@Mark Kovalsky

 

How high did the RPM go when it was slipping?

 

Not much at all. Basically if I hadn't felt a little shudder, nothing else was different. As soon as I felt it, I backed off, then slowly eased into it again. As I was moving a little I added another 10-15% throttle to see if it did it again, and it did. Eased on into the spot and never felt it anymore. So effectively it did it twice, each time maybe 100-200rpm over where it was holding. I wasn't looking at the tach at the time, but it wasn't a super steep hill. Last year I had one place that I had to use 4x4 to get enough traction and there was no slipping. Both are with my 12K 5th wheel on it.

 

This is going to be very hard to diagnose. It's possible that you had a little tire spin. It's also possible that the clutch slipped a bit.

Any issue with the trans could be caused by PC-A. That controls overall line pressure. I'd be more concerned with SSPC-D, that controls the direct clutch. It is used in fifth gear (1:1 ratio) and overdrive (0.71:1 ratio), plus reverse. If you have shift flare, that's usually going into fifth gear. That's the shift that is most susceptible to shift flare.

 

I definitely agree with the "hard to diagnose". I can say it definitely was not tire spin, I wasn't on the throttle that hard, and I was in gravel and would have heard that. It was definitely a shudder type of feel and I was just barely inching back when it did it. 99% sure it was a clutch slipping.

I am not sure how the PC-A controls the pressure in each gear, but the reason I question the PC-A is because I never noticed the shudder before replacing it, however, replacing it did fix the slow engagement. My thinking is maybe my old PC-A was slow to let the pressure come up, but maxed out higher? I don't know if that is even possible, but if it is, that may explain the reverse issue.

The flare could be a completely separate issue since it didn't really change that, or if it did, it was minor. I verified again how the shifts feel.
1-2 minor flare, but not a firm shift at all. Maybe 100-200 rpm increase, but only for an instant. .1-.2 of a second
2-3 larger flare, probably the biggest one, sometimes a long drawn out shift .75 of a second, sometimes only .25 of a second. Probably 300-500rpm increase.
3-5 very slight flare, but then engages firm. This one seems to be better after the PC-A as it didn't engage as firm previously.
TC lockup is not instant, but is solid. This feels like it's correct.
5-6 has no flare, just seems slow to bring RPM's down, however since the TQ lockup is engaged during this shift, i'm not sure how it really should feel. There is no rpm increase but takes probably .5 seconds for RPM to fully drop.

The direct clutch is one that I had to replace when I rebuilt it. If I remember right, it looked like it was the one that failed first at 190k, so I didn't feel it would be abmormal with that many miles on it.

 

The 1-2 and 5-6 shifts are identical shifts. All the happens for each shift is the overdrive clutch is engaged. There is no opportunity for a flare, unless the already engaged clutches partially release. That should never happen, but if line pressure is low it is possible.

The 2-3 shift is a special kind of shift. This wasn't feasible before computer controls. The overdrive clutch has to release and the intermediate clutch has to apply. They have to each finish what they are doing within about 0.030 of a second or it gets ugly. In your case the overdrive is releasing before the intermediate is completely engaged. This could be due to low line pressure.

The 3-5 shift is almost as difficult, and the timing requirement is the same. If the intermediate releases ahead of the direct being fully applied you get a flare. That's often a result of low line pressure.

I'm detecting a pattern here. Everything points to low line pressure. I recommend getting a 0-350 PSI gauge with a 1/8" NPT thread and installing it in the test port on the driver's side of the trans. Get pressure readings at idle in every shifter position, and at stall in R, D, 3, 2, and 1.

 

That is the detail I was looking for, and low line pressure is what I was thinking I had before I replaced the PC-A, but maybe that didn't fully bring it up to where it should be. I'll hunt down a gauge and go from there. I am fixing to dig into a head gasket replacement in about a week or so, i'll try to have a gauge beforehand so I can take care of both while it's apart.

 

Nice info Mark
and I just bought the gauge myself so i could verify Line psi of my Ford rebuilt 5R

Amazon.com: Advanced Tool Design Model ATD-5550 Automatic Transmission and Engine Oil Pressure Gauge Kit: Automotive

 

Great minds think alike, that is exactly the one I just ordered as well.

 

it worked perfectly and didn't flutter like some feedback mentioned

i almost just went with a sender and dash gauge so i could always monitor psi

 

Good to know. I would be tempted for the dash guage as well. That is what I did on my coolant side to monitor my head gasket issue.

