RB26powered74zcar Posted March 1, 2003 Share Posted March 1, 2003 Hey everyone! I have this reacuring problem with my crank dampner mod. As you can see in the pics, they don't last very long. The problem is with the floating (alt. pully) portion rubber. It keeps spinning loose. The backside of my dampner must be turned down as in the second pic, so that my TEC2 trigger wheel can be put on the backside. What I need to know is what do you think about tacking (welding) the solid pully (air con) to the floater (WP/Alt) pully. Would it be that big of a deal if none floated instead just one? ya know, make them both solid.... Whata you think?? Quote Link to comment Share on other sites More sharing options...
jeffp Posted March 2, 2003 Share Posted March 2, 2003 Well hi there, I also have been dealing with this issue as you may know. I have had a new three belt dampener made that will not seperate like the stock units will. The problem is that once you start spinning them in the 6K and higher rpm ranges they will always seperate. The Euro dampener Nismo has is just as bad for seperating. I have not called BHJ this week, but the new unit should be completed by now. Also Robello Racing has the single grove dampener that they made already if that is an option for you. The thing about the three belt dampener that you may be interested in is that options for that third blet pully. The dampener is made so that the third pully is optional so you can remove it and mount your crank trigger to that part of the dampener. I did mention to Brian the prospects of making the dampener in such a way that the after market EFI systems could mount a crank angle sensor to the dampener and that was a consideration when they designed the new part. I think this would be the best option for you, and for Donna when her dampener does what your and my dampener did (and it is going to seperate on her car also) This has been a big problem with the stock dampener, and any dampener Nissan has made for the L series engines. They just did not make the part to sustain high rpm levels and stay together. The majority of the drivers out there will not turn their engines to 6K-7K rpm's frequently so they tokk their best option and made the unit to cater to the average engine speed and the others could just buy a new part when it seperated. Your question regarding welding the two parts together is a valid question, but I would not recommend doing so. The harmonics that break cranks just happen to be in the 7k-7200 rpm ranges for the L28 engines, and in the 3-3500 rpm ranges. Looking at those numbers, that puts the most damaging harmonics in the max rpm ranges that I am sure you get to frequently, and worse yet in the cruising rpm ranges. I researched this problem to a great extent and did find some solutions that you may also want to look at. ATI also makes a NHRA dampener for the L series engines by Nissan, but for my application it was unsuitable. That part just may work for your application. Other then the ATI part there really is no other option for our engines and that is why I had BHJ design a totally new part. I sent in a three groove dampener, and Dave Robello sent in a two groove dampener. Both units were sent out for harmonic testing and returned the same harmonic dampening charactoristics. With this data BHJ developed their dampener. The only thing they forgot about was the relief cut in the back of the dampener for the timing chain front cover. So when they tried the dampener on an engine at Robello's shop it hit the cover. They had to wait until a run of dampeners were completed to do the modification on their unit and that was about two weeks ago. I will contact them Monday and get the status on the part. Anyway, I would strongly recommend that you do not weld the dampener and run it on your engine. I know you have allot of money invested in your engine, and it would really be bad if you broke that stroker crank, it would really ruin your day. In this case it is better safe then sorry, and if you do get this new dampener, installing the crank angle trigger on the unit will be easier they you would think. just my O2 Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted March 2, 2003 Author Share Posted March 2, 2003 Thanks Jeff for the info... I received a personal email from a guy on this issue, and this was his suggestion for a fix that impressed me as a damm good solution. On my big block we drill three small holes in the groove section andtapped in solid steel pins and ground them flat. I did not have to worry about spining it. Nikko Holguin SureShot PowderCoating 281-282-9907 I think I will give this a shot untill we can come up with a good new part... thanks again guys... Quote Link to comment Share on other sites More sharing options...
jeffp Posted March 2, 2003 Share Posted March 2, 2003 You can do that with the bolts, but again you will basicall be doing the same thing as welding the part. I would not recommend that as a solution to your problem. The point is that you need the dampener to do its job. There has to be a certin amount of flex in the dampener in order for it to do its job. If you want go go that route, and I would highly recommend that you dont, you may as well have a pully made. Paeco can make a pully for you for about 200.00 I realize this is a real problem for you, but you will end up with an outcome I dont think you will be very happy with at all if you take away all of the dampening charactoristics of the part. Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 2, 2003 Share Posted March 2, 2003 I lost a dampner while road racing, which stopped spinning the water pump. I checked the gauge at the end of the straight (long straight) and the temp was way past 240* I'd guess 280*+. I warped the head, holed a piston and most of the piston chunks stuck/ bonded to the head. I'm not trusting stock dampners any more. I just put some Az Z Car pulleys on. I will find out if not having dampening is worth the trade for a reliable crank pulley. I have only had the car on a dyno, so I can't give any long term feedback yet. Quote Link to comment Share on other sites More sharing options...
