80LS1T Posted March 7, 2003 Share Posted March 7, 2003 Ok well my engine will be done in about 3 weeks so I am just trying to get some of the "odds" and "ends" squared away! How do you guys figure out drive shaft angle? I know from reading through the achieves that it should be about 1 degree? But what does that mean? Please put it in the simplest terms as possible! I don't get how you measure it either. Also do you measure it with the car on the ground or up on a hoist with the suspension fully at rest/uncompressed? I could really use a pic/drawing if thats possible? Here is what I think you guys mean... Thanks Guy Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted March 7, 2003 Share Posted March 7, 2003 In the most simplistic of terms, imagine a line that connects the tranny to the diff and has then perfectly aligned. If the tranny tailshaft was 1* below that line, then the nose of the diff should be 1* above the line. You check your angles with a angle-finder tool which most good shops will carry or you can get one from harbor Freight or McMaster-Carr. See if this helps: http://www.iedls.com/guide.html Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 7, 2003 Share Posted March 7, 2003 Check out ths site as well: http://drivetrain.com/driveline_angle_problem.html Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 7, 2003 Share Posted March 7, 2003 Also, it makes no difference if car is up on jacks or not (because the IRS keeps the diff in the same position regardless). The key is finding a reference with which to measure the angle differnence. I measured the flat end of the tailshaft housing on the tranny, and then made sure the propeller shaft flange was the same angle. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted March 7, 2003 Share Posted March 7, 2003 What I did was have a perfectly straight, solid (no U-joints) driveshaft made. I then used that to line up the T56 and R230. 1* is not very much. I could not get my driveline to line up absolutely perfectly, but is probably within 2*. I had measured as carefully as possible before using the solid DS, and I was VERY surprised how far off it was once I installed the solid DS. I am very confident that once I install the U-jointed DS, everything will be smooth!! Tim Quote Link to comment Share on other sites More sharing options...
80LS1T Posted March 19, 2003 Author Share Posted March 19, 2003 Ok I took some measurements tonight... Here's a drawing with the measurements... Does it matter how much it is lined up from front to back? You know like if you were to look straight down the front of the car, how close do the tranny and diferential have to be lined up? Guy Quote Link to comment Share on other sites More sharing options...
DavyZ Posted March 19, 2003 Share Posted March 19, 2003 Uuugh, my head hurts from trying to remember all the geometry I took in school. Well, A squared + B squared = C squared and all that. Davy Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted March 19, 2003 Share Posted March 19, 2003 angle = arctan( drop / driveshaft length) = artan( 1" / 22.5625") = 2.5 degrees Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted March 19, 2003 Share Posted March 19, 2003 Mr. Powers calculation is correct but he misred the length as 22.5625. According to Mr. 80LT1, the length is 26.5625, giving 2.15 degrees. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 19, 2003 Share Posted March 19, 2003 The "droop" of the differential is really inconsequential in comparison to the angle difference between the tailshaft and the pinion gear. For example, if in this case the motor was tilted downward at the transmission end by 2.15* and the front of the differential was tilted upward by the same angle, then they would be "aligned" with no angular difference. So the droop from tranny-to-diff will not really be a problem. The big concern is getting the two "pointing" toward each other. Also (to split hairs here) is the lateral angular difference due to the pinion gear being displaced sidways, which I believe will account for a greater angular displacement than your example of the vertical displacement. Then you need to combine the two together (vertical and horizontal axis displacement to end up with a good number). Unfortunately, little to nothing can be done (in a pratical sense) to correct the sideways displacement (aside from moving the entire differential a couple of inches toward the drivers side). Just something to MUCK up the conversation here. Quote Link to comment Share on other sites More sharing options...
Guest Your Car is Slow Posted March 19, 2003 Share Posted March 19, 2003 So you are saying the vertical differencebetween the tailshaft and the flange on the differential isnt as important as the horizontal one? I have to yank out the engine/trans/rear out of my 70 this weekend...Now you people have convinced me to go measure it to see how far off it is stock Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 19, 2003 Share Posted March 19, 2003 They both are important, but in reality the two combine to form one single angle (i.e. an angle down and over toward the passenger side) I think that the side angle (based on your drawing) is going to be of greater magnatude then the vertical angle. The vertical angle can be eliminated completely with correct adjustement of differential nose angle, engine/tranny angle, or both. The side angle is going to be the major angle IMHO. It is very noticable, and with such a short drive shaft, I'm guessing it will be about 5-6 degrees (which is most likely where my vibrations are coming from) Quote Link to comment Share on other sites More sharing options...
80LS1T Posted March 20, 2003 Author Share Posted March 20, 2003 Hmm...so I am pretty close to the vertical angle, but now I need to try to correct the side to side angle? Guy Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 20, 2003 Share Posted March 20, 2003 What I believe you are missing is the importance of the angles that the transmission shaft and differention pinion make with each other. Look at this: Notice that at each u-joint they note the angle between the driveshaft and the transmission, differential, etc. That isn't totally needed, because you need to make the shafts of the transmission and differential pinion parallel. You need a method of measuring the angle that these make with the horizontal direction. The easiest way is to get an angle-finder: You can get this from Jegs : http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=3254&prmenbr=361 as well as other places. When you get these two things parallel, the front and rear vertical u-joint angles will be the same. At that point, you could do the math as Jim Power's shows, because your drawing makes one assume that the transmission shaft and differential pinion APPEAR to be parallel, which is not neceassrily the case if you just bolt in a V8/tranny, but must be made so. At the same time, the distance between the imaginary paralle lines extending out of the transmission tail shaft centerline and the pinion centerline can be used to determine the u-joint angles as shown, but this is more directly measured with the angle finder. 1) To find out the angle of the pinion with the horizontal, place the angle finder on the face of the flange on the pinion of the differential. It's perpendicular to the pinion centerline, so the angle is easily measured with the angle finder. 2) To find out the angle of the transmission tail shaft with the horizontal, try finding a flat surface on the transmission or engine that is horizontal or vertical. The starter mounting pad is a good place, as is the front of the block (water pump mounting surfaces, timing cover gasket surface, oil pan rail on the block, etc.). Even the end of the tailshaft isn't a bad. The longer the surface the better though. The angles measured in (1) and (2) must be within a degree of each other, preferably the same. If you can mount something between the center of the pinion flange and the center of the tailshaft (support a straight edge between the two and use the angle finder on the straight edge) and measure the angle it makes with the horizontal, you can add or subtract it from the angle measured in (1) or (2) above and determine the u-joint angle. Adding or subtracting the angles will depend on which way things pitch front to rear. Typically, if the car is level, the transmission tail shaft and differential pinion will be going from higher to lower heights from the horizontal as you go from the front of the car to the rear. The driveshaft will typically be from lower to higher as you go for to aft. If that's the case, then you ADD the transmission tail shaft angle to the horizontal (1) from the angle you measured from the center of the tail shaft to the center of the pinion. That'll give the VERTICAL u-joint angle. The horizontal u-joint angle is difficult to measure. I have no tricks for that, other than trying to reference the horizontal distance of the center of the tailshaft and diff pinion centerlines to a known reference line that is parallel to the transmission tailshaft and diff pinion centerlines. Again, this assumes that these centerlines are parallel to each other. 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.