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
>