A general auto trans question

[BigKriss]

the computer was down for a few days. I was reading this post. http://www.bimmer.info/forum/showthread.php?t=12990

I'm under the impression that if you you haven't changed your auto trans fluid in a long time, then the clutch packs eventually burn out. This contimates the trans fluid, making it a brown or black colour. Sometimes I get worried about my trans, when I changed the fluid (for the first time, about 9 months ago) it was almost black and smelt burnt. I understand when flushing the fluid the out you may get 50% out because a lot of the fluid remains in the torque converter.

Some members on here change the trans fluid almost as regulary as their engine oil. Most mechanics I'm talking to recommend a change at around 20-40k intervals. I've changed it 3 times in the last 15,000kms. I'm assume my trans is already damaged (the clutch packs). It's shift smoothly 70% of the time, and 30% it's so-so :( Whats the deal with my situation?.

[pundit]

...It's shift smoothly 70% of the time, and 30% it's so-so :( Whats the deal with my situation?.
I dunno but mine shifts smooth as silk sometimes and but then will suddenly shift with a thump. The change into top in generally the harshest when it does shift hard. Sometimes the last downshift just before it comes to a complete stop also occurs with a thump. Like it's hanging on in second or third almost fighting the brakes until I slow to about about 5-10km/h, then it will suddenly shift down with a thump. As it's so intermittant and random I can't seem to pin it down. I changed the fluid twice in about 10,000kms also, and added some Nulon trans conditioner. Still it occurs randomly. There's no sign of slippage and the fluid has never smelt burnt or appeared overly contaminated even after the first fluid change I gave it using Penrite Dexron III. I'm suspecting it may even be electrical? Maybe sticky solenoids or maybe a dirty electrical connection in the soleniod loom.

BTW - Has anyone tried synthetic trans fluid in a ZF4HP22?

[Russell]

I replaced about 7 quarts of my fluid with Mobil 1 Dexron III synthetic ATF in my GM trany. Did not notice any change in performance. Perhpas there was a bil more smoothness via the "butt meter". Not sure. No problems

[BigKriss]

BTW - Has anyone tried synthetic trans fluid in a ZF4HP22?

I put 4L of this in last time.

http://www.bimmer.info/forum/showthread.php?t=10774&highlight=synthetic+trans+fluid

[Blitzkrieg Bob]

If thats plugged up, it can impact the trans oil flow, and increase heat and wear.

[Nick.Hay]

Is it possible (Or would it really even be worthwhile??) to put some form of 'gunk-cleaner' additive in the gearbox oil, to clean all the residue and **** out??

[BigKriss]

I think i've changed the filter twice over the last three flushes. I haven't heard of gunk cleaner nick. The magnets on the bottom of the auto trans sump collect tiny particles of wear.

[mzarifkar]

[QUOTE=pundit] Sometimes the last downshift just before it comes to a complete stop also occurs with a thump. Like it's hanging on in second or third almost fighting the brakes until I slow to about about 5-10km/h, then it will suddenly shift down with a thump. As it's so intermittant and random I can't seem to pin it down.QUOTE]

I have this problem as well (among many), it only occurs whenever i brake hard, i think that all the oil is flowing foward and i am low on oil, so the pump doesnt get any oil but once ot flows back, it will shift.

Im trying to find this degunker that claims miracles, ill post it once i find it
Edit: http://auto-rx.net/ its called auto RX for transmission, anyone try this? i am chagning tran fluid one of htese days, maybe ill add some to it

[Kalevera]

Kristian, the 4hp should be serviced every 15k -- fluid (whatever will drain out of the pan), filter, and pan gasket (and I know for a fact that there's one in the kit I sent you way back when). That's how you get 200,000 miles out of it.

Now...To everyone who has experienced bad upshifting on the electronically controlled ZF, a story:

The day after my first 4hp was installed in January, I had to take the car to Ohio eCheck for emissions testing. The car would start pendulum shifting at about 40mph/~70kmh with no gas pedal pressure (coasting). I didn't think much of it as it was incredibly cold that day and I was driving the piss out of the car to get it warm. Car passed; that was good. Later that evening, or the next day (I forget which), I was cruising down a state route at about 50mph and came to a red light. As the car slowed, the trans didn't drop out of gear; I had to keep a foot on the gas and another on the brake to keep it from stalling. After that incident, it resumed normal pendulum shifting, as it had been doing over the past day or so. I took it back to Brett, we checked to see if there were any codes -- nada. I was, naturally, concerned about the transmission's health.

