Lower TB idler pulley

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Crumpler
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Lower TB idler pulley

Post by Crumpler »

Isolated a knocking in lower front engine at crank while getting ready for DE event.
It seems to be the lower idler. The bearings spun without noise but the carrier arm will rattle. Circlips are there but just enough laxity to rattle.
I’m sure it’s a by product of my super damper fail last week. But here’s my question: can the idler be deleted?
Or did I make that up? I seem to remember old threads on RL where people have ditched it.
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SeanR
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Re: Lower TB idler pulley

Post by SeanR »

You can shim it so it will quiet down, I've had cars come in that had it removed with no ill effect but personally don't run them w/o.
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worf
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Re: Lower TB idler pulley

Post by worf »

What Shaun said.

I'd never delete the inboard lower idler from a client's car.

However, the second idler (present on '89+/-, I forget) can be deleted.
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Crumpler
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Re: Lower TB idler pulley

Post by Crumpler »

Got it. Thanks guys. I will shim it.
Appreciate the feedback Sean.
Dave, how is the cat BTW?
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linderpat
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Re: Lower TB idler pulley

Post by linderpat »

Why was it put there to begin with? There must be a good reason?
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worf
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Re: Lower TB idler pulley

Post by worf »

Crumpler wrote: Sun Oct 04, 2020 2:28 pm Dave, how is the cat BTW?
Good question. Thanks for asking. I'll update in the cat thread. :cat:

BTW, if you want to replace the bearing on that roller, just read off the bearing number, order a high(er)-quality bearing (~$10-20) with the same number, press off the roller shell and press-in the new bearing. That's what I do, now, for both lower idler and tension idler if the shells are still good, since the new Porsche parts are stupid expensive. For 'bad' shells I just pick out a cad-plated replacement shell and toss the old one in the to-be-replated box.
linderpat wrote: Sun Oct 04, 2020 2:32 pm Why was it put there to begin with? There must be a good reason?
AFAIK and IIRC, the purpose is to keep the belt wrapped around the crank gear in "high belt flap" conditions and also if the crank turns backwards just a bit which can happen depending upon how everything 'stops.' It's probably 80% paranoiac German over-engineering, but the low probability part might have consequences severely inimical to warranty.
Hanlon’s Razor: Never attribute to malice that which is adequately explained by stupidity.
Heinlein’s Corollary: Never underestimate the power of human stupidity.
Worf’s Razor: Never attribute to stupidity that which is adequately explained by laziness.
Worf's Corollary: Once you've mitigated risk from stupidity and laziness in your endeavors, failure is usually the result of insufficient imagination.
:file_cabinet: My 928 Inspection Guide
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