buZy Posted July 16, 2004 Share Posted July 16, 2004 This site is sweet bythe way! Im new here. I have a sweet 71 240z,viper blue, 327 chev T56 R200 Arinoza Car Billet M-Bar. I have been building this car for years. First test run the drivetrian vibrated. I know very typical.. to a short drive shaft car. So im going though setting up the proper angles of alignment. And as of now I am very close to completing that very underestimated feat. So here is what i have so far....In the vertical plane,(side view of the car.) the trans shaft and pinion shaft angles are paralell within .10 degreee with the driveshat angle running 2.5 to 2.3 degrees. Thanks to Petes Driveshaft mods I found online I have fabbed up a front pinion mount similar to his design. THANKS! I will be supporting the bottom of the pinion housing with the 240z crossmember modified with nylon block which will act like a pillow and trap that housing and aid maintaining geometery though braking and old fashion time and gravity. HERE IS MY QUESTIONS...Alignment in the Horziontal plane I have found more difficult to document. (Looking down from the top of the car.) But from my measuring using plumb bobs hanging from the front of the engine crankshaft and trans tail shaft centers, also then alighning these points with a lazer on the floor. The degree from paralell is .883 to .652. Less than a degree off. Being everything else will be dead nuts on will this variation be ok?? Or will is cause massive vibration. I am willing to live with some as long as its ok and wont cause damage to the realted components. The reason I want to get away with this variation is that my long tube hooker headers will hit on the suspension strut rod if I bring into true paralell. Also exhaust and new crossmember refabrication issues. If I dont have to redo these parts it would be nice. In short...Where can I get away with variations and where cant I? I know the rear pinion angle is not one to mess with. Also what is a good way to measure these angle in the Horzontal plane. A digital angle finder works great in the Vertical plane by the way. Any help from someone who really know about this stuff would be great. Thanks Quote Link to comment Share on other sites More sharing options...
love-my-V8-280Z Posted July 17, 2004 Share Posted July 17, 2004 Here is some comments I pilferiged from the web some time ago..... That said, you may have some easy remedies if the u-joint angle difference of 2.5 degrees does cause vibration problems. The first one is to raise the back of the differential by modifying or removing the rubber washers above the ends of the mustache bar, etc. The JTR manual goes over this, but I heard about this method before it was part of the manual. Unless you have a solid diff mount, the "opposite and equal" reaction to forward motion torque at the rear wheels raises the front of the diff upward. The point is that the static angle measurements observed at rest are not the ones the car sees during actual use. Placing the driveline angle lower by one degree allows for a total driveline angle deflection of twice that amount before vibration causing misalignment occurs. This vibration is most severe under load, and for good reason. The differential is bucking upward under load, creating a disparity of angles which increases with load and torque. The angle that the motor is in now (assuming you have not already modified it) is actually the worst case scenario for vibration free driveline. For truly long term driveline health, the diff has to be limited to no more than two degees of angle change. (Zero degrees of change would be best, but the noise transfer caused by a solid front mount, is for some an unwelcome irritation.) Quote Link to comment Share on other sites More sharing options...
MikeJTR Posted July 17, 2004 Share Posted July 17, 2004 Vibration problems are often caused by transmission mounts that are too stiff, and by worn out differential mounts. Don't use the urethane transmission mounts -- they have been a very bad source of vibration problems. Use the softest transmission mount available -- most aftermarket transmission mounts are too stiff. Get the transmission mount from the Chevrolet dealer. The differential mounts tend to wear out and fail over the years, many vibration problems have been fixed by replacing the differential mounts. Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 24, 2004 Share Posted August 24, 2004 "Scumdog" is referring to: http://alteredz.com/drivelinemods.htm Especially the part starting with the heading "U-Joint Angles" 2.5 degrees might be the problem. I'm running at around 1 degree vertical (less than 1 degree horizontal, like you.) on the U-Joint angles and have NO drivetrain vibration. My opinion (that's all it is) is that the horizontal angles are small and even though they are not the same, not of concern. I'd go after getting the vertical angles down to 1 degree or so, as equal as possible, but 2.5 and 2.3 are matched pretty well IMO. Make sure you have the driveshaft balanced by a reputable place as well. Quote Link to comment Share on other sites More sharing options...
Cable Posted August 30, 2004 Share Posted August 30, 2004 So, if I am understanding it correctly, the horizontal angle isn't as important than the vertical angles, correct? I haven't even got my 280z moving yet, but I ask because I noticed that the motor/trans aren't sitting exactly even length-wise with the rest of the car. I am worried that the minor "crooked" engine/trans alignment would cause problems. It is still possible to correct, but I would have to pull everything back out and 'slot' the mounting holes even more. Should I even bother? Quote Link to comment Share on other sites More sharing options...
