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47re slip problem. just rebuilt

25K views 28 replies 9 participants last post by  SpoolinTurbo 
#1 · (Edited)
WHEN ITS HOT NOT FIRST START UP. Tranny was just rebuilt an was workin great. Went out plowing today and when i first go into drive from reverse or neutral it feels lik its slipping real bad but then it will hit in an pull out. I thought valve body poss? Cause i reused valve body after it had metal go threw it. But as i said it was workin great then this. I know it isn't clutchs cause once it goes it i coulda plowed the whole line of cars across the lot with no slip. What could it be?
 
#2 ·
How fast are you shifting it into drive after starting it? If your shifting it pretty quick after starting engine it might be that the torque convertor is draining when sitting and not full yet when you shift.

When you said you had metal in the VB, did you clean everything out and make sure all valves moved freely, flush the cooler & lines etc.. The factory used a check valve in the cooler line to prevent drain back, its possible that debris is in the check valve too.
 
#11 ·
How fast are you shifting it into drive after starting it? If your shifting it pretty quick after starting engine it might be that the torque convertor is draining when sitting and not full yet when you shift.
The torque converter will not drain back while the truck is still running and plowing snow. Drainback symptoms are no drive as well as no reverse at morning startup.

When you said you had metal in the VB, did you clean everything out and make sure all valves moved freely, flush the cooler & lines etc.. The factory used a check valve in the cooler line to prevent drain back, its possible that debris is in the check valve too.
A partially blocked (or even completely blocked cooler line) will not cause a no-drive condition at first. That flow is not used to engage any of the clutches. However, that flow IS needed to provide cooling and lubrication oil to the transmission's components - and the transmission will ultimately fail without it.
 
#3 ·
When you first crank the truck, make it a habit to drop in neutral, count to five and then drop in D or back up to R. If you do still have the factory antidrain valve in the trans cooler line, get rid of it. At minimum it will slow the flow of oil through the line and at worst could completely block flow and kill your new trans. The valve is located in the rear line on the cooler/exchanger under the turbo. It is in the little short flexible line. You can remove this line, remove the check ball and spring and reinstall the line. Remember, once you do this, it is mandatory to drop in neutral at startup to get that converter full.
 
#4 ·
This does it on start up and also once im driving. The check ball thing is only on start up right? Idk much about that stuff. I just re read and i wasnt clear with the symtoms it sounded like just when i first start it. It is doing it when im out and driving around. When i was plowing yesterday it would go right into reverse and then hang before goin into drive. It feels like its half in gear then it will go in and pull hard
 
#6 ·
dump some GUNK trannmedic in it worked for me and a couple of people i know , and just a tip ALWAYS allow around 15 seconds after start up to let the fluids go through the tranny..goodluck!
 
#7 ·
Ok ill have to give it a try. If that doesnt work i guess ill have to drop the valve body an pull all apart an go threw it maybe a pieve of metal from the drum last time got in there. Then throw it back in an try her out (which is fun to get back in with the park pin and all) Im gonna remove that check valve to cause i dont want that goin bad an destroyin my tranny
 
#9 ·
Just changed filter and fluid. It had some junk on the filter lik sylicone from the past guy. No clutch meterial or metal shaving. Changed filter and fluid and it still good when cold then intermitten slip when doing into drive. Not all the time just here and there. Im thinkin valve body? Anyone else? I need a couple people to agree or disagree to make up my mind on what to do
 
#10 · (Edited)
If it does this in Drive, but not Reverse, and you are 100% sure the shift linkage is adjusted correctly, it is most likely a pressure leak at the rear clutch. The piston's two lip seals are the prime suspects. 99.999% sure it is not in the valvebody.

The rear clutch is used for all of the forward ranges, but not for reverse.

Hot oil leaks past leaking seals much easier that cold oil.

The "when it hits" feeling is when the oil pressure finally rises enough to engage the slipping, partially applied clutch.

Oil pressure tests will confirm this.

The bad news is that the trans needs to come back out.
 
