Main Damper Bolt?

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John16
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Main Damper Bolt?

Postby John16 » Sun Aug 14, 2022 7:03 pm

I dont know how it happened but when I got off work my main Damper (dont know if thats the par name) Is the part (pulley) that holds all your belts the main one...Anyway can you believe that big bolt that holds that pullet or part came out loose and it was underneath my car??? The damper and all belts were just hanging there and I ask myself first how did it happened? and second how is that Im still alive??? :?

Does anyone knows the specific name of that part and the torque that is suppose to be?

:gotme :confused:


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VStar650CL
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Re: Main Damper Bolt?

Postby VStar650CL » Sun Aug 14, 2022 7:42 pm

Harmonic Balancer or Crankshaft Pulley are both accurate terms, Nissan prefers the latter. Torque is 105~112 lbs/ft, see EM-11 (PDF page 51) here:
https://www.nicoclub.com/service-manual ... _240sx.pdf

BUT, there's supposed to be a woodruff key that keeps the pulley from spinning on the crank, and the only way the pulley bolt can generally back out is if the key is stripped or missing such that the pulley can spin it loose. So a close inspection of the nose of the crank is in order before you bolt anything back up.

John16
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Re: Main Damper Bolt?

Postby John16 » Wed Aug 17, 2022 8:18 pm

Thanks! good info. Will do! I'll give the findings and results once I'm done!

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Re: Main Damper Bolt?

Postby John16 » Sat Aug 20, 2022 7:27 pm

Quick question. Is it possible to install the woodruff key by just taking out the Crankshaft Pulley?

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VStar650CL
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Re: Main Damper Bolt?

Postby VStar650CL » Sat Aug 20, 2022 8:07 pm

It should be, yes. There are actually two woodruffs, one for the balancer outside the front cover and another for the timing gear behind the front cover. Removing the balancer should expose the outer one.

John16
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Re: Main Damper Bolt?

Postby John16 » Sat Aug 20, 2022 8:11 pm

Ok got ya! How would I know If I need the one behind the front cover as well? Is here a way to verify? What are the symptoms of a bad key? I just got this engine rebuilt! This is what I get!
I got the seal and the woodruff key, got my torque wrench and I'm ready to install one of these days. Not difficult to do. Im still gonna take it to the shop so they can take a look at it as well.

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Re: Main Damper Bolt?

Postby VStar650CL » Sun Aug 21, 2022 6:30 am

The engine will have jumped time if the woodruff for the timing gear is stripped. That would be pretty much catastrophic on an interference engine, but if the engine will turn and has compression then the timing gear is fine. It's very unlikely the timing woodruff would have a problem, the gear is trapped behind the timing cover and can't move forward very far even with the balancer removed.

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Re: Main Damper Bolt?

Postby John16 » Sun Aug 21, 2022 3:40 pm

Thanks again! That's what I tough. You see like i said before this engine just got re-built and this is the last thing you can expect from a new engine literally. I told the shop that sent the engine to another shop and as soon I tell them they say that's the machine shop error and Im like ok but I'm under warranty so what's the deal? They said to me to bring it to them and I ask is this free? He didn't say nothing about that he just said just bring it to take a look at it so im afraid they will charge me for any intervention since is the machine shop fault. I personally think that I don't need to pay a cent.

Will see , I'll give a final result on this issue.
Thanks
JS

John16
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Re: Main Damper Bolt?

Postby John16 » Mon Aug 22, 2022 1:36 pm

Hello hello! So after a visual inspection things dont look too good. I took a couple of pictures and will like your opinion on how to fix this issue. Also is that little notch behind it for the other woodruff i mean for the one that gows inside the timing chain cover? It confuse me thinking that is for the same woodruff in front. Any advise will be greatly appreciated.
Oh by the way why in the world would this happened> Having in mind that this engine just got rebuilt? :facepalm:
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VStar650CL
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Re: Main Damper Bolt?

