Low servo repair: transmission slip problem solve

[northern piper]

Hi

Below is my repair of the low servo on the transmission, an AX4S, which is on many windstars. My van is a 2000, 3.8, that had 190,000 km, at initial symptom occurence.

Symptoms: on driving from a stop the transmission slips when approaching the change to 2nd gear. This slip is most evident when driving up hill, and at the transition between 1st and 2nd gear, the RPM will quickly jump while the transmission appears to be in neutral. 2nd gear eventually engages and the same symptoms may appear at the transition from 2nd to 3rd gear.

Repairs to correct symptoms: Initially I dropped the pan, replaced the filter, did a full transmission fluid change as detailed elsewhere on this forum. I also added, on the advice of the Ford service dept, 2 bottles of AT-205 which is an anti-slip product. The fluid I used for the change was MerconV as suggested. There was no noticeable change in the transmission performance.

Following this unsuccessful repair I pulled the low servo cover off. Approximately 1/2 litre of transmission fluid spilled out which I was prepared for. This fluid was discarded. See post # 6 below for suggested method for servo cap removal. On removal of the servo cover the gasket beneath the cover was ripped and the parts beneath it are pictured below.



As you can see, the e-clip which fills the grove between the spring and the piston was missing. This meant it was floating around somewhere in the transmission, which was not good of course. As luck would have it, I managed to find the bits of broken e-clip within the housing of the servo on the transmission body.




Carefully "puzzling" the parts, I was relieved to see it was complete, and nothing should be floating around the transmission.



Buying just this e-clip was difficult as it isn't a standard e-clip, but one that is thicker. I ended up purchasing a whole kit of parts which included:
piston, pin, replacement e-clip (which looks simply like a regular washer cut in half) servo spring, 3 rubber o-rings. Below is the kit (minus the piston and large servo spring).



The spring pictured above is the original spring and retainer. The pin as shipped is slightly longer than the original pin. This kit covers several different transmissions and therefore needs to be machined down. I carefully measured between the grove at the top of the OEM pin to the pointed end, then ground down the new pin at the pointed end to match. (I did leave 0.2mm longer as I've heard that the oem pin is slightly too short and reasoned as well that some wear likely would have occurred. This extra length has worked out fine). The 3 rubber o-rings were installed, the spring, retainer and new e-clip (split washer) installed, the new piston installed. The original e-clip from the old pin was removed and re-used for placement on the top of the piston on the new pin. This is per the instructions on the new pin kit and as they don't provide a new e-clip, I had no choice. Note the e-clip that breaks frequently (I've learned thru discussion) is that e-clip that is mid shaft on the pin, not the one on the top of the piston.

Here is a pdf link of the info that comes with the kit, along with installation instructions and part numbers.
servo instructions.pdf

You'll note on the instructions it says to measure travel of the piston by drilling a hole in a spare servo cap and measure with a caliper. Well, as I didn't have a "spare servo cap", I was unwilling to do this of course. As I said earlier, measuring the length of pin and adding a very small amount worked out fine.

Not included in the kit are the servo cap gasket, the rubber o-ring which is within the cap, and the rubber o-ring which runs around the perimeter of the piston. I replaced all of these as well.

Once everything was all assembled, I carefully inserted the assembled piston, new large spring (discarded the large OEM spring) into the transmission. I placed the cap on and used 12Ounce's suggestion of longer bolts. The bolt size on my transmission is 20 mm long, M6 x 1.0. I bought 3 sets (20, 25, 30mm) and used them to incrementally tighten the cap back on. I did not lower the sub frame. I have a 2 post lift which allowed me to stand beneath the van and work on the servo which was nice. It also (I'm thinking) caused the suspension to sag a bit allowing access, although it is tight.

Once the cap was back on, I filled with about 1.5 litres of mercon V. I started the van and went through the gears, things seemed ok. Took it for a drive and must say it shifts "better than new". The new longer spring (the 96995A as per the diagram) while the longer spring leads to smoother shifts vs the OEM one. I can confirm this.

The van is now back and on the road, my wife says "better than ever" which is great to hear. Total cost for this repair was around $150.

Any questions or things that aren't clear, please post and I'll explain better.

My bottom line, if your van is high mileage and is slipping, this is not a bad DIY job that could easily save you some big coin.

np

[phil-l]

Piper -

Wow!

Thanks for sharing your very clear pictures and write-up. This is very useful!

My transmission has never been opened (except for filter replacement), but I'm considering doing this as a preventive item.

After reading many Windstar transmission horror stories, it's great to see that - with care - these transmissions really can be dependable, long-term runners.

[northern piper]

no problem Phil...we're all in this together eh?

If I look back on the day the trans slip started, it's pretty easy to see what happened. The day was very cold (-34 degrees Celsius). My wife took the van from our driveway, without warming the van up, to drop kids at school, then back home. Total trip was probably 3 miles. Knowing that the e-clip was original, the freezing cold temp, the block on the motor just as cold, cold trans fluid,... little wonder that the clip shattered.

Since posting my write-up I also learned that the pin and new e-clip package is an aftermarket "fix" for frequently breaking e-clips. Funny as I haven't heard a lot of folks complaining about e-clips breaking but possibly they're just not opening the low servo and finding it, instead just having the trans replaced... which is huge bucks of course.

Choosing to remove that e-clip before it breaks I feel is a good idea. If I wasn't lucky enough to find the 4 pieces, then it WOULD mean tearing the whole trans apart.

If I'd known how weak this e-clip was a month ago, I'd have replaced it as a maintenance procedure, as it wasn't too bad a job now that I've completed it. Granted, I had to do a lot of digging to find out which parts and numbers, picking peoples brains for help, but that being said, it's no more difficult than lots of windstar repairs we tackle.

