Driveline Vibe Diagnosis Help

interesting? is this what matches to my hand drawing? i was under the impression, from the output shaft , this is your starting point for ups and downs... so my output flange is down... the 1st driveline, is down... the 2nd driveline is not as down as the 1st but still down... and then the rear end is up. so thats down down down up... but i see how manipulating your ups and downs can give me your result..

im confused now.. i was thinking i needed axle angle shims, but this most recent math looks pretty good.

 

Tremec phone app worked well for me

 

i tried tremec app, but it only does 1 piece drivelines.. i guess i could measure it to the carrier bearing, but visually i can see the angle from the rear end to rear driveline, its way greater than the angle in the front.. so im confused on what a2lowvw is saying.

 

The first measurement is taken on the forward driveshaft

 

can you link me a tutorial.. or explain this process..? i measured my truck on level ground.. and then i measured my hand drawing from 90degree oriaintaion. so from level, my output shaft is down 4.4. then the 1st driveline from level ground is 9 degree down.. 2nd, 6 down. and then my rear end is up, 8.2 degrees.

 

i guess your right when i put 1 driveline numbers.. start with 9, 6 in the middle, and 8.2 rear end is turning out with some good math.

 

but if i go down down up... i get that 14 degree rear.

 

Not good enough with this forum but the search function gave me what I needed when dealing with a 2nd gen Prerunner lifted an inch or 2. BTW I also found collapsed transmission and motor mounts complicating things.

 

Ughh...I hate those calculators. They don't explain anything or tell you if it's set up correctly. Is it for a 2 piece with 3 standard u-joints? That looks like one for a 1 piece with 2 standard u-joints. Should show 3 operating angles...don't know what good knowing only two does someone.

From your post, I get:
A=4.6 down
B=3 up
C=14.2 up

This, of course, is not right.

I think a big part of the problem is, what you're calling an up/down slope vs how the calculator interpretates it, isn't jiving cause the calculator is not correct.

 

split bolt, i don't know if we are on the same page.

my initial hand written pic on page1, is 4.4 down. 9 down. 6 down, 8.2 up. i can see the 9-6 is 3... so i have 4.4 down, 3 down. 8.2 up.

without the driveline angle in the conversation i have a difference from the output shaft 4.4, and rear pinion 8.2... the different on level playing field is 3.8 degrees off.. if i understand correctly those 2 ins and outs should be as close to 0 as possible.

 

Here is Tom Woods page and calculator makes it pretty straightforward

https://4xshaft.com/blogs/general-tech-info-articles/slopes-vs-angles

 

Why are you trying to equalize the A and C working angles. This would only work if you had a zero B working angle.
We're definitely not on the same page...
When you go from 6 down to 8.2 up, that to me is 14.2...
When you say up or down slope, make sure it is in reference to your zero level and not other slopes.

 

That doesn't help with a 2 piece 3 u-joint shaft.
They only explain 1 piece 2 u-joint geometry.

In a 1 piece 2 u-joint shaft, A=B...that's it.

In a 2 piece 3 u-joint shaft, you can have 4 different ways:
A=0, B=C
A=C, B=0
A=B,C=0
A+B+C=0
The latter being the most common method.

 

I chased this ghost for a year before I said fuck it and ordered a single piece shaft from TW. Solved. pissed I didn't do it sooner.

 

The only problem I had was between 82-85 mph serious harmonic 86-100 was smooth but man that 82-85 was real bad.

 

I spend mere seconds at that rate, if ever. I wound her up real good after I first put it on and it was silky smooth. All the shaking and nonsensical thrashing about ceased.

 

It's a shit design, IMO. They could have at least made a 2 piece with 2 u-joints and 1 double cardan.

I assume you had a shop install yours? I would expect those same ghosts would have haunted a 1 piece install. Was it a 1 piece w/ 2 u-joints or 1-piece w/ 1 u-joint and 1 double cardan? In the former, A=B. In the latter, A=B, C=O.

 

Look at everything from left to right. If the right side is up, it is up slope is it goes down it is down slope. Just because the pinion is pointing up doesn’t mean the slope is up. Now if you measure from the passenger side then it will be up slope but so would your driveshaft.

 

I installed it. Quite simple. good design. no ghosts. thats why I bought it. cv and a u joint at the diff.

 

if this is correct, under 5 degrees in every angle, is that acceptable, or should they ideally be less? if atleast the rear end, and 2nd driveline numblers more inline,.. will or could it help my 55-65 mph vibes? cuz im just throwing what if's at this problem right now..

i kinda want to buck up for the 1 piece driveline, but they are expensive...