SOA and driveshafts

[Woody Long]

I know this has been talked about to death but I am having problems with the driveline shops getting my setup right.

I have a 1980 Jeep Wagoneer Custom Ltd. AMC 360, TF727, NP208, SOA D44 Front and Rear Shackle Flip AMC20 Rear with 63" Chevy springs.

I got all the measurements they asked for and this is what I have. (These are all the angles the yokes will work at)

Front Diff 15 deg
Front T-case 30 deg
Rear T-case 12.2 deg

Front drive shaft tube slope 26 deg
Rear drive shaft tube slope 19 deg
Rear Diff 12 deg

Is this normal?

What does everyone else have?

[rustywagoneers_com]

i have dana's 'expert' and allison's driveline programs both on my PC here at work..

i dont like the 5 degree difference in the front DL angles... but isnt the t-case end a CV joint?

i will have all your angles on a sticky-note here in a few.. i will keep track of this post and run the drivelines when we have numbers nailed down...

peace,
Dave

[rustywagoneers_com]

hey, looking at your numbers on paper, i think the rear stuff is fine going down the road...

i will run the program at lunch... can i clarify the t-case angle, i want the angle it sits at, and around here we just use the frame as the 'Zero' line... you can get the angle of the t-case output by just using the angle on the yoke bolting surface, and translate it 90 deg.

let me know when you can.

peace,
Dave

[Woody Long]

Thanks man.

The front is a CV setup. I can't get to the truck today, but when I do I can get that corrected angle for you.

[rustywagoneers_com]

ok, looking at the note again, you have a 4 degree difference between front pinion angle and driveshaft angle... they should be as close to 'zero' as possible, since you have the CV at the t-case.. 4 deg probably wont hurt much... (part time, right?) but if there was an EASY way to get the front shaft and front pinion closer i would do it.. assuming it didnt wreck your caster..

will fire up the DL programs in about 2.5 hrs local time..

also, projected road speed / gears / tire size (or save me a few minutes and work that all out to a driveshaft max RPM please)

thanks
peace,
Dave

[ April 07, 2006, 07:39 AM: Message edited by: rustywagoneers_com ]

[Woody Long]

I will be running it ont he highway and trails. The diffs are stuffed with 4.10's and I have 35" tires on her (but they measure 33" high, that will change soon)

I can't figure out the D-shaft speed but I have found a online calculator to help.

http://www.wallaceracing.com/driveshaftspeed.htm

Now for the engine speeds....hope these help.

Highway Table
Transmission Gear: top gear (1:1)
Transfer Case: high (1:1)

mph rpm
50 1968
51 2007
52 2047
53 2086
54 2125
55 2165
56 2204
57 2244
58 2283
59 2322
60 2362
61 2401
62 2440
63 2480
64 2519
65 2558
66 2598
67 2637
68 2676
69 2716
70 2755
71 2795
72 2834
73 2873
74 2913
75 2952

Total gear ratio: 1:4.1

Stoplight Launch Table
Transmission Gear: 1st gear (1:2.45)
Transfer Case: high (1:1)

mph rpm
1 96
2 193
3 289
4 386
5 482
6 579
7 675
8 771
9 868
10 964
11 1061
12 1157
13 1254
14 1350
15 1446
16 1543
17 1639
18 1736
19 1832
20 1929

Total gear ratio: 1:10.04

Crawling Table
Transmission Gear: 1st gear (1:2.45)
Transfer Case: low (1:2.61)

mph rpm
1 252
2 503
3 755
4 1007
5 1258
6 1510
7 1762
8 2014
9 2265
10 2517
11 2769
12 3020
13 3272
14 3524
15 3775

Total gear ratio: 1:26.22

[rustywagoneers_com]

ok, looking at a max shaft speed of 2500 RPM, it appears that the maximum accelerations of the shaft (inertial effects) are just barely exceeding dana's safe limits of 1000 radians per second squared.. (1025.4 R/S/S on the one which goes out, and 967.5 R/S/S on the other)

the torsional effects are very low, (57.9 R/S/S) because the T-case and Pinion are so close on angle.. basically i think the rear is not a problem at all going down the road, and if you feel some vibration at 70, back it down a few..

the front i cannot check easily, but if you have a full-time t-case, or drive plates instead of lockouts, let me know an i will figure a way out..

peace,
Dave

[Woody Long]

I just talked to Arizona Drivelines and they tell me I can possibly get away with the Bad Boy Jr CV that operates at 40 deg and locks out at 60 deg. This is way freaking cheaper than the $1200 CDN I've been quoted in the last little while, and they can't guarntee it holding up.

