jmark06 Posted February 1, 2006 Share Posted February 1, 2006 I have a 240mm flywheel that I plan to have lightened and put on my turbo motor. When I called the machine shop they said that in order to balance the flywheel after lightening that I had to break the whole engine down. I've attempted to rebuild the engine mostly by myself b/c of money issues. I did not have the crank turned or balanced and now I'm worried that might be a problem but it wasn't out of tolerance when I pulled it. Am I in trouble now (I kept the same pistons and everyting, just changed bearings and had the head reworked) and can the flywheel be balanced without the rest of the engine? Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted February 2, 2006 Share Posted February 2, 2006 The shop asks you to bring the internals to them so they know how much material to remove from the flywheel. They are not going to balance your internals. You bring home the very same crank/rods that you gave them. You can't balance a flywheel without the rest of rotating assembly unless the rotating assembly is internally balanced. THEORETICALLY, without taking the engine apart, you can balance a new flywheel using the original flywheel as a reference(make the new and old equally off balance). BUT you must know the original mounting position of the old flywheel relative to crank or it's useless. Quote Link to comment Share on other sites More sharing options...
zcarman1259 Posted February 2, 2006 Share Posted February 2, 2006 ....THEORETICALLY, without taking the engine apart, you can balance a new flywheel using the original flywheel as a reference(make the new and old equally off balance). BUT you must know the original mounting position of the old flywheel relative to crank or it's useless. Since there's no positioning dowels on Z L6's (right?), then would that apply? Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted February 2, 2006 Share Posted February 2, 2006 If you marked both the crank and flywheel when they came apart then you have the information. Theoretically you can couple two flywheels together and balance them. That'll give you two equally unbalanced flywheels. However if you mention this method to your machine shop they'll just hate the idea. They don't have a perfectly balanced, correct size spindle to rotate the couple with, they don't have perfectly balanced, correct size fasteners to couple the flywheels. It is just easier to give them the crank/rods etc. I am going to balance the whole thing in my L28ET because I use a diesel crank. Quote Link to comment Share on other sites More sharing options...
TimZ Posted February 2, 2006 Share Posted February 2, 2006 You can't balance a flywheel without the rest of rotating assembly unless the rotating assembly is internally balanced. ...so the L-series is not internally balanced? When did that happen? Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted February 2, 2006 Share Posted February 2, 2006 From my point of view, I will be using L24 rods and diesel crank, internal balancing never happened in my scenario. Quote Link to comment Share on other sites More sharing options...
Clifton Posted February 2, 2006 Share Posted February 2, 2006 You don't need to pull your crank to have a flywheel balanced. It would be no different than putting a flywheel from another L on your car. They are balanced seperate from the engine. Just like your wheel and tire is balanced seperate from the hub. HKS sold flywheels that were balanced. They never required a crank sent in. Quote Link to comment Share on other sites More sharing options...
TimZ Posted February 3, 2006 Share Posted February 3, 2006 From my point of view, I will be using L24 rods and diesel crank, internal balancing never happened in my scenario. Yes, you'll need to balance that, but as Clifton just mentinoed, you zero balance the crank/rods/pistons and then zero balance the flywheel seperately. You DO NOT want to balance them as a unit - specifically to avoid the scenario where you have to rebalance the crank whenever you change the flywheel (or the clutch for that matter). Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted February 3, 2006 Share Posted February 3, 2006 ...zero balance the crank/rods/pistons and then zero balance the flywheel seperately... Guess I was wrong about the flywheel balancing. There was a lot of material removed from the flywheel I have so I thought the flywheel must have been balanced with the internals, since the flywheel itself is a even disk. Do I have to match the counterweights of the crank to the weight of the rods/pistons? Because I am contemplating lightening the crank, maybe even drill the crank pins. Either way I would like to get the crank as light as possible. Thanks Quote Link to comment Share on other sites More sharing options...
jmark06 Posted February 3, 2006 Author Share Posted February 3, 2006 So they machine shop should just be able to lighten and balance it by itself? What do I tell them, that the engine is "already balanced internally"? I don't want to sound like I don't know what I'm talking about when I go over there and he tells me he doesn't recommend it. Quote Link to comment Share on other sites More sharing options...
