PapaSmurf Posted May 15, 2005 Share Posted May 15, 2005 Hey guys I'm a brand new Z owner I just traded my old grandma car (1991 pontiac sunbird) for a 78 280z straigt across! I'm looking for some information on U joints as I keep getting mixed information. I know that my U joints are bad I feel slack in the drive line when starting out and if I'm in a low gear and let off the accelerator it'll thump. I've been told that a 78 has ONLY half saft U joints by someone and that it also has U joints in the drive shaft as well by someone else. I've also been told that it is nearly impossible to replace halfshaft U joints by someone and that it is easy as pie by another person! I have 4 half shaft U joints in the mail to me and I'm nervous! Will I be able to replace these or will I have to take it to a mechanic :S I like to turn my own wrenches and can not afford a mechanic to do it! plus I hate it when someone I dont know has got his hands on my baby! So the questions were do I have drive shaft U joints as well as halfshaft joints and can I replace the halfshaft joints in my 78 Z Quote Link to comment Share on other sites More sharing options...
blueovalz Posted May 15, 2005 Share Posted May 15, 2005 Well Pappy, the U-joints are on the driveshaft and the half shafts (once you get under the car it will become obvious). BTW, your "thump" could also be caused by a separated diffential nose mount. Anyway, changing the U-joints is not a real hard job. Even those with minimal skills and tools can tackle this one. If you've got a vise and a descent socket set (use the sockets to push the U-Joints out (after the cir-clips are removed) you'll be in good shape. The only part of the whole operation the I considered a PITA was the fact that the outside of the U-joint housing is an irregular angled surface, which prevents one from easily using a large socket as a mandrel for pushing the U-joint through. Other than that, take your time and don't get in a hurry. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted May 15, 2005 Share Posted May 15, 2005 Just something I've noticed in every Z, there is ALWAYS a slight issue with driveline slack. I've talked to a few people who had these cars brand new, and it was common for the rear to make a bit of noise/klunking right from the factory. I have to do the driveshaft ujoints in my 75 actually.. Sometime next week hopefully, and I can take a few pics while I'm at it if you like. Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 16, 2005 Author Share Posted May 16, 2005 yeah some pics would be great! well shoot now I gotta buy some driveshaft U joints too since they are probably bad as well. This poor thing is better suited to being a parts car than a project car! I'm looking all around for some diagrams on the vacume system too it looks like some fool went crazy with disconnecting all the vacume hoses he could find... Shes burning oil too I'm getting a ring job done next week and I'm praying that will fix it for now, my goal is to eventually build a 3 liter stroker engine for her but thats when I get me some moolah together for now I just gotta make due with what I have Quote Link to comment Share on other sites More sharing options...
Here comes trouble Posted May 16, 2005 Share Posted May 16, 2005 Papa Smurf before you buy U-joints for that 78 280 Z.... jack the car up or get it on a lift and Then get under there and manhandle that drive shaft and half shafts to check for clunks and thunks. With a little twisting and elbow grease bad u joints can be identified. One problem with a 78 Z is that they came with non-replaceable u-joints. Apparently this problem can be remedied by a machine shop. My 78 has replaceable u joints but I believe this was due to an exchange with an earlier drive shaft. Terry's suggestion is also very plausible as the source for the noise since that IRS rear has a lot of parts going whiz and zip-zip Quote Link to comment Share on other sites More sharing options...
datsunlover Posted May 16, 2005 Share Posted May 16, 2005 Just a thought.. your oil burning might just be bad valve seals.. really bad, like mine were.. (they were brittle and cracked with slight finger presure) I thought i'd need rings too, but my bottom end was pretty much mint when I tore it down this past winter. I'd try some oil restore product of some sort and maybe a slightly heavier weight oil. (I had an oil burning/leaking 85 200sx some years ago that I ran DIESEL oil in just to help keep some in her! ) Don't get too down on the car yet.. Mine was EXTREAMLY rough when I got it, and as you can tell, I'm still in the process of getting it back to good. Definatly check that the diff mount and 'arrester strap' are in good shape before getting into the u-joints... they wont help a bit if the nose of the diff is lifting, and will probly wear prematurely if the diff'f floating around. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted May 16, 2005 Share Posted May 16, 2005 wow 78 u-joints are not removeable? maybe thats why it took us so long with no results...t hats weird though because we had the u-joint clips ont he r-200 and removed them... then we hit it with a sledge, tapped with nromal hammers, and basically beat bones gaianst it like monkeys in front of an obelisk... what are we doing wrong or are these simply permanent u-joints sorryf or post hi-jack Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 16, 2005 Author Share Posted May 16, 2005 I took her into a shop today paid um 5 bucks to lift her up so I could see the underside. My Halfshaft U joints are toast! My driveshaft joints arent in good shape either but since they are nonreplacable it looks like I'll have to live with it for a while until I can find me a new driveshaft, one of those aluminum ones with replacable joints on MSA might be nice but I dont really have 300 bucks for it right now gonna call some bone yards. The car has been backfiring like crazy today after I cleaned the spark plugs! I used injector cleaner to clean them and made sure they were dry and lint free before I put them back in but damn it's going off like a damn machine gun. I'm worried for it. I checked the differential mount and I have declaired it to be the ONE non broken part of this car haha so it's definately the U joints! hopefully the half shaft joints will fix the problem a little bit if not the whole way! Yeah I do have a rather badly leaking valve gasket I tightened the cover down to try and fix it and am running 10w40 to cut down on the leakage for now. What weight do you reccomend I dont wanna go to heavy because the darn thing has enough trouble starting. I gotta have the accelerator held all the way down to start it and even then it's hit and miss. I read somewhere that that was a sign of a bad mass air sensor? where can I buy one of these new? I looked on msa and found nothin. I gotta post a pic of my ignition you guys'll get a kick out of it, the previous owner somehow found a way to break the key in the ignition so I'm using a makeshift method which only aggravates the starting issues. I gotta get some money into this poor thing! Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 17, 2005 Author Share Posted May 17, 2005 finally got the new U joints in the mail today cant wait to get these bad boys installed! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.