That feeling we all dread

JDPlowboy

JDPlowboy

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So I built a friend of mines transmission. He dropped it off Monday and I've been working on it till 3 every night this week after work. Everything went together great, nothing questionable. I felt really good about it. I was taking it off jack stands when he showed up unexpectedly (we all know how awesome it is working who someone over shoulder). So I buttoned everything up, cleared taps, jacked up the rear end so wheels were off the ground so I could put it in drive for a bit before putting in reverse To back out. Everything went good. So we hopped in and went for a drive. I was super nervous because I had no idea how it was gunna go. Took off 1/4 throttle, had all 5 gears I was happy, slowed down to go thru town, left town, gave it a half throttle pull, went down the road a ways, turned around and punched it from a dead stop. It pulled great shifted awesome and locked up firm. Everyone was smiling ear to ear! Slowed down to a stop Before town and decided to do another full throttle pull. When I was slowing down I didn't feel it downshift, and when I went to take off It felt like it was still in 4th so I eased it home. Only code I have is p0872. Hooked up to efi scan tool i put in the commanded gear, current gear, on and off going clutch pressure, current malfunctions, and tc slip. When I put it in drive it said it commanded 1st but then within a second you feel it hit 4th. Then it shows commanded gear is 4th, and that goes the same for 321. Clutch psi is 232. Sorry for the long post. But I am just trying to give the best description so I can get pointed in right direction.




Sold all my 6.6's and bout a 97 6.5... Life is good haha
 
Y

yellowchevy

Well-known member
Sep 9, 2010
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I was very nervous right after I built mine and drove it.

Just thinking out loud, would a bad wire connector not give the computer the correct voltage? How about all the solenoids? NBS? Did all the floots slid back and forth easy in the valve body?

Sorry I can't help more, just some of the main things I could think off.

Yellowchevy
 
J

jkholder09

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Jan 8, 2012
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yup its the e shift valve stuck.
Its the center valve in upper valve body.
To confirm this drop pan and pull fluid pressure switch.
Take scan tool under truck and monitor tfp data.
Use pencil eraser and gently push buttons on switch to verify they change.
SWITCH MUST BE GROUNDED TO CASE DURING THIS.

If they all change then pull the vb, and scotch bright up the valves until they slide smooth.

It will be fixed in no time.
good Luck:thumb:
 
JDPlowboy

JDPlowboy

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Hey thanks for the replies, I dropped valvebody this morning and sure enough e valve was hung. I pulled it out lubed it up good and it slid like new. Re assembled. Rolled
Out garage and did the same thing. Guess I'll keep dropping it out and cleaning till I get it freed up. Thanks


Sold all my 6.6's and bout a 97 6.5... Life is good haha
 
JDPlowboy

JDPlowboy

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Gun bore brass bristle brush be too course to run thru? I'm afraid to use a fiber brush


Sold all my 6.6's and bout a 97 6.5... Life is good haha
 
JDPlowboy

JDPlowboy

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Just ordered the sonnax resizing tool. I'll see what that helps


Sold all my 6.6's and bout a 97 6.5... Life is good haha
 
Mike L.

Mike L.

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jkholder09 said:
Bore buddy?

Sent from my SPH-L300 using Tapatalk
Click to expand...
Bore buddy is not a good thing to use. The edges on the valve and valve body casting need to remain sharp as that is what pushes debris off the valve. If the edge of the valve or valve body become chamfered it will jam the debris between the two every time and ruin the valve bodies ability to clean itself. All edges must remain sharp.
 
J

jkholder09

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Mike L. said:
Bore buddy is not a good thing to use. The edges on the valve and valve body casting need to remain sharp as that is what pushes debris off the valve. If the edge of the valve or valve body become chamfered it will jam the debris between the two every time and ruin the valve bodies ability to clean itself. All edges must remain sharp.
Click to expand...


Like a scraper.
That's a good point and I really never thought of it that way.
I use the bore/accumulator buddies a good bit and I guess knock on wood never had a problem.

A full annular tcc valve is chamfered in order to help reduce oscillation, and they do not pack contaminants in.

You are the resident allison expert, I just do all make and models so I sort of use a general guide.

Thanks for the tech tip.

I think the best solution is to keep trans parts as clean as possible during the building process.
 
motoking_1990

motoking_1990

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May 9, 2011
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I always had luck using fine emery cloth and lube guard. But if Mike thing the bore is the problem I would go that way. He has probably had his hand on more allisons than anyone.

Sent from my C811 4G using Tapatalk
 
Mike L.

Mike L.

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I have built every kind of trans there is. I used to be a Mercedes and exotic trans specialist. I just choose to work on diesel transmissions now because it's fun.
A valve body is a valve body. What pertains to one pertains to all. If you really think you're a trans expert; why don't you have a freezer in your shop? This is the best way to tell if you're going to have a valve stick.
 
DBUSHLB7

DBUSHLB7

Team DMAX
Mar 9, 2012
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I just went through this myself. Although having an ATS Trans fresh in off warranty rebuild, Mike was kind enough to explain this problem to myself and friends involved in helping out who didn't understand why polishing the valve or emery cloth wouldn't work. He like a Dr prescribed a fix and he was right as usual. I have a thread on this problem/fix and my Sonnax tool is still availible to members if they need it. Sounds like the OP already got it ordered though.

http://www.duramaxdiesels.com/forum/showthread.php?t=51953
 
motoking_1990

motoking_1990

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May 9, 2011
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Terre Haute, IN
I wasn't being a smartass when I posted that sorry if you took it like that. And yes I have heard of people using freezers and toaster ovens for certain things in transmissions. I wasn't trying to make it a pissing contest by no means. I know for a fact you know way more on any trans than I do. You have peoples word on how good you are. I have just worked on many transmissions and at a transmission shop for two years after high school. I just know little tricks here and there. So again sorry for the misunderstanding

Sent from my C811 4G using Tapatalk
 
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