socorob Posted March 30, 2015 Share Posted March 30, 2015 First thing is my car is a 78 280 with an LS1, T56, infiniti Q45 R200, with all Johns Cars and TTT mounts. I had bad vibration at 70+ mph. I rotated the tires and the vibration moved around with the wheels, so I called the shop that mounted them and said I think the balance is off, can you check and fix them? Since I had them mounted several months ago they wanted to charge me again even though it's only been a few hundred miles driven on them. When I had them mounted, I even asked them if I could take it back if I had any problems as I wouldn't have the car driveable for several months. Of course the lady at the counter gave me the oh sure, no problem, but when it came time to deliver she didn't remember that and couldn't find any record of me in the computer. I said screw you guys and brought it elsewhere, and these guys came and said these tires are way off. they ran it twice for me, and said they are all perfect now. I got it out and now the vibration is around 80. The new balancing took over half the vibration out and it moved it up in speed some. At this point I'm going to trust these guys have them properly balanced and move on down the line trying to figure out what's vibrating. My questions are: What kind of driveline angles should I have? Has anyone had any issues with the balance on the driveshaft from Johns Cars? Do CV shafts have to have a certain angle and is there such thing as balancing them? What about brake rotors, any such thing as balancing those? Anywhere else I should look? The vibration is there whether in gear, neutral, or with the clutch depressed and in gear. Quote Link to comment Share on other sites More sharing options...
socorob Posted March 30, 2015 Author Share Posted March 30, 2015 I went on a few hours car drive today with a group of about 20 cars. Only 1 other Datsun , which is pictured below, some kind of special crazy high hp car. Anyway the vibration was irritating my wife which in turn made to be sure to REALLY irritate me about the car shaking, so I really need to try to solve this. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 30, 2015 Share Posted March 30, 2015 Is it still at 80 mph? That's some high speed cruising. Just 80 or 80 and above? People have been known to temporarily swap their custom wheels for a set of stock steel rims just to see if the wheels are the problem. Quote Link to comment Share on other sites More sharing options...
PLATA Posted March 30, 2015 Share Posted March 30, 2015 I had a similar issue not with my Z but on my new Mustang, after a wheel set swap one rotor got worped due to over torque when installed, had to replace the rotor and problem solved. Quote Link to comment Share on other sites More sharing options...
NgoZ Posted March 30, 2015 Share Posted March 30, 2015 Rob, if you want you can borrow the set of wheels off my roller if it doesn't sell on Tuesday, to test it out to see if it negates the current set. Quote Link to comment Share on other sites More sharing options...
socorob Posted March 30, 2015 Author Share Posted March 30, 2015 Its 80 and up. I'm not sure how up it goes because I didn't get too too high over 80, but it still was there, the same amount. It didn't get worse or better. The wheels are from a G 35 that someone gave me. They didn't seem to have any noticeable bends, dents or scratches on them, but I guess you never know. Thanks Kiyet, but I have 5 lug wheels, so not sure if they would work. Quote Link to comment Share on other sites More sharing options...
socorob Posted March 30, 2015 Author Share Posted March 30, 2015 How did you find out the rotor was warped? Just spun it and checked for runout? Quote Link to comment Share on other sites More sharing options...
PLATA Posted March 30, 2015 Share Posted March 30, 2015 ^^^^ A shop that does spin balancing on the car not the take off car type. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 30, 2015 Share Posted March 30, 2015 My questions are: What kind of driveline angles should I have? Has anyone had any issues with the balance on the driveshaft from Johns Cars? Do CV shafts have to have a certain angle and is there such thing as balancing them? What about brake rotors, any such thing as balancing those? Anywhere else I should look? The vibration is there whether in gear, neutral, or with the clutch depressed and in gear. There's some about driveshaft angles and measuring them here: http://forums.hybridz.org/topic/43993-differential-laser-alignment-tool/ Can't speak to driveline balance, but I've felt driveline vibration from bad angles, and that changed a lot depending on load, so I think you can rule it out. CV shafts have a range of angularity that they work in, never seen a Z come close to maxing one out. If you figure that they work in FWD cars that turn, you can see that you're unlikely to get there with an IRS that doesn't. I can't remember seeing any weights on a CV shaft that I recall, but it should be able to be balanced if necessary. They spin a lot slower than the driveshaft though. Brake rotors are balanced from the mfr. Stupid question: has it always had this problem? If not, then it's likely the wheels and tires. The fact that you had them re-balanced and it changed the vibration seems to me to indicate that it's the tires, unless it's always done this and you're just now getting to fixing it. Did the new shop use weights on the inside and outside of the wheel? If the do the inside only that is a static balance which is not the same or as good as a dynamic balance. Road force is supposed to be the best, I've never actually seen one, but that's what they say. Quote Link to comment Share on other sites More sharing options...
