Icehouse Posted March 20, 2007 Report Share Posted March 20, 2007 Well I've been driving my 620 as a daily driver for some months. Well at 70mph and 85mph okay so my speedo is off so it is more like 60 and 75. That is besides the point the real question is why does it wobble at high speeds. I checked the driveline and all the U-joints are good the leaf spring bolts where tight. I didn't see anything loose. The carrier bearing seems looseish... like if I pull or push on it with a little force it will move like 1 inch. My truck is really low so maybe that has something to do with it. I want to space the carrier bearing up an inch and see if that helps. O and I put different wheels on it and it doesn't go away. If I jack up one rear wheel and get it up to wobble speed it doesn't change from side to side. Any ideas? Quote Link to comment
Bleach Posted March 20, 2007 Report Share Posted March 20, 2007 I would think its the driveline. if have you have time, try lifting the back. Take the blocks out or put a spring back in. If the wobble goes away or is less then its the driveline angle. A block under the carrier bearing should help a little in that case. Also make sure you're using angled blocks. Quote Link to comment
Pacific coast Datsun Posted March 21, 2007 Report Share Posted March 21, 2007 Sounds wierd but make sure all your lug nuts are tight. Could also be bad bushings on the front suspension. May be the wheel weights fell of causing it to vibrate too. If you do raise the carrier bearing here a pic of mine...I raised it 1 3/4 inches using a piece of square tubing...I actually got the idea from Bleach.:cool: Quote Link to comment
yello620 Posted March 21, 2007 Report Share Posted March 21, 2007 Bet money on the driveline vibration problem. They all seem to do it until the carrier is spaced up. I think that you will find that 1.5"-1.75" will work best, rather than just 1" spacer if you are really low. Your driveline isn't bottomed out into the tranny is it? After the KA swap? If it is bottomed out it could cause a good vibration. Later Jason Quote Link to comment
Icehouse Posted March 21, 2007 Author Report Share Posted March 21, 2007 Okay guys I will shim up the bearing and get back to you. I hope it works, a vibrating trucks is annoying. O and I tried different wheels in the back and it didn't change. Quote Link to comment
datzenmike Posted March 22, 2007 Report Share Posted March 22, 2007 Whenever there is a bend in a driveshaft, the U joint does not travel in a circular path but in an ellipse or oval shape. (as seen by looking down the driveshaft axis) Now the drive shaft is turning at a constant speed, so this means the U joint must speed up and slow down as it turns, and this is felt as a vibration, and there is a way to remove it, or eliminate most of it. Just make sure that the bend at the front U joint, is exactly the same angle as the bend at the rear U joint. The speeding up and down are effectively canceling each other out. Below are two possible set ups. As long as the transmission to driveshaft angle is the same as the driveshaft to rear end pinion angle, vibration is canceled out. On two piece driveshafts the center bearing and transmission mounts can be shimmed to adjust the TWO SETS of angles. Special thanks to airedout (NWDE) Quote Link to comment
sjeff64 Posted March 24, 2007 Report Share Posted March 24, 2007 dont think thefactory drive shafts were balenced for 70-80 mph LOL Quote Link to comment
71-521 Posted March 24, 2007 Report Share Posted March 24, 2007 once balanced they should be good to go.... had my 521 up to 100+ several times and no vibrations... trans just didn't last long after that though! Quote Link to comment
oregondime Posted March 24, 2007 Report Share Posted March 24, 2007 i just got my driveshaft shortened and balanced at a driveshaft work only shop, well see how fast i can get it now :-D Quote Link to comment
Icehouse Posted March 28, 2007 Author Report Share Posted March 28, 2007 So I got new tires and it helped, it still wobbles, I'd say about 40% better :) I will report back as soon as I get the carrier bearing shimmed up. Quote Link to comment
71-521 Posted March 29, 2007 Report Share Posted March 29, 2007 Have you pulled your axles and replaced your bearings? I checked mine recently and found them to be very bad...more than 1/4" play... next time you're in town stop by and take my rig for a drive to feel what some bad bearings feel like! Quote Link to comment
Icehouse Posted March 31, 2007 Author Report Share Posted March 31, 2007 No Paul I haven't checked the bearings. I did get a piece of 1.5 inch square tubing, I also got a piece that is 2.5 maybe it will fit :D I want to go another inch down once I get the exhaust fixed. They are never low enough :D Quote Link to comment
Icehouse Posted April 1, 2007 Author Report Share Posted April 1, 2007 AAAWWWWW!!!!! okay it still vibrates... I shimmed the carrier bearing up 1.5 inches and it still wobbles on the freeway. It is less, I want no vibration though. I don't know what to check next. So Paul weren't you saying something about the rear end being wore out? While I was under there I noticed the front seal on the pumpkin was leaking. There was sauce everywhere. I wonder if the bearings are bad? I'm running out of things to try. I think next I'm going to jack up one tire at a time, then ramp them up to 60-75mph and see it they both vibrate the same. Maybe get the drive line balanced, or a new carrier bearing? Quote Link to comment
Pacific coast Datsun Posted April 1, 2007 Report Share Posted April 1, 2007 You have have just said it but could be a unbalanced driveshaft or worse a bent rim maybe?! Quote Link to comment
