ZF Transmission Lubrication

The recommended transmission oil is a 5W-30. I hate the noise that the 6 speed in my '90 makes when it is in neutral with the clutch out. This is not the dual-mass clatter, but the input shaft noise. I have been considering changing the oil for either Mobil 1 synthetic gear lube (or maybe the Red Line Brand) which is 75W-90. I was considering the higher viscosity as the 6 speed makes considerably less noise when cold than after it is really warmed up. I know, get over it....but I can't .....I want a reasonably quiet transmission because to me >>> noise = trouble<<<

What is the general opinion of those more mechanically inclined than I?
Has anyone ever had a chance to figure out why those transmissions (other than the dual-mess (no typo) flywheel) are so loud.

Thanks...this is a great group....hope to see many of you at the Sharkfest or at Bloomington.

Louie

I'm also interested in the replys that you get.

Bill C

[69MyWay]

Louie,

I went up to 80W 90 in our 89 six speed. Virtually no noise! However, it was very hard to shift cold, and espcially in cold weather. It lasted about three months, and came out in favor of smoother shifting regardless of the noise.

You can try it, but I really don't think you will like the side effects of the thicker oil.

Good luck!!!

Maybe do a compromise. Try a 20/50 synthetic. I can see how 80W-90 would be hard to shift COLD. That stuff is like mud when it real cold out! We did a Differential oil change on a 78 Vette in December. It was 35 degrees out. The hand pump wouldn't even pump it out of the bottle until we warmed the lube up in HOT water for 20 min. Your trans synchros would go to h#!! in a hurry if you lived in a very cold area.

Bill

[trrgod]

These trans are SO expensive to fix or exchange that a word of caution is needed here. ZF recommends only GM oil (look up part number in owners manual) or a synthetic sold by BMW dealers. Experimenting with different weights, viscosities and types could be a VERY COSTLY MISTAKE.

I think that the compromise viscosity would be a worthy suggestion. Now I just have to find some. I am amazed that there would be a difference in the frigid cold of Florida. I would really have trouble here in Bend, OR where it was a balmy 25 when I woke up this morning. I would sure like to have a ZF to tear down, just to see what makes them so noisy. Any volunteers???

[racecar]

I agree "I would sure like to have a ZF to tear down" I would like to see the inside of one of those also. When rebuilding a 4 speed trans, I have put shims on the input shaft to keep it tight against the front case bearing. If your transmission is out of the car and you can move the tip of the input shaft up and down, that may be a clue about the source of the noise. Some of the racing transmissions (Hewland) torque the front bearing to 180 lbs. to keep the input tight. Of course when things heat up all the clearances change. I am not sure about how the front bearing is retained in the ZF trans, but that is the first place I would start looking for a noise problem. I don't have the answer for the ZF, just a lot of curiosity. Rebuilding a trans is not a simple project.
If you have the trans out, a needle bearing pilot bearing is a good idea also. I have switched to synthetic in a 4 speed and it made a noticable difference in how the synchros worked. It took more force to shift as if the synthetic was too slippery. I changed back quickly.

[Cigarman]

Be very cautious about using anything except the ZF recommendations.

The ZF fluid is NOT gear oil or trans fluid, but rather engine oil. The alternative to the GM oil that you mention is Castrol motor oil. When you buy it from BMW you are not buying the trans fluid for the M-5, it is the engine oil used in the M-5.

Judge for yourself this is the ZF site:

http://www.zfdoc.com/techinfo.htm

I really agree on the caution that should be exercised. I couldn't get your link to work, cigarman.....could you e-mail me the site?

Thanks

the link didnt work for me either.

[Cigarman]

For some reason it did not showing correctly.

If you look through it, there is discussion re: noise
Here it is:

http://www.zfdoc.com/techinfo.htm

[racecar]

Has anyone ever seen an exploded view drawing or side view enginering drawing of the ZF box??? I would really like to see how the gears are stacked in there!

Thanks for the link on the transmission.

Now I just have to practice my powershifting technique as described in the link:

How to practice your Shift Reaction Timing:
*
Out of vehicle*-
While standing and balancing on your right leg, raise your left leg 7" up off the floor. Simultaneously tap the floor with the bottom of your shoe tip and snap your right hand fingers (ring/thumb)*so as to make one combined noise between*the two. Match'em 30 times in a row, and you are dialed in.


Now, if I can do that without my wife seeing me and laughing her a__ off, I will be surprised.

ZF is the abbreviation for Zahnradfabrik Friedrichshafen.....that little tidbit was also enlightening.....thank goodness cuz I don't think I could say that without spitting.........

I never thought that it would happen but I have sent my wife for three quarts of BEEMER oil for the ZF trans. It is the only other oil that was factory recommended for this transmission. I will report back when I test it out.....Until then, I am here practicing my power shifting/tap dancing.

FYI - the BMW 10w-60 oil is fully-synthetic and is used in the BMW M5 engine....it better be good at $9.00/qt!!!!!

Zahnradfabrik Friedrichshafen.....the sound of a German guy sneezing?????

[Cigarman]

You are getting off lucky--the GM oil is 12+ a quart here (if you can get it).

BB