 

me also I used an Auber guage and sender for coolant psi /and EGT's

i was thinking of the same for line psi

only reason is i lost my last 5R for some unknown reason and would have loved to have caught the issue before it put metal through the whole system

 

I just used a cheapy digital oil pressure guage and sender. It's not very accurate down in the single digits, but it lets me know when it's leaking. 8-9psi on the gauge, then if it starts leaking it climbs rapidly into the teens. As soon as I back off, a few seconds later it comes back down to 9-10psi. I'm assuming 9 on the gauge is actually 16 where the cap holds it at. I've seen 22 on the gauge, which is approaching 30psi in the system! EEK!

 

wow thats high mine around town is -.3 to 16

i can maintain around 10 i haven't towed since i put it on but last time i hit hill it puked and i am pretty sure it was whistling

i would have done my gaskets already but the trany went so i just finished that

 

Yep, mine started about like yours. 2 years later and it's time. Cleaning my shop out and going to be pulling the cab for head gaskets next weekend if all goes as planned.

 

Wellllllll,,,,, I think that is definitely the problem.

At idle
P=85psi
R=80 Stalled up max 125
N=85
D=85 Stalled up max 110
3=90 Stalled up max 125
2=80 Stalled up max 110
1=95 Stalled up max 125

Now, if I stab the throttle hard to the floor and then off again quickly, I do see about 200psi for an instant, then it drops back to the 100-125 range.

So,,, did the PC-A solenoid not fix the problem? Maybe higher pressure at idle than it had before, but then not rise like it should? Just guessing since I didn't test the old solenoid before pulling it.

 

Update: Last night it was late, I was setting in gravel so couldn't get a full throttle test. Today, I was on pavement, had to put it in 4x4 to keep from turning the tires, and I still couldn't hold it to a stop with just brakes. I will say though, the reverse pressure is MUCH better than it was last night, but it would still slip under very heavy throttle. I do have a tuner, but I had it turned down, but it's still pushing a lot of power at that point. Last night there was little to no variation between reverse and any other gears, however, today there is a 50-60psi increase in reverse. Engine was at 195 today, probably 175 last night.

P=80psi
R=140 Stalled up max 200-250 at 80-90% throttle, but jumpy so hard to tell exactly. RPM was holding at 1500-1800 until 65-75% throttle, then it started to slip and went to 2500 before I backed off. Maybe .5-1 second is all I gave it once it started slipping. It was at about 200psi when it started to slip.
N=80
D=80 Stalled up max 250ish. I only got to about 80% throttle and I couldn't hold it back.
3=80 Stalled up max 275 WOT
2=80 Stalled up max 175 WOT
1=80 Stalled up max 275ish, again about 80% throttle

When I was backing the trailer up the other day, the truck was up to full running temp and I was at maybe 30-40% throttle when I felt the shudder. I'm wondering if there might be a sticky valve that wasn't letting pressure come up, but today it did?

 

This might be of help. Came out after work, tested all gears and all were right around 80psi. Drove home, tested again, 80psi. Did a stall test in reverse and pressure jumped up and then at idle it only went down to 125-130. Now all gears are 80 except reverse is 125-130. Is the solenoid sticking, or is there a valve that is sticking until after I do a stall test?

Another thing, on the drive home the most I see is 125psi at highway speeds no matter how hard I stomp on it, is that normal or should it still increase with throttle?

 

So what was the pic-a solenoid reading when you ohm'd it out? I've got one saying 5.8 and having the exact problems.

 

I've slept since then..... lol I've still got the original. I can test it tonight.

My reverse issue is still there, but I only feel it if backing the camper up a steep hill under pretty good throttle. Several more times camping and only one site that was steep enough to feel it. I switched to 4-low and it wasn't an issue. It will never do it while empty, just spin the tires.

 

My stock one ohms out at 5.5 with my cheapy meter. You are having the same issues as I originally had (slow to engage) or the issues I have now with reverse slipping under heavy load?

 

Mine shudders and slips. But it's all the time. On flat ground. And shifts like crap from 4-5

 

It could definitely be line pressure caused by this. If you have a tuner, it could also be that causing some issues. I have a mini-max and had plenty of flares and odd shifts with the default tunes. Switched to gearhead and all shifts are great now. the only issue I still have is a little shudder in reverse when heavily loaded and a fair amount of throttle. Daily stuff is no problem, just when I try backing my camper up a decent hill so I go easy on it then.

 

I guess for $60 it's worth a try!