The car continued to do this on and off until April 1, when the trans fried itself and was replaced yet again (unrelated circumstances?). After Hendrick installed another trans, the car still shifted erratically, albeit less than it previously had. I tolerated it. What began as a feeling of imprecision in the accelerator had turned into something of a minor nuisance in the occasional bumping of the tach needle while coasting.

When I started at KMS, I began reading a lot of stuff and had access to proficient diagnostic tools. I spent a day reading a handy manual on the three early AEGS systems; between that and Modic III, I confirmed that all of the electrics were working as they should be. "So what the heck do I do now?!" I thought...

A day later, I pulled my valve cover to check unrelated valve noise. I thought, what the heck, I'll check the throttle body. It was dirty. I cleaned up the butterfly and reassembled. Since then, there have been no problems.

So, to make a long story short: if there isn't a check engine light associated with erratic trans behavior, it's likely a physical issue. In my case, it was dirt confusing the TPS. My mileage has also increased since that cleaning (could also be me using a different brand of gas, but who knows).

best, whit

[genphreak]

The setting of the Throttle Position Sensor surely has something to do with it Whit? The idle speed in and out of gear is key to a smooth change down... especially under brakes.

On that point, everyone I know plays with their AFM screw, so perhaps the TPS adjustment is something we should all pay good attention to. I need to chk the Bentley, but AFAIK once you have the air-bleed (AFM bypass screw) set you are advised check to the TPS as well. From what I have seen (in a country where there are NO emissions tests and very little good education on Engine Management Systems) there are a lot of local mechanics who adjust the AFM as a short term fix (consciously or not) to make the Motronic run 'properly' (in spite of the few 'too hard to find vacuum leaks').

This is hardly surprising as for some discovering the bleed screw under the factory anti-tamper plug is a major boon- I've even seen one gleefully rip out the plug in disgust and exclaim excitedly whilst he jammed his dirty scredriver into the very hard to get to recessed torx head grubscrew to 'fix it right up'. :D That's what these complicated computer systems need- an experienced feel on the bleed screw. I guess for these types it is the holy grail of adjusters as it can help them to make it run (and somehow this often impresses the customer).

For many, working on a motor almost completly devoid of any adjustment this is a bit of a breakthrough, regardless of the actual cause (and ultimately the effects)

[BigKriss]

The setting of the Throttle Position Sensor surely has something to do with it Whit? The idle speed in and out of gear is key to a smooth change down... especially under brakes.

On that point, everyone I know plays with their AFM screw, so perhaps the TPS adjustment is something we should all pay good attention to. I need to chk the Bentley, but AFAIK once you have the air-bleed (AFM bypass screw) set you are advised check the TPS as well. From what I have seen (in a country where there are NO emissions tests and very little good education on Engine Management Systems) there are a lot of local mechanics who adjust the AFM as a short term fix (consciously or not) to make the Motronic run 'properly' (in spite of the few 'too hard to find vacuum leaks').

This is hardly surprising as for some discovering the bleed screw under the factory anti-tamper plug is a major boon- I've even seen one gleefully rip out the plug in disgust and exclaim excitedly whilst he jammed his dirty scredriver into the very hard to get to recessed torx head grubscrew to 'fix it right up'. :D That's what these complicated computer systems need- an experienced feel on the bleed screw. I guess for these types it is the holy grail of adjusters as it can help them to make it run (and somehow this often impresses the customer).

For many, working on a motor almost completly devoid of any adjustment this is a bit of a breakthrough, regardless of the actual cause (and ultimately the effects)

Damm you write elequently

[genphreak]

I say ol'd boy!

Thank you... Grammar School education in Britain has a permanent effect I'm afraid, eh what! Lucky I made it to Oz though, might have become a stand-in-line when you're told conservative lacky otherwise... Doesn't help me read German much though... that we could really use! :( GP

[pundit]

Damm you write elequently
"It was a dark and stormy night.
As I rounded the twisting mountain road in my trusty E34, the waves crashed over the craggy rocks below.
Little did I know that within a few short moments my life would flash before my eyes....."

To be continued.... :D

Hmmm.... Do you think that'll get me a publishing deal? :p

Apologies to Edward George Bulwer-Lytton for a little plagiarism.