5HP18 Valve Body rebuild question

[Frank87]

The 5HP18 Valve Body Kit is no longer available. I have spent over 5 evening hours to get any kind of supplier to check his stock. 0... Even ZF no longer delivers (here in Europe). I have:
- Ordered all traction springs & 1-2-3-4-5 springs
- Ordered all orifices 10x
- Ordered 4 6mm balls (just to be sure, need only 2)
- Ordered the one way check valve (but came without a ball)
- Ordered the VB gasket

So basically, I took the critical parts from the list and ordered those myself. My spare trans already had the updated selector. This does not need replacing.

This is what I will do for now:
- Finish the internals of the spare 088 I am rebuilding. This completes my hardpart rebuild
- Install the rebuilt 088 transmission (w/o valve body)
- Take the valve body from the trans I remove (runs ok) and put it under the rebuilt one
- Drive and test. If it runs great (or almost great) I at least know I did not screw up on the internals.

A good friend of mine runs the garage where I do my tires and yearly certification. A good friend of his runs a very professional auto trans shop. They do regular rebuilds but also custom work on transmission internals & valve bodies and all kinds of other customized work with CNC equipment. They have a test machine for valve bodies. After I get a 1 way check valve WITH ball, I will rebuild the valve body and let them test / adjust it according to ZF spec or their own knowledge.

I will keep you guys posted on this. Tomorrow I'll call ZF and order a new one way check valve. If it comes with a ball, I'll measure it and post it.

[Frank87]

As posted before, ordred a new 1 way check valve. Got the correct combination this time BUT already combined. I could not take it apart to measure it. Sorry guys.

- Installed the 1 way check valve and assembled the valve body.
- Drained ATF, removed pan, removed filter, removed stock valve body
- Swapped solenoid block from old to overhauled valve body to ensure I would get the pressures right
- Installed the overhauled valve body
- Installed a new filter & pan gasket
- Filled the transmission untill it overflowed
- Start engine, kept it in idle and switched lever through position while a comrade kept adding oil
- Quit filling when filler started to overflow while shifting positions. Total oil added: about 6 - 7 liters

Here is the strange part. Shift quality was fine, it is now near excellent but a jerk that I had from 2->1 has become more noticeable. I consider "almost excellent" to be between "very good" and "factory new".

In sum:
1->2 = almost excellent
2->3 = almost excellent
3->4 = almost excellent
4->5 = almost excellent
5->O = almost excellent

5->4 = almost excellent
4->3 = almost excellent
3->2 = almost excellent
2->1 = acceptable but with a jerk

P <-> R & R<->N & N<->D = No jerk, no noise & instant action. I consider it to be excellent

So, we have a 2->1 jerk / shock. On the previous stock (12/1993) valve body, that 2->1 jerk was also there but much less noticeable. Although it jerks, the shift action is instant. No slippage, no noises.. Instant 2->1 gear change but with a jerk.

What I would like to know:
- What springs and pistons are used for 2->1 action?
- What other causes are there for a 2->1 jerk?

Thanks in advance.

[whiskychaser]

I'd have a look at solenoid 1 and shift valve 1. If they were not working or sticking, you wouldn't get first gear. So I think that's the first place to start. Do the engine revs increase or does it just go in with a bump?

[632 Regal]

I'd have a look at solenoid 1 and shift valve 1. If they were not working or sticking, you wouldn't get first gear. So I think that's the first place to start. Do the engine revs increase or does it just go in with a bump?

When I got the EAT chip my 5HP18 would rev neutral between shifting 2nd and 3rd. Would slam so hard the Trans would have blown if I didn't swap it right out. This was on mild acceleration only, full throttle shift was fine.

The stock engine chips cut the engine momentarily between shifts so they are smooth. Doubt it is your problem but throwing it out here anyways.

[whiskychaser]

When I got the EAT chip my 5HP18 would rev neutral between shifting 2nd and 3rd. Would slam so hard the Trans would have blown if I didn't swap it right out. This was on mild acceleration only, full throttle shift was fine.

The stock engine chips cut the engine momentarily between shifts so they are smooth. Doubt it is your problem but throwing it out here anyways.

Some of the 5HP18s had a fault with 2-3 shift 'flare'. Mine did. You can solve the problem with the '2-3 flare correction kit' 5HP18.SK01. It is just two new springs you replace in the valve body. But it works

[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.

[whiskychaser]

The springs in the SK01 kit replace springs 0732042581 and 0732042115 (numbers for the 088 valve body). They are the 2-3 traction valve and F brake control valve springs. If you have flare from 2-3, the engine revs increase but your speed doesn't. The effect is similar to driving a manual with a clutch which is slipping slightly on hills

Great news that the box seems to be working fine. Of course you will want to find out why the problem remains on your 'spare' valve body. While you can't really bench test the gearbox, you could test the solenoids for operation. I'd also be taking a look at traction/shift valves 1056327028 and 1056327029. I don't imagine you want to take parts from a working gearbox so I may be able to help if you don't have spares for testing.

[Frank87]

If I could get my hands on all the springs brand new, I'd slot them all in. Just to be sure.

Problem is that ZF over here delivers 80% of the springs x10 when ordering. Basically, you are looking at a valve body kit of over 600 euro's. Thats a little steep.

I'll be re-opening that spare valve body. The 20% of the springs I could order per piece, have all been slotted into that valve body. I'd like a fully rebuilt valve body in my almost-completely-overhauled spare transmission.

[whiskychaser]

Automatic Choice in the UK are still showing the full valve body kit (5HP18.VBK) in their catalogue so it may be worth contacting them. I found they are pretty good at responding on the phone but a little slow if you use email. Link is below:
https://www.automaticchoice.com/en/catalogue

[Frank87]

I have ordered my overhaul parts from them. Even they said the vbk is no longer available.

I have used: http://eshop.original-teile.de/index.php?

To order valve body parts piece by piece. All original ZF.