EvilC Posted September 23, 2007 Share Posted September 23, 2007 Ok this is my last effort for this week to try and get my car down to Daytona. My problem is.......around 30 mph my car starts to vibrate. It only gets worse the faster I go. It is coming from the rear of the car and my setup is a q45 diff with a "solid mount" diff setup, axles from MM with Mas280 CV adapters, MB from AZ and what I think is the problem.....the driveshaft. Yesterday I spent all day going through the mounts, rebolting the entire rear end. I took the wheels off the car while on the lift and the problem remained....the problem is speed sensitive....so this can only mean moving parts in the drive train. I believe the drive shaft is too long. When the drive shaft is unbolted, I have no fwd movement to take it out. So I have to hammer(once) to slide it past the diff to take it out. The shaft has u joint on both ends and was balanced when made. I want to know if the dirve shaft is too long, what will this do to the car if anything? Also I read about the angels and I think I understand them.....so help me!!!! lol 2 beers on @ the convention on me for info that helps Quote Link to comment Share on other sites More sharing options...
buZy Posted September 23, 2007 Share Posted September 23, 2007 I went through the same thing. Your DS sounds a bit long if it has to be hammered out. You might want to have a shop shorten it about a half inch. Driveline angles, check them. Parallel running axis in the horizonal and vertical planes which relates to the total running driveshaft angle under 1.5 to 2 degress. Also check to make sure the halfshafts are running straight looking down from the top of the car. That the diff is not to forward in the car or to the rear etc. I think the azc MB should have it located properly though. Good luck. Hope you make to Daytona. Wish I was going. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted September 23, 2007 Share Posted September 23, 2007 What changed between the day when it didn't vibrate till now? Diff swap? Engine swap? Tires? Wheels? Wheel spacers? Does it vibrate while coasting or does it get worse when under power? Quote Link to comment Share on other sites More sharing options...
m1noel Posted September 23, 2007 Share Posted September 23, 2007 If the DS is too long it will probably bind the U-joints a little and will cause vibration. And starting at 30mph is definately forward of the rear end. Mike Quote Link to comment Share on other sites More sharing options...
EvilC Posted September 24, 2007 Author Share Posted September 24, 2007 Pop N Wood......this is the first time my car has ever been on the road....complete swap of everything. What I did guys as a double check, I pulled the axles andhad only the DS and Diff "working" and still got the vibrations. I pulled the DS and measured...it has to be cut an inch. I also see i can adjust my mounting point of the noise of the diff. I will play with this tomorrow when I get the DS back. I will check the angles if I can borrow lasers from Rags. Yes I do thing the U joints are binding up and I hope I can get this all solved before weds! Quote Link to comment Share on other sites More sharing options...
auxilary Posted September 24, 2007 Share Posted September 24, 2007 it only happens at a specific speed, and not in specific gear at certain rpm, right? Quote Link to comment Share on other sites More sharing options...
EvilC Posted September 24, 2007 Author Share Posted September 24, 2007 It happens rpm related to the DS not engine rpm. So me saying 30mph was a mistake on my part. To clear this up for anyone who might read this in the future....I will explain. If the car is in 1st gear and I rev it to 6000 rpms, there is no vibrations. If the car is in 3rd, 4th, 5th or 6th.... when the rpms reaches around 2500 the vibrations come in. The higher the gear the faster the DS is turning and is not dependent on engine rpm but is on the tranny. Hope this makes sense, anyone can add or correct if they like. Drive shaft or Driveshaft being too long cause the 2 U-joints I have to bind. The U-joints do not function well at all during compression. This compression right now I believe is a combo of my DS being too long and where the nose of my diff sits right now. So it is a very good idea to read up on the drive train angles and how things should look. I hope to get my DS today and get this back together.....wish me luck. Quote Link to comment Share on other sites More sharing options...
EvilC Posted September 24, 2007 Author Share Posted September 24, 2007 Buzy.....I had pulled everything out to check for what you are speaking of. Thanks for in the insight.... Quote Link to comment Share on other sites More sharing options...
EvilC Posted September 24, 2007 Author Share Posted September 24, 2007 Here are two pics to help see exactly what i am talking about. Notice first pic shows the driveshaft all the way into the tranny. No 1/2 inch movement there. BAD BAD BAD. Second pic is standing right under the diff looking forward. Does anyone see something wrong, I know hard to tell by pics but maybe someone elses eye can catch something I didn't. Notice the tranny fluid coming out of the tranny? If I wipe that way..around 10-15mins lata a slight drop reappears. Ideas? My DS won't be ready until the morning! Guess I can do some other things just incase my car is ready to go. Quote Link to comment Share on other sites More sharing options...
2126 Posted September 24, 2007 Share Posted September 24, 2007 Just a thought...if the DS was originally modified by someone, check to see if the U-joint trunions were welded in out of phase. This can cause vibrations. Quote Link to comment Share on other sites More sharing options...
EvilC Posted September 24, 2007 Author Share Posted September 24, 2007 Just a thought...if the DS was originally modified by someone, check to see if the U-joint trunions were welded in out of phase. This can cause vibrations. Can you explain more in detail? I want to get a full understanding for myself and anyone else who reads later on. Do you mean my u joints can be out of phase with one another? I had a drive shaft shop make mine. Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted September 24, 2007 Share Posted September 24, 2007 The oil leaking, is probably from the drive shaft hammering into the transmission. You probably ruined the seal and most likely the bearing too. Make sure to check it out before reinstalling you DS. Quote Link to comment Share on other sites More sharing options...
m1noel Posted September 24, 2007 Share Posted September 24, 2007 I doubt that you have ruined your tail shaft bearing as little as you have driven it. It doesn't even look like the drip is coming from the DS in the pic. I overfilled mine a little when we put it in and it has just now stopped dripping after a drive. Good luck with all.... Mike Quote Link to comment Share on other sites More sharing options...
KenshinX Posted May 5, 2009 Share Posted May 5, 2009 Did you ever get the problem fixed? I am interested to hear the results I too have the vibration problem. Actually my driveshaft just came apart on me on the interstate today. the bolts are gone so I will be replacing them and the u joints and go from there. Quote Link to comment Share on other sites More sharing options...
EvilC Posted May 27, 2009 Author Share Posted May 27, 2009 I started building another v8 Z, I couldn't track down the vibrations. I wil let you know what happens when I have the "new" one together as it is getting all the parts from the first one. Quote Link to comment Share on other sites More sharing options...
KenshinX Posted May 27, 2009 Share Posted May 27, 2009 The drive shaft was the problem when I replaced the 4 bolts that connect it to the differential yoke the problem went away. I believe the PO installed lower grade bolts cause them to wear and break. Since then all vibration is gone only a tinyyyy little steering wheel shake at high speed but I know thats the rear passenger tire. Quote Link to comment Share on other sites More sharing options...
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