Transmission shaft angle question

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Steven190

Steven190

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On my 69 Dart I have been redoing the suspension after breaking a spring perch and have a question.
The car has a Tremec 5 speed. After measuring the angles I have; 5 degrees down on the rear axle, 5 degrees down on the transmission, and a 5 degree angle on the drive shaft.
So the rear angles are good, my question come from, after reading the Mopar Chassis book.
It says that the transmission angle should be 2.5 degrees or less. There is no way to raise the tail shaft up that far to get that angle. The manual says that 1/8" changes the angle 1/4 degrees.
Who has measured their tail shaft angle and what are you seeing?
 
I just went thru this with my 67 dart, 904 gear vendor OD. My trans is 1.5* down with no shimming 67 OEM style trans mount, 4 cross member bolts tightened with floor jack pushing cross member up. With an 1/8" shim the trans is .5* down, so on my car 1/8" = 1*. My driveshaft 38.5" C to C is 2* down, rear pinion .5* down. Working angles should be less than 3* for long u joint life. I run an adjustable snubber at the track 1/4" from the floor pan.
Measuring Angles | Spicer Parts
Driveline Operating Angle Calculator | Spicer Parts
 
Thanks for the reply.
The car seems to be smooth, no noticeable vibrations, but kinda concerned about the same angle on each. I will look into the sites, for more info. Some of my trouble is that the trans is all ready very close to the tunnel, There is not much room to raise the trans. Will let you know.
 
Lowering the front of the engine will help if possible. Maybe you have shimmed the engine mounts up in the past to get headers to fit better?
Lowering blocks raise the rear axle and decreases the driveshaft angle; doing this will improve trans and pinion u joint working angles.
I cut my trans tunnel and made a raised cover to get the GVOD up closer to 0*. I'm not a purist so cutting a car to make stuff work is ok with me.
I spent a good amount of time getting my setup right. Good luck
 
The angles, in relation to the flat ground aren't important. What is important is that the crankshaft centerline angle is equal to the differential pinion centerline. On a leaf spring car the pinion can point down a few degrees because, under power, it twists up. As long as the two centerlines are parallel, and the centerline to driveshaft angle isn't excessive you are good.
 
According to the article the trans to driveshaft angle is 0 degrees. I have 5 - 5 = 0, the driveshaft to axle is 10 that is 5+5=10 it is a down angle of the shaft and a up angle of the axle. That is look from front to back.
So the front is good at 0 but the back is high at 10 with leaf springs?
 
d55dave said:
The angles, in relation to the flat ground aren't important. What is important is that the crankshaft centerline angle is equal to the differential pinion centerline. On a leaf spring car the pinion can point down a few degrees because, under power, it twists up. As long as the two centerlines are parallel, and the centerline to driveshaft angle isn't excessive you are good.
Click to expand...
Thanks. This is a confusion issue, because everything you read is different. The Mopar manual says 10 is good for the back with leaf springs.
 
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