TimZ Posted March 2, 2003 Share Posted March 2, 2003 Jeff is spot on with his comments. These cranks are well known to have problems with harmonics at high rpm. It's pretty much unavoidable with a long crank like you have on an L6. While there are several suppliers out there making solid crank pulleys, I have no faith whatsoever that any engineering goes into these products, save for maybe making sure they fit (sometimes they don't even do that much). Hell - Unorthodox Racing has repeatedly demonstrated that they don't even understand the issue. This should worry you. Alot. If you only need a single groove pulley, then you should consider the ATI piece. If you need more than that, the options that Jeff is researching look pretty promising. Personally, I never liked the idea of machining the floating part of the stock pulley, and then adding the rotating mass of the trigger wheel to it. The mass of the floater and the durometer of the rubber are critical to determining the damping characteristics of the pulley, and I can't help but think that this mod will screw that up. Because of this, I had a sleeve machined that fits into the center of the stock pulley (the solid part), and the trigger wheel mounts to that, instead. I have been running this setup for five or six years now with no problems (knock on wood) with seperation. One final observation - the pulleys in the picture don't look like they are particularly new. Please tell me that you weren't relying on a (possibly 20 year old) junkyard pulley. If so, then you shouldn't be too surprised that it failed. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted March 2, 2003 Share Posted March 2, 2003 Are stock dampners rebuildable or do we need to visit our local Nissan dealer for a new one? I need a two groove pulley with my setup so I guess I'll have to wait for JeffP's solution or keep the stock unit. The ATI solution would be perfect if only they had two or three pulley grooves. Can a custom two or three groove pulley be adapted to the ATI balancer? This seems like the easier way to go rather than having a whole new dampner designed. I'm watching this thread closely as I expect to have a higher RPM range with my new (almost installed) cam. Personally I will never go with a solid balancer as I've heard too many stories about high RPM crank problems in the L6. Regards, Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted March 2, 2003 Author Share Posted March 2, 2003 On my big block we drill three small holes in the groove section and tapped in solid steel pins and ground them flat. I did not have to worry about spining it. What I would do with this idea is, NOT bolt these pullys together per say. If you were to drill say a 1/8 hole all the way thru the floater and the solid, then drill in the same hole, a 3/16 hole but only go thru the floater pully, then you could press a 1/8 pin thru the 3/16 hole and this way would not bind them together... The pin would have a press fit in the solid pully but allow the floater to still "float" but not spin.. Whata ya think ?? Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted March 2, 2003 Share Posted March 2, 2003 Well, I did spin a pulley 3 years back, but do not know the age of that pulley and I did get oil on the dampener material which eats it up. My new Euro pulley has lasted 3 years with no problems and I rev it to 7200rpm all day long. Also, my trigger wheel was secured to the center portion of the pulley and not the dampened portion. Maybe I am just lucky and maybe TimZ has just been lucky, but until my luck runs out I will stick with a new stock jobber. Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted March 2, 2003 Author Share Posted March 2, 2003 I sure would like to see some pic's of the way you guys have yours set up. Quote Link to comment Share on other sites More sharing options...
