New timing chain sprocket won't fit on to crank
 

Hello. I drive an '09 SS with the LNF motor.

I'm currently swapping the timing and balance chain and all of the associated guides using the two Cloyes kits. In the process, I noticed some chewed up plastic on the timing chain sprocket on the crank. I bought the Duralast version of the replacement.

The original sprocket pulled out pretty easily. When I try to install the replacement, using quite a lot of force and a bit of tapping with a hammer, it gets jammed about 1/4" out from its proper place against the balance sprocket. It took a sprocket puller to remove it. When I reinstall the original sprocket, it still slides on nice and smoothly.

My question is, does this take more than a reasonable amount of force to install this the first time? I'm not comfortable with brute forcing something like this on, but if I'm just going to order another one and wait a couple of days to get the same results then I can just get it over with now.

Below is a photo of the two sprockets, the top is the original and the bottom is the replacement.

Thank you in advance!


https://cimg0.ibsrv.net/gimg/www.cob...b29580a724.jpg

I don't know if it's just me or not but the keyhole on the top one looks bigger than the bottom one.

i was looking at that. In person, if you hold it up to the light they look much more similar. The rounded edges of the original make it look worse in this picture. However, it's definitely hanging up on that keyway, you can feel the resistance increase as it slides over the key.

Try the old gear, if it slides in just fine then I suggest finding out what the difference is between the old and new gear. That would mean checking every critical dimension associated with sliding onto a crank snout. Also check for defects in the new gear like damage and burrs.

If that leads to nothing you may need to finely emery paper the snout and take down any burrs with a mini fine file (rat tail file).

It should fit tight though it does not hurt to take some measurements of old vs. new. What you are experiencing could be a result of a difference within the allowable tolerance. I'm sure it's fine. My sprocket fit very tight as well. I would recommend against tapping the sprocket on with a hammer. Even if you aren't tapping hard enough to negatively effect the crank thrust bearings you may not be driving the sprocket on with even pressure. I like to use the crank pulley with the crank pulley bolt to push the sprocket into place by slipping the crank pulley on and tightening the bolt against it. They make proper kits that thread fully into the crank and then you tighten a nut against the crank pulley so you don't risk damaging the crank threads but just make sure you have a minimum 3/8" of the bolt threaded into the crank before using it to put force on the pulley and it should be fine. I like to put some grease or assembly lube in between the crank bolt washer and the head of the bolt so that he bolt head can slide easily against the washer.

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I wonder if putting it in the oven for a few min would help, like the opposite of putting your control arm bushings in the freezer to slip them in? Lol, hey look, found someone that actually tried it https://www.corvetteforum.com/forums...haft-gear.html

Or blast it with a torch for a few minutes. Just hope you never have to take it off again if you go that route.

Neither should be done lol, the plastic could come apart after heating like that. The sprocket is not supposed to have to be pressed on, at most it may take one light tap to fully seat. I would get a oem and get rid of that duralast one.

didn't realize it has plastic on it lol. i was kinda being facetious but didn't come across that way

Never had a problem using oem/cloyes ones. They should basically slip right on.

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I wasnt meaning cook it. Just like 150 degrees or so. Think that would hurt the plastic using a lower temp like that? I do agree with oem being best tho. Mine slides on easy by hand

I figured you were lol. Yes there is a plastic ring on each side. I think its supposed to be for balancing and resonance reduction.
I was just concerned bc in that thread they talked about going up to 350*. 220 is as far as I would go since that is the close to the max safe operating limit but your gonna need a very even heat and accurate oven. Conventional ovens tend to have hot spots.
Regardless the issue is the ecotec crank sprocket is not a press on part :lol:. If it don't fit, get a different one.

Take it back and tell them to try again.

i enjoy cooking my parts before using them. adds a nice crisp look to em u just cant find these days

Thanks for the replies everyone. I got the feedback that I was looking for which was that others have had the sprocket slide on easily. Jdbaugh had a good tip with using the crank pulley to force the sprocket on, but I'm just getting another one that fits better.
Also, I'm not trying to Rambo this thing on there. While I'd use a blowtorch to remove something like this if I had to, you shouldn't need a blowtorch to install a sprocket. Especially a sprocket with a plastic collar and the timing chain running on it...

Regardless of whether an OEM sprocket typically slides on or not a tighter fit isn't going to hurt anything though I too recommend OEM Cloyes timing chain kits because I have ran store brand before and it was crap out of the box. Within reason, a tight fitting sprocket should actually perform better than a loose fitting sprocket. I may be missing something but the only negative characteristic, I can see, of a tight fitting sprocket would be installation/removal. I can't remember if I had to use a puller to remove the one I installed that needed coaxing or not. The stock crank pulley also slides on and off easily but from a performance standpoint that is not ideal. My aftermarket ATI harmonic balancer has a much tighter fit.

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And dont forget to the shim back on when you are putting it back together. I had the cover halfway back on one time before I realized the shim was still sitting on the cardboard beside me lol.

It's been a while since I put the timing chain sprocket on but I don't recall the shim you are referring to and now it me worried I missed something. What shim are you referencing here?

L61/LE5 dont have a shim.

I think it may only be the DI engines that use them.

Only some engines came with a shim. I have yet to figure out what the reason is. Seems completely random, gm just states to be mindful during disassembly and reinstall it after repair. Im guessing it has something to do with the machine tolerances and its more cost effective to measure and shim during final assembly instead of junking cranks/sprocket/oil pump(whatever the reason for the shim is).

Usually you want to use an oil bath to do this, not a forced air oven. Although I'm not sure if the steel will give enough clearance only heating to 150-200. I know old school machinist would use a deep fryer to heat oil to warm up steel ball bearings for easy install save the burn your hand temperatures aspect.