I’m setting an engine in a ch***is and was concerned with making sure the engine was aligned properly. I wasn’t sure how this would be measured but this is what I came up with. I dropped a plum bob from the ceiling rafters and centered it over the harmonic balancer bolt. I then dropped a plum bomb and centered it over the read diff yoke. I stretched a line between the two points on the ceiling. I then dropped a plum bob over the transmission output shaft to see where it fell. If the engine was in-line, all three points 1) the engine crank bolt, 2) the trans output shaft, and 3) the diff yoke should fall on the line. You can see in the picture below that the trans is off, maybe an 1/8-1/4 in., meaning I need to push the rear of the trans a little to the left. Or, maybe it’s just measurement error. What do you think, is it good enough? Is there a better way to do this? See pics below:
I'm up to speed on pinion angles versus transmission angles, but not to hijack the thread, but what about all those offset differentials of the world? Seems to me that those driveshafts suffer from non-complementary angles in the horizontal plane. Experts?
To the OP... if you can live w/it , won't hurt a thing.... to the second poster.. ALA the working angles of the u-joints are less than 3* & greater than 0* , it's fine u--joints don't care... dave
I don't think I've ever dealt with one. Example? As long as the trans and pinion are parallel I wouldn't expect it to cause a problem.
cant view your pics, but the engine can be offset a bit to one side (factory did it all the time). But it needs to be running straight down the car north/south and not pointing the tailshaft at the dif. As long as the crank is parallel with the pinion gear, it's ok-as long as it's not offset so much that the ujoints see more than 3degrees or so of angle. As stated before, it can be offset above the pinion or to the side of the pinion shaft- the ujoints only see the degree of angle-they dont care if the driveshaft is offset above,below, left or right. -rick
Exactly. The rear doesn't care if it is offset on a vertical or horizontal plain. It doesn't know the difference as long as the trans output and the rear end are at right angles to each other. When I install engine/trans in a ch***is I just center the engine by measuring from the center crank bolt to the frame rails, then I do the same thing at the rear from the trans output shaft to the frame rails. Then I make sure the output shaft is angled down about 3 degrees from level. I haven't had a problem so far.
Well, I've never bothered with ceiling joists. I've always built things over a center line drawn in a table, the floor ect and used a square or plumb bob from the object down to the center line. Seems like there could be plenty of error especially in ceiling joist.
If your mindful of the set up and why it works, it causes no problems. If your mind can turn the set up you'll be able to see You can use an offset differential to your advantage in some cases on particular configurations. A ford exploder 8.8 pinion is offset from center by about 3"
Who says the joist is straight? It probably isn't. Do like 31Vick says and pull a straight line on the ground to measure up from.
Some of you need to reread the OP first post, he said he hung the plumb bob over the center of the harmonic balancer and from the center of the pinion, then chalk lined a line conneting those 2 points on the ceiling and hung the plumb bob to the trans output shaft, which will be a very accurate way to get it lined up.
you can't change the center line of the crank and trans so don't worry about it. Lots of engine center lines are off set to the side. It is not critical to have the center line of the engine centered in the frame. I'd keep the center line equidistant from sides but it does not need to be centered. The U joint will take care of any off set.
Oh I read it just fine. A straight line across a skewed surface (like the bottom of ceiling joists) isn't a straight line either. Try it. Plus I'll be damned if I need a ladder just to Check to see if something is on a center line.
I always just make sure the frame is square ( measure opposite corners front to rear. If the measurement is the same the frame should be square. Then set the engine and trans between the rails and center it with about a 3 degree downward angle to the rear. Square the rear end in the frame with the pinion 3 degrees up. Done. No ladders, no plumb bobs !! Been doing it like that for many many years on more then a few cars.
U-joints run a lot longer if they are not lined up perfectly. They have to "work" a bit to keep the rollers from wearing in to the cross.
I don't know about the ceiling in your garage, but if I did that in my garage it would yield a straight line, guaranteed. I do have to admit that I also don't know about HUSSEY's ceiling and ***umed it would work like it would in mine. Now that he is is where he is in setting the engine in and wants to verify that it is setting properly, I think what he is doing will work well.
Sometimes the engine/trans are offset the same as an offset pinion and only the vertical angle is present. However, when there is a horizontal U-joint angle as well as a vertical, it becomes a compound working angle, and both angles have to be included to arrive at the actual working angle.
The u joints are constantly changing angles as the suspension moves around, no need to worry about "working"...
Maybe I didn't explain what I did very well but **** got it exactly right. No, I didn't use the ceiling joist as my straight line, I can't say I would be that naive to think a 2x6 would that straight. Beside they run the opposite direction of the line I stretched between the crank bolt and rear diff plumb points. With my frame it isn’t straight like a pair of straight frame rails, it has a more complex shape to it making it hard to determine the center.
Very good point that helped clear things up for me. If the engine was inline with the rear diff then you would have an angle on one plane. If the diff and or engine was offset to one side you would have two planes and two angles. As long as the center line of the engine and diff are parallel and all your angles are equal but opposite, then they cancel one another out.
