Pinion Angle/ Snubber Question

[68suprB]

So I'm chasing this crazy vibration that can be felt most in the tranny tunnel area, but also shakes the hell out of the rearview mirror to the point I can barely make out the cars behind me in the mirror..Nothing in the steering wheel though...I'm looking at the pinion angle and trying to understand the mountains of info out there online and made an attempt to do some measuring today and here's what I have:
Tranny slip yoke is at 3º
Front of Driveshaft 1.4º
Rear yoke .09º
Rear of Driveshaft 1.5º
This doesn't sound at all right given what I've read and THINK I understand about the pinion angles...Also, I bought a mopar adjustable pinion snubber and it won't even come close to fitting even on the lowest setting. I actually had to take the entire bumper and post out to even get it to go on top of the 3rd member. Any ideas out there? It's a 68 super bee, all stock components to my knowledge,4 spd, 742 casting 8 3/4..Not lowered or anything which is why I have no idea why it won't fit..Could the leaf springs be shot? It doesn't look like it sits any lower than normal..

 

[5.7 hemi]

Your perches dictate the pinion angle on the rear, not the leaf springs. If memory serves, trans should be at 3 degrees up, rear 3 down. Don't quote me on this, somebody will chime in that knows more than I do.

 

[daredevil]

most trans are 2* down so the pinion should be 2* up under power. So you shim the rear about 2* down so when it rises 4* under power the angles cancel each other out.

 

[5.7 hemi]

I knew somebody would chime in that knows more than I do!!

 

[Meep-Meep]

You basically want equal angles front and rear. Picture the pinion center line and main shaft as one continuous shaft then change the elevation until you get no more than 3 deg difference. The increased nose down of the pinion is to deal with axle wrap up under racing conditions. For street cars extra nose down is not as critical.

 

[65 Plymouth Satellite 426]

I Went Through The Same Headache With My Plymouth!

 

[70redbee]

I may be stupid, but I am confused about Dare Devil's explanation. Does trans go 2* down, level or 2* up. Is rear pinion 2* up or 2* down. I thought trans should be 2* up and pinion 2* down to cancel each other out. My pinion snubber is tight to the floor and I was gonna take it off to try and stop the vibration.

 

[daredevil]

You basically want equal angles front and rear. Picture the pinion center line and main shaft as one continuous shaft then change the elevation until you get no more than 3 deg difference. The increased nose down of the pinion is to deal with axle wrap up under racing conditions. For street cars extra nose down is not as critical.

Not entirely true.All cars have spring wrap under load, look at the pinion at a car put in gear while holding the brake. You will see how much the pinion rises when its loaded.Race cars do move more though.

 

[67 coronet]

daredevils responce is correct and can be confusing if you dont know to compare the axle to the trans without using the ground as a reference point.all motor and trans assemblys are tilted slightly backwards in our cars,so some angles will get really weird depending on the rake of your car.just look at the pinion angle in this pic.

 

[68suprB]

Any ideas on why the pinion snubber won't fit? Maybe springs are done and its not riding as high as it should? I got the shims for the rear leaf springs, gonna try a 2 deg and see what happens

 

[Cranky]

Your springs could be flat. There should be some arc at rest....and springs can change pinion angle. The angle changes all throughout the spring travel from one end to the other. Can you post a pic of your car from a side view and then take a pic of what the springs look like from a rear shot but off to the inside just a tad?

 

[68suprB]

Thanks cranky, I will get some pics tomorrow or Monday. I have no idea how old the springs are but they don't look ancient by any means. The part #'s are as follows: driver side behind the u bolts read "P4452983" in front of the u bolts shows a pentastar symbol and "1916" below that "80566PN". Passenger side reads "P4452982" in front of the u bolts..looking at the yoke on the 3rd member, it's definitely more level/ pointing towards the floor of the car more than the ground..I know the pinion angle isn't related to the ground but this might be one of the reasons the snubber won't fit..

 

[daredevil]

Is your trans yoke 3* up or down

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If its 3* down your car must be level or a little higher in the front. 3* up and it would have to be jacked up like the one in the picture, post 9.

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pm sent

 

[Supershafts]

Why are you automatically blaming the pinion angle for your vibration ???

The adjustable pinion snubber are for race cars that are modified, so it shouldn't fit your car

You haven't gave ANY detail as to how, when and any speeds or anything with where this vibration starts and what it does as speed changes, and from that little you have given surely i wouldn't jump at the pinion angle.
.

Also you could shim the trans up and get it closer to 0

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Also i have no idea how any of you can see the pin angle or trans angle from that pic....

 

[68suprB]

Not blaming the pinion angle, simply looking at it as a possibility...right before I bought the car the motor was completely rebuilt, new clutch, pressure plate, resurfaced flywheel, new green axle bearings, new wheels/tires, new 3rd member w new gears/bearings and a new driveshaft I had made at a place in NJ. The only thing in the drivetrain that isn't new is the transmission. Like most of the guys on here, this car was made long before I was around so 99% of my knowledge comes from reading forums and articles online. A lot of people's vibration issues that I've read about came from pinion angle issues, so I'm gonna look at that.
As far as the vibration goes, it comes in at 2800 rpm and goes away at 3400 rpm. Before and after, smooth as glass. Does it in every gear but not as bad in 4th. The two things that confuse me are these: if I wind it up in 4th past that window and let the revs fall back down, it sometimes goes away completely, and it does it w the clutch in and out in neutral. While coasting, but only over ~60 mph..

As far as the pinion snubber, are you saying they're ONLY for modified cars and will never fit a stock setup? I thought it would fit because there ARE provisions for it drilled into the 3rd member. Also, my computer took a crap so I'm gonna have to wait a few days to post pics. Thanks for the help guys.

 

[Supershafts]

The adjustable snubber or the factory snubber, the adjustable race version will be against the floor.

 

[68suprB]

It's the mopar performance adjustable pinion snubber. What does a stock one look like? If I search all I can find is the mopar one and another that Mancini sells that you can rotate up or down.

Do you think I should just try to level up the transmission and leave everything else alone?

 

[68suprB]

Anyone know the length of a stock pinion snubber for a '68 b body? I found a few used ones but they come in two diff lengths

 

[Supershafts]

There shoulda been one on it, see a junkyard and if need be you buy different bottom out bushings for a truck that are different heights. Measure from the bolt hole on your diff and eye ball where the reinforcement plate is, thats where the bushing should be and see which of those work
Yes try and shim the trans up and level it

 

[68suprB]

Ok thanks for the help. I found a 6 1/4 and 7 3/8 long snubber, looks like they would both fit..one almost covers the U joint, the other would go past it