/R servo is used to engage both reverse and Manual Low, but you dont tell us about Manual Low performance, so we cant cross check that either.
When any forward gear is selected, the forward clutch(called rear clutch by Ma) engages.
When you put the selector in drive, the tranny always starts in 1st/low. However it is a different way of engaging low, and is called Drive-Breakaway.In this condition,the forward clutch(called rear clutch by Ma) is engaged, and the L/R drum is held stationary by the overrunning clutch instead of the band.Same job, different powerhandling.So if it slips in Drive-Breakaway, its most likely to be a slipping forward clutch.
So by now we have two slipping clutches, and very likely a bad L/R band.And that takes us back to post #5."Theres no cure for this other than parts replacement."
The tranny needs to come down.

 

[rick1062]

The shuddering is a sign the clutch plates are slipping. Since you said that only happens in 1st and 2nd that indicates it's the rear clutch slipping either because it's toasted or the seals are dried up and not applying it good. The rear band is possibly slipping due to wear or the servo seals are dried out so much it doesn't actuate the rear band to cause slow or erratic reverse. If it was ran with no throttle pressure linkage for a while (doesn't take long) it probably toasted the trans. The fluid you used is ok. Plain Dexron was what they originally used but now it's not even available so you have to use what ever Dexron is available and it'll work fine. Even type F will work fine. As for not being able to push it, it's possible the brakes are adjusted too tight.

Fishy68, thanks for your input. All sounds like good diagnostics.

I am sure it is not the brakes dragging. Once I move the shifter back and forth a time or two, it will go into gear correctly and in neutral I can push it easily and it is as free as it can be.

I have one more idea about not being able to push the car. I also find that sometimes when I put it in gear, reverse or forward, it won't move, but it feels like it wants to move. Then, I move the shifter back and forth a time or two and then it will go into gear and drive. Could it be that the park cable is out of adjustment and not pulling the pawl out far enough? Might that answer both of these problems.


Rick