4R70W problems

[IN2FORD]

O.K. I have a 1996 Explorer 2wd with the 5.0/4R70W combo. On the way home it downshifted, and then when I went to speed back up, it slipped and felt like the brake was on. Then at a traffic light from a dead stop twice when I stepped on the throttle, it slipped and then caught. After setting for a couple of hours I checked it again. Reverse works fine, first slips when I press on the throttle, but as soon as I lift it comes back into gear again. It has about 140k miles on it. I installed the Transgo kit about 15k ago. Any ideas?????


IN2FORD
Barry

 

[Glacier991]

Hmmm difficult to diagnose this one from afar.

Did you torque the VB with a torque wrench? I might be inclined to retorque it. Beyond that I am a little mystified. It sounds like a pressure issue.... and I will assume the fuild is up to snuff.

 

[IN2FORD]

Just checked fluid for the third time and it appears good. Why would reverse work fine, but forward gears not?

Barry

 

[Glacier991]

reverse in the typical FORD tranny gets a "boosted" pressure applied.

 

[IN2FORD]

Just learned something else. I can put it in low 1 or low 2 and everything is fine. If I put it in D or drive, that is when it slips. What is that telling me????

IN2FORD
Barry

 

[IN2FORD]

Talked to a trans shop this moring and he told me that when you are in drive you are only engaging one set of clutches. When you are in low 1 you engage two sets of clutches. He said evidently the first set is bad. Make sense????


IN2FORD
Barry

 

[nismotunedgtr]

Talked to a trans shop this moring and he told me that when you are in drive you are only engaging one set of clutches. When you are in low 1 you engage two sets of clutches. He said evidently the first set is bad. Make sense????


IN2FORD
Barry

Check for codes. Could be the MLPS?

 

[IN2FORD]

I am not getting a flashing light. What is a MLPS?

IN2FORD

 

[nismotunedgtr]

I am not getting a flashing light. What is a MLPS?

IN2FORD

You wouldn't get a flashing light. Take it somewhere and get the codes read, like Autozone. It's free.

THe MLPS is the Manual Level Position Sensor / Neutral Safety Switch.

On the older 4R70W's the MLPS would get water inside it and corrode, cause erratic and weird shifting. A newer updated version of this came out in 1997.

Could also be the TPS (Throttle Position Sensor) becasue the transmisson reads this signal also to decide when to shift / downshift.

Get the code's read.

When was the last time the filter in the tranny was changed?

 

[IN2FORD]

I changed it about 15k ago when I installed the Transgo valvebody kit. I'll see what I can do to get codes read. Not sure if I can drive it in to Autozone so it may be time to purchase a new tool.....got a hate that.

Barry

 

[IN2FORD]

I scanned for codes and there are none set. So do I assume it is the clutch pack that the trans guy suggested?

Would it be worth a shot to change fluid and dump some Lucas trans stuff in it? I really think I would be wasting money since it seems to be something broke.

Opinions please????

IN2FORD
Barry

 

[Glacier991]

Talked to a trans shop this moring and he told me that when you are in drive you are only engaging one set of clutches. When you are in low 1 you engage two sets of clutches. He said evidently the first set is bad. Make sense????


IN2FORD
Barry

I politely say BS.

In the 4R70W here is what is engaged in each gear

Manual low: low-reverse band - forward clutch
Manual 2nd: overdrive band - intermediate clutch - forward clutch
Reverse: low-reverse band - reverse clutch
D or OD:
1st: forward clutch
2nd: intermediate clutch - forward clutch
3rd: forward clutch - direct clutch (int cl applied but ineffective)
4th: Overdrive band - intermediate clutch - forward clutch

Now this ignores the operation of the one ways (sprags)

But if your forward clutch was bad you would have NO forward gears. 1st low only adds a reverse band, but without the forward clutch you would still have nothing. So, his theory (which implicates the forward clutch) is crap. Sorry. That's how it is and I call BS when I see it.

So, if his theory is crap you ask, what is MY theory (if I have one....)

Let me think a little and my next post will be my suggestions.

 

[IN2FORD]

Now you have me sitting on the edge of my seat!!! I don't know much about auto transmissions, but what he told me just did not make sense to me. So I'll wait for your theories.......

Thanks!
Barry

 

[IN2FORD]

So why are the bands not used in drive like they are on manual selection?

Barry

 

[Glacier991]

the forward clutch is used in all forward gears....bands are mainly used to select different gearing ratios (shifts) It is all about "freezing" one parts rotation in relation to others.

This is a very instructional little animation:

http://auto.howstuffworks.com/automatic-transmission.htm

Part 2 is especially good.

And bands are used in auto operation as well as manual.

 

[IN2FORD]

So if not the clutches, especially since low one uses the same clutch as Drive, do you think it is something in the valvebody that has came apart???

Barry

 

[Glacier991]

At mid-high mileage a lot of things can contribute their part to tranny problems... but for me, I am thinking Valve Body, separator plate/gaskets and solenoids. The 4R70W is an easy VB to rebuild and the solenoids are cheap.

I'm inclined to think the VB route is worth a shot, and to replace the EPC and shift solenoids while you are there.

The "hard parts" seem to work, depending on the gear... I am doubting a clutch failure. You might want to try the Glacier "fix an old tranny" route too.... add trans-x and run it a week or two, then flush the tranny. Rebuild the VB and replaced the solenoids and refill with new MerconV fluid and add LUBEGARD platinum or RED to it.

It might just work.

Then again. Maybe not... but.....

Beats rebuilding a tranny if you do not have to. And if you do the VB will be up to snuff.

 

[IN2FORD]

Thanks for all of the thought you put into this. I'll give it a try and see what happens. Where is the best place to get trans parts quick? Would local parts houses have the VB stuff?

Also how ould I recognize the plate gasket leaking? What would it look like?

IN2FORD
Barry

 

[Glacier991]

www.transmissionpartsusa will have the gaskets and solenoids... you might also want to put in a shift kit (they stock) and a sonnax pressure regulator ( I think anything Sonnax makes is worth installing).... torque is critcal on VB's so pick up an inch lb torque wrench. The $30 models at Harbor Freight, though only closely accurate are good enough.

ps. you might not recognize a leaky gasket, OR it may be blown out somewhere. Don't bank on an AHA! moment.

pps. re-reading I see you already did the shift kit, nevermind.

 

[IN2FORD]

Well here's the scoop....I just finished pulling the pan and guess what I found??? Glacier991 you were right! I fuond a bolt out of the valvebody laying in the pan. So I put it back in and rechecked the others, poored a bottle of TransX in it and it is 80% better. Now it is kicking in and out of 3rd so I am guessing the gasket is blown. So purchase valvebody gaskets and go back in it. Hopefully that will fix it!!!

Thanks a bunch Glacier991!! You pointed me in the right direction!!!

IN2FORD
Barry