Vanagon – quick throttle body re-bush

A few years ago i tried re-bushing a spare throttle body using Delrin as the bushing material. I couldn’t get the throttle action smooth, it seemed as if the Delrin had a stiction property that I just couldn’t over come either by sizing the bushing or lubricating. So I laid the project aside and forgot about it.

Then this last summer I noticed some play in the shaft of the throttle body installed in the van. There was enough play to make adjustment of the throttle position switch very fussy. So i though back on my previous experiment and I thought I’d try making bushings again, but this time out of HDPE.

First let’s go back to my spare throttle body, the one I re-bushed with Delrin. I have a blog post here showing it before I started screwing around. I even went as far as cleaning up the wear marks in the bore and making a new butterfly plate to compensate for the now enlarged bore.

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See the Delrin bushing?

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And on the other side, the throttle position switch side.

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My daily driver one on the left, the re-furbed one on the right.

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Not the larger cam on the one on the left. This is the newer, revised throttle position switch system.

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It appears like a lot of space around the butterfly, but it really isn’t that bad. I can’t recall the gap size (I measure with wire).

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It kinda looked ok to me.

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The dried up seal on one side.

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And the other.

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Wear in the bore from the butterfly.

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I decided to leave bore and the butterfly untouched. I chucked up a hunk of polyE and turned and reamed a couple of bushings.

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Recessed on the throttle position switch side.Why? because the switch plate has little locating tabs that fit into the hole.

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Pretty well flush on the other side.

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Gosh, i can’t recall for sure the butterfly shaft diameter, maybe it was 8 mm, yeah I think so. I do have an 8mm reamer. Anyhow, I did think about bearings instead of bushings. But the bearings I had on hand had a larger OD and that would have meant taking the throttle body to work to use the milling machine; tedious set up and then a boring head.

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Assembled. I have to say the action of the butterfly is smooth as silk, much better than the Delrin. Come to think about, I wonder if I reamed the bushings the last time?

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The throttle position switch now is easier to set, there is no wobble in the butterfly shaft.

  1. #1 by edbee on September 14, 2014 - 9:29 am

    Hi Al, nice work as always 🙂

    • #2 by albell on September 14, 2014 - 9:58 am

      Thanks Ed,

      You know I keep meaning to email you to discuss something, you know, that nightmare samba thread.

      Cheers

      Ab

      >

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