What I did was basically like what you did, but instead of putting a center line on the floor, I put a center line on the ceiling. I don't know why I didn't think of dropping the plum bob from the crank, trans, and diff to a center line on the floor. I plan on checking it one more time and I think I will use this method instead of hanging it from the ceiling. Thanks for the advice, plus I'll be damned if I have to climb that ladder all the way up to my ceiling again!
Engine / transmission axis must be parallel to centreline of car, it can even be offset to one side as in Mustangs and Corvettes. Irrespective if frame tapers or is shaped, drivetrain centreline must be parallel to centreline. Don't forget 3 degrees down on engine and 3 degrees up for pinion. As stated check diagonals and lengths of frame to ensure that it is square before you commit to anything. If frame is damaged, repair it before you go any further, some minor variances would be OK and be considered normal. A mistake here could lead to strange harmonics and possible handling issues later. Not all pinions are centred, I would sort out the engine trans set up first and the later will take care of itself. The tail shaft might be off to one side but that isn't unusual. Lots of thread on pinion angle. Lay an angle bar across frame using 2 x common reference points at front of engine and rear of transmission. Measure the distance at outside edges and halve the distance, that is the centre, it should be equidistant from the centreline of crankshaft and transmission output shaft. I presume that the frame (ch***is) is symmetrical. Use the plumb bob to determine centres and you're done. Fabricate the mounts and or make patterns.
I don't see anywhere that you made sure that your line on the ceiling is perpendicular to the rear axle. You used the damper and the pinion, if the damper was in the wrong place compared to the pinion your crank centerline isn't necessarily parallel with your pinion and that is the one thing that you have to have for good U-joint life without vibration. When trying to square something, here is a little trick I use, it is called the 3-4-5 rule. I take a sheet of cardboard and starting a few inches from a corner measure out 3'. now from one end of that 3' line measure 4' perpendicular and swing an arc (don't draw a line yet) Now measure from the other end of the 3' line and swing a 5' arc that intersects the 4' arc. Where those arcs cross is perpendicular to the first end of the 3' line. This may sound complicated, but when you do it once it will make sense. the 3-4-5 rule works for any multiple of 3-4-5, (1 1/2-2-2 1/2), (30-40-50) makes no difference, they all work!
If you think it's basically the same, where's the problem coming from then? If it were the same, even on a basic level, you'd be able to see empirically without doubt exactly where the problem is. When laying out a car, there are 2 very important center lines. 1st is front to back and the track of the tires and suspension should fall equally about this center line. Second is the perpendicular center line of the rear axle. It's imperative that this be truly perpendicular. Now these 2 lines will be the bench marks that the rest of the car is referenced too, an unchanging, unwavering absolute. Maybe the pinion falls on the 1st center line maybe it doesn't but it doesn't matter, in your exercise you made it matter and a control point. this point needs to be irrelevant. What matters is that the wheel mounting surfaces are equidistant from the 1st centerline and that the axle flanges and shafts are on the 2nd center line and that the shaft of the pinion is only parallel to the 1st center line The engines crank and transmissions center shaft need to be parallel with the 1st center line. They can be directly on it or offset, but they must remain parallel. In your exercise this is where your unknown shows, With those 2 centerlines you can build any type of car, any configuration and asymmetrical. You could even take 34 rail on one side and a upside down 34 rail on the other, or a banana on its side configuration and make it go straight down the road.
****, Apparently we see things differently. Ask any drywaller/board hanger how flat a ceiling is. Lol Ask any carpenter how true foundations are or how true dimensional lumber is. Ask a cabinet maker how true ceilings are. Then let's find out how true and centered hussey's pinion is to the housing
Seb; I'd have to agree with your take, on the working underway motions. However, I once erred, and set up a shaft that had an angle on the pinion coupling, but Not the trans. Later realized the was no canceling of the "speed-oscillation" of input to the pinion itself. (due to the joint angle) Oooops! This does suggest setting up equally opposed angles. I stick close to three degrees; as sufficient to move lube around the rollers.
You can get a laser pretty cheap these days. They do wonders for this sort of thing. That's how I set up my ch***is. worked great. And you can get one that has a digital angle finder and use that to set up your pinion/trans angles.
I get it now. An offset rear still has the trans output shaft and rear pinion in parallel. If you added "yaw" to the engine, then that may cause a problem. So then offset in either plane doesn't matter as long as the shafts are parallel OR the working angles of the U-joints are (nearly) equal and opposite, and obviously don't exceed the working angles of the joints. So, while we're on the subject, why the hell don't the manufacturers put a nice little level surface on the trans and the rear so we can measure these damn angles?
Sorry but I just don't think you have grasped it. Maybe I need to provide you with more pictures? What I did was exactly the same. The only difference is that I created a center line from above the ch***is versus one below the ch***is. The drywall, lumber, ceiling etc. are irrelevant. Stretching a string between two points (screws in the ceiling joist) is going to create a straight line, simple. Though I don't appreciate you hijacking my thread, thank you for your input, at least I learned the idea of marking a centerline below the ch***is.
Good idea, I was thinking about that. I'm sure once I have one I could find all kinds of uses for it. I'll have to do some research and see what's available.
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