Postby VStar650CL » Mon Aug 22, 2022 2:16 pm

That looks chewed but only at the top, you can probably file or dremel it clean. The slot behind it is in the timing gear, it has to slide over the inner woodruff just like the balancer slides over the outer one. The shop probably forgot to tighten the balancer bolt and it gradually came completely out, letting the balancer walk off the crank. The damage in the keyway would have occurred right before the balancer came off, when the woodruff was being torqued sideways. That's why the damage is all at the top of the slot and not at the bottom. That's fortunate, because the only way to fix damage to the whole slot would be to machine it for a straight key or replace the crank.

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Re: Main Damper Bolt?

Postby John16 » Mon Aug 22, 2022 2:26 pm

wao So hummm ill see what the shop can do and tell them what you just indicated.Option number one will be to machine and clean it good to fit since the key to slide into the notch against the timing chain as you can see is blocking its path. To make sure the key fits nice and tight as well, Changing the crank will be to open engine again and more money. How about after that work is complete putting some threadlocker on the bolt? :facepalm:

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Re: Main Damper Bolt?

Postby VStar650CL » Mon Aug 22, 2022 4:13 pm

Threadlocker won't be necessary if the woodruff is a good fit. The bolt is torqued to 108 lbs for a reason, but what really prevents it from working loose is a tight key. Consider what happens if the key is slack. The balancer can twist ever-so-slightly back and forth on the crankshaft every time the load changes, and the CCW twist will loosen it but the CW twist may not re-tighten it. So very slowly the bolt works its way out and the balancer with it. So the bottom line is, that key must be a decent fit, or all the threadlocker on earth won't prevent the bolt from working loose.

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Re: Main Damper Bolt?

Postby John16 » Mon Aug 22, 2022 4:43 pm

Thats the thing that when measuring the key the new oem key i ordered it seems too loose in the gab of the pulley and the tip of the crankshaft it seems that it wont fit tighly unless theres a way around and let the shop do their magic.

So ,y last question for now will be, The key has to be inserted in both hatch ends right? I mean it has to reach and go inserted on the xnatch coming from the cover chain and the other end into the tip the pulley.

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Re: Main Damper Bolt?

Postby VStar650CL » Mon Aug 22, 2022 4:51 pm

John16 wrote:
Mon Aug 22, 2022 4:43 pm
So ,y last question for now will be, The key has to be inserted in both hatch ends right? I mean it has to reach and go inserted on the xnatch coming from the cover chain and the other end into the tip the pulley.
No. it's a half moon key and the timing gear has its own key just like it. The latter is inside that slot in the timing gear and out of sight. The balancer key only secures the balancer and doesn't need to extend back. The key can be loose on the front-to-back axis, once the balancer is in place the straight edge will keep it from turning. It needs to be a snug fit side-to-side so it doesn't let the balancer rotate on the crank nose.

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Re: Main Damper Bolt?

Postby John16 » Mon Aug 22, 2022 7:54 pm

Right! Got ya! The woodruff won't stay tightly. Even at the pulley it stays loose. How to install this half moon thing. Put the pulley first and snuggle it softly? Or stick it on the crankshaft first and then get it in with a rubber hammer?

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Re: Main Damper Bolt?

Postby VStar650CL » Mon Aug 22, 2022 8:30 pm

Put some axle grease on it to hold it in place, and incline it ever so slightly toward the balancer so the groove in the balancer can pass over it to get it started. Then tap the balancer on, the key will rotate flat once it's fully beneath the groove.

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Re: Main Damper Bolt?

Postby John16 » Mon Aug 22, 2022 11:09 pm

This is the only thing i can relate my issue with and solution

https://youtu.be/z7PGGGW7MHA

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VStar650CL
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Re: Main Damper Bolt?