jmark06 Posted February 6, 2006 Author Share Posted February 6, 2006 Anybody? I'm hoping to get the engine in this weekend so I need to have this done soon. Should the machine shop be able to balance the flywheel independent of the rest of the engine after lightening it? Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted February 6, 2006 Share Posted February 6, 2006 Yes Quote Link to comment Share on other sites More sharing options...
zcarnut Posted February 6, 2006 Share Posted February 6, 2006 Your situation reminds me of one I had. I lightened a Maxima flywheel and I wanted it balanced. The machine shop could not balance it separately. Why? Well the reason is they needed something to bolt it to. A crankshaft works very nicely. The balancing procedure is to first balance the crank separately, then bolt on the flywheel and re-balance. I had a spare crank so I was able to balance the flywheel. Maybe this what your machinist is talking about. Quote Link to comment Share on other sites More sharing options...
Mack Posted February 6, 2006 Share Posted February 6, 2006 If they are just lightening it, I dont see how it can get out of balance in the first place. I mean, they are just going to stick it on a lathe or mill some material off the back, right? either way, a uniform amount of material is going to be taken off the entire circumfrence of the flywheel, unless this is jim-bobs machine shop and he is out back with a die grinder........ Thats like having to "re-balance" a brake rotor after having it turned. Not necessary because it is removing a uniform amount of material everywhere on the disc. Tell the machine shop that all L-series engines are internally balanced and dont need a flywheel to balance them out. Most engines that do not have a counterweighted crank are american engines and ALSO have dowel pinned flywheels. Quote Link to comment Share on other sites More sharing options...
jmark06 Posted February 7, 2006 Author Share Posted February 7, 2006 Well I called the machine shop today told him I had an inline 6, nissan 280zx engine that was internally balanced, could he balance the flywheel by himself. He said he would research it and then I called him back a few hours later when he said I need the crank, rods, damper, and flywheel. What should I do, he seems to think that it's not possible without the rest of the engine but several here say it is? Quote Link to comment Share on other sites More sharing options...
TimZ Posted February 8, 2006 Share Posted February 8, 2006 What should I do, he seems to think that it's not possible without the rest of the engine but several here say it is? Find another machinist? Quote Link to comment Share on other sites More sharing options...
olie05 Posted April 4, 2006 Share Posted April 4, 2006 I agree. Get a machinist that does what you want, not what he wants. Quote Link to comment Share on other sites More sharing options...
JessZ Posted April 10, 2006 Share Posted April 10, 2006 I am in a similar situation as you. I'm doing an L28 setup and the engine shop wants me to bring in the flywheel and clutch assembly so they can balance it to the internals. I thought this was the way it's done, but after reading this thread I'm not so sure now. However, the shop I'm using, Lesco, is very reputable. Jon Mortonson from Hybridz had his L series done there I think, so I guess I will just trust them. According to Lesco having the flywheel and clutch assembly balanced to internals just allows the engine to spin that much more freely, but it also seems I would not have to hard press my Lesco guy to leave that part out if I just wanted to save some money. Just go for it, I bet you'll be stoked either way. And this forum is so technical it's easy to keep second guessing youself that you'll spin out of balance ---Hope this helps. Quote Link to comment Share on other sites More sharing options...
TimZ Posted April 10, 2006 Share Posted April 10, 2006 I agree that all of those pieces should be balanced, just not as a single unit. Zero balance the crank and then zero balance the flywheel/pressure plate separately. This way if/when you get a different clutch, you won't mess up the balance of the engine. Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted April 11, 2006 Share Posted April 11, 2006 I am on the same boat as those guys told by their shops to "bring in everything" for a balance job. The shop I went to was a very reputable shop that has been around for some 50+ years and they said I should bring in everything for the balance job after I told them about the whole "I6 is internally balanced" story. Maybe what the shops were after is a level of finer balance higher than that of the stock job. Quote Link to comment Share on other sites More sharing options...
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