driveshaft and rear pinion angle

[1961BelAir427]

I've seen valve cover rails machined pretty crappily. I'd think the prefered method would be to measure at the pan rail, but that may be difficult.

 

[jim_ss409]

One extra U joint sure does complicate things.

I ran Kdurgin's numbers through the computer program and they came out really good.
I input 6,000rpm plus a .83 overdrive so everything has to be really close before it will give you a "good" rating. I just guessed at 24 inches for each shaft, they're probably a little longer than that. But there could still be a problem because I left the phase angles at 0 degrees. I can't remember for sure but I think the driveshafts on these cars might be phased at 90 degrees. For that matter I might be confused about what 90 degree phasing looks like. I'll check it out a little later and report back on that.
I'm not sure how clear it will come out but I'll post a picture of the screen.

 

[Kdurgin]

I can't quite see the chart. I don't want you to get in trouble through work but are you able to email the results? If you can, I will give you my email address. I'm going out in the garage after snow removal duty tonight. I will measure each shaft length and check phasing too. I am going to play with my ride height a bit and then pinion angle. I'm going to raise the chassis ride height slightly to reduce my shaft to shaft angle then reset the pinion at the same split as the tranny to front shaft joint.I have an adjustable upper arm so it only takes a minute to change pinion angle setting. I think I can get the split of all 3 angles the same but then that would be my permanent ride height. If it is not too much trouble maybe you could run the new set of numbers for me? Thanks alot, Kevin.

 

[Kdurgin]

I've seen valve cover rails machined pretty crappily. I'd think the prefered method would be to measure at the pan rail, but that may be difficult.

I have the luxury of accessing everything and getting accurate repeatable measurements as my chassis is not under the car. The Tremec TKO tranny has a machined boss on top where the machined shifter plate mounts. This is parrallel to engine and tranny centerline. I also have Edelbrock heads that have the ends machined exactly perpendicular to the crank centerline. I have set the digital gauge on all these surfaces with the same reading. I have GM Performance cast aluminum valve covers and that reading is within .1 of all the others and sometimes right on depending on location on cover I take a reading. I take the shaft readings on the tube O.D. but you need to be parrallel with tube or it's radius could throw off the readings a bit. I also take readings on the machined sides of the yoke with them parrallel to the ground, these always equal the reading on the tube. Pinion angle I measure on the machined flat of the yoke or the front machined area my pinion bearing support mounts to. ( Moser 9")

 

[Kdurgin]

Here is a photo of the stock shaft assy. and my Inland Empire assy. On the IE setup, both shafts have yokes that are in phase. On the stock shaft assy, rear is and front is not. I'll measure them later.

 

[jim_ss409]

I would say that the front shaft on the factory setup is 90 deg. and the rear is 0 deg.
I'd say both shafts on the Inland Empire setup are at 0 degrees.
So the readings you got are really good for the Inland setup but go into the red with the factory setup. A shim under the center support and a little adjustment on the pinion brings the factory setup into the green. Below are the pictures of the factory setup before and after.
By the way, I used a driveshaft out of a one ton cube van in my car and it's phased the same way as the Inland Empire setup. It doesn't vibrate so either style of phasing will work if it's set up properly.

 

[Kdurgin]

If possible here is all the new accurate info for my setup. I would agree phasing is zero. Both of my shaft sections are 28" long. My 5th gear is actually .82 my rear gears are 3.70 My new angles are as follows:
Motor Front higher 3.2 degrees
Front shaft front higher 1.2 degrees
Rear shaft rear higher .7 degrees
Pinion Down 2.6 degrees

If I am figuring this correctly it gives me 3 u-joint angles of 2.0, 1.9, and 1.9 which hopefully is good. These readings were taken with my chassis at what I am planning on running as a ride height

 

[jim_ss409]

I ran the numbers and they came up as marginal but all that was needed to get it well into the "good" zone was to raise the pinion 2 degrees. With an input of 6,000rpm and a .82 overdrive you've really got to get everything right to get into the "good" zone. I ran the "marginal" numbers at 2,500 rpm instead of 6,000 and the rating was almost perfect. I didn't do the math but I'm guessing that 2,500rpm in overdrive would put you fairly close to 65mph.
You might not want to actually raise the pinion a full two degrees because even under light load the torque might tend to raise it about a degree or so. Either way, your driveline is really close to perfect, it shouldn't give you any vibrations.

