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-   -   Putting a crank pulley on a Lathe, Good Idea??? (https://www.miataturbo.net/engine-performance-56/putting-crank-pulley-lathe-good-idea-27060/)

patsmx5 10-15-2008 01:21 AM

This is like a thread where you debate the weights of different fire extinguishers. I mean come on. Some things are better left alone. You know that's a really important part that was designed around the 1.8L engine it's bolted too. How do you know a different one from a different engine retrofitted to it will work? What if a balancer from some honda weighed 5 lbs less and bolted right up? Would it protect the engine?

Lord help us all you better be running a 1.6 aluminum flywheel and the lightest clutch available for it if you're worrying about loosing 1/2 a pound with a low moment of inertia on a highly critical part.

Curly- I still don't think you get it. The ruber is not the balancer. The unit is the balancer. Big hunk of metal bolts to crank. Big steel ring goes around it and is mounted by a rubber ring. You mess with the big metal ring, you're messing with the dampner. It's NOT just the rubber ring.

patsmx5 10-15-2008 01:23 AM

Nother thought: You could try running only 4 flywheel bolts instead of 6. Or maybe 3 oddly spaced. Or maybe ditch the lock washers and use a spec of locktite instead. Maybe drill the centers of the bolts out to. And grind the heads down some after torquing them. Why not?

944obscene 10-15-2008 01:40 AM

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Originally Posted by hustler (Post 319331)
ok. if thats how you want it to be, your choice. do you honestly think i cant bribe rick for your ip adress? everyone has a price. im on 2 grams of test a week and a gram of tren. do this a couple months back, ok i mightve let it slide, now, someone so much as looks at me the wrong way and theres gonna be probs, lucky for me they always back the fuck down so i dont gotta get my hands dirty. i know youll try the same when shit hits the fan but dont think ill be so linient, cause i wont. dont say i didnt warn you.

Jesus tits...

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matttheniceguy 10-15-2008 04:13 AM

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Originally Posted by curly (Post 319896)
yup its agreed, no damage to the harmonic balancer if you don't touch the rubber, and a little less than a 1/2lb of weight savings, whoopie.

Not quite true. You can't touch the rubber, or anything suspended by the rubber. Technically changing the weight of anything in the entire rotating assembly will have an effect on the efficiency of the damper, but it is not nearly as pronounced.

If the material you want to remove is attached to the inner ring in the uber-ghetto picture attached, you can safely remove it (from a vibrational standpoint at least). If it is attached to the outer ring, then it is a functional part of the damper and removing it will effect the dampening. Removing this material won't destroy the damper completely, it will just change it's natural frequency (increase it if you remove material), and this will change the effectiveness of the damper over different RPM ranges. For example, you could change where the damper is effective, and make it not effective in a range that you regularly operate your engine at.

Does anyone happen to have a link or something to some decent damper design info by any chance? They're pretty simple torsional vibration systems and the math behind them shouldn't be all that tricky, I'm surprised they still seem like such a dark art.

paul 10-15-2008 07:43 AM

uber ghetto is right. Can you say wobble?

What's funny is Mike is a local to me and he posed this question a day or 2 within our local club. I answered him with a resounding NO and he said OK, he won't touch it. Then he goes and posts it on here. But then again this is the kid would wants to go through all the effort of putting back together and installing a block with rusted cylinder walls with the only R&R on the engine being going around each cylinder with a rubber squeegy to rub the rust off while the pistons are still in the block! I get no respect.

patsmx5 10-15-2008 08:30 AM


Originally Posted by paul (Post 319954)
uber ghetto is right. Can you say wobble?

What's funny is Mike is a local to me and he posed this question a day or 2 within our local club. I answered him with a resounding NO and he said OK, he won't touch it. Then he goes and posts it on here. But then again this is the kid would wants to go through all the effort of putting back together and installing a block with rusted cylinder walls with the only R&R on the engine being going around each cylinder with a rubber squeegy to rub the rust off while the pistons are still in the block! I get no respect.

Psh, what do you know about turbocharging a miata or harmonic balancers????

Mike, you don't know me or curly. You can't trust some guy on a forum. How do you know I'm right? You don't. I could be pulling all this out of my ass. Either "play it safe" and leave good enough alone (assuming stock is good enough), find someone more knowledgeable you trust whos experienced and take their advice, or do your own research on the matter and draw your own conclusions.

MikeRiv87 10-15-2008 11:28 AM

In god we trust... Says it on the dollar bill. Oh and Flyin' Miata told me i can use the 1.6L pulley on a 1.8L

curly 10-15-2008 09:03 PM

PS pulley is not suspended by the rubber on the 1.6 pulley. which is why I removed it, but did not go further by removing the 'nose' labeled in my previous pictures. And as I said in the beginning, you could face off that nose to save some more weight, while still maintaining a harmonic balancer. whether or not that harmonic balancer with the lightened load would still work, I have no idea.

To add more fuel to this fire, if the damper was so sensitive, wouldn't removing the tension of the p/s belt or a/c belt affect the properties of the damper?

curly 10-16-2008 12:01 AM

I should clarify, my MS Paint drawing on the first page is incorrect, the green line representing the rubber should be to the right of where the PS pulley is secured, which means the PS pulley (again, on a 1.6 only) is not part of the weight for the harmonic damper

I also wanted to say Patsmx5 makes a good point, the weight reduction is very minimal and is probably not worth the effort, much less does it make any difference. my car is street legal, yet only really used for racing (<1000 street miles per year) so any weight reduction is good by my book. I also work in a machine shop, so I didn't spend any money, I didn't even take time out of my day to drive to a friend's machine shop, I simply brought the pulley to work and spent 1/2 of my 10 minute break on the lathe.

matttheniceguy 10-16-2008 01:37 AM


Originally Posted by curly (Post 320229)
To add more fuel to this fire, if the damper was so sensitive, wouldn't removing the tension of the p/s belt or a/c belt affect the properties of the damper?

