5HP18 Valve Body rebuild question

[Frank87]

@Regal:
I think your 2-3 shift problem had more to do with slammed teeth on the F drum and a bad F drum glide bearing. Because:
- From 2-3 the G clutch disengages
- From 2-3 the F clutch engages
The friction plates IN the G drum that lock into the F drum will, over time, slam the teeth on the F drum meaning it will take a little longer before F engages / disengages
The bad F drum glide bearing inside the F drum will cause the F piston to move in and out at a slower rate

This is a typical early 5HP18 fault. You will not nessecarily notice slippage or jerks as the engine indeed stops revving during shift moments. However, when the engine does rev, it will put torque on the G friction plates who will put that torque on the damaged F drum. The result is some slippage since those plates do not instantly grab-hold or release. I have opened up multiple "18" boxes and all show slammed teeth on drum F from plates belonging to drum G.

Edit:
I do not exactly know what that correction kit does but I guess it modifies the fluid pressure to G and F. Have never had to use that kit though.

@whiskeychaser:
No kind of rev changes, no kind of slippage. It is an instant 2-1 downshift but with a bump. I will check all the shift valves. Thanks for the tip. Solenoids are 100%. Ohm resistance checks out and no gunk in the solenoids or the small pit behind them.


I have now:
- Overhauled the valve body I pulled from my car last week (the one originally mounted in 1993)
- Swapped the 2-1 jerk body with this valve body
- Refilled tranny.
Result: no jerk, good shifting.

I also replaced many springs in the valve body that I mounted last week (the one with the 2-1 jerk). Shift valves, 12345 springs and all kinds of other small springs. Although I have checked every part number and location 100x, I may have done something wrong. I will open up the valve body and see if all has been mounted as it should have been. I DO have to note that replacing those springs gave me:
- A bit more responsiveness to my throttle management from the transmission
- Slightly quicker shifts: rrrrRRRRR - rrrrrrrrr instead of rrrrrRRRRRR - - rrrrrrrrrrr
- All round slightly better feel when upshifting.

I guess that new springs ensure that all the pistons will almost instantly go back to their position when fluid pressure is lost. Since the springs in the valve body mounted today are original 1993.. they probably lost some of their force meaning the valve body functions a few %'s less effective.

In any case, I will look over the entire piston / spring layout again. Also important to check is if I have put all the metal clips correctly on the various pistons (although I am sure I have).


For those of you who would like to know what I have done with the valve body I mounted today, check my YouTube DIY:

Part 1:


I added a reference to whiskeychaser and shogun for the info on the pressure regulator.


To be continued. Thanks for the help.

[632 Regal]

@Regal:
I think your 2-3 shift problem had more to do with slammed teeth on the F drum and a bad F drum glide bearing. Because:
- From 2-3 the G clutch disengages
- From 2-3 the F clutch engages
The friction plates IN the G drum that lock into the F drum will, over time, slam the teeth on the F drum meaning it will take a little longer before F engages / disengages
The bad F drum glide bearing inside the F drum will cause the F piston to move in and out at a slower rate

This is a typical early 5HP18 fault. You will not nessecarily notice slippage or jerks as the engine indeed stops revving during shift moments. However, when the engine does rev, it will put torque on the G friction plates who will put that torque on the damaged F drum. The result is some slippage since those plates do not instantly grab-hold or release. I have opened up multiple "18" boxes and all show slammed teeth on drum F from plates belonging to drum G.

Mine was the 94 530, and the EAT chip was the problem. After changing it out I went another 110K miles before I sold it with no trans issues.

[Frank87]

Update:

Started clean with a completely overhauled transmission.

When using a valve body in which I only worked on the main channel plate (cleaning + replacement of balls and orifices) the transmission shifts like new except for the 1->2 shift.

When using a valve body in which I worked on the main channel plate AND where I have also replaced ALL springs with OEM ZF new ones, the transmission shifts like new except my 2->1 downshift gives me a slight jerk as described in this topic.

This means I am dealing with a valve body related issue. The valve body I talked about previously in this topic is a different valve body. I have 3 valve bodies:
1: Valve body of which the main channel plate has been done, gives me a not-so-smooth 1->2 shift, solenoids show proper ohm resistance
2: Valve body of which the main channel plate and most springs have been done, gives me a 2->1 jerk, solenoids show proper ohm resistance
3: Valve body of which the main channel plate and ALL springs have been done, gives me a 2->1 jerk, solenoids show proper ohm resistance

Valve body 2 and 3 are definately the better valve bodies for all other shift points when compared to valve body 1.

The 2>1 does NOT jerk if:
- The car is in S mode
- The car upshifts to 2 gear but never goes higher than 2. So 1->2 and then 2->1.

Which means the jerk is there if:
- The car is in D mode and has shifted to 3 or higher

The jerk is more apparant the more braking power you apply. An emergency stop from 50 to 0 gives a clearly noticeable jerk. Rolling the car from 30 to 0 gives a less noticeable jerk (but still there)

This 2->1 thing is the final piece of the puzzle!

[632 Regal]

Did you try disconnecting the brake light switch yet? Could be some issue with the check control unit that enables engine braking while slowing down however it shouldn't have anything to do with the 1-2 upshift.

[Frank87]

It must be valve body related. Old sloppy valve body gives me a good 2-1 downshift. Completely overhauled valve body gives me a bad 2-1 downshift.

[632 Regal]

It must be valve body related. Old sloppy valve body gives me a good 2-1 downshift. Completely overhauled valve body gives me a bad 2-1 downshift.

Which leads me to question other partially related items.