47re no 3rd gear

madmikeismad

madmikeismad

So mad
Joined
Dec 19, 2009
Messages
14,347
So trans has been good since I got the truck back a couple weeks ago. Been hauling with it, no racing, haven't even been full throttle with it yet. Today while driving home from work, I unlocked the trans while slowing down at a red light. Went to take off, 2nd gear shift was very delayed and then harsh, and it wouldn't go into 3rd at all. Then I lost 2nd for about 10 seconds.

Any ideas? Oil is full, doesn't smell burnt.
 
Went out and test drove it again this morning with some rest and a calm mind.

Got 3rd gear twice, and then on 3rd attempt it just stays in 2nd. No sure if it's heat related this time or not, but it's pretty annoying.
 
Regular high pressure valve body or Full manual? Govenor pressure controls 1-2 and 2-3 shift points, so if the solenoid is stuck or the Output shaft speed sensor is glitching it can give you those symptoms. Does 3rd feel solid when it does engage?

Lavon
 
LAmiller said:
Regular high pressure valve body or Full manual? Govenor pressure controls 1-2 and 2-3 shift points, so if the solenoid is stuck or the Output shaft speed sensor is glitching it can give you those symptoms. Does 3rd feel solid when it does engage?

Lavon
Click to expand...
Full manual, constant pressure. When it does shift, it feels normal. I'll check the speed sensor tonight. Is it possible for the Speedo to still be accurate if the sensor is bad in any way? Can I unplug the harness to help diagnose?

Thanks!
 
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If its full manual then the Gov pressure solenoid is unplugged and run wide open all the time so the speed sensor/gov pressure control should not be your problem. try loosening your TV cable a little and see if it shifts (assuming you have it tied back)

Lavon
 
LAmiller said:
If its full manual then the Gov pressure solenoid is unplugged and run wide open all the time so the speed sensor/gov pressure control should not be your problem. try loosening your TV cable a little and see if it shifts (assuming you have it tied back)

Lavon
Click to expand...
I'll try that.

But I was under the impression that the tv arm was no longer functioning. I could have misunderstood though. I know the cable is just tied out of the way under the truck.

Thanks.
 
Damn mike you must live on top of Indian burial grounds or something!
 
madmikeismad said:
So trans has been good since I got the truck back a couple weeks ago. Been hauling with it, no racing, haven't even been full throttle with it yet. Today while driving home from work, I unlocked the trans while slowing down at a red light. Went to take off, 2nd gear shift was very delayed and then harsh, and it wouldn't go into 3rd at all. Then I lost 2nd for about 10 seconds.

Any ideas? Oil is full, doesn't smell burnt.
Click to expand...

LAmiller said:
Regular high pressure valve body or Full manual? Govenor pressure controls 1-2 and 2-3 shift points, so if the solenoid is stuck or the Output shaft speed sensor is glitching it can give you those symptoms. Does 3rd feel solid when it does engage?

Lavon
Click to expand...

madmikeismad said:
Full manual, constant pressure. When it does shift, it feels normal. I'll check the speed sensor tonight. Is it possible for the Speedo to still be accurate if the sensor is bad in any way? Can I unplug the harness to help diagnose?

Thanks!
Click to expand...

LAmiller said:
If its full manual then the Gov pressure solenoid is unplugged and run wide open all the time so the speed sensor/gov pressure control should not be your problem. try loosening your TV cable a little and see if it shifts (assuming you have it tied back)

Lavon
Click to expand...

madmikeismad said:
I'll try that.

But I was under the impression that the tv arm was no longer functioning. I could have misunderstood though. I know the cable is just tied out of the way under the truck.

Thanks.
Click to expand...

Just for organization.

Went out tonight and tried again. Just a bunch of starts and stops. Start in 1st, through all the gears, then OD and LU. 3rd works every time for about 4 minutes. Then I lose 3rd until I let out of the throttle/rpm's just a tad, and it grabs. Then I lose it completely until I shut down the truck and it completely cools down.

I looked for the TV lever, can't find it, and where I remember it being on the front left above the trans pan flange, is just what feels like a plug (can't see it).
 
Did some more diagnostic driving. Same as before, but today I locked it in 2nd, and then shifted to 3rd, wait 5 seconds and success! Jerks really hard and chirps the tires unless I stay in the throttle, but it does do locked shifts to 3rd, and then everything works from there. I can unlock, turn OD on/off, etc and it will always hold 3rd, even if I slow down to a crawl and roll back into it softly. I didn't think to flip OD on and see if it would shift, but I didn't think it would be of any value to try.


So conclusion:

Full manual, constant pressure valvebody, fresh rebuild less than a month ago.
Truck will only shift to 3rd if it's cold, or if converter is locked when warm.

What could that mean?
 
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So using this chart, my front clutch pack isn't engaging? What tells it to engage, and why would it only do it with locked converter? I'm assuming a small leak somewhere, that's why pressure is ok when it's cold, but I don't get the converter deal.

bb33e840a04389e5fe06ebd548883dc7.jpg
 
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lorendiesel5.9 said:
Isn't line pressure higher when the convertor is locked?
Click to expand...

I'd like to say yes, but I don't know for sure. If it is actually higher, that would explain the problem, and I believe that would mean I am indeed losing pressure somewhere that keeps the front clutch from engaging?
 
Line pressure should be higher in lockup. Mine increase by about 20-25 psi in lockup.
 
Mike,

Put a pressure gauge, at least 200 psi in the front servo port of the transmission. Check the pressure gauge when you shift to 3rd. Check it cold when it is working and check it when it is hot when it is not working. This will tell you the apply pressure for direct (3rd). Use the same rpm to check... say 1800 rpm for both checks. If you see a large pressure drop from cold to hot that will explain the delay in 3rd. Trans fluid from cold to hot should experience a 3-5 psi drop in overall pressure with dex 3. I had something similar bite me a few years back and it was a cracked case which like you took a few drops of the transmission to get ironed out. My other recommendation would be to run a stock VB as a double check.

As for converter drain back. Unfortunately many builders drill a passage in the lube regulator valve passage which allows for lube in park but the converter will drain when not running.

Get back to us on this.
 
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raychem said:
Mike,

Put a pressure gauge, at least 200 psi in the front servo port of the transmission. Check the pressure gauge when you shift to 3rd. Check it cold when it is working and check it when it is hot when it is not working. This will tell you the apply pressure for direct (3rd). Use the same rpm to check... say 1800 rpm for both checks. If you see a large pressure drop from cold to hot that will explain the delay in 3rd. Trans fluid from cold to hot should experience a 3-5 psi drop in overall pressure with dex 3. I had something similar bite me a few years back and it was a cracked case which like you took a few drops of the transmission to get ironed out. My other recommendation would be to run a stock VB as a double check.

As for converter drain back. Unfortunately many builders drill a passage in the lube regulator valve passage which allows for lube in park but the converter will drain when not running.

Get back to us on this.
Click to expand...

Thanks, for clearing up that drain back thing. The lube in park is probalby what I've always experienced, so I never noticed the drain back lol. Maybe the hole is just a little bigger now or something.

Anyhow, the truck is back to get fixed, so hopefully this week I'll know what was wrong. I can tell you, the builder is not afraid to thrash on a trans lol. Once I told him it will shift just fine with the tc locked, he proceeded to do every upshift and downshift with the tc locked LOL What a ride. I'm very glad I just put in new ujoints.
 
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