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  1. #1

    Default ZF63iv clunking in gear

    I'm new to the forum and I have a question about a Hurth ZF630V-1 transmission. We put a new forward gear clutch pack, seal kit and filter in this transmission and before installation in the boat wanted to test it to make sure it worked ok. We attached a 1/2" drill to the input shaft and it seems to work ok and shift properly, but it makes a rotational clunking noise when it's in gear and I'm concerned that the rotational speed of the drill is not sufficient to produce the necessary pressure to fully engage the clutch. The noise sounds like a broken tooth, but all of the teeth were carefully inspected when we tore the transmission down.
    Also is there a pressure port in the control assembly that we could use to check the transmission operation?

  2. #2
    Join Date
    Sep 2008
    Maryland - USA

    Default Re: ZF63iv clunking in gear

    yes, there's a pressure test port on the control valve....not too far from the neutral safety switch.
    Service book I have shows a MAX value of 375 PSI an a min value that varies with input shaft rotation up til about 1600 RPM where it flattens out @ ~ 310 PSI....looks like 600 RPM should get you ~ 110 PSI.

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