drive line angles

reborn55 · August 24, 2010, 08:47:28 PM

Hate to beat a dead horse--Wifes coupe has 4-5 degrees down at pinion and 5-6 degrees down at trans. I am going to start by raising the trans(easiest to do) gradually and see what happens. Needs motor mounts also which may have a bearing on it. Has Chevelle clip and S-10 rear with CE suspension. Has some vibration here and there. Having some shims made for rear end but not ready yet. Just trying to get it where it runs smooth going down the road and then do the final settings over the winter. any insight is welcome

enjenjo · August 24, 2010, 09:18:38 PM

Read this http://www.roddingroundtable.com/tech/articles/driveline.html

It should have the info you need

sirstude · August 24, 2010, 10:03:36 PM

Frank beat me to it, but that article says it all. Your # of degrees is correct, just one end is the wrong direction, and I bet new motor mounts makes it worse by raising the motor a bit..

Doug

reborn55 · August 24, 2010, 11:00:05 PM

so the rear end is pointing down and upon acceleration the pinion (rear end) lifts so then to be in parallel shouldn't the trans be raised up as close to zero as possible/

enjenjo · August 24, 2010, 11:07:43 PM

Since the pinion angle and the trans angle are similar, but opposite, I believe your problem is the angle between the driveshaft and the pinion is more than the angle between the driveshaft and the tailshaft of the trans. In that case, raising the trans will make it worse, not better. I believe you are going to have to raise the pinon about 2 to 3 degrees to get the angles right.

reborn55 · August 24, 2010, 11:17:00 PM

OK--I am going to remeasure tomorrow with my angle gauge. Both ends are pointing down. Getting close to parallel. By raising the rear 2-3 degrees, upon acceleration it could raise to zero or so. Getting the trans close to that should help also--wouldn't it. I am getting some 3 degree shims for the rear end. I am looking at my 55 for general reference and it looks almost parallel. Way lot better than the coupe

Digger · August 25, 2010, 02:27:15 AM

Unless this is a race car you need to have the front of the pinion up about the same degree the tailshaft is down. Neither should exeed 4or5 degrees. Don't worry about where it goes on acceleration, your vibrations are going to come at cruising speed.
Good Luck

Digger

Beck · August 25, 2010, 08:56:13 PM

Front end alignment shops should have pre-made shims to use for pinion adjustment, or be able to get them. They are availabe in a couple different angles.

reborn55 · August 25, 2010, 09:27:45 PM

OK--went out and double checked it tonight. Took glasses off to see(hell getting old--could not fine magnifying glass.) Any way rear end pinion is down 4 degrees and yoke at the trans is down 8 degrees...What I am needing to figure out is if I raise the the trans up 1/2 to 3/4 of inch using new Energy suspension trans mount, will it cause a problem. It would help in bringing the radiator fan closer to radiator at the top--kinda make it straighter up and down..Bigger gap to radiator at top than at the botom. Might even things out in the driveline. I am going to try and change rear ends over the winter--get ride of S-10--3:42 posi for 56 Chevy 3:08 rear end. Can redo all angles then.

Fat Cat · August 25, 2010, 11:03:22 PM

Quote from: "reborn55"OK--went out and double checked it tonight. Took glasses off to see(hell getting old--could not fine magnifying glass.) Any way rear end pinion is down 4 degrees and yoke at the trans is down 8 degrees...What I am needing to figure out is if I raise the the trans up 1/2 to 3/4 of inch using new Energy suspension trans mount, will it cause a problem. It would help in bringing the radiator fan closer to radiator at the top--kinda make it straighter up and down..Bigger gap to radiator at top than at the bottom. Might even things out in the drive line. I am going to try and change rear ends over the winter--get ride of S-10--3:42 posi for 56 Chevy 3:08 rear end. Can redo all angles then.

As referenced in the article above having both of them down is not a problem as the angles are opposite angles. The problem comes from the fact that one is 4 and the other is 8. That is a 4 degree difference which induces a vibration into the driveshaft. The optimum angle is 3 degrees at both ends. But if you could make them 4 at both ends that would be within the range of acceptable. Whatever you do those angles should be the same at both ends.

Mikej · August 26, 2010, 01:57:49 PM

The carb should be level. The intake should have 3 deg built into it. Could be mistaken.

enjenjo · August 26, 2010, 04:55:50 PM

We seem to be getting things confused here. The idea; is to have both angles the same. if the trans is 5 degrees down, then the pinion should be 5 degrees up. This make both u joint included angles the same, measuring the angle between the driveshaft, and the input and output shaft on each end.

With both the tailshaft, and the pinion pointing at a down angle, this gives you a secondary ideal position, but it's measured differently. Instead of measuring the angle of the shafts from horizontal, you have to measure the included angles, and make them the same.

For instance, with the tailshaft 8 degrees down, and the driveshaft 4 degrees down, the included angle is 184 degrees. With the pinion 5 degrees down, and the driveshaft at that end going 4 degrees up, the included angle is 189 degrees, or 5 degrees different.

If you raise the trans 2 degrees, that would make the included angle 182 degrees, and the rear angle 191 degrees, which would make it worse.

If you raise the pinion 3 degrees, that angle becomes 186 degrees, and while not ideal, it's closer to right.

Mikej · August 26, 2010, 05:39:35 PM

The point I was trying to make is that if the carb is level, at ride height, that should be the proper angle for the motor and transmission. Then the rear end can be adjusted to it. It sounds like he needs to address the motor first. You see to many cars with the motor installed at fun angles.

enjenjo · August 26, 2010, 06:14:23 PM

Quote from: "Mikej"The point I was trying to make is that if the carb is level, at ride height, that should be the proper angle for the motor and transmission. Then the rear end can be adjusted to it. It sounds like he needs to address the motor first. You see to many cars with the motor installed at fun angles.

No argument Mike. I agree. But it's not always possible. And, it's not really critical as far as the engine is concerned. I have mounted them with as much as 11 degrees engine angle using a tapered carb spacer, with no problems.

chimp koose · August 27, 2010, 12:31:56 AM

I believe the best way to explain is that the output shaft and the pinion shaft should be PARALLEL, horizontally and from viewing directly from above. In a drag car we typically install the pinion 3-4 degrees down FROM PARALLEL to the output shaft in the horizontal plane .