zeeboost Posted March 30, 2015 Share Posted March 30, 2015 (edited) Back when I still worked at a dealership I was pretty familiar with the road force machine that we had, and found it to be one of the best tools for fixing any tire/wheel vibration...in fact it was mandatory for warranty vibrations (which I did a lot of) since it provided concrete data for me to use in figuring out the source of the vibration and if it was or wasn't fixable. It measures the rim runout, then measures the runout of the tire, plots a diagram of both of their runouts (since they're never perfectly circular) and tells you the best spot to re-index the tire on the wheel, in addition to how many lbs of force the tire runout has. Typically on a small passenger car like these, anything over 18 lbs of force begins to feel excessive. In my experience it didn't matter if the wheels were just slightly off balance or not, the tire runout was the major factor. Sure you want them to be dynamically balanced to zero, but you shouldn't get worked up on that being the only cause. Your tires may also have flat spots on them for sitting so long, and not sure what tires you have but typically cheaper / harder rubber tires don't have the best runout. I'm not sure how the shop did the balance but a static balance with stickies in the center of the wheel is less than ideal. I always had the best results using dynamic balance while placing the weights on the outermost sides of the wheel. I'd recommend finding someone with a road force balance machine, and is experienced using one. At least then you'll have some data on the condition of the tires and wheels, instead of just guessing. Or like was mentioned earlier throw another set of wheels and tires on and see if it goes away or changes. Edited March 30, 2015 by zeeboost Quote Link to comment Share on other sites More sharing options...
AkRev Posted March 30, 2015 Share Posted March 30, 2015 Just to trying to get more information, but does it do the vibration under acceleration? How about deceleration? How about if you put it in neutral at 80mph? Quote Link to comment Share on other sites More sharing options...
socorob Posted March 30, 2015 Author Share Posted March 30, 2015 Thanks for the links and suggestions. I haven't even heard of a road force balancer, but I will check around. These are used wheels with new 200 Treadwear tires (rivals). I guess I will start with the driveline angle and go on from there. I'm just worried I'm going to have to end up sending every rotating piece out to be checked for balance. This is the 1st car I've had that had this problem, so not sure what the best plan of attack should be Quote Link to comment Share on other sites More sharing options...
socorob Posted March 31, 2015 Author Share Posted March 31, 2015 The weights are inside of the wheels, stick on. I think it does it on acceleration and deceleration at that speed, under load, clutch in, or in neutral. Quote Link to comment Share on other sites More sharing options...
PLATA Posted March 31, 2015 Share Posted March 31, 2015 Do this>>> https://www.youtube.com/watch?v=7UP97bO-MpU and relax. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 31, 2015 Share Posted March 31, 2015 not sure what the best plan of attack should be Can't get much cheaper and simpler than swapping some different wheels on and going for a drive. Quote Link to comment Share on other sites More sharing options...
PLATA Posted March 31, 2015 Share Posted March 31, 2015 ^^^^ Or to watch the video on the type of balancing that is more effective. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 31, 2015 Share Posted March 31, 2015 The weights are inside of the wheels, stick on. I think it does it on acceleration and deceleration at that speed, under load, clutch in, or in neutral. There's your problem. Take Plata's advice. Quote Link to comment Share on other sites More sharing options...
socorob Posted March 31, 2015 Author Share Posted March 31, 2015 i guess I will start calling around to see if anyone does that in these parts. Now if you get it balanced like that, and you remove the wheel, do you have to make sure it goes back on in the same position since its balancing everything? And the brake rotor also? Quote Link to comment Share on other sites More sharing options...
PLATA Posted March 31, 2015 Share Posted March 31, 2015 ^^^ In my case the ,rotor issue was detected as the problem for the erratic vibration. On the rotation was ADVICE to extend the intervals and have it rebalance with same method, yes a bit more $ but that is part of the joys in owning GT type cars.FWIW Quote Link to comment Share on other sites More sharing options...
whatnow123 Posted April 2, 2015 Share Posted April 2, 2015 I had the same problem (vib after 75 or so) and started chasing the wheels. Turns out it was my driveshaft. Part of it was when the driveshaft was made, part of it was the angles. The U joints were not aligned (had an old guy make it who was winding down his driveshaft shop after 60 years in the biz and I guess he isn't as sharp as he used to be). Pulled the drive shaft and took it to another shop to check the balancing who informed me of the U joint alignment. They corrected it and rebalanced it. Anyway, after installing it I measured the angles and had to raise up the nose of the diff 1/4 of an inch to get it to 2 degrees difference from the trans/shaft and with the diff/shaft. So check your angles is my advise. Get the trans flange within 2 degrees of the driveshaft and do the same with the diff/driveshaft. I just got mine back together yesterday, took her up to 115 and smooth as glass now! I couldn't be happier. So, my money is on the drive shaft angles on where you vibration is coming from. Quote Link to comment Share on other sites More sharing options...
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