I'd suggest if people haven't done this upgrade, I'd be seriously considering doing it.

Hopefully my pictures and write up will help those that tackle the job.

[phil-l]

Yes, I suspect most people just head to a shop - which will likely tell them that the tranny needs to be replaced/rebuilt.

[phil-l]

Piper -

As I'm reading more closely...

How difficult was it to take the servo cover off originally - with the OEM bolts? Is there anything special to do in order to prevent things from flying out?

Where did you purchase parts? Did you get the servo kit from the same place you got the gaskets?

Thanks!

[northern piper]

the servo cover comes off easily. I should edit my original post but what I did was loosen the first bolt, insert one which was 2 cm longer, then loosen the second, insert a 2 cm longer bolt, then the third bolt 2 cm longer bolt. That let me gradually ease the cap off without having the spring shoot the piston out. Installing was just the reverse, except I started with the longest 3 bolts, then removed one of them, inserted a 1 cm shorter bolt, (then 2nd then 3rd) then finished with the OEM bolts. It was a bit tedious in doing this but really made the cap slip on perfectly. The new piston with o-rings means for a tight tolerance and if the cap goes on slightly cock-eyed you risk breaking the bolts. When the cap is squarely aligned, the bolts really tighten quite effortlessly. I don't know what sort of torque I used in the final tightening; couldn't find a value for that anywhere, but they weren't very tight when I undid them. "Just tight enough" is what I did... then check for leaks.

I got all my parts from a place called KingOMatic as I'm in Canada. It's here. http://www.kingomatic.com/ProductsMain

but I understand they come from the place I refer to in the instruction pdf file called Sonnax. Here is their "where to buy" page. http://www.sonnax.com/where-to-buy

It seems these parts are readily available, which is nice.

[phil-l]

Piper -

Thanks for the clarification! I suspected you did something like that - but your confirmation goes a long way toward completing a job like this with confidence.

[northern piper]

Just because it was bugging me not knowing I looked for the torque spec for the servo cover. I couldn't find the value for the lower servo (the one I've done this write up about) but did find that the overdrive cover (which looks identical) has a bolt spec of 10 Nm or 89 Lb-in (yes "inch" pounds..) so anyone doing this repair, there's your setting.

As a follow up, I put the van on the hoist this weekend. Everything was dry, no leaks and the transmission continues to function very well. Here's hoping that continues.

[phil-l]

Piper -

Thanks for the updated info.

Yes, watch those "inch-pounds". Some people on this board got messed up on that issue for the isolator bolt fix.

Congrats - I'm pleased your repair is working out well!

[scubacat]

Originally Posted by phil-l

Yes, watch those "inch-pounds". Some people on this board got messed up on that issue for the isolator bolt fix.

All thanks to the haynes manual for that typo.

[scubacat]

Originally Posted by northern piper

The original e-clip from the old pin was removed and re-used to hold the piston on the new pin. This is per the instructions on the new pin kit and as they don't provide a new e-clip, I had no choice.

What do you mean by this? Isn't the e-clip the thing that broke into 4 pieces (or am I missing the point entirely??)

[northern piper]

good catch scubacat... I wasn't particularly clear on that part. I've edited the posting.

The e-clip that I am referring to is the one that sits on the top of the piston. From what I've learned, it's the mid shaft e-clip that breaks frequently. 12Ounce I think had this happen IIRC. Anyway, the retrofit with new parts asks you to use the old e-clip from the top of the piston on the new pin. It fits perfectly, which was a relief of course.

Here's a pic. It's kinda dark but you can see how the e-clip (the OEM one) fits into the new pin before inserting into the housing of the trans.

pistontop.jpg

[12Ounce]

When I had my clip break, it was very early-on and I suppose not enough clips had broken to trigger the update kit being designed. Therefore, when I went to Ford for a replacement clip ... I got just that: a replacement clip of the same design. Many miles later I replaced my tranny with a Ford reman, which I still drive.

I may now pull the low-servo to see if it has been upgraded on the reman.

[scubacat]

I have a 2002 with an AX4N. I don't see any sort of repair kit for it so hopefully this won't be an issue for us. This is still some good info though as it's nice to know about serviceable transmission parts just for reference.

BTW - I picked up a junkyard OEM right CV axle that appears to be in amazingly great shape (and also seems to not be a rebuilt one meaning it would actually work) that wouldn't quite fit.................... because it's an AX4S axle that is identical other than being exactly 1.5" longer. Anyone in the Atlanta area is welcome to drop by and pick it up. It's currently doing a nice job holding down the floor in the garage.

[mdare35]

Thanks for the write up! I'm having this similar problem with my 2000 windstar w/ 169K. I took it to a tranny shop that I have had good results with in the past on two other cars but this time the owner's helper noticed the ABS light on, cleared the codes before he drove it and then didn't feel any shift problems and thought they were some how related. I think the only reason he didn't feel anything is because when the tranny is cold it usually shifts ok. I think the only relation to the ABS is heat. THe ABS light will never come on during cold winter days. So I'm going to take my van back by the shop with some of this info in hand and see if he'll humor me and swap out this servo. I should do it myself and then go tell him I did it but I have a busy schedule this week before I leave for vacation next week...oh yea and I feel lazy!

If I do change it myself I'll probably buy the parts from here

http://www.transmissionpartsusa.com/

One think I do not see in their list of parts or in any of your pics is an o-ring called out as item 7 on this exploded assembly view
http://ww2.justanswer.com/uploads/tr...135530_223.pdf

IS there an o-ring in the groove around the edge of that piston?