I was expect the plastic seals to work fine for the life of the
throttle shaft. As you point out, Alu & steel is not such a great mix
either...
Jon

On 9/14/2014 9:39 AM, Alistair Bell wrote:
> I don't want to beat this to death but I understand now what you mean with the erosion of steel with plastic bearings. I can see how particles can become embedded in the plastic and wear the metal. But in this situation, throttle shaft, I doubt that is a big concern.
>
> The stock seals are nothing to write home about. Mine were dry and brittle. The throttle body material, some sort of aluminum alloy which does not turn a very nicely at all, probably rubbed the shaft worse than my plastic bearings will. I ink the shaft is hardened but to be honest I didn't take a file to it to test.
>
> Cheers
>
> Alistair
>
>
>
>> On Sep 13, 2014, at 8:58 PM, Jon VonOhlsen <jondvo@gmail.com> wrote:
>>
>> Generally plastic bearings do tend to wear the metal shafts more than expected. May be related to the plastic "holds" impurities which tend to provide a nice substrate for wearing the metal. This is a known phenomena in industrial/commercial apps, and I have seen this issue. Not sure about the throttle shaft/bearing as there is relatively low loading on the bearing. The factory seals are more compliant.
>> Jon
>>
>>
>>> On 9/13/2014 5:37 PM, Alistair Bell wrote:
>>> Really? You think in this application the throttle shaft will be worn away?
>>>
>>> Geez, I better tell the guy who bought the 600 buck HDPE shaft bearing for me to install in his sailboat rudder :)
>>>
>>> Don't mean to sound snarky, it's just e first I have heard of such a thing in such an application.
>>>
>>>
>>> Alistair
>>>
>>>
>>>
>>>> On Sep 13, 2014, at 1:31 PM, Jon VonOhlsen <jondvo@GMAIL.COM> wrote:
>>>>
>>>> One issue may be wear on the throttle shaft. HDPE, Delrin, and PFTE
>>>> actually can wear the metal out. I have seen this in industrial plastic
>>>> & metal applications.
>>>> Jon
>>>>
>>>>
>>>>> On 9/13/2014 1:54 PM, Neil N wrote:
>>>>> very helpful Alistair.
>>>>>
>>>>> I still may buy the gowesty vacuum operated TB switch for my '88 but
>>>>> knowing that HDPE likely works (untested?) is really helpful.
>>>>>
>>>>> Do you see HDPE wearing well over the long term? I'm sure I could
>>>>> google up some info too.
>>>>>
>>>>> Thanks.
>>>>>
>>>>> Neil.
>>>>>
>>>>> On 9/13/14, Alistair Bell <albell@shaw.ca> wrote:
>>>>>
>>>>>
>>>>>> http://shufti.wordpress.com/2014/09/13/vanagon-quick-throttle-body-re-bush/
>>>>> --
>>>>> Neil n
>>>>>
>>>>> Blog: tubaneil.blogspot.ca
>>>>>
>>>>> '88 Westy http://tinyurl.com/c8rlw6p
>>>>>
>>>>> '81 VanaJetta 2.0 "Jaco"  http://tubaneil.googlepages.com/
>>>>>
>>>>> Vanagon VAG *Gas* inline-VR Engine Swap Group:
>>>>>
>>>>> http://tinyurl.com/d7gd5ej