Driveline and Pinion Angle

[colonel]

Does anyone out there have what the stock transmission angle and pinion angle are in or cars?

 

Is it different for TH350 and TH400 trans?  How about 10 bolt vs 12 bolt.

 

Trying to decide on starting point for changing mine as my 4l60e and 12 bolt pinion are both pointing down about 2.8 degrees.  It does not like that after about 60 mph you feel a vibration.

 

Didn't have this vibration problem with this drivetrain in other 70 but do in this one.  Trans is as high as it can go and is about 3/8 inch to drivers side of center so changes have to come in pinion.  Have global west control arms so no rubber bushing to flex and new coil springs.  Driveshaft has new u joints and is rebalanced.

[Sam (Bones)]

you want the angle of the (trans/driveshaft) the same or within 1 degree of the (rear axle/driveshaft)

[colonel]

So you are suggesting I change the pinion angle to 1.8 degrees down to get rid of the vibration?

 

You don't have what to original angles are though?

[Sam (Bones)]

it all depends on how you are measuring your pinion angle

 

ideally...you want the pinion and the transmission running parallel to each other

 

 

 

 http://www.hotrodhotline.com/md/html/drive_shaft_harmonics.php

[colonel]

That is a good article.  I haven't seen it before.

 

I measured the trans at the edge of the tailshaft housing.  You can't measure the shaft as it moves and will obviously alter the readings.   You can also measure the balancer pulley unless you suspect it is bent a bit but it should give the same angle.

 

Pinion and driveshaft are measured as they do in the article.

 

Spoke with Global West and they suggested to start with pinion at 0 and see what happens with the vibration.  Ideally the angle should be equal but opposite or as you said earlier within 1 degree.  The driveshaft will be what ever it is.

 

The other thing to consider is how much applying power would cause the pinion angle to move.  Perhaps I should move it to 2 degrees up.  At sruising speed it may move up to 2.8 and be equal.  With regular rubber bushing it would certainly move more than with the setup I have but don't know how much.  Perhaps with rubber bushing keeping it at 0 degrees would be OK  That is why I was asking for what the angles are in a more or less factory setup.  I could have measured mine before the mods but too late now.  Can't make an educated guess without knowing those numbers so hopefully someone can supply them.

[colonel]

For documentation sake I have finally solved my Hydraboost Issues and have been able to drive the car a couple times now.

 

I had the driveshaft worked on by a different company and they found excess weight on the driveshaft and it had .018" of runout at the front, .022 in the middle and .008 at the back.  So the previous company tried to balance it without adjusting the runout.  It now has .01, .008, .006 respectively and only 1.5 onunces of weight on it rather the 4-5 ounces.  I am sure that would have made a difference all on it's own but I also changed the pinion angle to 2.25 degrees up.   That moved the trans to 2.4 degrees down now and the driveshaft has a small angle down towards the pinion.  At 60-70 MPH there is no vibration at all where before there was a steady surge of it coming in and out.  Really unexpected thing with this is the rear main seal in my new engine is no longer leaking like a siv.  There are no 3" puddles under the car anymore overnight.  Seems like that was a far worse problem than I believed and am very glad it has been fixed before causing me any further failures or issues.