2004 6.0 NV4500 Tahoe

[Dantheman1540]

I did not go with adjustable arms. I went with AC Delco uppers and Spohn boxed lowers for more rigidity.

That makes sense as I did the same and likely took the idea straight from your thread . I need to find a stock UCA so I can re-engineer them and make some nice adjustable tubular arms with poly bushing instead of sphere joints.

I'll probably check to see where its hitting again tonight and chop some more. I also ordered these 2" bump stops which I think will solve the problem with out without more chopping. The bottom picture is the current bump pads.

 

[Dantheman1540]

Pinion angle may be worse than expected. Ordered a little digital angle finder this morning and it was home before I was. Measuringthe driveshaft angle was easy but since the casting on the yoke is kinda rough and rounded edges I took a measurement off the top and bottom to see the difference. In the picture you can see my math and that my out come is a pinion angle somewhere between 8.7 and 7.5 which is much worse than I expected. I think some adjustable control arms will be in my near future. My research shows between 1-4* is perfect for a link setup so I will strive for 2.5-3* in the future.

Also it still hits but I'm making improvements even without the bump stops because no it just kisses the very corner of the evap mount.

 

[iamdub]

You have a single driveshaft connecting the trans output to the rear end's pinion, right? All you need is for the pinion angle to match the trans output angle, but with the rear rotated down slightly, like 1-2 degrees.

 

[Dantheman1540]

You have a single driveshaft connecting the trans output to the rear end's pinion, right? All you need is for the pinion angle to match the trans output angle, but with the rear rotated down slightly, like 1-2 degrees.

Yes single shaft. I did not know that I will have to check the trans output angle. Thank you!

But today it's back in work truck mode repossessing my buddies RX7 from a body shop scum bag that's had it 7months and made it worse.

Car is so low I have to borrow a buddies landscape trailer because its lower deck than my car hauler. But it's still to much angle so I have to jack it up all ghetto.

 

[Tonyrodz]

Yes single shaft. I did not know that I will have to check the trans output angle. Thank you!

But today it's back in work truck mode repossessing my buddies RX7 from a body shop scum bag that's had it 7months and made it worse.

Car is so low I have to borrow a buddies landscape trailer because its lower deck than my car hauler. But it's still to much angle so I have to jack it up all ghetto. View attachment 253380 View attachment 253381 View attachment 253382

I hope he didn't give him any money--or if he did, gets it back.

 

[iamdub]

Yes single shaft. I did not know that I will have to check the trans output angle. Thank you!

Yup! No need to overthink it. Vehicles that have multiple driveshafts with double Cardan joints are what get messy, but even that's just because they're over-thought.

A U-joint needs to be 180° out of phase from the the one on the other end of the shaft so the angles don't work against each other:




...And a .GIF to show the ideal smooth operation from the two ends having matching angles:



If you could watch just one of the four sockets of the U-joint, you'll see that when one is "tilted out", it's corresponding one on the U-joint of the other end of the shaft is "tilted in". As it rotates, the joint is constantly pivoting out and in and the opposite one is pivoting 180° out of phase from it.


The point of having the rear pinion a degree or two lower is because it rotates upward under load, even just the load from propelling the vehicle at a constant velocity on a flat surface. Setting it a hair low with the vehicle at rest means it'll be right where it needs to be when moving. A leaf-sprung rear lets the pinion rotate much more than a linked rear, so you set the pinion much lower, like 5-7 degrees. Links maintain the angle much better so you're only having to account for deflection in the bushings.

 

[Dantheman1540]

I hope he didn't give him any money--or if he did, gets it back.

Not getting any money back honestly just glad it's not gone or stripped. He only paid $900 upfront which isn't terrible. The place was a total crap hole idky he ever trusted them to start with they literally paint in a shed.

Yup! No need to overthink it. Vehicles that have multiple driveshafts with double Cardan joints are what get messy, but even that's just because they're over-thought.

A U-joint needs to be 180° out of phase from the the one on the other end of the shaft so the angles don't work against each other:




...And a .GIF to show the ideal smooth operation from the two ends having matching angles:



If you could watch just one of the four sockets of the U-joint, you'll see that when one is "tilted out", it's corresponding one on the U-joint of the other end of the shaft is "tilted in". As it rotates, the joint is constantly pivoting out and in and the opposite one is pivoting 180° out of phase from it.


The point of having the rear pinion a degree or two lower is because it rotates upward under load, even just the load from propelling the vehicle at a constant velocity on a flat surface. Setting it a hair low with the vehicle at rest means it'll be right where it needs to be when moving. A leaf-sprung rear lets the pinion rotate much more than a linked rear, so you set the pinion much lower, like 5-7 degrees. Links maintain the angle much better so you're only having to account for deflection in the bushings.

I actually have that same exact picture saved on my phone I guess I should have looked at it better.

So I really need to measure the angle on both ends and draw a new picture on a new piece of wood. I'll probably do that later this week as I'm leaving the trailer hooked up until we can drop the car off on Monday at the new body shop.

I also added the new bump stops and they still aren't long enough to stop the joint from hitting the bracket so more cutting later this week as well.



In this pic you can see the paint booth shed in the back.

 

[iamdub]

So I really need to measure the angle on both ends and draw a new picture on a new piece of wood.

Lol
No need to draw any pictures on anything. Rotate the output shaft so one of the flats of the U-joint are at the bottom then stick that angle finder to it. Record the number it displays. Then stick it to the flat of the U-joint on the rear pinion. You want that number to be no more than 1-2 less than the first number but definitely not higher.

 

[Dantheman1540]

Lol
No need to draw any pictures on anything. Rotate the output shaft so one of the flats of the U-joint are at the bottom then stick that angle finder to it. Record the number it displays. Then stick it to the flat of the U-joint on the rear pinion. You want that number to be no more than 1-2 less than the first number but definitely not higher.

Well I'm an artist so I will draw another pic!

Thank you for simplifying it. The day I drop all this crap off and can fit it back in my garage I will be doing this again.

 

[iamdub]

Well I'm an artist so I will draw another pic!

Thank you for simplifying it. The day I drop all this crap off and can fit it back in my garage I will be doing this again.

Okay, but use grease pencil on Balsa next time. lol