Postby VStar650CL » Tue Aug 23, 2022 5:02 am

If the slot is too sloppy then I don't see why JB wouldn't work. The repair will basically be "trapped" underneath the balancer, so the epoxy can't go anywhere once the balancer bolt is tightened. It's certainly a cheaper option than replacing or machining the crank.

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Re: Main Damper Bolt?

Postby John16 » Tue Aug 23, 2022 7:23 pm

I have no clue what you ment by..."The repair will basically be "trapped" underneath the balancer, so the epoxy can't go anywhere once the balancer bolt is tightened""

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Re: Main Damper Bolt?

Postby VStar650CL » Tue Aug 23, 2022 7:37 pm

The slot and hole in the balancer are a tight fit to the nose and key of the crankshaft. So once they're assembled together, if there are no voids in the epoxy, it can't collapse and has noplace to go.

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Re: Main Damper Bolt?

Postby John16 » Fri Aug 26, 2022 7:32 am

So the protect is coming out as planned. Got the woodruff put back in place fill damage with litelock 660 something like that. Anyway so Im tighning my balancer bolt put it in gear to specs at 110psi and it keeps spinning. Is theres any other way to tight this bolt without the engine spinning?

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Re: Main Damper Bolt?

Postby VStar650CL » Fri Aug 26, 2022 8:30 am

Pop out the handiest plug and feed some rope into the cylinder. The rope will jam it when it hits TDC and then it won't be able to spin further. Yank the rope out once you get the bolt tight.

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Re: Main Damper Bolt?

Postby John16 » Sun Aug 28, 2022 5:45 pm

I dont get it

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Re: Main Damper Bolt?

Postby VStar650CL » Sun Aug 28, 2022 6:51 pm

Feed some rope (regular rope like you use to tie up a boat) into the spark plug hole. When you turn the engine from tightening the bolt, the rope will coil up as the piston rises in the bore and stop it at the top of its travel. Then the crank can't turn further and the bolt will tighten. You just pull out the rope and reinstall the spark plug when you're finished.

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Re: Main Damper Bolt?

Postby John16 » Sun Aug 28, 2022 7:21 pm

I pass on this advise. Any other way?

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Re: Main Damper Bolt?

Postby VStar650CL » Sun Aug 28, 2022 7:50 pm

Sure, if the car is a M/T you can put it in gear and let the tranny and clutch hold it for you, but make sure you e-brake and block the crap out of the wheels. You can also deliberately hydro-lock a cylinder by removing the plug and filling the cylinder with oil, then reinserting the plug. When done, pull the plug again and crank the motor to spit the oil out. Or you can yank the starter and wedge the ring gear. Rope is easiest, least dangerous, and least messy.

John16
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Re: Main Damper Bolt?

Postby John16 » Sun Aug 28, 2022 8:57 pm

It is a M/T even though in gear and e-brake still spins. I think I will keep on searching better. Thanks.

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Re: Main Damper Bolt?

Postby VStar650CL » Mon Aug 29, 2022 5:13 am

John16 wrote:
Sun Aug 28, 2022 8:57 pm
It is a M/T even though in gear and e-brake still spins. I think I will keep on searching better. Thanks.
Not a good sign. The only place it can slip and let the engine spin is the clutch. :tisk:

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Re: Main Damper Bolt?

Postby John16 » Mon Aug 29, 2022 10:01 pm

Then my Tranny is jacked!! It runs really good. No issues with the tranny! It shifts nice and smooth!!

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Re: Main Damper Bolt?

Postby VStar650CL » Tue Aug 30, 2022 4:29 am

John16 wrote:
Mon Aug 29, 2022 10:01 pm
Then my Tranny is jacked!! It runs really good. No issues with the tranny! It shifts nice and smooth!!
No, either your clutch is wearing out or your pressure plate is jacked. If it's slipping with 100 lbs/ft from a torque wrench applied to the crank, it will be slipping when the crank applies 100 lbs/ft to the tranny.


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