jeffp Posted March 3, 2003 Share Posted March 3, 2003 A couple of things here that I noticed in some of the posts. The mounting of the trigger wheel should NEVER be attached to the pully, in other words, the trigger should be mechanically be attatched to the crankshaft so that it will not move from its location under any operating circumstances. The pully on the dampener, though it is fixed for the most part well, will move on its relative position. That is why it seperates, so what is happening is the TDC notch on the trigger wheel will be moving before and after TDC under various operating conditions. This is incorrect palacement of a crank angle trigger. You must make the TDC trigger accurate and mot a moving mark even if it is but a couple degrees. Thatt will screw up your whole fuel management system. This will not make it unfunctional, but it will not let you optimize the system either as the trigger points for the various components will be slightly off of the exact timing mark they need to be at to get the correct trigger. I called ATI and spoke to them at length regarding their product, and I was very impressed with the dampener. I did however find out and figured what it would take to install the pully/s that would be needed for the cars. In my case and every case, the pully/s would have to be made, and they would be bolted to the front of the dampener. Doing the calculation of the spacing of the pully/s and comparing that to a strock dampener/pully, the part on the ATI dampener would sit to far forward to the rest of the pullies on the engine like the water pump and alternator pullies. Now I did design a pully, that would be built to fit over the dampener, and place the groove in the correct positioning for the water pump and alternator, and that is doable. I had the drawing completed with the parameters of the pully and was seriously considering that option. The one thing that made me scrap the project was the fact that I could not get the pully the correct diameter to spin the various components at the correct speed because of how the pully had to be machined to fit over the top of the dampener. The dampener if I recall correctly is 6.500 in diameter, and the pully for the stock dampener was about 6.800 at its biggest diameter. That was not enough meat on the pully (made in aluminum) to make it strong enough to work, and get a belt on it at the same time. then there was the option of making the pully bigger to compensate for the difference and that would have made the water pump spin to fast, but if I remember correctly AZ zcar has a pully for the water pump that is an under drive pully. The last option I looked at was going cerpintine belt and tht would have been very cool and very functional, but again all of the pullies on the engine would have to be made. So what do we have with the ATI dampener. We get to change the dampener @ $450.00 the new pully @ $200.00 and the AZ pully @ $100 for a grant total of about 750.00 plus the shipping and all that jazz. I felt that was a little to expensive an option and that the majority of the guys out there would not even consider it. The cerpintine belt sure would be killer tho. So I then asked if they would design a dampener, NO. Then I called fluid dampener to see if they had anything that would work, NO, they had much the same configuration as ATI regarding application and size of the part. I then asked if they would make a dampener, again NO. The truth is that hte fluid dampener would be IDEAL because it would attenuate all second order harmonics across the frequency band at any rpm level. Ever wonder why top fuel cars run fluid dampeners??? that is why. So you could say I was shot down in flames. I then did some more calling and found BHJ that would be willing to make a unit that would fit our applications and requirements. That is when I started working with them, and found out I was about a couple of weeks behind what Dave Robello did with the single grove dampener, and that is available now through Robello racing ONLY. Robello incured all of the engineering costs for that part and hold the patent on the dampener. The one Brian and I are, were working on is going to be a BHJ part, with a BHJ part number, and as I said, it should be just about completed. So there you have it. Now drilling the dampener so that it has some movement, but limited to what Joel has suggested may work, but to be sure you havent screwed up the dampening effect of the part, it really should be tested for harmonics attenuation to ensure it still operates as it was designed to work. You know, yopu can do what ever you want with your cars, but for me, I have entirely to much invested in my mechanical rotating assembly to take a chance I will make a bunch of bent broken parts. That is precisely wht my car has not been on the road, and I am not going to throw good money away again to have the same problem. I will wait for my new part and go from there, besides, I have decided to build the engine bigger, and get a newly modified tranny that will handle the power along with a number of other modifications I have been waiting to do to the car. I really do hope this info helps you guys and gals out. I did spend a lot of time in research and explored all options before I decided to have BHJ make the part, and it was the best solution, and the cheapest solution to a big problem that keeps rearing its ugly head every time someone turns around (get it, LOL, I just break myself up LOL) anyway! Quote Link to comment Share on other sites More sharing options...
