drive train alignment
Thread Starter
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
drive train alignment
hi
i'm doing a body off on a 70 convertible. just set the motor-trans on the engine mounts. two questions. the exhaust cross member torques down quite a lot with the weight on it-it was a th400 that i'm changing to a 4speed so the member is bolted in. how much is too much? should i weld the cross member it place? a professional mechanic friend mentioned an angularity guage to set alignment of the trans-propeller shaft. how is this done, and what are the tolerances? ok, 4 questions.
thanks
jeff
i'm doing a body off on a 70 convertible. just set the motor-trans on the engine mounts. two questions. the exhaust cross member torques down quite a lot with the weight on it-it was a th400 that i'm changing to a 4speed so the member is bolted in. how much is too much? should i weld the cross member it place? a professional mechanic friend mentioned an angularity guage to set alignment of the trans-propeller shaft. how is this done, and what are the tolerances? ok, 4 questions.
thanks
jeff
Instructor
Joined: Mar 2003
Posts: 217
Likes: 1
From: Buffalo MO
I have done this in the past with great success by simply placing the engine/trans assembly onto the engine mounts and letting the transmission fall into place, with reasonable visual alignment. The engine mounts will point you in the right direction, as long as they are correct. The trans is not going to have much of a choice where to go accept where the engine places it.
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
You need to make sure the drive shaft angles are exactly ( within 1 degree) opposite at the front and rear of the driveshaft. Up and down and side to side.
If the angles are NOT equal but opposite you will have a vibration at speed.
If the angles are NOT equal but opposite you will have a vibration at speed.
Thread Starter
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
thanks for the info
i don't know what you mean. should the angle that the trans makes with the propeller shaft be the opposite of the angle that the differential makes with the shaft, or the same? that is, if the shaft drops from trans, should the diff also drop more, or should it raise up, and visa versa? with the torquing i'm getting on the cross member, the angles are going to be a lot more than 1*. my mechanic stressed to me the vibration potential, but unfortunately he lives quite some distance so he can't inspect the car for me.
thanks
jeff
i don't know what you mean. should the angle that the trans makes with the propeller shaft be the opposite of the angle that the differential makes with the shaft, or the same? that is, if the shaft drops from trans, should the diff also drop more, or should it raise up, and visa versa? with the torquing i'm getting on the cross member, the angles are going to be a lot more than 1*. my mechanic stressed to me the vibration potential, but unfortunately he lives quite some distance so he can't inspect the car for me.
thanks
jeff
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
Theactual angle of the drive shaft to the transmission does not have to be 1 degree, it just has to be the same as the angle of the other end of the drive shaft to the diff but in the other direction. These angles need to be the same, but in the other direction...
read more here...
http://www.streetrodderweb.com/tech/..._shaft_angles/
http://www.drivetrain.com/driveline_angle_problem.html
read more here...
http://www.streetrodderweb.com/tech/..._shaft_angles/
http://www.drivetrain.com/driveline_angle_problem.html
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
The transmission points DOWN. Measure this angle and you will find it about 3 degrees DOWN
Now measure the pinion anglen and you will find it points UP.
The important thing here is that each angle must be the same but opposite directions. So one points up 3 degrees, one points Down 3 degrees they cancell each other.
If both point say down they add the sum of the 2 and you get a vibration.
The angles must be opposite direct but equally opposite in direction.
The arguement was never settled but looking down from the top like a bird I believe the drivetrain should line up. A string passed through the center of the harmonic balancer through to the center of the rearend everything should fall on this line.
This is my idea and has been shot down before so take it or leave it.
I have absolutely NO vibration at any speed and while cruisng at 120 or 130 mph the car is absolutely smooth.
The up and down theory is not disputed but the side to side is.
Now measure the pinion anglen and you will find it points UP.
The important thing here is that each angle must be the same but opposite directions. So one points up 3 degrees, one points Down 3 degrees they cancell each other.
If both point say down they add the sum of the 2 and you get a vibration.
The angles must be opposite direct but equally opposite in direction.
The arguement was never settled but looking down from the top like a bird I believe the drivetrain should line up. A string passed through the center of the harmonic balancer through to the center of the rearend everything should fall on this line.
This is my idea and has been shot down before so take it or leave it.
I have absolutely NO vibration at any speed and while cruisng at 120 or 130 mph the car is absolutely smooth.
The up and down theory is not disputed but the side to side is.
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Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
Can anyone give me a good reference point for measuring the transmission and pinion angle. I've read the links and a bunch of comments but can't figure out what to use as a Zero reference point. Some reference to using the starter housing doesn't make sense, it's at the same angle as the transmission tailshaft would be. Should the angle be in reference to the ground, frame?? I'm a little thick in the head I know so be easy on me!
And Norval, I agree that the side to side should be the same issue, it's a rotating assembly so the same conditions should apply in that direction also I would think. Sort of like putting the car on it's side, what's up and down now was once side to side.
And Norval, I agree that the side to side should be the same issue, it's a rotating assembly so the same conditions should apply in that direction also I would think. Sort of like putting the car on it's side, what's up and down now was once side to side.