johnc Posted August 30, 2004 Share Posted August 30, 2004 Funny... On my L6 install (engine back 4" and down 2") with a Quaife trans the vertical angles were 5* front and rear for a combined 10*. The horizontal was perfect. Engine, trans, and diff were all solidly mounted and I had no vibrations until I got to speeds over 100mph. Even then, it was hard to tell if the vibrations were driveline or wheel/tire. Just another data point for discussion. Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 30, 2004 Share Posted August 30, 2004 Project_BBZ: I'd not worry about the horizontal angle - it's probably small. Anyway, they don't exactly sum either (the vertical and horizontal). To find the total angle, you do a root-sum-sqaure (RSS) of the vertical and horizontal angles: Total angle = square root of ( vertical_angle_squared + horizontal_angle_squared ) or (for instance, in MS Excel parlance): Total angle= sqrt( vertical_angle^2 + horizontal_angle^2 ) If you have ~ 0.9 degree horizontal and 2.5 degree vertical, the total angle is 2.66 degrees. In other words, the relatively horizontal angle isn't really adding much to the total angle. love-my-v8-z 's assessment is right-on, IMO. Limiting the u-joint angles under load is the key. Most likely, the vertical angle will change under load, but the horizontal MAY not, if it's a stiff setup. The diff could move around in the horizontal plane since the mustache bar doesn't have alot of stiffness in that direction (mostly due to the mounts). The front mount like I have does not either. Some instrumenting might be in order (maybe some telltale type indicators that show what the max movement of the case is horizontally and vertically, front and rear?) The front mount that I have (from Ron Tyler) provides alot of stiffness vertially, since the mount must be compressed, not pulled apart like a bottom front mount will do (without a limiter). Also, the aftermarket polyurethane mount (for a GM tranny) that I'm using to hold the front of the differential is interlocking, so it doesn't have as much compression compliance as an all rubber stock GM trans mount. That may be why I have no vibration as well. johnc: The reason you can have so much of a u-joint angle and not much vibration is because of that wimpy little engine in your Z (j/k) Sorry, couldn't resist . Seriously though, that is interesting. I wonder if it has to do with the point that love-my-v8-z brought up. You may well have a stiff mounting system for the drivetrain and they never get much above what you measure statically? Still 5 and 10 degrees gives some huge speed variations from one end of the shaft to the other, compared to 1 and 1 degrees. 5 and 10 degree angles gives a +/- 1.1% speed variation during half a turn. 1 and 1 degrees gives +/- 0.0000015% speed variation during half a turn. Hmm. Does your mounting arrangement somehow make the operating angles more equal under load? If so, and they were more like 10 and 10 degrees, then the speed variation would be +/- 0.016% during a half turn. Big difference! Quote Link to comment Share on other sites More sharing options...
johnc Posted August 30, 2004 Share Posted August 30, 2004 Still 5 and 10 degrees gives some huge speed variations from one end of the shaft to the other, compared to 1 and 1 degrees. Maybe my post was confusing. The output shaft of the trans and the input pinion shaft of the diff are almost exactly parallel both horizontally and vertically (+/- .125 degrees). But, the pinion shaft points up at a 5 degree angle from horizontal so I built the engine and trans mounts so the trans output shaft points down 5 degrees from horizontal. My 10 degree number is the total degrees out of parallel with the driveshaft tube. Quote Link to comment Share on other sites More sharing options...
jbc3 Posted August 30, 2004 Share Posted August 30, 2004 In the F-body world the LT1/T56 equipped cars are known for high speed vibration. Frequently referred to the "vibashaft" problem. Many times it shows itself when swapping rear gears. In the f-body it is commonly corrected by replacing the stock steel DS with an aluminum DS. There are some that continue to have the vibe. I replaced my 1LE aluminum DS with a Denny's 3 1/2" aluminum DS with 1350 u-joints and still had a vibe. (balanced to 10,000 rpms) I found that my tailshaft bushing was worn and the yoke moved a little when inserted in the tailshaft. (probably worn due to driving with the DS vibrating) Replaced the tailshaft bushing and solved the problem. Take the yoke and push it up and down in the transmission and see if there is a lot of play. I am still new to the IRS world, but in my Fbody, w/ Moser 9" with a drag race set-up I set the pinion angle to -4 degrees. Any more than -5 and I get a vibe at high speeds. Less than -2 degrees and I see more wheel hop. YMMV Jody Quote Link to comment Share on other sites More sharing options...
Cable Posted September 1, 2004 Share Posted September 1, 2004 Hey guys, me again. I don't know if we are talking about the samething. My engine/trans sit "crooked" or "angled" in comparasion to the frame rails, car body, etc. It isn't very much, but enough for me to notice the tailshaft was pointing slightly toward the driver rear tire. So, because I worry about things too much I decided to remove the JTR supplied tranny crossmember and "slot" the stock tranny mount hole so I could move the tailshaft so its pointing dead center toward the rear decklid keyhole. I loosened the motor mount nuts to allow easier movement. The good news it worked (to a point), the bad news is I didn't "slot" it enough (only .5" or so) to get where I wanted it. So, I am going to remove it again tomorrow and "slot" the hole even more to get the tailshaft inline with the rest of the car. What do you guys think? Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted September 1, 2004 Share Posted September 1, 2004 Project_BBZ: To find the total angle' date=' you do a root-sum-sqaure (RSS) of the vertical and horizontal angles: Total angle = square root of ( vertical_angle_squared + horizontal_angle_squared ) or (for instance, in MS Excel parlance): Total angle= sqrt( vertical_angle^2 + horizontal_angle^2 ) [/quote'] To be technically precise, you are dealing with angles and not distances. The spherical trig identity is Cos(Total Angle) = Cos(Vert Angle) * Cos(Hor Angle) Although admittedly with such small angles the difference between the two equations is negligible. And to echo what jbc3 said, Ron Tyler's website strongly recommends an aluminum driveshaft to minimize vibration http://www.home.earthlink.net/~rontyler/rontyler.html Quote Link to comment Share on other sites More sharing options...