datzenmike Posted April 1, 2007 Report Share Posted April 1, 2007 AAAWWWWW!!!!! okay it still vibrates... I shimmed the carrier bearing up 1.5 inches and it still wobbles on the freeway. It is less, I want no vibration though. I don't know what to check next. So Paul weren't you saying something about the rear end being wore out? While I was under there I noticed the front seal on the pumpkin was leaking. There was sauce everywhere. I wonder if the bearings are bad? I'm running out of things to try. I think next I'm going to jack up one tire at a time, then ramp them up to 60-75mph and see it they both vibrate the same. Maybe get the drive line balanced, or a new carrier bearing? jeff, don't ignore the leak. By the time i noticed mine it was too late to save the pinion. I had a spare but didn't realize it was a 4:11 'till it was almost in. Did not vibrate bur growled. Check your carrier bearing, well not the bearing but the rubber dough-nut surrounding it. It should support the shaft firmly and if you tug on it, it will just move from side to side, an inch is a bit much. Take a really close look at the U joints by locking in gear and really tugging on each of them hard, up/down and side to side. Roll the truck ahead to get at the difficult ones. If there is ANY movement or taking up of slack in the joint just replace, hell if you do one, do 'em all. Quote Link to comment
Bleach Posted April 1, 2007 Report Share Posted April 1, 2007 my truck wasn't as low, but for quite a while I had no rubber around the carrier bearing. The driveshaft was so well balance it would just float in the middle of that ring and I had no vibration. I took it up to only 80 though at the most. Quote Link to comment
71-521 Posted April 1, 2007 Report Share Posted April 1, 2007 check the play on your diff and then pull an axle and check your bearings... if you want to hear a toasted carrier bearing at 80mph, you can drive mine...and then take a good corner and feel the axle bearings wobble! Quote Link to comment
Icehouse Posted April 3, 2007 Author Report Share Posted April 3, 2007 You have have just said it but could be a unbalanced driveshaft or worse a bent rim maybe?! I could check the rims but I just had it at the Schwab and they didn't say anything. They are a bunch of punk kids though :rolleyes: jeff, don't ignore the leak. By the time i noticed mine it was too late to save the pinion. I had a spare but didn't realize it was a 4:11 'till it was almost in. Did not vibrate bur growled. Check your carrier bearing, well not the bearing but the rubber dough-nut surrounding it. It should support the shaft firmly and if you tug on it, it will just move from side to side, an inch is a bit much. Take a really close look at the U joints by locking in gear and really tugging on each of them hard, up/down and side to side. Roll the truck ahead to get at the difficult ones. If there is ANY movement or taking up of slack in the joint just replace, hell if you do one, do 'em all. Dude I checked everything, all I can think is that the DL is out of balence or maybe when I made the motor mounts I didn't center the engine.... It doesn't seem like 1/2 and inch would make much of a difference, maybe it does... I will add some sauce to the diff to, I really don't want to have to find a new one. my truck wasn't as low, but for quite a while I had no rubber around the carrier bearing. The driveshaft was so well balance it would just float in the middle of that ring and I had no vibration. I took it up to only 80 though at the most. 80..... shit child's play :D check the play on your diff and then pull an axle and check your bearings...if you want to hear a toasted carrier bearing at 80mph, you can drive mine...and then take a good corner and feel the axle bearings wobble! I have to take it apart :eek: You should do it for me :D Quote Link to comment
71-521 Posted April 3, 2007 Report Share Posted April 3, 2007 bring it and lets do it! Quote Link to comment
Bleach Posted April 3, 2007 Report Share Posted April 3, 2007 85 is top speed for an L18 :D hehe... do did the driveline rub? Quote Link to comment
Icehouse Posted April 4, 2007 Author Report Share Posted April 4, 2007 bring it and lets do it! How long will it take? 85 is top speed for an L18 :D hehe... do did the driveline rub? You should of went with the L20 :D Quote Link to comment
Icehouse Posted April 4, 2007 Author Report Share Posted April 4, 2007 I almost forgot.... I need a new drive line I bent mine :( I need one cheap, I'm going to drop it off at the DL shop so they can balance it and put new U-joints in if needed. I'm also going to pull the rear half off tomorrow and check the pinion bearing. I added about .5 liter of gear oil today (metric for my buddy mike :D ) Quote Link to comment
71-521 Posted April 4, 2007 Report Share Posted April 4, 2007 so you found the problem? Quote Link to comment
Icehouse Posted April 5, 2007 Author Report Share Posted April 5, 2007 so you found the problem? No I think I just added to it. I didn't work on it today. I was going to but I'm kinda board of looking for the vibration. I figure if I give it some time it will work itself out :D I really don't want to mess with it anymore. It is supposed to be my daily, lately its been my daily project.... Quote Link to comment
71-521 Posted April 5, 2007 Report Share Posted April 5, 2007 I picked up a spare set of axles from Ted and will get new bearings pressed on so that when I take them out again, the new set will go right in...you might want to look into that as well...wouldn't hurt the gas mileage either! Quote Link to comment
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