Graver666 Posted January 8, 2015 Share Posted January 8, 2015 First time posting at all, and I hope I am asking this in the right area. Lately when turning left or right at sharper curves my 280z jerks, and it feels like a tire is locking up or what not. My diff is welded (which i am changing soon. I'm not a drifter...). Anyways, I am hoping someone has experienced this before. I was told by a friend that it's possibly the U-Joints, which I'll be possibly replacing this weekend. Anyways, I am hoping he is right, and it's not something far worse. tl;dr - Long story short, I am wondering if it's the U-Joints as to why it's jerking so much harder lately. I know 75% is from the differential being welded and the wheels not moving freely, but I am hoping it's a simple fix. Thanks Quote Link to comment Share on other sites More sharing options...
Phantom Posted January 9, 2015 Share Posted January 9, 2015 Naw - it's the welded diff. Fix that and then revisit. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted January 9, 2015 Share Posted January 9, 2015 Need more info. With the assumption that you have had the welded diff for a while and this is relatively new. It would be caused by slack in the differential or suspension. Anywhere from diff mount bushing, mustache bar bushing, control arm bushing, spring perch condition, loose strut, worn strut insulator mount, and yes even a loose u joint or axle could cause a jerking sensation. This is also of course with the assumption that it is felt in the rear and has nothing to do with your front suspension. It really isn't hard on our cars to lay on the ground and pull on the u joint to check. A welded diff definitely will amplify any of the slack in the system. Quote Link to comment Share on other sites More sharing options...
Graver666 Posted January 16, 2015 Author Share Posted January 16, 2015 Soooo figured out a few things. One, it's the diff, 2nd the rattling I thought was coming from the u-joints was actually coming from the rear bushings, which are gone, and slamming against the caps that are in the back. Now for the noob question, since I am new to all of this and get all my auto mechanic knowledge from the internet. What are the bushings called? They go on top of the shocks. Also, are there any good videos out there on how to switch out the diff? I can't seem to find any that make sense. Thanks Quote Link to comment Share on other sites More sharing options...
Graver666 Posted January 16, 2015 Author Share Posted January 16, 2015 Looking up some of the stuff that Seattlejester posted, the strut insulator mounts look exactly what the mechanic was talking about, but he was telling me the bushings on top of the strut need replace, and made it sound like the struts are supposed to move around in there, but I find that unlikely, because it looks like these mounts hold the strut in place. This is so damn confusing. haha Quote Link to comment Share on other sites More sharing options...
Savage42 Posted January 17, 2015 Share Posted January 17, 2015 Yep, worn strut mounts can make bad noises, clunks, etc. They are different between the 240Z & 280Z, so make sure you get the right ones. They are easy enough to change if you have a spring compressor. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted January 18, 2015 Share Posted January 18, 2015 The strut isolator bushing is exactly as it sounds, it isolates the strut from the chassis so it doesn't transfer as much NVH. There's a strut cartridge on our cars, so it isn't one unit, but it shouldn't bounce around. Can you take a picture? I'm kind of worried you might be referring to the mustache bar bushings on accident. Couple things to note. A diff is fairly heavy, be prepared for when it falls. If you tilt the diff more then 45* it will spill oil out of the vent hole. Make sure your car is very securely mounted. I don't recall if you have to remove the LCA mount at the moment, but best to support the chassis not the suspension. Jack up the car and securely put it on jack stands. Once you are sure it is not going to move on you head under the car. If you are just removing the diff, remove the nuts on each half shaft and drive shaft 12 in total. You probably won't have enough room to remove them quite yet, don't worry. Support the rear diff and undo the front and rear diff mounts, two bolts in the back and two bolts in the front. You can undo either the mustache bar bolts from the chassis or you can remove the diff from the mustache bar, I find the mustache bar itself easier to remove and reinstall. Now slowly lower the differential, you should be able to free the front by moving the drive shaft forward into the transmission. Installation is reverse. It's real important that you don't call the bolts or nuts. They are especially thin nuts and the bolts are special D bolts. If possible having spares from another diff would be ideal as it is difficult to remove all the nuts without rounding one or two of them. I might edit this tomorrow morning, but enough to get you started. Quote Link to comment Share on other sites More sharing options...
Graver666 Posted February 1, 2015 Author Share Posted February 1, 2015 Any chance you can post a pic of the insulator mount? I can't seem to find the right part. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted February 1, 2015 Share Posted February 1, 2015 (edited) ^Those are the bushing that go onto of the shocks, is that what you are referring to? Or are you thinking of the bumpstops? So I think we may need to slow down here. Why did you want to remove the differential to change out the strut top insulators? This is not really going to work if we have to guess at what you are looking at. Do us a favor and snap a few pictures with good lighting at what you are referring to, we would hate to recommend the wrong part. I mean this would really help you get started in the correct nomencalture. Edited February 1, 2015 by seattlejester Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 2, 2015 Share Posted February 2, 2015 actually coming from the rear bushings, which are gone, and slamming against the caps that are in the back. he was telling me the bushings on top of the strut need replace, and made it sound like the struts are supposed to move around in there, There are "bump stops" on the strut shock shaft. If the car is lowered and the shocks toasted, "slamming" could happen. The front struts have a bearing inside the insulator so the strut can twist. The rears don't. Here's some pictures and names - http://www.carpartsmanual.com/datsuns30/DatsunZIndex/Axle/FrontSuspension/tabid/1729/Default.aspx http://www.carpartsmanual.com/datsuns30/DatsunZIndex/Axle/RearSuspension/tabid/1731/Default.aspx Quote Link to comment Share on other sites More sharing options...
Graver666 Posted February 4, 2015 Author Share Posted February 4, 2015 (edited) This is what I'm talking about. The bushing inside of here is gone and the strut rattles like crazy on bumps inside. Edited February 4, 2015 by Graver666 Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 4, 2015 Share Posted February 4, 2015 Pop that cap off. This is like guessing horse teeth. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted February 4, 2015 Share Posted February 4, 2015 I mean even if the insulator deteriorates, it really shouldn't be bouncing around if it is tightened, unless it has crumbled apart and isn't seated. The piece I posted is correct if it is your insulator, make sure you buy the appropriate one the 240z and 280z ones are different height. So either the insulator has really fallen apart and it is loose and rattling around (at which point you really should stop driving and pull the suspension), or the shock is rattling around in the shock tube and needs the gland nut tightened or a spacer inserted in-between the gland nut and the insert. I do advise against attempting this by yourself as this is suspension that keeps your car on the ground. You need to make sure that you are capable of keeping track of how things come apart and are reassembled, applying the proper torque, and replacing worn parts are all important in the tear down and reassembly. If you are unfamiliar, farm it out or bribe a more knowledgeable friend or mentor to give you a hand. Just make sure your mentor is familiar with older cars and what working on them entails. Quote Link to comment Share on other sites More sharing options...
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