#12 ·
One last thing, I do not ever recommend any of those transmission "miracle fixes" in a bottle.

The seal conditioners will swell seals to try to make up for wear and get them to seal again, but softer seals no longer have the strength or wear resistance that they should have.

No fix from a bottle will ever repair a cut or blown lip seal.:thumbsup:
 
#16 ·
If it is doing it in reverse also it could be many things.

Low fluid level - check and adjust it according to the instructions on the stick
Overful with oil - causing aerated oil which causes erratic oil pressure
Oil pump problem - erratic pressure from starvation or sucking in air
Shift linkage - not putting manual valve into the detented position
Transmission internal leakage - lip seal(s), gasket(s), seal ring(s), damaged hard parts
Valve body contaminated with debris
Transmission mechanical problem - front and/or clutches, rear band, servo, overruning clutch, damaged hard parts

All of this is assuming the transmission was properly re-assembled.

It also could also be a combination of these. For example, a leaking rear clutch causes low oil pressure and the result is slippage when entering Drive. If you were driving it on the road and it is in 3rd gear (or OD) and the leak caused the oil pressure to drop enough for the front clutch to slip and burn, then the damaged front clutch will cause problems in Reverse.
 
#17 ·
Ok now this is honest question and just trying to ask asmany questions as possible. Dont think at one point im sayin this is wrong or that wrong. Im just trying to ask as much as possible to try pin pointing somethin.
Fluid level is good
The shift lincage seems to be putting in the detent an clicks in good (checked to my knowledge when pan was down) not sure if theres special way
Now for the questions asfar as mechanical problems if clutch pack burnt it should have fiber in the oil right? And also as i said once it goes in it will push a house over with no slip.
And all the seals were replaced now for that question alot of times i know that when seals are bad there usually hard an slip worse when cold. Could it possibly of ripped? What could have ripped it? And also once again these are honest questions if it was due to low pressure would it do it just when going into gear? Or would it be low pressure when i let off an it comes to an idle to? Asfar as once it goes in an i drive would it slip if i let it idle while in drive an then lay the pedal down to go? Cause it goes everytime once its in.
And also it doesnt do it every pull out so if it wasnt burnt clutch's or a seal would it be doing it everytime? If it is valve body could it hang up every so often? I know aluminum and steel swell at different rated so if there is stuff in there once it swells could it be more likely to stick?
 
#18 ·
That's a lot of questions. But questions are good. It shows me you are thinking about how it works and how to troubleshoot it.:thumbsup:

A burned clutch typically puts some clutch lining into the pan / filter and is normally consistent in how it does not work right.

The linkage adjustment is correct when the lever on the steering column agrees exactly with the corresponding lever position on the trans. Each position "lines up" and does not try to have the transmission lever only partially in a detent. Sometimes rust and corrosion inhibit the motion and goof things up. My 94 was an prime example of that. Another possibility is if the manual valve isn't in the right position because of a bent lever. If the transmission is acting like it is not engaged completely, does moving the selector lever a little in either direction make any difference? If so, maybe the manual valve is not in the right position for Drive.

A transmission that has the classic "morning sickness" has a very slow engagement even though the torque converter is full. The symptoms go away as soon as the first engagement has been made because the oil pressure stretches the lip seals out. When they sit unused for a while (like say overnight), they shrink back down and will leak again. Also, cold rubber is not as conforming as warm rubber.

The oil pump puts out a volume of oil at a rate that corresponds with engine speed. More RPM = more oil flow rate. If the trans slips but a little more RPM's make the slip immediately go away, internal leakage is most likely the culprit. Internal leakage can be from cut or damaged lip seals as well as worn seal rings or grooved bores that they ride in. A worn pump can also cause low flow and the resulting slip due to low perssure. A worn pump will perform consistently for a give oil temperature though, not erratically.

Damaged seals and seal rings behave different. If a lip seal is nicked or torn, the "flap" may or may not seal and can be erratic. Once completely pressurized, the pressure can hold everything in place and the transmission will seem OK as long as it stays in that gear. The front clutch outer seal can easily get cut as it is not possible to guide it in while installing the piston. You might remember that one, forcing it in will damage it. Seal nicks and cuts are caused by assembly error unless there was a bad spot or burr in the bore or something along those lines.