 

[jim_ss409]

Just out of curiosity I tried running the factory settings that Models posted. Again I used the really high 6,000rpm with a .82 overdrive which gives you a driveshaft speed of 7317rpm and a road speed of something like 150mph.:eek: These high rpm's will cause the program to get super critical about the angles. Anyway it came up as "marginal" but when I tipped the rear end up a couple of degrees like would happen under load it came out "good" My guess is that the factory wants it set like that knowing that as you load the car with people or accelerate, it will be right on. Again, the driveline angles don't have to be perfect, in fact they can't be because just filling the gas tank throws things off. If they're reasonably close they're fine and again, the reading only showed "marginal" because of the high rpm.

 

[Kdurgin]

Thanks. What I don't understand is raising the pinion up made it better but I won't have the same angle split front and rear anymore? I can easily raise the pinion up with my adjustible 3rd arm. I would think the further away from each other you are on your sets of angles, you would get worse readings?

 

[Kdurgin]

What does it show if I raise it only 1 degree? Then raise 1 degree and put in 5000 RPM?Thanks.

 

[jim_ss409]

Yeah you're right, raising the pinion will effect the angle at the center bearing. I ran a few through with a few different settings. I'm not sure what order they'll be in but the marginal one is your present setting. Then I raised the pinion one degree and guessed that that would increase the angle at the center by 1/2 of a degree. That setting showed "good" then I raised the pinion another degree and increased the angle at the center by another degree,,, that was also "good" The best reading came with the pinion angle set at -0.7 degrees.
This is an older version of this program but I've heard that some of the later versions have an auto correct feature that shows the best possible settings.
I'll post three pictures on this post and add three more on the next post.

 

[jim_ss409]

Here's the last three...

 

[Kdurgin]

Thanks! This is quite interesting AND helpful. I'm thinking the last one with the pinion at .7 degrees is so good because with those settings, the first joint angle and second joint angle are close to equal and the rear shaft angle and the pinion angle are in the same exact plane so they almost don't even factor into the equation. If you had multiple shafts all in a row and they were all parrallel with each other, you would have zero vibration other than from wear or out of balance shafts etc. I wish this thing was all together so I could take it out and drive it after changing each setting. Thanks again

 

[Tic's60]

I think the saying "On a knatts ***" is about where the settings are now after all of this great info

 

[Kdurgin]

Here's the last three...

Can I get you to run another set of numbers?

Engine 2.9 down in rear
First shaft .9 down in rear
2nd shaft 1.0 UP in rear
Pinion 1.0 down

.82 fifth gear
28" shafts

Thanks, Kevin.

 

[jim_ss409]

Can I get you to run another set of numbers?

Engine 2.9 down in rear
First shaft .9 down in rear
2nd shaft 1.0 UP in rear
Pinion 1.0 down

.82 fifth gear
28" shafts

Thanks, Kevin.

I ran the numbers and it came back as "marginal"

I used the same tranny and front shaft numbers but changed the pinion and rear shaft numbers on the next one and it came out nearly perfect.
It doesn't show on the screen but I actually input -3.343 on the pinion to get a slight improvement over -3.34 Of course in the real world you can't get anything set that accurate and even if you could it would vary every time your ride height changed. We find that our trucks have to be well into the "fail" zone before you can even feel a hint of vibration.

 

[Kdurgin]

Shouldn't both my phase angles be ZERO on my Inland Empire shaft? Can you run both at zero phase and check again? Thanks, Kevin.

 

[Kdurgin]

How about one at:

2.9
.9
1.1 neg
3.1 neg

0-0 phase

 

[jim_ss409]

Shouldn't both my phase angles be ZERO on my Inland Empire shaft? Can you run both at zero phase and check again? Thanks, Kevin.

Yes you're right. The program defaults to 90deg. I forgot to change it. By the way, I double checked in the descriptions section and we're right about what a 90 or 0 degree driveshaft looks like.
Anyway, your numbers came out really good once I entered the proper phasing. By changing the second shaft to -1.1 instead of -1 the score was almost perfect.
The last set of numbers came out as "marginal"