Would it be worth it to shim the front axle? I have 8 deg shims but I've been haring that that is a no-no. Thought I know a guy that had them in and it drove fine on the highway @ 70MPH.

The shafts at Arizona Driveline would be the Bad Boy Jr CV with long splines and the rear having a CV. The complete setup would run me about $800 US opposed to a local shop that can only lengthen mine for $650 US and tell me how to grind out the CV to make it droop more.

Think that is a good deal?

[rustywagoneers_com]

if you go CV on the rear, the you need to rotate the pinion angle up to match the driveshaft angle (theroetically at least) i dont think you have an angular problem at all in back.

i think 15 degrees is fine for the stock CV, if it isn't then change it

my big question is if the front driveshaft will be turning when you are on the highway

full time t-case? driveplates or lockouts?

that's what we need to know next.

peace,
Dave

[Woody Long]

The t-case is a part time case and I have lockouts.

The angel finder on the frame is sitting at 2.5 deg and the rear t-case output is sitting at 87.5 deg.

[rustywagoneers_com]

just looked at sticky note again, and then had to check first post..

i was wrong on front shaft details... (i was looking at the 26 and 30 and thinking, good... but they are not numbers that go together... the 15 and the 26 do... not so good..)

how did the shaft wind up at 15, and the diff at 26?? how hard will it be to get them closer??

good thing it is part time...

drive it and see what the rear is like, we can tackle the front later....

peace,
Dave

[Stuka]

The stock front shaft isnt a CV, its a double carden joint, and doesnt have near the operating angle of a CV.

[rustywagoneers_com]

yes, technically the name is double cardan joint, however, i dont really feel like typing it out each time. the resulting output is constant velocity, even though a ball type CV joint has a greater operating angle.

peace,
Dave

[Bob Barry]

Originally posted by Woody Long:
I know this has been talked about to death but I am having problems with the driveline shops getting my setup right.

I have a 1980 Jeep Wagoneer Custom Ltd. AMC 360, TF727, NP208, SOA D44 Front and Rear Shackle Flip AMC20 Rear with 63" Chevy springs.

I got all the measurements they asked for and this is what I have. (These are all the angles the yokes will work at)

Front Diff 15 deg
Front T-case 30 deg
Rear T-case 12.2 deg

Front drive shaft tube slope 26 deg
Rear drive shaft tube slope 19 deg
Rear Diff 12 deg

Is this normal?

What does everyone else have?How can your front and rear transfer-case outputs be at different angles??? Unless you bent your transfer-case, the angle of the rear output should be the opposite of the angle of the front output. So, if your rear output points 12º down from horizontal, your front output is going to have to point 12º UP from horizontal.

You are using a magnetic angle-finder flush to a surface perpendicular to the yokes, right?

[Stuka]

Originally posted by rustywagoneers_com:
yes, technically the name is double cardan joint, however, i dont really feel like typing it out each time. the resulting output is constant velocity, even though a ball type CV joint has a greater operating angle.

peace,
DaveIts not a consant velocity though, the input and output of the joint rotate at different speeds.

Bob: I believe he is measuring the drive shaft angle in relation to the t-case. So the angles should be different, as the shafts are different lengths.

[rustywagoneers_com]

well, i don't think there is any way to say 'yes a double cardan joint has the input and output at the same speed' without having this thread turn into another 'have you ever seen an SOA' thread...

so i will allow you to believe that they rotate at different speeds..

peace,
Dave

[Woody Long]

Yeah Bob, I have the angles that the u-joints will be working at.

The angles that the pinions are at:

Front axle: 9 deg up
Front of t-case: 5 deg up
Rear of t-case: 5 deg down
Rear axle: 6 deg up

And as I stated before potential tube slope angles; front 26 deg and rear 19 deg.

Sorry about the confusion.