buZy Posted September 1, 2004 Author Share Posted September 1, 2004 Here everyone I orginally posted this thread. Great seeing all the thoughts and variations on this subject. Well I tweaked my DS set up further. I am now running a parallel 1.8 degree driveshaft angle the vertical plane (side view of car). Not bad. I coudn't tell if it vibrated even less this time, its still runs smooth with no half shafts in the car I might add. As I am way into the DS angle stuff doing testing. It's Cool! In the Horzontal plane ( top view of car looking down) I'm off a known .438 degree with the tail shaft pointing to the pass side of car. Less than one degree. It favors pointing to the pinion shaft. All this works well. I should add I have a very intersting front pinion nose mounting system if any of you would like to see it and you are going through what I did. It "traps" the pinion housing from the top as well as from the bottom. Rigid on the bottom. Poly mounted from the top with stops for lifting under power loads. It's not perfect but should work pretty well as I spread the load out as much as possible. Would really enjoy posting pictures here to show you all... but I am too stupid to figure out how. I'm better with welders and tools. lol. I have done much work all over the car for years and like to show others. So could some one tell me EXACTLY step by step how to post them.??Thanks everyone! Quote Link to comment Share on other sites More sharing options...
Guest trickz Posted September 5, 2004 Share Posted September 5, 2004 scumdog, I also have the same posting problem .I have 3 v8 z's and 2 have overdrive (700r &200r4?) both have vibrations at 1800 to2100 rpm. I question the driveshaft blance at speed. I just installed the 200r 2 weeks ago (350 out 200r4 in) gas mileage is up 13 to 20 but the vibrasions are there now. I did not have any problems with my 240 that I built in 78 and it still runs fine(muncie 4, soon wct5). we need a" how to " forum to help us out. drive shaft speed /drive shaft angle ? Quote Link to comment Share on other sites More sharing options...
buZy Posted September 10, 2004 Author Share Posted September 10, 2004 I orginally posted this thread a few weeks ago about driveline angles concerns. After a year and half of hard work... I test drove my 71 327 T56 240Z tonight! It runs smooth as glass! No Vibrations at all in the driveline. Thanks everyone! This site has helped so much watching what others do. And thanks Pete, your web site on driveline mods helped a great deal. What a difference! The car feels like it picked up another 10% HP to the back wheels and it just bolts down the freeway with ease! I will become a paying member soon and posting pictures. Brian Quote Link to comment Share on other sites More sharing options...
Guest 305240 Posted September 10, 2004 Share Posted September 10, 2004 photobucket.com is your answer for posting pics. Super user friendly. If I can use it, anyone can. Quote Link to comment Share on other sites More sharing options...
363z Posted December 13, 2020 Share Posted December 13, 2020 16 years later I'm trying to figure this issue out myself. Any pictures around of undersides? my t56 to r230 diff is quite offset. I have engine 3/4 inch offset in bay to side to get the alignment close on horizontal plane Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 13, 2020 Share Posted December 13, 2020 You don't want to move things sideways, you want to rotate them around their axis until the axis of the diff and the axis of the transmission are parallel. Typically (always from a factory install) the diff and transmission/engine are already correct side to side, with axes parallel to the wheelbase (except for transverse engines and front wheel drive), it's the up and down that needs to be worked on. https://www.drivelinesnw.com/part-trouble-shooting/vibration-analysis/angle-analysis/ Quote Link to comment Share on other sites More sharing options...
363z Posted December 13, 2020 Share Posted December 13, 2020 laine family mount is 3/4 off to side and build blog mention 3/4 inch so yes moving things sideways. Rotation? so motor should be tilted until trans is parallel to diff?? Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 13, 2020 Share Posted December 13, 2020 You rotate either or both. Don't know why the Laine's moved their engine sideways. Maybe they had clearance issues or something. Just because someone else did it doesn't mean it's the best way to get it done. The principles of powertrain alignment are pretty clear and simple. Just get those two axes parallel and don't make the angles too steep. Quote Link to comment Share on other sites More sharing options...
363z Posted December 13, 2020 Share Posted December 13, 2020 r230 rear end is almost inch over towards passenger side. So rotating the motor enough to line that up would be quite a bit. So moving engine over will make them parallel horizontal to each other. La8nes moved sideways because stock L motor was offset to side Quote Link to comment Share on other sites More sharing options...
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