Pinion angle and driveshaft length.

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72ScampTramp

72ScampTramp

Scamp Tramp
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Rear Suspension is SS springs, CE shocks. Dana 60. Ive read many write ups and all them are different including the tech pages on BBD. I imagin I need to set pinion angle before measuring driveshaft length correct? What should pinion angle be?

Also I have a 440, 727 and Dana 60. If ive read right i put the yoke in the rear of the trans and slide all the way in then pull out 1" then measure from the center of the yoke to the center of the rear yoke is that correct?
 
pinion angle is in direct relation to your engine intalled angle.

most mopars are set up with about 2* slope. picture the front of the engine higher than the tail of the trans by 2*.

measure this first.

you want the pinion yoke to be at the same parallel angle as the engine/trans under full acceleration load.

so if the engine is pointing up 2* at the front then you want the pinion pointing up the same amount under full acceleration load.

now your suspension dictates how much you need to compensate for axle wrap.

my caltraces called for 3-5* so i set it at 4*.

so you take your 2* upward slope at acceleration and subtract the 4* axle wrap and you get pointing down 2* under no load.

its hard for me to put it into words. but i hope you get what im saying.
 
I just got off the phone with Denny from Denny's Drive Shafts and he says the exact same thing. Start with the car frame level and have both the trans and rear slope 2 degrees down. He said to ignore all the other stuff that is on the internet about matching angles up and down. He also said to set those angles before making the measurements. He has a worksheet on his website for all the measurements needed.
 
That's fine advice from denny's if you want a -4 pinion angle. Probably about the max for an everyday driver too.

Some stuff needs more than 4*.
 
Right now you have a 2* up angle which is BAD!

If the output shaft is 1* down, the pinion needs to be 1* UP to be a 0 angle.

"If you want a 5* down pinion angle, you'd roll the pinion down so it's at 4* below level.

I've had a SS spring car need 9* down... 5* is not a bad place to start. You likely wont find a 7* shim to correct the current angle issue. The locator pin won't engage the perches, too short."


Ok gonna pick a horse here. I noticed in all the pinion angle threads Rob is dead on. This quote is posted from another thread you posted on.

Example. Say with the SS leaf springs i want to be 5* down. Street car with limited strip action. If i were say 2* down on the trans tailshaft. I want to be 7* down on the rear pinion pinion correct?
 
If the perches aren't welded in place simply point the pin at 0 for now and measure for length.
After the shaft is installed then correct the angle to oppose the shafts angle, and adjust the angle so that it is at 0.0 with the shaft under load and nothing else.

The length isn't going to change much to have any negative effect on SY engagement.

.
 
72ScampTramp said:
You likely wont find a 7* shim to correct the current angle issue. The locator pin won't engage the perches, too short."
Click to expand...

You do not EVER lay a shim over the pin, you ALWAYS always use a new pin and the shim is part of the spring pack...
You always machine the drilled hole in the shim for the pin to sit square to it.
 
Confirmed the trans is 2* down and the pinion is 13* down. I will set the pinion at 0 and see what I come up with.
 
72ScampTramp said:
Example. Say with the SS leaf springs i want to be 5* down. Street car with limited strip action. If i were say 2* down on the trans tailshaft. I want to be 7* down on the rear pinion pinion correct?[/B]
Click to expand...

Try again... :(

Trans is 2 down, where does the pinion need to be for a 0 angle?
 
I guess im confused here... From my readings SS spring cars like 5* down or more. Why would I set it to 0*. Maybe Im figuring 2 different things here. The trans is at 2* down. Is one reading just to measure driveshaft length then the other is to actually set pinion angle?
 
72ScampTramp said:
I guess im confused here... From my readings SS spring cars like 5* down or more. Why would I set it to 0*. Maybe Im figuring 2 different things here. The trans is at 2* down. Is one reading just to measure driveshaft length then the other is to actually set pinion angle?
Click to expand...
Wow I'm lost here. I guess when I get to this point on mine I'll be asking all these guestions all over again. lol !
 
72ScampTramp said:
I guess im confused here... From my readings SS spring cars like 5* down or more. Why would I set it to 0*. Maybe Im figuring 2 different things here. The trans is at 2* down. Is one reading just to measure driveshaft length then the other is to actually set pinion angle?
Click to expand...
Yes setting at 0* is for driveshaft measurement(length).When I set my Dana60 up,I set the pinion 4* down.FYI Mr Crackedback helped with advise back then.Works for me.:D
 
younggun2.0 said:
i wasnt accounting for the axel wrap.

if we are using the sinerio of the superstock springs that cracked mention then the pinion would be down 3* to be at zero.
Click to expand...


That depends how you set the SS springs up, if you even set them up at all which most do not modify them at all so even then 3 will also be off, unless you have \6 power.
If you just bolt them in and go then if the trans is at a 2dg slope and not corrected you may need (dependent on power) 5,6 or 7 at the diff.
You don't want angles though
 
Power-train set up for 2 joint driveshafts is easy, unless you have a severely raised or lowered vehicle:

1. With the vehicle's weight resting on its suspension, make the pinion parallel to the transmission as a base-line.

2. Roll the pinion downward 2 degrees from the base-line (most street/strip cars) to 4 degrees (maximum) and weld your spring perches. This is the pinion angle.

3. Slide the slip yoke forward until it bottoms out inside the transmission.

4. Measure from the center of the front U-joint to the center of the rear U-joint.

5. Subtract 3/4" to 1" to compensate for slip yoke travel. This is the ideal driveshaft length.
 
Hey Cass good to see you posting! And yup thats exactly what i did. except i pulled the slip yoke out an inch then measured. I came up with about 47 5/8ish. It was exactly 48" to the raised part on the yoke little rectangle piece that sticks up.
 
Let me make sure i,m following along right. If the trans is down 2* then you want the yoke up 2* under accelleration.So if your springs flex 5* under accelleration you would want your pinion set 3* down at rest?
 
You are correct.

A true 5 degree negative pinion angle is pretty extreme, however. I don't like to go more than 4 degrees down, as this usually creates a vibration during braking.
 
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