Automatic Transmission Shifting Issues

[vwleadfoot]

This may be grasping at straws. Had a problem with my '88 735i where, after the car was warmed up, the indicator on the dash would suddenly not show any gear and the car would shift back into 3rd while on the highway. Took the top off the centre consul and the area was full of cigarette ash and dust. After vacuuming out the area I notice the white electronic box at the base of the shifter. I removed said box and it comes apart quite easily. Inside is a number of small brass lines and the shifter connects to a set of fingers. Once I cleaned them all up and re-installed it I had no more problems. This is now one of the things on my yearly maintenance schedule (I smoke). I didn't see any one suggest this, so give it a try.

I replaced mine with one from the stealership and the only thing it fixed was the indicator in the dash. Still chasing my hard shifts over here. It always seems to come back to taking the valve body out and having it rebuilt. Ugh, I really didn't want to have to do that......

I wish there was someone local who could plug into this thing and do a computerized check of my solenoids and what not. Car is too old and too rare though....

[dawedler2]

Well hopefully tomorrow will bring this saga to a conclusion. I had my transmission rebuilt and just received it this week. I plan to install it tomorrow. Looking forward to having my 7 back on the road. If anyone has any install tips, let me know.

[dawedler2]

So when they rebuilt my transmission, apparently they replaced the intermediate plate assembly with an older style plate. Now my trans cooling lines will not fit into the transmission. Does any one know of a solution? Is there an adapter available? Do I need different lines? I plan to call the transmission repair shop on Monday. Just wondering if there is an easy solution? Not sure at this point what size fittings these are, I just know my lines do not fit in them.

[dawedler2]

I called the transmission shop and they looked into it and basically said the supplier shipped them the wrong part and they installed it and missed that the ports were different. They took responsibility and said they could either pay to have it shipped back to them to install the new part or they could ship me the new part and have me install. Even offered to pay my labor. Said they wanted to make it right. I was pretty impressed with their response. I guess I was expecting some sort of retrofit solution or worse that they would not fix it at all. Thumbs up to Trans Specialties Transmissions.

[94bimmer740il]

Please keep us informed..

[dawedler2]

I received the transmission back from the trans shop with the new intermediate plate assembly. Installed the trans, filled with new fluid, replaced exhaust system. Started car, no leaks, checked fluid. Got to temperature and checked level again. Then drove the car about 5 miles or so, everything seemed to be shifting fine. Then 20 minutes later, went to back out of my drive again and reverse was acting up, went into reverse but then no power and then forward gears were acting up. Drained the fluid and it is brownish and has a burnt smell.
Incredibly frustrated. It's a brand new rebuilt trans. Not sure what is my next step. Going to call the trans shop on Monday.

[kansei]

I realize this is late to the party, and you have already had the trans rebuilt, but for anyone else in a similar situation-

Had the same problem on my '94 740iL before I got it from my friend. He left the car with me to pull the trans, have it rebuilt and then reinstall it because the previous owner and a BMW dealer thought the trans needed rebuilt or replaced. I consulted a local trans rebuild shop's top tech I know doubting the diagnosis and he too told me it needed completely rebuilt. I still didn't think so, and I was right- turns out the ZFs in our cars were very susceptible to the check balls in the valve body wearing out. Believe it or not, several of them are just hollow plastic. One of two things happens- either a check ball or balls wears over time from the fluid pressure and they will actually reduce in diameter, allowing them to blow through the ports in the valve body, allowing a drop in pressure on the related circuit, or the intermediary plate(s) of the valve body wear and allow the balls to fall through. You will notice that this condition is not mentioned at all in the factory service manual as a possible culprit. I'll bet 100 to 1 all you needed to do was pull the valve body, rebuild it with the proper rebuild kit, change the fluid again and you would have been good.

Neal.


- - - Updated - - -

As a side note to the problem you are still having with reverse- if they used a rebuild kit for a later trans, then swapped in just the older plate(s)- the check balls will be a different diameter and could be your problem. The older plates use specific check balls, the newer ones likewise, as there were some changes made to the valve bodies during running production. You can't mix and match parts from what research I did when I worked on (what is now) my car's trans a couple of years ago.

Neal.

