zf question

[performancelaw]

I just did the swap about a month ago. I love the 5 speed vs the auto. It has a noise ( I assume gear roll ) when I lug the motor. That doesn't bother me. At about 60 til about 65 or so the tranny gets quiet loud. It stops once you get it over 65. Is that normal ? If not how do I fix it ?

 

[rjjp]

The noise you hear when lugging isn't necessarily gear rollover, ZFs do make a lugging noise (under about 1100 rpm) hence the reason ZF recommends avoiding lugging the engine. (on takeoff is acceptable, but not cruising).
As to your 60-65 noise, are you 2wd, or 4wd? Put the transfer case in neutral (disconnect drive shaft if 2wd) and go through the gears, if you still hear the noise it's the transmission, if not then it's something in the drive train.

 

[gdhillon]

Whats lugging?

 

[performancelaw]

The noise you hear when lugging isn't necessarily gear rollover, ZFs do make a lugging noise (under about 1100 rpm) hence the reason ZF recommends avoiding lugging the engine. (on takeoff is acceptable, but not cruising).
As to your 60-65 noise, are you 2wd, or as4wd? Put the transfer case in neutral (disconnect drive shaft if 2wd) and go through the gears, if you still hear the noise it's the transmission, if not then it's something in the drive train.

It's a 4 wd tranny but the truck is currently 2 wd ( got a hell of a deal on it ). I never heard it with the auto. It's not really something that scares me to badly. I was just wondering what it might be. As far as lugging the motor I try to avoid it as much as possible. I've heard running different fluids in it will quiet it down ??

 

[towcat]

ideally you should only run ATF but I have run 30w and 50w in very loose ZF's. most of my ZF's that need heavier oil have been run dry due to leaking PTO units.
the reason why has mainly to do with the syncros. unlike most other syncros, ZF syncros actually have a sintered metal electro-deposited on the backside of the ring in order to slow down the gear faster. this works fine in a trans that is not "burned up" and the ideal oil is ATF/10w. I've learned from flogging dead ZF's that if you don't push the trans too hard, ie. "speed shifting" that a 30w or a 50w will keep one alive for some time. see pics for illustration. the serations on the backside of the ring is normally more pronounced, this one happens to be worn out badly.
hope this helps.

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