SOA question

[jnau99]

Did a quick search and couldent find anything but I've almost got a SOA with Old Man springs on a 40. I am trying to finish and was wondering what the best angle to turn my housings would be. It is also reversed shackle home made if it matters. I was thinking 10-12 degrees. Any input?

[ROCK HUGGER]

I cant remember how many *'s I did but it was somewhere in the range 10-15*.
Here is my drivline angle with Old Man Emu springs.

[TRD]

the correct way to do it (if you have enough driveshaft) is to make the centerline through the axel parallel with the center line of the output shaft on the x-case. That is what i did and i have plenty of shaft. I havn't driven it very far yet though.

[BJ On Roids]

Originally posted by TRD
the correct way to do it (if you have enough driveshaft) is to make the centerline through the axel parallel with the center line of the output shaft on the x-case. That is what i did and i have plenty of shaft. I havn't driven it very far yet though.

wouldn't this cause vibrations?

[TRD]

Originally posted by BJ On Roids


wouldn't this cause vibrations?

no, it eliminates vibrations because the 2 ujoints are at the same angle.

[Eskimo]

Originally posted by TRD
the correct way to do it... (miscellaneous web-wheeler BS snipped)

The way to do it is like Rock Hugger's... get that pinion UP and out of the rocks, AND, get your 5* of caster, so it drives down the road nicely.

It only causes vibes with the hubs locked, and if you don't have a CV at the t-case. Otherwise, making the pinion and the output parallel *is* technically the right way to do things, but the drawbacks are much worse.

I went 2* too much at 18*, so I'd say do 15-16 total... that's 10-11* rotation, and 5 or caster.

[woody]

IMO, the accurate way is with the axle under the truck and the springs compressed....you need to set not only pinion angle but caster relative to pinion angle and perches relative to that. I had my front axle in/out of the truck about 5 times to get it exact.

[td]

RockHugger,

Nice setup. Where did you get your stainless brake lines? Do they connect directly to the calipers? Thanks.

/td

[jnau99]

Thanks for the info. I got my brake lines from Crown, any length and any fitting and they are cheap.

[TRD]

sorry i thought you were doing the rear not the front

[dieselcruiserhead]

What would be the method to get NO vibration whatsoever with less concern for the pinion angle, keep them parrallel? (then wouldn't that be like not cutting and turning?) Ideally I want my pinion out of the way but no vibration is a must, hubs locked or not....

[cruzer75]

i beleave the no vibration method is

Cut and turn to point the pinion at the Tcase, GOOD CV drive shaft. and you are done.

Cheap way to get a CV in there...cut turn, square driveshaft...with mini truck or fj60 CV...gives you the extension that you need at a fairly cheap price


Stew

[TRD]

you will get no vibe if you do what i said about making the planes parallel or you can also run a cv at the top and point the pinion.

I don't see a need to spend money on a cv because (atleast for me in the rear) in the shaft angle is very low and i can eliminate vibration the way i described it.

[BJ On Roids]

Originally posted by TRD


no, it eliminates vibrations because the 2 ujoints are at the same angle.

how does that work, the u-joints obviously have to be at the same angle to eliminate vibrations, BUT once you rotate the pinion up you fawk the angles and it will vibrate like a mofo w'out a cardan joint.

[BJ On Roids]

Originally posted by dieselcruiserhead
What would be the method to get NO vibration whatsoever with less concern for the pinion angle, keep them parrallel? (then wouldn't that be like not cutting and turning?) Ideally I want my pinion out of the way but no vibration is a must, hubs locked or not....

this is what I was hoping TRD would point out.

[BJ On Roids]

As long as the angle of the unis is the same top and bottom you will have no vibration. You cna rotate the pinion and end up with no vibes. You just have to do it right.

[BJ On Roids]

Okay, so here is a rough CAD drawing i just mocked up with some crayons. Escuse my artistic genius.

TRD with yours being the third example, do you think you could show me HOW what you did, stops the driveline vibrations. I am just wondering because with the example I have drawn it seems to suggest your universal joints are NOT at the same angle where, you said they were...

I am confused. The drawing is certainly not indicating exact lift heights, but it does show really well how yours will still be out of phase. Also the faster you go, the more RPMs are on the shaft, and you will notice the vibes REAL BAD... now IF you only offroad it or do round town, but no highway then it might not ever be a problem, or for some rare highway with a small amount of driving, maybe you will put up with the vibes?

Anyways, maybe I am wrong and some gurus could come in and set me straight. I am not real knowledgeable on the subject.

BUT I do have a solution, while it certainly isnt mine, one of the most switched on guys I know told me about it, and in my mind, it is simple genius. Maybe you already know, maybe im just being nasty.... But I hate to see stuff done wrong, I certainly wish I had as much knowledge and skills about these areas 4 years ago. But I guess with age comes experience and knowledge, and such is life. Anyways enough crap, just how did your unis become the same angle simply by rotating the shaft up?