[shogun]

Neal, the ball problems were on the 5HP30 as you have in your 740, but dawedler2 has a 4HP22 in his 735. And there were no ball problems.
5HP30 and 4HP22 are 2 completely different things. Do not mix that up.

[dawedler2]

Thanks for the responses. So, if it is not a check ball issue, any thoughts on the cause/solution?
I was pretty careful with the install. The BMW mechanic who helped me said I did the install correctly. Trying to keep this car but I feel I may need to sell her. Just spent $1600 on this trans rebuild.

[kansei]

shogun- Fair enough, though when my car was having similar issues, two BMW dealerships, a well known trans shop and ZF all said the 5HP30s did not have any issues having to do with the check balls or valve body woes. No one agreed with my diagnosis, they all said the trans needed to be rebuilt, and they all figured it was a clutch drum or related issue. but I have worked on enough automatic transmissions over the years that I knew I was right. Trans operated like new after repair, and has since operated flawlessly for roughly 30k miles. Just because you said the 4HP22 transmissions did not have any check ball issues, I still would not rule it out- no disrespect intended,

Neal.

[shogun]

Yes, but only a few 4HP22/24 compared to 5HP30. Usually I replace the balls also on 4HP22/24 when I open the valve body. Last year I have seen 1 case with a 4HP22 on a E34 535, where one ball was heavily damaged on the outside.
Of course for many shops to say the trans must be fully overhauled is the easiest answer to a customer who does not understand the transmission. Reading the color of the fluid and smelling of the ATF tells us much.
BMW dealerships do usually not work on a trans to open + repair it, they just replace it and send the old one back to ZF for remanufacturing.

[dawedler2]

So, the new fluid is brown with burnt smell after only five miles. Is my new transmission shot? Check balls? Pump not working?

[shogun]

If it is brown and smells burnt, that is basically a sign for a burnt clutch pack. Talk with your trans shop.
Did you flush the system before you installed the new trans?

[dawedler2]

I did flush the system. Used a can of Trans Flush Transmission Cooler Flush, ATF and air to flush the system. The fluid seemed to be running clean through it.
Trans shop said to pull the pan and see whats in there. His initial thoughts were possibly failed torque converter, cooling system not flushed well and dumped gunk into filter. Said something must have clogged the filter to stop flow.
I am pulling the pan today. Will update.

[dawedler2]

Pulled the pan and sent pictures to the trans shop. They said I must not have flushed the cooling lines from what they saw in the pan photo, that the particles were left over from the original trans (not sure how they can distinguish if it is from the old trans failure or new trans failure). However, I did flush the system with the can of Trans Flush that the trans shop sold me. I asked to buy two cans and they said that one would be fine. I addition, I ran ATF and air through the system to make sure it was clean. Trans shop said when it heats up it can release all that debris. My neighbor who has been helping me has been a BMW mechanic for 40 years. He said that he thinks I did everything right and something is wrong with one of the clutch packs. Hoping they will cover the repair. When they first repaired it, they installed the wrong model year intermediate plate assembly so they already paid shipping to replace that part. I'm sure they are reluctant to ship it again.
Again, any input would be helpful. Thanks.
Below are pictures of the pan, valve body, and filter:
1 Trans Pan.jpg2 Valve Body.jpg3 Valve Body inlet.jpg4 Filter top.jpg5 Filter bottom.jpg

[shogun]

I am not a pro, just a trans amateur wrencher with some hands on experience, but to me the pics look not bad, have seen much more dirt in trans which I opened up, but of course these have beeen use for >200 k miles and some never the ATF has been changed.
I would discuss with them in a friendly manner, first time they were cooperative and sent you a replacement when they shipped the wrong intermediate plate.
For them the cost for a new clutch pack is not very much.

[dawedler2]

So far they have been good to work with. They actually paid to ship it round trip to replace the intermediate plate which cost them $380 just to ship plus the new part. I think that might be part of the issue is shipping again roundtrip Orlando to New Jersey. Trying to diagnose what is caused it to fail so quickly. Is the filter plugged up? Is a clutch pack gone?
I don't know if I need it rebuilt again or if I can just replace the filter, clean it out and run it. Although it is clear that something is not right. I'm not sure I can do the work.

