PLATA Posted July 26, 2014 Share Posted July 26, 2014 (edited) I had a light rear noise/clank and to my surprise it was the outer bolt on diff mount that was loose to the point that it came out by hand. That bolt was put tight when a weld was needed on the old Nippon part last summer . >> my diff set up . the outer passenger side bolt that was loose . What could be cause to that bolt to become that loose , the former owner never had an issue with the set up Edited July 26, 2014 by PLATA Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 26, 2014 Share Posted July 26, 2014 That diff mount design puts a twisting motion on the four mounting bolts of the cross-member. The nose of the diff is pulling up on a fairly long lever arm with the four bolts of the cross-member as the fulcrum. It wouldn't be surprising if the heads of the bolts broke off eventually. Quote Link to comment Share on other sites More sharing options...
PLATA Posted July 26, 2014 Author Share Posted July 26, 2014 (edited) I have a Q45/r200 diff on my Z.>>>> this is the mount that set up give the former owner zero problems with 10K miles during his ownership , last summer a crack on the old Nippon metal part of the custom made mount was repaired .. and last week the bolt next to the weld repair came loose. That diff set up has a total of 18K miles, any suggestions in order to avoid future issues. Edited July 26, 2014 by PLATA Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted July 26, 2014 Share Posted July 26, 2014 Drive it like a girl. That's probably what the first owner did. There have been several similar posts by short-nose diff owners using that style of front mount. It's a bad design. But....I haven't seen anything better. Yet. Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 26, 2014 Share Posted July 26, 2014 You could run two legs from the cross-member up to the old diff strap mount holes. The diff strap mounting bolts would be in shear and would stop the motion. Basically a boxed mount off of the cross-member with the two tongues sticking out front to hold the diff nose. It would be stronger but still puts a bending load on the tongues. Adding two more legs diagonally from somewhere close to the front of the tongues back and up to the diff strap mount hole areas would help that problem, making the tongues shorter. If there's room. As an assembly it might be pretty big and bulky. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted July 26, 2014 Share Posted July 26, 2014 "Somebody" willing to sacrifice a pile of money needs to design a crossmber for short nose diff installation into the Z. It would weld into the unibody and distribute forces into the body correctly. Until that happens, I think we will continue to see these kinds of problems. If you look hard at the tiny tabs that the RT bolts to, you will not bolt it in with total confidence, even with a long nose diff. I'm figuring the Nissan engineers saw these problems, so they put a little motor in the car and cobbled together that crazy busquit and strap contraption that the Z left the factory with. So long as you had 150 hp at the flywheel, at put it to the ground with 5-1/2" tires, life was good. Well, we kinda screwed that up! Quote Link to comment Share on other sites More sharing options...
motomanmike Posted July 26, 2014 Share Posted July 26, 2014 Have you had an issue since the other weekend? Quote Link to comment Share on other sites More sharing options...
PLATA Posted July 27, 2014 Author Share Posted July 27, 2014 Have you had an issue since the other weekend? That is a negative, but I am reluctant to hammer her Quote Link to comment Share on other sites More sharing options...
PLATA Posted July 27, 2014 Author Share Posted July 27, 2014 "Somebody" willing to sacrifice a pile of money needs to design a crossmber for short nose diff installation into the Z. It would weld into the unibody and distribute forces into the body correctly. Until that happens, I think we will continue to see these kinds of problems. If you look hard at the tiny tabs that the RT bolts to, you will not bolt it in with total confidence, even with a long nose diff. I'm figuring the Nissan engineers saw these problems, so they put a little motor in the car and cobbled together that crazy busquit and strap contraption that the Z left the factory with. So long as you had 150 hp at the flywheel, at put it to the ground with 5-1/2" tires, life was good. Well, we kinda screwed that up! Quote Link to comment Share on other sites More sharing options...
PLATA Posted July 27, 2014 Author Share Posted July 27, 2014 You could run two legs from the cross-member up to the old diff strap mount holes. The diff strap mounting bolts would be in shear and would stop the motion. Basically a boxed mount off of the cross-member with the two tongues sticking out front to hold the diff nose. It would be stronger but still puts a bending load on the tongues. Adding two more legs diagonally from somewhere close to the front of the tongues back and up to the diff strap mount hole areas would help that problem, making the tongues shorter. If there's room. As an assembly it might be pretty big and bulky. Mike aka motomanmike ,this looks like a possible solution and a case of beer Quote Link to comment Share on other sites More sharing options...
PLATA Posted July 27, 2014 Author Share Posted July 27, 2014 Can I have the correct 4 bolts bolts size info and a source in order to replace them , I tend to believe that metal fatigue is a factor there Quote Link to comment Share on other sites More sharing options...
AkRev Posted July 27, 2014 Share Posted July 27, 2014 (edited) How is the vibration in the car? Are the u joints in good shape? As I look at this I am reminded of an issue I had when one of my u joints failed on an old truck of mine. Good Luck Edited July 27, 2014 by AkRev Quote Link to comment Share on other sites More sharing options...
PLATA Posted July 27, 2014 Author Share Posted July 27, 2014 No vibration, she is solid . U joints healthy . Quote Link to comment Share on other sites More sharing options...
johnc Posted July 27, 2014 Share Posted July 27, 2014 Stop guys! The bolt came loose from the heating and cooling caused by the welding. Absolutely normal. Get a new bolt, lock washer, and washer and torque to spec. Quote Link to comment Share on other sites More sharing options...
PLATA Posted July 27, 2014 Author Share Posted July 27, 2014 ^^^^ That bolt came loose almost a year after the weld/repair . Quote Link to comment Share on other sites More sharing options...
johnc Posted July 28, 2014 Share Posted July 28, 2014 Yes, it lost torque and slowly worked out. You noticed it after a year but is was loose soon after the welding. A good practice is to loosen and retorque any bolt affected by the welding heat. Quote Link to comment Share on other sites More sharing options...
PLATA Posted July 28, 2014 Author Share Posted July 28, 2014 (edited) My plan >>> new high grade bolts, new washers and a single tack weld to prevent any movement of the bolt Edited July 28, 2014 by PLATA Quote Link to comment Share on other sites More sharing options...
johnc Posted July 28, 2014 Share Posted July 28, 2014 Don't tack weld the bolt! That will cause a loss of torque even though the bolt head does not turn. The heating and cooling will cause the thread faces to loose friction. Just install new fasteners correctly per the FSM and use some blue Loctite if it makes you feel better. Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 28, 2014 Share Posted July 28, 2014 Don't tack weld the bolt! That will cause a loss of torque even though the bolt head does not turn. The heating and cooling will cause the thread faces to loose friction. Just install new fasteners correctly per the FSM and use some blue Loctite if it makes you feel better. ^^^Please listen to John!!!^^^ Also, as far as the notion of "nobody has addressed this yet" (paraphrasing), have you looked in the FAQs? Jon Mortenson did a writeup on this back in 2006... http://forums.hybridz.org/topic/50499-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount-faq/ Quote Link to comment Share on other sites More sharing options...
PLATA Posted July 28, 2014 Author Share Posted July 28, 2014 (edited) What about this, I think a can tackle this type mod in there >>>> and will this prevent that bolt to unsnap . Edited July 28, 2014 by PLATA Quote Link to comment Share on other sites More sharing options...
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