ZF Transmission Trouble Shooting Manual

I found this on line.

http://www.zf.com/na/content/media/...kup_driveline/troubleshooting_guide/S5-42.pdf

I've been doing a little research on idle noise from the ZF. They define it as neurtal rollover vibration which is caused by idle pulses being transmitted through the gears. They eluded that some idle noise is normal. Looks like some type of 2 stage clutch or flywheel dampening might have been incorporated in some applications to improve the condition. It might be agrevated as the 302 is a lighter (less dampened) engine. Just a thought.

I'm also wondering if the close ratio gear set will interchange into the wide ratio housing? I think that would be a pretty usable sport truck gear ratio. I drove around the block and imagined a first gear just a touch lower than 2nd is now and a tighter spread in between. Right now my 5.72 first with 3.55 gears and 31" tires is a touch low to start with a bigger than desired gap to 2nd. I think that the close ratio gears with 4:56 gears and 35" tires would be sweet.

edit: It appears that one could swap out the 1st 2nd and 3rd gears and counter gears. But I can not verify that yet. I've got a lead on close ratio ZF for cheap and may investigate further.

Wide Ratio: 5.72 2.94 1.61 1.0 .76 rev 5.24

Close Ratio: 4.14 2.37 1.42 1.0 .77 rev 3.79

NV 3550 - : 4.01 2.33 1.39 1.0 .78 rev 3.57

Someone asked a question about which ZF to put on a 4BT. The close ratio might be a good match for that too since an adator is required anyway.

Dave...

excellelent info Dave thanks for sharing.

marc

The close ratio tranny is for the diesel engines anyways. Not really worth the effort to swap gears(if you can even do it) in my opinion I believe its only first gear thats any different.

first gear is for wheeling. I don't ever use it for street driving. If your trying to stop the gear noise at idle. get louder exhaust. I haven't heard any that didn t sound like they weren't ready to explode at any second. Mine only has 5000 miles since the rebuild sounds exactly the same as before the rebuild. Loud.

That's good to know, that noise was making me a little paranoid....
After my 435 started to sound like that, it got ugly.

JB Fab said:

That's good to know, that noise was making me a little paranoid....
After my 435 started to sound like that, it got ugly.

Click to expand...

I've been driving mine for about 5 years now and other that a little idle/neutral noise it's been smooth and quiet even with a quiet exhaust. I cut a sound blanket out of a piece of 3 inch visco-elastic polyurethane foam that formed a nice noise blanket between the transmission and the tunnel. Its the same stuff that they use for factory noise blankets. It tollerates some heat but don't let it get too close to your exhaust. Oil and gas don't seem to deteraite it. That along with a stock (dampened) shifter and a good boot and its barely noticeable. Keeping the tunnel cutout as small as practical also helps. It's never sounded like "its ready to explode at any second" as described in a reply above. That would really bother me and make me wonder if the preloads were set up correctly in the rebuild.