[dieselcruiserhead]

The only setup I ran I did not point the pinion up and I used a CV so I definetely did not have vibration Pretty much as I see it as soon as you rotate that pinion up you will loose the "parallel" factor so you must use a CV? I plan on probably running one anyways (but a cheap one, used, off a Toy probably) but I don't believe if they aren't parrallel then you will always get vibration. Is that really true?

[TRD]

Originally posted by BJ On Roids
Okay, so here is a rough CAD drawing i just mocked up with some crayons. Escuse my artistic genius.

TRD with yours being the third example, do you think you could show me HOW what you did, stops the driveline vibrations. I am just wondering because with the example I have drawn it seems to suggest your universal joints are NOT at the same angle where, you said they were...

I am confused. The drawing is certainly not indicating exact lift heights, but it does show really well how yours will still be out of phase. Also the faster you go, the more RPMs are on the shaft, and you will notice the vibes REAL BAD... now IF you only offroad it or do round town, but no highway then it might not ever be a problem, or for some rare highway with a small amount of driving, maybe you will put up with the vibes?

Anyways, maybe I am wrong and some gurus could come in and set me straight. I am not real knowledgeable on the subject.

BUT I do have a solution, while it certainly isnt mine, one of the most switched on guys I know told me about it, and in my mind, it is simple genius. Maybe you already know, maybe im just being nasty.... But I hate to see stuff done wrong, I certainly wish I had as much knowledge and skills about these areas 4 years ago. But I guess with age comes experience and knowledge, and such is life. Anyways enough crap, just how did your unis become the same angle simply by rotating the shaft up?

I don't think you understand what i said. What i said matches the first 2. In the last drawing the u-joints are not at the same angle. Maybe you should read what i wrote again

what i did looks like the first 2

[TRD]

Originally posted by dieselcruiserhead
The only setup I ran I did not point the pinion up and I used a CV so I definetely did not have vibration Pretty much as I see it as soon as you rotate that pinion up you will loose the "parallel" factor so you must use a CV? I plan on probably running one anyways (but a cheap one, used, off a Toy probably) but I don't believe if they aren't parrallel then you will always get vibration. Is that really true?

you are 100? correct from what i understand.

As far as the vibration thing, you will always have some it is just a matter of how little you have. Before i did the SOA on mine the 2 wern't parallell and i didn't have any significant vibration.

As an example whenever the suspension flexes (assuming leafs) the angle of the u-joints will change (whether they were // or pointed at the x-case output) and will no longer eliminate the vibration. But do you feel vibration when you load your truck down? Usually not, this is because the angle of variance is at a low enough angle that it doesn't create significant vibration

[Eskimo]

Originally posted by woody
IMO, the accurate way is with the axle under the truck and the springs compressed....you need to set not only pinion angle but caster relative to pinion angle and perches relative to that. I had my front axle in/out of the truck about 5 times to get it exact.

Absolutely the way to do it... and how I did mine. I added in another 2* to allow for pinion drop under throttle... shouldn't have. Oh well..

[BJ On Roids]

Originally posted by dieselcruiserhead
The only setup I ran I did not point the pinion up and I used a CV so I definetely did not have vibration Pretty much as I see it as soon as you rotate that pinion up you will loose the "parallel" factor so you must use a CV? I plan on probably running one anyways (but a cheap one, used, off a Toy probably) but I don't believe if they aren't parrallel then you will always get vibration. Is that really true?

"If they aren't parallel then you will not always get vibration."

TRUE!

There is certain tolerances and a solution that come iwthin this boundary.

[BJ On Roids]

Originally posted by TRD


you are 100? correct from what i understand.

As far as the vibration thing, you will always have some it is just a matter of how little you have. Before i did the SOA on mine the 2 wern't parallell and i didn't have any significant vibration.

As an example whenever the suspension flexes (assuming leafs) the angle of the u-joints will change (whether they were // or pointed at the x-case output) and will no longer eliminate the vibration. But do you feel vibration when you load your truck down? Usually not, this is because the angle of variance is at a low enough angle that it doesn't create significant vibration

OKAY I had quoted the wrong guy, yours a parallel then they are good... if one is rotated up and the other is factory that is where vibes will be caused...

sorry TRD... my mistake... thanks for taking it so well. I would have got all angry if some idiot like me was jumping all over my posts cause he was a stoner and quoted the wrong person

peace

[BJ On Roids]

sorry dudes, here is an idea to run by you, obviously the picture makes the pinion angle look a little steep, but you can get the theory behind it, if you could keep the angles where the red lines are, do you think they unis would vibrate or not?

also IRL the t-case points down a little, or the d-line aint that sharp. Not only does it give the pinion clearance it keeps a factory angle on the tailshaft uni?

[BJ On Roids]

forgots the pic

whats your thoughts... This is not new and not my idea, it was a friend of mine and I thought he had a good point, after he explained it to me i couldn't see the problem. But if there is its probably in how I interpreted it and not in what he has done. Anyways, whats your thoughts am i smmokin the fresh

I got a little off on the CAD drawings this time and use the finite element adjustment to give it that free-hand feel!