Synlubes Posted March 3, 2003 Share Posted March 3, 2003 My new Euro pulley has lasted 3 years with no problems and I rev it to 7200rpm all day long. James, Are you talking about the High Dollar signal pulley one that Nissan sells? Or is there others? Quote Link to comment Share on other sites More sharing options...
jeffp Posted March 3, 2003 Share Posted March 3, 2003 Robello had a new part designed and made. The EURO dampener was only lasting 5-6 races and it also seperated according to Dave Robello. Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted March 3, 2003 Author Share Posted March 3, 2003 The mounting of the trigger wheel should NEVER be attached to the pully, in other words, the trigger should be mechanically be attatched to the crankshaft so that it will not move from its location under any operating circumstances. The pully on the dampener, though it is fixed for the most part well, will move on its relative position. That is why it seperates, so what is happening is the TDC notch on the trigger wheel will be moving before and after TDC under various operating conditions. This is incorrect palacement of a crank angle trigger. You must make the TDC trigger accurate and mot a moving mark even if it is but a couple degrees. Thatt will screw up your whole fuel management system. This will not make it unfunctional, but it will not let you optimize the system either as the trigger points for the various components will be slightly off of the exact timing mark they need to be at to get the correct trigger. I don't know what pully set up your refering to here. Mines not attached to a floating pully where it can move around... It's attached to the back of the pully on the part of it thats solid. There is no way this trigger wheel can move. It's screwed to the peice that the large crank bolt goes thru. I think the best set up would be to not have to take any material off the backside, but to attach the wheel on the front of the pully, like TimZ stated he did. I can't use the single groove pully because I MUST have my air-con Quote Link to comment Share on other sites More sharing options...
D83ZXT Posted March 4, 2003 Share Posted March 4, 2003 Joel, My crank trigger is also mounted in front as TimZ said, with a custom made perfect machined billet insert for mounting it "into" the outer pully. (I can send you pics if you need) I couldn't wait around for one to be made, so I went ahead and bought a brand new Nissan unit so I could get my new motor balanced. Donna Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted March 4, 2003 Share Posted March 4, 2003 280 crank pulleys can't take the rpms.I wasted two of em in the past. There were two different sized pulleys made for the 2.4L The early pulley has a smaller diameter. I have run the early 2.4L pulley on my 2.9L stroker motor for over 4 years now.It's over 32 years old and gets spun to 7000 rpm about every time I take off down the road. They might be harder to find now, but they do seem to hold up allot better than the later ones. later,norm Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 5, 2003 Share Posted March 5, 2003 Maybe i'm just being stupid here, because there is some serious mecca on this post, but here goes: From what i understand of this issue is that only 2 or 3 groove pulleys have this separation issue. If that is correct, when the new electric water pump finishes(due real soon or maybe done now, from CSI?) whats to stop you guys from just running a single groove pulley driving only an alternator. Cuz thats all you'd need, if the water pump was electric and im shure that most of you guys run electric fans? I cant see a reason why this hasn't been brought up IE you guys are serious racers thats why you have the balancer issue, yet serious racers could gain from the electric pump idea.... i know that i will be using the electric option it will free significant rotating and pulley drive mass. It will make the engine more responsive and posiblly gain at least 5hp. Would think that a single groove pulley would me stronger wouldnt it physically lessen the resonation of the crankshaft due too less mass/load on it? Quote Link to comment Share on other sites More sharing options...
TimZ Posted March 5, 2003 Share Posted March 5, 2003 Not a stupid question. The electric water pump is an interesting proposition. Unfortunately, the alternator and the water pump share the same pulley, so that won't buy you anything - you'll still need the same number of pulleys. The second pulley is for the AC - in some parts of the country you can't easily part with it in a street car. With a single groove pulley you still need the dampner, but there are some workable solutions available for that. Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted March 5, 2003 Share Posted March 5, 2003 It's a DAMPER. Not DAMPENER or DAMPNER. It DAMPS crank torsional harmonics, it doesn't dampen or dampn them. Damper damper damper. Or harmonic balancer. My possibly 30+ year old stock 2-groove one lasted about 38 track days, with 7000 rpm seen routinely and more on a couple of overrev occasions. I installed a new single-row Nismo unit at the beginning of last year, as I could see chunks of rubber missing from the old one. Am I now in greater danger of this new one coming apart? It's the same size as the old one, BTW. Narrow groove, also, unlike the wider groove unit that came in '7?. Quote Link to comment Share on other sites More sharing options...
jeffp Posted March 7, 2003 Share Posted March 7, 2003 you could be in some danger of the part seperating. I will say tho, that Robello spins his engines to 8500 rpm for the cars they build engines for, and according to Dave the Euro damper (or dampener which ever suits your fancy) was lasting 5 to 6 races. Quote Link to comment Share on other sites More sharing options...
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