[rustywagoneers_com]

OK.... 5 deg at tcase Rr (dn) and 6 deg at Rr Pinion (up) is good.... however... 19 degrees for the driveshaft is not good...

exceeds dana's recommendations by about 4 times..

the front of 26 means your included angle between the t-case and the driveshaft up front is like 31 degrees... that has to be way near the limits... if not out of the limits for the double Cardan on your truck..

i sure wish the pinion and t-case were in that 12 neighborhood from before...

big lift = big $$$ at some point...

peace
Dave

[ April 11, 2006, 01:06 PM: Message edited by: rustywagoneers_com ]

[Woody Long]

If I use that Bad Boy Jr CV 40 deg operating angle and 60 deg max, would that take care of the front issue?

http://www.driveshaftsuperstore.com/images/badd.jpg

Again thanks Dave for all the input!!

[rustywagoneers_com]

yep, that is a 'twin-ball and centering plate style double cardan joint' (sec 3.2.4 of the SAE manual AE-7) high angle driveline and a few others are making / using them.. i still think you are gonna hafta rotate the rear up to match (nearly match) the driveshaft angle and run a CV at that end also (double Cardan)

looks like that is an entirely welded assembly from what i can see... welded yoke to flange.. and the centering plate is in a welded housing too.. SAE considers them to be a low-speed device, but for front i am sure you would be fine.. the rear should probably be more normal..

back to the front.. you could probably use that joint at one end, and the stock double Cardan at the t-case and just remember not to leave the front locked on the highway.. no more messing with angles...

the rear... well... you could drive it and see how fast you can go before it gets shaky.. but remember, forces rise at the square of RPM... so going from 1000 to 2000 is double the speed, but 4 times the destructive force... so be dang careful.

peace,
Dave

[rustywagoneers_com]

Oh, also... a few notes from the SAE...
typed word for word from the manual...

Sec. 3.2.4
‘Double Cardan Universal Joint (Twin Ball and Centering Plate Type)’
page 123

Introduction
The twin ball and centering plate type of double Cardan universal joint was patented by Geisthoff in the late 1960s and has been used primarily for slow speed applications such as in agricultural implement power take-off driveshafts.
The double Cardan universal joint (twin ball and centering plate type), shown in Fig.1 in a typical design, is a constant velocity universal joint which consists of two Cardan universal joints whose crosses are connected by a two-piece flanged coupling yoke with internal supporting and centering means, and has intersecting shaft axes. At all operating angles within the design range, the instantaneous angular velocity ratio is unity.
The two ball centering device divides equally the total joint angle between the two halves. This joint transmits constant velocity because the second joint compensates for the fluctuations in angular velocity created by the first joint. Also, this joint is similar to the conventional double Cardan joint with the principal difference being in the design of the centering mechanism.

-me again – this joint above is the type of joint used by ‘high angle driveline’ like i said, and like your picture shows... those are true Constant Velocity at any angle within design range..

Sec 3.2.3
‘Double Cardan Universal Joint (Trunnion Pin Type)’
page 119

Introduction
The patent literature shows that the concept of the trunnion pin type of double Cardan universal joint was developed as early as 1903 and that patents on various applicable features were issued through the mid 1930s. Its first known vehicle usage began in the late 1920s as the outboard joint in an early American front wheel drive passenger car. Since that time, it has been used as the outboard joint in German trucks and other heavy-duty highway and off-highway, all wheel drive vehicles for both commercial and military applications
The double Cardan universal joint (trunnion pin type), shown in Fig.1 in a typical design, is a near constant velocity universal joint which consists of two trunnion pin type Cardan universal joints whose trunnion yokes are connected by a coupling yoke with internal supporting and centering means, and has intersecting shaft axes. At the design joint angle and at zero, the instantaneous angular velocity ratio is unity while at other joint angles, it is near unity.
This joint, which is similar to the conventional double Cardan joint, also has the same kinematic advantages as that joint. Its other advantages are generally the same as for the conventional double Cardan joint. Also, its design configuration permits a relatively rugged construction. The principal disadvantages of this joint are its relatively higher swing diameter and greater manufacturing cost when compared with the (conventional) double Cardan joint.

-me again – This is the type of joint used in FSJ’s and most other 4x4 OEM double Cardan driveshafts –

SO, anyway.. though the term gets thrown around loosely sometimes... we are talking about CV joints, despite the various names...

peace,
Dave