5r110w Reverse issue

[kleake]

Rebuilt my 5R110w a few years back and it's been fine, except for the occasional slow reverse engagement. Go from drive to reverse, touch the throttle too quick and you would get a little shudder then it would lock in solid. I was also noticing a little flare between some of the shifts, so I changed the PC-A solenoid. This definitely fixed the slow reverse and now it bumps in solid every time. It also seems to have helped the flare, but didn't get rid of it completely. BUT, when towing my camper the other day I was backing up a slight hill and it felt as if reverse was slipping under heavy load. It hasn't done this before, and I towed about a month ago and backed into a similar spot. Could this be related to the PC-A solenoid?

 

[ckrueg]

This was posted up in another thread and should help you figure out what solenoid it could be. What gears does it flare in?

Sent from my SM-G930V using Tapatalk

 

[kleake]

Almost all gears have a slight flare depending on throttle, but the biggest are noticed on the 1-2 and 2-3 shifts. 3-5 is usually pretty good and 5-6 is good.

I re-loaded the tune so it would re-learn after the solenoid. It shifted pretty firm during that time, but after a couple of days it has slowly went back to about what it was before.

 

[kleake]

what the he!l are you talking about?

My trans has always had a flare on most shifts. A slight rpm increase as it shifts. Usually just a split second before the next gear is fully engaged. I rebuilt it a couple of years ago due to a clutch pack giving out. It had just about 190k on it at the time. I did several upgrades at the time, mostly in strength. Red alto clutches, billet input shaft, low rpm torque converter, etc.. None of this really fixed the flare, and it's not bad enough that it's really a concern, just an annoyance.

Recently I had been noticing when i go from D to R, reverse would lightly go in then a second later you felt a second "bump" as it fully engaged. At idle it was fine, but if you accelerated to back up faster before the second bump, you would feel a shudder. Once the second bump was felt, it was all solid as much throttle as I needed. This issue appeared to be caused by the PC-A solenoid that is sticking. I replaced this solenoid and it definitely fixed the slow engagement and it now locks in much faster without any hesitation. However, after changing this solenoid I noticed a slip in reverse under heavy throttle as I was backing my camper up hill.

Hopefully I explained it correctly.

 

[sootie]

i ******d my post before you responded.

 

[kleake]

i ******d my post before you responded.

I noticed that, no biggy, I tried to explain a little clearer what is happening, hopefully it makes better sense.

 

[kleake]

I put a pressure gauge on it, here is the results:

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

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. During firm acceleration on the street, I might see 150, but normally no more than 125.

 

[kleake]

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?

 

[kleake]

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?

 

[Mark Kovalsky]

You're way, way low on pressure in all gears. This points to a bad EPC/PC-A, a massive internal leak, or a bad pump.

5R110 Pressure Chart:

Line Pressure - Idle
P,N - 50 psi
R - 100 psi
D - 70 psi
3 - 80 psi
2 - 80 psi
1 - 80 psi

There are WOT stall numbers also:
R - 320 psi
D - 320 psi
3 - 260 psi
2 - 215 psi
1 - 270 psi

 

[kleake]

Considering the previous slow engagement but no slipping, do you think I should put my original EPC/PC-A solenoid back in and see what the pressures are? The replacement solenoid I used is an ATP brand, not OEM, but should be ok?

As I mentioned before, I rebuilt this one about 3 years ago. It always had a little flare, and that did not change with the rebuild so i'm guessing whatever the issue is, it was there previously. When I rebuilt it, I found a little sliver of metal that came off the pump gear and had wedged in a valve in the pump. I assumed this was causing low pressure, and allowed the direct clutch to burn up. This sliver notched up the gears bad enough they needed replaced, which I couldn't find anywhere so I replaced the entire pump with a tested replacement. Many other things were replaced, but after the rebuild it "acted" the same as previous, just stronger internals.

 

[kleake]

I also installed this kit which effects pressures. Based on this, i'm right where I need to be, with the exception of reverse. It stays the same as all other gears, until I stall it up once, then it acts differently. Also, how much throttle do you have to add before pressures start to reallyclimb. I can be at about half throttle before I see them go above 125ish.

 

[Mark Kovalsky]

I also installed this kit which effects pressures. Based on this, i'm right where I need to be, with the exception of reverse. It stays the same as all other gears, until I stall it up once, then it acts differently. Also, how much throttle do you have to add before pressures start to reallyclimb. I can be at about half throttle before I see them go above 125ish.

That's correct. I don't know why reverse doesn't increase. It should be higher any time it's in reverse.

 

[kleake]

Do you know if there is another valve or something that moves to create the higher pressure? The reason I ask is that once I stall it up pretty high, then reverse pressures increase as they should, but if I don't stall it up first, there is no change.

 

[Mark Kovalsky]

I don't remember the hydraulic schematic so well. It's been several years since I looked at it. I think I remember a feed from reverse pressure to the main regulator valve, but I could have that confused with another trans.

 

[kleake]

Ok. I just started a head gasket replacement on the truck so i'll have to circle back around to this. I'm thinking my pressures are ok, with the exception of that lower reverse until it's stalled up. I'll probably leave the gauge hooked up for a while so I can watch it and if I notice it slipping, I'll stall it up and see if that helps. Sounds like I may have a secondary valve sticking a little creating that issue. The flare is still a concern though. It's not critical, but it will cause extra wear over time so finding the source of that would also be nice. It could be in the tuning though since while it's doing a re-learn, most shifts are much firmer. Maybe a custom tune would solve that?