48re manual shift 2nd to D = neutral??

[Matt400]

I noticed something odd recently that while in 2nd (manually selected) that when I move the lever to D, I get neutral for a second or two. This has happened under power and also while decelling. An interesting thing noted is for that second or two the dash shift indicator shows no selection of any gears.



I did a search here and have not found anything however Issue #58 page 62 I see "Jim's" truck (an 06 model) is having the same issue.



I also notice (same as his) that while decelling in 4th and then select T/H for a downshift there is a second or two of neutral before 3rd locked hits. one thousand one - one thousand two kind of count, not split second so its enough where you pick up speed on a downhill.



Anyone having this issue? Anyone seen any threads about it?



Thanks

 

[Hoefler]

All is normal. The 2nd to D shift is 2nd coming out of lock up before it shifts.

 

[Matt400]

Can't be. . maybe I didn't write that correctly. Under power it feels like I just pushed in the clutch on a stick without letting off the fuel, Rpm's go up and then a hard bang as it grabs 3rd.



As I am decelling down a grade in manual 2nd. . when I move the lever to D I get neutral with no dash indication, speed picks up as it freewheels in a neutral mode and once again a bang as it hits 3rd.



It doesn't always do this but seems to be more frequent. Getting neutral is enough of a surprise that you look down at the selector to see "what the heck?" and note no gear is selected, then bang and D lights up. The bang is not super loud but its very harsh and gets not only my attention but any passengers as well.

 

[JApol]

my truck has the same thing as yours Matt, except mine showed up after Dodge replaced the valve body.

 

[CPG]

Matt400,



I have this problem when in the mountains towing our 26' 5th wheel. I have a 04. 5 and am useing the exhaust brake when this happens. It makes a big notable bang as if the clutches or torque converter is applying too hard. Am in tow/haul when this happens. It really shakes my Wife and I up when this acute shift is made.



Chuck

 

[cerberusiam]

Can't be. . maybe I didn't write that correctly. Under power it feels like I just pushed in the clutch on a stick without letting off the fuel, Rpm's go up and then a hard bang as it grabs 3rd.



As I am decelling down a grade in manual 2nd. . when I move the lever to D I get neutral with no dash indication, speed picks up as it freewheels in a neutral mode and once again a bang as it hits 3rd.

Its not right, but, it is a pretty common occurence on a stock transmission. The overlap shift from 2nd to drive is extremely sloppy under power. Any little misadjustment or slowness in the shift gives you a cut loose situation.



The same thing happens on decel when you manually shift it. The TC unlocks, it goes into free wheel until drive applies. The load just makes it feel worse.



I have the same issue but it is too much Smarty that causes it. :-laf



The 2-3 shift is band release and clutch apply on the same hub. If the pressures are low, the band not adjusted correctly, a little slowness in the shift valve, you get what you are feeling. Its a timing issue internaly nd one of the inherent weaknesses of the 727 based transmissions. Its fixable with a few parts and a little VB work.

 

[Matt400]

If the pressures are low, the band not adjusted correctly, a little slowness in the shift valve, you get what you are feeling.

I did do the gov. solenoid TSB a while back for the shuttle thing but that didn't fix that issue either. When you said: If the pressures are low, the band not adjusted correctly a light went off that has me thinking the pressure issue might be fixed with a DTT shift enhancer along with a band adjustment. The truck has 30K on it and I have just started to notice this.

 

[CPG]

cerberusiam,



A very good explanation. I think that you lit the light at the end of the tunnel for me. Sounds like I am due for some trans. mods. Truck has 30,000 on it now.



Chuck

 

[cerberusiam]

I did do the gov. solenoid TSB a while back for the shuttle thing but that didn't fix that issue either. When you said: If the pressures are low, the band not adjusted correctly a light went off that has me thinking the pressure issue might be fixed with a DTT shift enhancer along with a band adjustment. The truck has 30K on it and I have just started to notice this.

If the gov solenoid and transducer did not fix the shuttle shift then you have something else that is not quite right, in my experience. I did both of those pieces, Sonnax valves, and added some pressure in the VB. Completely solved the shuttle shift with stock power. When I add the DTT piece I could then run Smarty mild TQ management up to #3 with no issues.



I am currently running moderate TQ management on #3 and it is borderline on shuttle and the cut away on 2-3 shift. Half throttle or better and it works fine, less than half throttle and I get occasional shuttle and slow 2-3 shift. The shuttle shift and sloppy 2-3 is definitely tied to APPS position and power generated at that level.



IMO, the biggest problem is the 2-3 accumulator spring and VB pressure. Still working out what pieces are needed along with a shift kit to be able to run more power with the less throttle and still get a good shift.



Good luck.

 

[Matt400]

If the gov solenoid and transducer did not fix the shuttle shift then you have something else that is not quite right

The TSB calls for just the governor pressure solenoid valve, thats all I replaced. Is there another part I missed?

 

[cerberusiam]

The TSB calls for just the governor pressure solenoid valve, thats all I replaced. Is there another part I missed?

Yes, there is a transducer that reads the actual gov pressure and interacts with the ECU to determine the position setting for the TV pressures. If either the solenoid or transducer malfunction problems occur.

 

[Matt400]

Where is that transducer mounted?

 

[cerberusiam]

Where is that transducer mounted?

Right next to the solenoid on the governor plate.

 

[Matt400]

Ok I see, you are talking about the governor pressure sensor. I wonder why they didn't include that on the TSB.



I will do that one too and might experiment with a pressure change.