4R70W Shifting Problems

[TallGuy_AZ]

Hey everyone, new to this forum, but not to the 4x4 world. I've spent lots of time and money messing with my 81 F150.

On to my question. I just picked up a 98 Mountaineer, 5.0 and AWD. I plan to swap in solid axles and a real transfer case, but at this point I first need to fix the transmission. Right now, when I put it in drive, it'll shift from first to second, then hold second for a long time, and after revving it a ways, it'll shift, but acts like it's in Neutral. I got it to shift to 3rd once or twice by moving the lever from D to N and back to D, but only a couple of times.

Am I pretty much screwed, and in need of a rebuild? It doesn't make any weird noises or anything. Just won't shift.

Thanks!

 

[Glacier991]

I hate to tell you this, but the 2-3 shift in this transmission utilizes the direct clutch. If you go to the 4R70W Rebuild Diary you will see that this is a problem child in this transmission. I am guessing you have a leakage issue... there IS a checkball involvved that could be slow in seating, there could be sealing ring issues, OR there could be valve body issues (For those more technically inclined ...that might include the 1-2/2-3 shift valve, the 2-3 capacity modulator valve or the 2-3 backout valve - OR possibly the EPC solenoid - used to modulate the 2-3 backout valve).

The good news is there is a pressure tap on the direct clutch circuit that enables a quick diagnosis of a pressure problem. I'd recommend you have that investigated before you burn up a direct clutch. you MIGHT avoid a rebuild, but not able to promise.

How is the fluid? Age, color, smell?

 

[toy720]

Also Exact same symptoms my moms expedition had last week dropped the valve body and the 2-3 accumulator spring was broke replaced it and the vb gaskets no problems shifts like a beauty.

 

[Glacier991]

Wow. It doesn't get any better than that! THANKS Toy ! Pull the VB and check that out. I look at circuit diagrams and just *ASS*ume working accumulators. GREAT call Toy.

ps/ Your E-bay 4R70W parts sound sooo good but I aready have enough parts to build several 4R70W's... just need cases.

 

[TallGuy_AZ]

Fluid is a little dark. I need to pull the pan and take a look. I think the person who had it before me mentioned that it had been slipping a little in overdrive before it started doing this. I'm not sure though, as I'm not able to visit with them anymore. I won't waste any money on new fluid yet, but I will drain it and maybe look at the valve body. Truthfully, I'll probably just pull it and do a complete rebuild when I get a chance.

How hard is this to rebuild compared to a 700R4 from an early 90's chevy truck? I just finished one of those....

 

[toy720]

IF you rebuilt a 700r4 than you can do the 4r70w same principal.Glacier Ive got my eye on an Aod at A Ft.Worth Auction If I dont rebuild It maybe I can get you the case to make some sort of frakentranny or are the cases the same on the 4r70w And Aod. Iknow Alot of the Guts are Interchangeable not sure about cases.

 

[97BlackX5.0]

Same problem with my truck a long time ago. Glacier is right on....For me it amounted to a rebuild because the clutch drum was burnt up and I didnt drive it any more than bringing it home about 10 miles locked into second gear with the gear select. If your lucky you can generally just get away with new seals and the new clutch material (because you havnt grenaded anything) But it requires a COMPLETE teardown of the tranny because its the last thing that comes out of the case.

 

[toy720]

I would still try to yank the vb and see if the 2-3 accumulator spring is broke it is alot easier than tearing into it if thats all it was. But then again you could be in for a rebuild but go with the simple stuff first.

 

[97BlackX5.0]

I agree check the outer stuff first... But I have a feeling your in for a rebuild.

 

[boominXplorer]

I broke my 2-3 accumulater spring at 90K. I found it when I was going to put in my baumann shift kit. The spring is 6$ from ford.