# Toro 521 pulley bolt



## paulm12 (May 22, 2015)

On the older 521 units, is the bolt that holds the pulleys on the crankshaft just a standard bolt with blue loctite? The drawings call it a "special screw", but it appears to be a 7/16-20 bolt (I need to confirm pitch). I have cleaned the old loctite off the screw threads with a dremel wheel, but before I chase the threads on the crank I wanted to be sure.

part #24 on this reference diagram: https://www.toro.com/en/parts/partdetails/?id=2834 

Thanks


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## UNDERTAKER (Dec 30, 2013)

paulm12 said:


> On the older 521 units, is the bolt that holds the pulleys on the crankshaft just a standard bolt with blue loctite? The drawings call it a "special screw", but it appears to be a 7/16-20 bolt (I need to confirm pitch). I have cleaned the old loctite off the screw threads with a dremel wheel, but before I chase the threads on the crank I wanted to be sure.
> 
> part #24 on this reference diagram: https://www.toro.com/en/parts/partdetails/?id=2834
> 
> Thanks


* If that is zee bolt you pulled oot. then that is what it is. should be a Grade 8 bolt though. k:k:k:k:k:k:*


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## paulm12 (May 22, 2015)

ahh, the wisdom of PS93 :grin: It was actually a 3/8-24. My question is really what makes it "special" There are other bolts the use loctite, why is this one called out?
.


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## UNDERTAKER (Dec 30, 2013)

paulm12 said:


> ahh, the wisdom of PS93 :grin: It was actually a 3/8-24. My question is really what makes it "special" There are other bolts the use loctite, why is this one called out?
> .


* Grade 8 Bolts have the highest tensile breakage point of them all. that is what that bolt was spec'ed at. When it left the Little TORO Factory Here. you don't want anything to break on you when you are going FULL BORE on in the BIG ******. Now do you?????? :smiley-think001::smiley-think001::icon-doh::icon-doh::icon-doh:*


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## paulm12 (May 22, 2015)

hmm. the one I took out was grade 5 bolt. Do you have a torque spec for this? I could not find one, only for the cylinder cover bolts.

Thanks.


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## dbert (Aug 25, 2013)

I don't think it's all that "special". 









Is it all threads (no shank). If I were to make a guess at what makes it special, it would be the shank-to-thread ratio.


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## dbert (Aug 25, 2013)

My new guess is it may be the pre-applied thread locker. If it were me....I wouldn't hesitate to get an off the shelf bolt.

Here is a link to one (with photo) for anyone that wants to add their opinion.
https://www.ereplacementparts.com/screwspecial-p-685653.html


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## paulm12 (May 22, 2015)

yeah DBert, that is the only supplier picture with an image. On mine, it is not all threads, about 1/4 of the length is not threaded. I'm thinking the pre-applied loctite is the "special" part too. Note that I am not worried about this part, just inquisitive about it.


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## dbert (Aug 25, 2013)

Understood. I appreciate you pointing it out. Being labeled as "special" that is. 
As for the torque value, when all else fails there is always the ole "standard" torque values.
https://www.boltdepot.com/fastener-information/bolts/US-Recommended-Torque.aspx


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