RebekahsZ Posted April 17, 2011 Share Posted April 17, 2011 Having trouble sourcing drive shaft bolts for my 240z/LS2 swap. I did search, so please nobody bawl me out. Ordered from smoorenc's source and part number a few weeks ago. What came in are 10.9 (?) spec fasteners. The bolt shank is only 1/4 inch, which doesnt span the interface between the diff flange and the thick JCI driveshaft flange. How have the GenIII/IV guys been working around this? I can't seem to find an internet bolt dealer that sells a true grade 8 - 8mm bolt. I am starting to think about drilling my flanges for the next higher size SAE bolt. I also don't know how important the length of the shank (unthreaded portion of bolt) is, but on my 240z driveshaft and half shaft bolts, it looks like Nissan put a lot of thought into it. I don't want to drop a driveshaft, even if it is only into my driveshaft loop. Any suggestions from the experts? Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted April 17, 2011 Share Posted April 17, 2011 (edited) Hello, The bolts you received with 10.9 markings (metric) are equivalent to a grade 8 SAE bolt. There are some minor differences but I would would not worry about them. I am not a mechanical engineer but I would say you have the correct bolts already. There will be a little play but you need to put a measuring caliper on your bolt openings and the bolts. 35mm long bolts should be adequate. Below are a couple of links for you. There is not much room up there when trying to tighten the driveshaft to the pinion flange and I believe JTR recommends a socket head bolt but don't quote me on that. I received my pinion flange from JTR and not the Johns Conversions so there might be a difference. http://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx http://www.boltdepot.com/product.aspx?cc=20&cs=77&cm=22&cd=1328 Danno74Z A bolt with partial threads vs a threaded bolt should not matter but again I'm not a mechanical engineer. A grade 10.9/8.0 bolt should spec. with or without threads at the grade specified. If I had a choice I would use a standard bolt with partial threads use red loctite or locking nuts with split washers. I went to the garage and I measured the pinion flange bolt hole diameter and it's 8.07mm or .317inches. If your dead set on using SAE a 5/16(.3125)bolt should also work but based on my calculations a 8mm bolt would have less clearance (tighter fit) then the 5/16 bolt. I have to say an 8mm bolt is kind of wimpy for attaching the driveshaft and I also thought about enlarging the holes to 10mm. 10mm is about .394 or about 20thou over 3/8" way better in my opinion. I'm sure others will voice their opinions. Edited April 17, 2011 by Danno74Z Quote Link to comment Share on other sites More sharing options...
h4nsm0l3m4n Posted April 17, 2011 Share Posted April 17, 2011 Mcmaster-carr should have all the 10.9 bolts youd ever need. You also pick them up at your local Fastenal though they typically have to special order any 10.9 bolts. I agree with Danno, socket head bolts would definitely be better. Quote Link to comment Share on other sites More sharing options...
kj280z Posted April 17, 2011 Share Posted April 17, 2011 (edited) I got mine at the local NAPA store. They were the correct hardness and had the correct shank. They were a little too long so I had to trim them, but no big deal. Edited April 17, 2011 by kj280z Quote Link to comment Share on other sites More sharing options...
zdlite Posted April 23, 2011 Share Posted April 23, 2011 The best bolt to use on the drive shaft is AN5 bolts with matching nylon locknuts. The fit is near perfect and they are much stronger than the other stuff you are looking at. http://www.aircraftspruce.com/catalog/hapages/an5.php Quote Link to comment Share on other sites More sharing options...
kj280z Posted April 23, 2011 Share Posted April 23, 2011 The best bolt to use on the drive shaft is AN5 bolts with matching nylon locknuts. The fit is near perfect and they are much stronger than the other stuff you are looking at. http://www.aircrafts...hapages/an5.php DO NOT use nylon style locknuts on your driveshaft bolts!!!!!! - use the proper locknuts! Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted April 23, 2011 Share Posted April 23, 2011 Whether you go SAE or metric is not that important. The differance is negligible. What is important, as you seen to indicate that you already know,is that the shank be unthreaded where the flange and yoke meet. If you need to get a slightly longer bolt and cut it off, as kj280z did, that's fine. If you have a driveline shop nearby they should also be a good source for these bolts. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted April 29, 2011 Author Share Posted April 29, 2011 I appreciate everybody's input. Will go to the next larger SAE grade 8 bolt with a proper shank, then drill the parts out to fit and cut off any threads that are too long. Will use lock washer and red locktight. Thanks again. Quote Link to comment Share on other sites More sharing options...
zdlite Posted April 29, 2011 Share Posted April 29, 2011 DO NOT use nylon style locknuts on your driveshaft bolts!!!!!! - use the proper locknuts! Yes, using both. good catch. Quote Link to comment Share on other sites More sharing options...
MoNkEyT88 Posted April 30, 2011 Share Posted April 30, 2011 I found out what a 500hp v8 will do to the wrong drive shaft bolts.. stretched bolts, loose drive shaft.. weird noises. Lucky, that was all, no drive shaft poking through the floor to say "Hi". Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted May 16, 2011 Author Share Posted May 16, 2011 This part of my install is done. See pics. 8mm is essentially same size as 5/16. Sourced some grade 8 size 5/16X1.75 inch bolts from bolt depot. This gave me the shank length I needed to ensure full sized bolt at the junction between both flanges. Shorted bolts had insufficient "shank" or "shoulder". Had to cut off 3/8 inches of threads with dremmel tool with cut-off wheel. Remember to put on a nut before cutting to allow you the clean threads as bolt is removed. One pic shows the shorter bolt that another forum member recommended in a metric 8mm 10.9 spec; the length is good but the shank is too short. Next is comparison between stock Datsun bolt and the modified grade 8 bolt. Then part numbers from boltdepot.com. Next shows how grade 8 bolt shank spans junction of the two flanges. Last shows difference between stock flange (bottom) and JCI flange. Anybody know correct torque setting for 5/16" grade 8 driveshaft bolts (if I can get a torque wrench under car with crows foot socket)? Quote Link to comment Share on other sites More sharing options...
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