inline6 Posted June 3, 2014 Share Posted June 3, 2014 My engine builder has made an observation about the grip length of the hub of my engine damper. I don't have exact measurements on me, but when the damper is installed on the front of an L6 crank, the hub portion over hangs the front of the crank snout by a good bit... like more than an 1/8 of an inch, I think. I have removed (and chucked) the stamped steel oil slinger, by the way. And the amount of "grip length" is not all that much in comparison to other engines with which he is also familiar. Because vibration can become an issue on these L series engines at engine RPM's I plan to be going through, I'm wondering if anyone has done some investigating to see if the damper could be installed onto the crank snout a bit "more" with "modifications". My engine builder is going to be taking a look into this. The oil pump drive gear has a lot of "wasted" area on the front side of it. However, he is going to look to see about where the oil seal is in relation to the damper. Assuming that the damper won't bottom out on the front of the seal, and there is room on the OD of the damper hub/shaft for the oil seal to still ride on the portion that is not radiused, he will look at what would need to be done to the alternator/pulley, and water pump/pully also. As with anything on these engines, I don't want to go off into uncharted waters... If this is ground that has already been covered, I'd appreciate hearing about it. Thanks in advance, Garrett Quote Link to comment Share on other sites More sharing options...
Xnke Posted June 3, 2014 Share Posted June 3, 2014 The space is normally used to allow the crank bolt washer to be thick enough for a centering register while still not contacting the nose of the crankshaft...that gap is there to make sure that you don't clamp the crank bolt up on the crank, instead you should be clamping the crank damper. Quote Link to comment Share on other sites More sharing options...
inline6 Posted June 3, 2014 Author Share Posted June 3, 2014 (edited) The space is normally used to allow the crank bolt washer to be thick enough for a centering register while still not contacting the nose of the crankshaft...that gap is there to make sure that you don't clamp the crank bolt up on the crank, instead you should be clamping the crank damper. Ok, noted. I realize that some space there is necessary to keep the washer from bottoming - so proper torque can be achieved on damper installation. My engine builder and I discussed the washer I am using a bit. I am using the Nissan Comp bolt and washer. That washer has a step in it which puts some of the washer inside the hole in the damper hub. I was under the impression that the part of the washer that goes inside the front of the hub ID performed the same function as sliding the damper onto the crank a touch (.060"?) more, but he says absolutely not - that the part of the washer that goes inside the hole of the damper hub is 100% useless - and it doesn't index the front of the hub at all. By the way, this is why we are considering the mod - this was done to the front of the crank with about 700 light "tuning" miles where I only crossed over 7k a few times. You can also see the "step" on the washer here and the amount of "extra" on the oil drive gear: The damper only had about .0005" interference fit. The rebuilt BHJ unit now has ".0015" which is the right spec. per BHJ. Edited June 3, 2014 by inline6 Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted June 3, 2014 Share Posted June 3, 2014 (edited) Sounds like I'd find a different engine builder... Anyway. As long as the hub is bottomed out on the oil pump drive (or the oil slinger between), then it has enough engagement. I'm sure Nissan would have made the crank snout longer if this was an issue. Moving the hub back is going to cause other issues, with pulley alignment for the water pump and alternator. It's been a while since I had my crank snout exposed, but it was around 1/4" or so of distance between the end of the crank snout and the face of the hub, where the washer sits against. Edited June 3, 2014 by Six_Shooter Quote Link to comment Share on other sites More sharing options...
TimZ Posted June 3, 2014 Share Posted June 3, 2014 Ok, noted. I realize that some space there is necessary to keep the washer from bottoming - so proper torque can be achieved on damper installation. My engine builder and I discussed the washer I am using a bit. I am using the Nissan Comp bolt and washer. That washer has a step in it which puts some of the washer inside the hole in the damper hub. I was under the impression that the part of the washer that goes inside the front of the hub ID performed the same function as sliding the damper onto the crank a touch (.060"?) more, but he says absolutely not - that the part of the washer that goes inside the hole of the damper hub is 100% useless - and it doesn't index the front of the hub at all. By the way, this is why we are considering the mod - this was done to the front of the crank with about 700 light "tuning" miles where I only crossed over 7k a few times. You can also see the "step" on the washer here and the amount of "extra" on the oil drive gear: 100_0722 (640x426).jpg The damper only had about .0005" interference fit. The rebuilt BHJ unit now has ".0015" which is the right spec. per BHJ. Have you checked to be certain that you aren't bottoming that washer? I use that same setup, and my washer had to be machined in order to clear. Or, even easier, you could just flip the washer over and not worry about it... 1 Quote Link to comment Share on other sites More sharing options...
Xnke Posted June 3, 2014 Share Posted June 3, 2014 I too, had to machine a little off the washer I had. Even with the modified stock damper and it's line-fit (not even a true press fit) I have no scuffing and no marks to the nose of the crank, even driving the supercharger. Quote Link to comment Share on other sites More sharing options...
inline6 Posted June 5, 2014 Author Share Posted June 5, 2014 I too, had to machine a little off the washer I had. Even with the modified stock damper and it's line-fit (not even a true press fit) I have no scuffing and no marks to the nose of the crank, even driving the supercharger. What RPM's are you running? Quote Link to comment Share on other sites More sharing options...
Xnke Posted June 5, 2014 Share Posted June 5, 2014 Shifting up at 7200-7300. Quote Link to comment Share on other sites More sharing options...
inline6 Posted June 7, 2014 Author Share Posted June 7, 2014 I too, had to machine a little off the washer I had. Me three. I did that before I ever used it. Evidently, that is a requirement when you use this Nissan competition washer. With .015" interference fit, installer and puller are absolute requirements. This thing is TIGHT! Quote Link to comment Share on other sites More sharing options...
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