HRX217HZA Crankshaft replace...in home stretch need help with Timing Belt Gear Pulley

mesaboog

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  • / HRX217HZA Crankshaft replace...in home stretch need help with Timing Belt Gear Pulley
I am about to install the new crankshaft into my GCV190. I used a puller to get the old metal "Timing Belt Gear Pulley" off the old bent crank. It is in perfect shape. It has no key, so I am confused...does it stay put with dry (no lube) compression?

OK, so main question is...What is best way to install the gear onto the new crankshaft. My puller is not deep enough to pull it on. Is there a trick to this. I haven't tried yet because I don't want to screw it up. Service Manual doesn't address this.

Any tips or pointers you can provide would be greatly appreciated. Don't want to screw this up so would prefer to err on side of caution.
 

cpurvis

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  • / HRX217HZA Crankshaft replace...in home stretch need help with Timing Belt Gear Pulley
I have encountered two types of gears timed to shafts without using keys--one used conical compression rings; the other was hydraulically expanded. Neither of these applications experienced the torque variations that an engine crankshaft sees.

My guess it is an interference fit. The crank is cooled and the gear heated to get the clearance necessary to assemble the two. When the assembly cools off, the two parts are stuck together. You would need a jig to time the gear to the crank throw correctly.
 

mesaboog

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  • / HRX217HZA Crankshaft replace...in home stretch need help with Timing Belt Gear Pulley
I don't understand the jig part. There is no mark on the timing gear or key to try to orient to. The timing is done with the mark on the crank and Cam gear correctly positioned at TDC. I suppose I should freeze the crank heat the gear and pound it on with using a pipe?
 

cpurvis

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  • / HRX217HZA Crankshaft replace...in home stretch need help with Timing Belt Gear Pulley
The jig is necessary so that the gear won't be off in relation to where the cam gear needs it to be. You could be up to a half tooth off if you don't index the crank AND the gear.

When doing the cold/shrink, hot/expand interference fit, it usually just drops on. No pounding necessary. But it has to drop on in EXACTLY the right place, hence the jig.

Keep in mind, I'm just guessing that that is the method they used to assemble the crank and gear. It may be something entirely different.

But I do know that Mesa/Boogie makes a fine amp.
 

mesaboog

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  • / HRX217HZA Crankshaft replace...in home stretch need help with Timing Belt Gear Pulley
Ok here's an update:

So I had to order a different crankshaft "kit" that included a plastic timing gear pully. It goes onto the shaft easily and has a key so no need for me to index. However, I am perplexed about something else: On the new crankshaft magneto side, there are a couple black marks above and below to the flywheel keyway. See photo. What are these for? My understanding is that I need to install the crankshaft with the keyway (and little triangle mark) exactly 180 degrees from the spark plug and align the cam gear so the 2 marks (on the cam gear) are parallel to the edge of the cylinder head case. Can anyone tell me if these black marks on the crankshaft are important, or just ignore them? See photo.

20180406_180517.jpg
 
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