Sure would, but I don't think by a noticeable amount. The stiffness of the crank and damper are much much higher than that of the belts, and the vibrations that the damper is made to dissipate are at fairly high frequency (and very low amplitude). The belts are on the damper and would have some effect on it, but I am fairly sure the frequency's are so high and the stiffness of the belts so low that it would not really change anything.

MikeRiv87 10-16-2008 11:09 AM

I wanted to remove the PS Pulley purely for aesthetics. The slight weight reduction is an unintentional added bonus.


Originally Posted by paul (Post 319954)
What's funny is Mike is a local to me and he posed this question a day or 2 within our local club. I answered him with a resounding NO and he said OK, he won't touch it. Then he goes and posts it on here.

What's also is funny is that you didn't mention our local club is a SMS based Text messaging service. You could only reply with a "No" because there is not much room for elaboration. Perfectly valid to post here for the full story.

paul 10-16-2008 05:43 PM


Originally Posted by MikeRiv87 (Post 320458)
I wanted to remove the PS Pulley purely for aesthetics. The slight weight reduction is an unintentional added bonus.



What's also is funny is that you didn't mention our local club is a SMS based Text messaging service. You could only reply with a "No" because there is not much room for elaboration. Perfectly valid to post here for the full story.

Aesthetics? You mean assthetics. Your cara was painted by a crackhead who offered to give you head for an additional $5. How concerned were you with the cars looks then? And then you drilled a hole through the hood when installing hood lifts. And I'm sure a few of us remember how you "rolled" you fenders in my driveway.... HAHAHAHAHAHAHA

No is no. Is it not?


I love Mike's threads.

patsmx5 10-16-2008 06:23 PM


Originally Posted by paul (Post 320614)
I love Mike's threads.

I feel like I'm just wasting my time replying to all his threads. Seems like he's looking for us to say what he wants to hear.

paul 10-16-2008 06:38 PM

seriously. 1 engine = 4 failed threads

thread 1 was of the original pics of the shitty engine
thread 2 was of the "reconditioned" with rubber squeegy engine
thread 3 was destroying the harmonic balance to give shitty engine even more reason to fail
thread 4 was trying to sell 100% perfect pistons/rods from shitty engine

did i miss any?

patsmx5 10-16-2008 07:00 PM

Hey now, never underestimate the power of rubber squeegies...

Now the truth comes out He said he "honed it 3 spins" in his thread. I...... doubted that.

First of all, 3 spins with a hone wouldn't do anything. It takes a clean cylinder and a hone on a drill a while. Easy to spend 10 minutes just honing one cylinder to get the final clearance right. Hell they make threads where you manually crank down the tension to speed the process up.

Second it had he honed it, it would be pretty obvious. Clean scratches intersecting one another. From his pics, it looked like he too steel wool to them or something.

btabor 10-20-2008 05:07 PM

I had an OBX crank pulley on my short nose. My uncle machined the a/c and ps groves out and it worked fine. This was done in 3 different STS2 miatas and none of them ever had a problem. The pulley cost $60. We also had to drill new holes on it because the original ones were a little off. But compare $60 to $100+ from other brands an you have a good deal

paul 10-20-2008 10:54 PM

and how much power were these miatas in sts2 making?

btabor 10-22-2008 08:11 PM


Originally Posted by paul (Post 321902)
and how much power were these miatas in sts2 making?

At a dynojet here in Indianapolis, one (lets say A)was low in power @ 110hp at the wheels @ 16 degrees of timing. That was before a rebuilt, the leak down test for A showed some substantial leakage.
Specimen B pulled 120 hp with only 10 degrees of timing. But the head was rebuilt by Steward Engines and we havent dynoed it yet.
Specimen C (used to be my car) was never dynoed, leakeage tests were excellent after using the pulley for an year and 3 months on a gt2554 pulling around 200hp (I estimate).
(ALL THESE SPECIMENS WERE SHORT NOSE)
I think as long as you do a professional job (not cutting the pulley with a hack saw) you will be fine. This is just my opinion

patsmx5 10-22-2008 08:14 PM


Originally Posted by btabor (Post 322634)
At a dynojet here in Indianapolis, one (lets say A)was low in power @ 110hp at the wheels @ 16 degrees of timing. That was before a rebuilt, the leak down test for A showed some substantial leakage.
Specimen B pulled 120 hp with only 10 degrees of timing. But the head was rebuilt by Steward Engines and we havent dynoed it yet.
Specimen C (used to be my car) was never dynoed, leakeage tests were excellent after using the pulley for an year and 3 months on a gt2554 pulling around 200hp (I estimate).
(ALL THESE SPECIMENS WERE SHORT NOSE)
I think as long as you do a professional job (not cutting the pulley with a hack saw) you will be fine. This is just my opinion

Yeah. Good luck convincing paul though. He broke a motor from not running one. And he wasn't the first.

paul 10-22-2008 11:07 PM

1. those are all low power if you ask me
2. a year and 3 mos don't mean shit, you might drive 4000 miles in that time while I drive 50k. how many miles on the 200hp car with butchered pulley?
3. why are we talking leak down tests? the oil pump gear shatters


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