[shogun]

I use this ATF wide 3-D from SUMICO in my 5HP18 with green label in my M3, they have a good explanation of the difference in colours and the causes
http://www.sumico.co.jp/e/qa/qa_c_atf_e.html
Does your fluid look like that #3 where they state: Wear particles or sludge from the clutch or gears is mixed with the fluid.

[dawedler2]

Yes, it looks like number three. The particles easily crumble and turn to a black powder when you roll them between fingers. I'm guessing that is clutch material.
The fluid was new Castrol Transmax Import Multi-vehicle
Is it a possibility they installed the clutch packs wrong? Or is it more likely clogged filter?

[shogun]

That is all speculation now, it will be clear when the trans is disassembled.
Maybe someone knows what happens if they did not install enough fiber clutch frictions? Pressure too low in the pack?
Here is a cross section http://www.nmia.com/~dgnrg/side_view.jpg

and a technical bulletin, ZF4HP22/24 1989-up valve body gasket change
There has been an update in the valve body gasket, this change involves the addition of 2 new holes and the revision of 2 existing holes.
The new gasket # 1043 328080 will retrofit all previous 1989-up models.
Previous gasket # 12457
new gasket # 12954
http://www.europeantransmissions.com...W/BMW.bull.htm

[dawedler2]

Talked to the shop today. They said they would go ahead and pick up the trans and ship it to their shop to repair it.

[vwleadfoot]

I replaced mine with one from the stealership and the only thing it fixed was the indicator in the dash. Still chasing my hard shifts over here. It always seems to come back to taking the valve body out and having it rebuilt. Ugh, I really didn't want to have to do that......

I wish there was someone local who could plug into this thing and do a computerized check of my solenoids and what not. Car is too old and too rare though....

OK so on with our solution and some resolution. I've done it. After two years of investigating and waiting until I had another car to drive so I could tear into my 750 trans, I finally got it fixed. I had to go down the line of many potential problems that could have gotten in the way of it, but ultimately had to get into the valve body. And it was my first time doing an auto trans and I'm damn proud of what I came up with. I wanted to share this because these forums have helped me resolve numerous other issues that I've had along the way, and I thought it was time to give back.

As the beginning of this thread says, I've had two cars that were doing the same thing. The first worst than the second. The shifts in these cars were downright obnoxious. And I mean tooth loosening up and down shifts that were tearing my drivetrain apart.

Changing the fluids didn't do it, the trans switch didn't do it. Cleaning the abs sensors didn't do it. Ultimately, it was pulling the valve body down from the trans and cleaning one simple screen in the torque convertor lockdown solenoid that did it.

On a hunch, I took the valve body out of my parts car trans apart and found tons of what looked like dried, and clumped together, clutch band material in the solenoid in question. Here is what it looked like when I pulled it from the parts car.

[URL="http://rs78.pbsrc.com/albums/j101/vwleadfoot/null_zpsd94e37f4.jpg~320x480"]



Fast forward a few weeks, I dropped the valve body of my other car down and found the same solenoid to have the same crap in it. This solenoid is the ONLY one with a screen in it and apparently gets blocked up enough that the pressure to the torque convertor cannot be changed, therefore effecting the shifts. All you have to do is undo all of the larger bolts that hold the valve body to the trans, lower it down and pull the one solenoid as pictured here;



Clean the screen and put it back together. I put a new filter screen in it, and some Synthetic atf. Boom, I now have some beautiful shifts.

Pics of the patient, and the others in my collection, for posterity;









Special thanks to Shogun and all others that have chimed in here. You guys rock.

edit-----just realized that i put this in the wrong thread. Oh well, you get the point.

[dawedler2]

vwleadfoot,
Thanks for this post. I wonder if this might be causing my issues? Do you know if the 735i with 4HP-22 transmission has the same solenoid screen as the 750 4HP-24 trans?

Doug

[vwleadfoot]

I would assume it does. Shogun would know, but thought it was mostly in the size of the bands and TC.

[dawedler2]

Talked to the trans shop and mentioned the solenoid screen. They said they cleaned the solenoids out during the valve body rebuild so it probably was not the issue. They believe the reverse issue has something to do with the valve body but can't pinpoint the issue. Said they are going to replace my valve body with a remanufactured one. I wish they could identify a clear problem. Hope this solves the problem.