Another possibility is replacing a seal with the wrong one, since there are different seals used for different year transmissions and the kit manufacturers want to have their one kit fit all.

I always match up the seals when replacing them and also air test each component before installing it into the transmission. That way I have fewer bad surprises. You need to double and triple check all of the parts if there is a possibility that someone was into that transmission before you.

Performing the hydraulic pressure tests will confirm whether the rear clutch is leaking or not. A leaking rear clutch can cause an erratic engagement into Drive. I recommend you perform those pressure tests. See if moving the selector lever around slightly changes the pressures. If so, the manual valve is not in the right position.

Another possible cause for an erratic drive engagement condition could be a slipping overrunning clutch (aka sprag), but it would most likely put some metallic debris into the pan and onto the magnet. If the overrunning clutch were not working right, placing the selector lever into "1" will apply the rear band. The rear band locks the same component that the overrunning clutch is trying to hold (the lo-rev drum), so that is a good way to check the overrunning clutch.

Does the transmission ever act up when in or going into 2nd, 3rd, etc? Or are the problems limited only to the Neutral to Drive engagement? Does it ever act up if you shift it from Neutral to "1"? When you stated that the Neutral to Reverse was acting up, is it as frequent as the Neutral to Drive troubles?

Why did you need to rebuild this transmission previously?

Was there metal in the oil then? Did you clean the valvebody? Did you flush (or replace) the two coolers and all of the cooler lines?
 
#19 ·
My dad did the rebuild and he pressure checked everything an all worked great. And he does rebember that drum being hard to put together as you said. An another dumb question if it is a seal would it have done it from fresh? Or could it of gotten worse? Cause it was perfect for about 6,000 miles with no problems. Could the seal have been ripped a little and now all the sudden ripped the rest off the way? Cause i just went out and tried and it seems like its doing it more often once it heats up. I pulled it all the way to first and still does does it.
Asfar as the reuild it was due to the input drum? I guess it would be called the very front drum had all the splines ripped off that the steels on the clutch grip to. Now i blew the lines out but didnt get to clean the torque convertor real good or anything so there is a possibility that there is metal going threw it. Thats why i kinda thought maybe it was in the valve body and once the alum an steel swell different maybe hangs up some how? But im not sure what there is in there to mess up. So as far as metal shavings in there there was a posability
 
#24 ·
FIXED!!!!!! I dropped the valve body and pressure tested the clutch drums and they applied all the way down to 10 psi (when i quit lowering pressure). Me and my dad pulled the valve body appart cleaned all threw it. Had some junk in it, He talked to suncoast and they had us drill it an all the stuff they do to valve bodys as far as shift kit and what not. I put it back together filled it back up and it seems to work better than ever. Its workin so im happy!
THANK YOU GUYS SO MUCH I REALLY APPRECIATE THE HELP!!!
 
#25 ·
Do you know what holes you guys drilled out?? Got to drop my pan in a couple of days because of a hole in it, and figure ill check my valve body out as well.
Thanks
 
#26 ·
I agree with ART with the posibility of a seal might have a slight tear in it, Mine would go like a champ in reverse after we rebuilt it but no forward gears, Turns out it was a tear in one of the new seals. The pressure test described in the factory manual will tell you were to look and what your pressures should be.. I made the mistake of thinking the valve body was the issue also and spent a ton of money on a BD one that I didnt need. Good luck
 
#27 · (Edited)
Valve body fixed it as i listed in my last post. I been drivin it for about 500 miles and its workin great with no problems at all. Like i said i pressure tested and all was well so i did the VB mods and cleaned threw and problem fixed
http://www.tciauto.com/Instructions/
You will need to look up in the search for the part # of the shift kit for your trans. As example mine (96 47re) number is 220500. No use in buying the high dollar from what the guy told me. He said this basically makes a stock into a bd etc.
 
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