SAS questions

[jroc]

I've just finished my SAS - Lets hope it works as good as it looks! 2 questions

1) what is the proper pinion angle. 90 degrees to ground? Mine is raised a little and I think it handles a bit weird.

2) My calipers are frozen and I don't want to die! What are the correct model landcruiser rotors to use with the IFS calipers? Any particular year? I think my front axle is out of an 84 pickup. Also which bearings fit this rotor? IFS or solid axle? Or do I need to buy new bearings?

Thanks for the help!

[Mcfly]

81-83 lc rotors for 81+ front end or 79-80 lc for 79 or 80 axle, same bearings, just remove backing plat, i asked this same question

[jroc]

Thanks, what about the pinion angle?

[fourwd1]

I've just finished my SAS - Lets hope it works as good as it looks! 2 questions

1) what is the proper pinion angle. 90 degrees to ground? Mine is raised a little and I think it handles a bit weird.

Thanks for the help!

The pinion should be pointed up towards the t-case, and the Drv Shft should have a double-Cardan CV joint at the t-case end.
If your pinion is pointed more downward, the caster will be off and it will handle a bit weird, steering wise. 90 degrees to the ground is not right (for the front, for the rear yes (unless you have a CV joint on the rear DS too)).

[TRunner]

I think you're referring to your caster angle (alignment). the desireable pinion angle is straight toward the t-case, but that will give you a way negative caster. you want slightly positive caster. I don't know what the relation from the pinion angle to the caster is, but if you look at where your steering arms mount to the knuckle that flat surface is what you reference to ground. the front should be tipped up just a little. as a good rule of thumb it is better to have it tipped up (+ caster) too much than tipped down.

[fourwd1]

I think you're referring to your caster angle (alignment). the desireable pinion angle is straight toward the t-case, but that will give you a way negative caster. you want slightly positive caster. I don't know what the relation from the pinion angle to the caster is, ...

Yes I was refering to caster angle, what else ? :rolleyes:

With the pinion pointed up at the t-case, the caster will be the correct, positive amount for a Toy axle.

[jroc]

So your're saying that my highsteer arm should be level to the ground or up a minimal amount? See crappy drawing

[fourwd1]

W/o my truck to look at I can't say for sure, but that sounds right.
If your pinion is pointed upwards at the t-case, so the DS forms a straight line w/the pinion (more or less), your caster will be OK (that's how a stock truck is).

[TRunner]

Yes I was refering to caster angle, what else ? :rolleyes:

With the pinion pointed up at the t-case, the caster will be the correct, positive amount for a Toy axle.


ok, so I read your entire post after I sent mine and saw that you had mentioned the caster angle, sorry :frown:

But to further clarify the issue, the pinion angle cannot be used to check alignment. lets take 0 caster for example, with a stock solid axle and NO lift the pinion just might point right to the t-case (that was too long ago for me to remember :grin: ) however with a lift the pinion angle would change even is the caster is the same. I assume that when doing an SAS there would be several inches of lift involved. my point, you cannot use the pinion angle as a measure of caster!

Jroc - Yes, you have the right idea. good luck with the finishing touches on the SAS!

[fourwd1]

... But to further clarify the issue, the pinion angle cannot be used to check alignment. lets take 0 caster for example, with a stock solid axle and NO lift the pinion just might point right to the t-case (that was too long ago for me to remember :grin: ) however with a lift the pinion angle would change even is the caster is the same. I assume that when doing an SAS there would be several inches of lift involved. my point, you cannot use the pinion angle as a measure of caster!


On a stock solid axle Toyota the front pinion does point up at the t-case, because the front DS has a double Cardan (CV) joint at the t-case end. For that CV joint to work at it's best and to realize the full advantage of it's design, it has to be that way. The more the pinion is pointed downward from that the more the CV will bind.

Now if it had a normal u-joint at each end (like the back), the pinion angle would need to be in the same plane as the t-case output (ie, parallel with the ground, like the back).

The caster on the Toyota solid front axle is fixed, it's designed in to be correct for the stock suspension setup. Therefore if you change the stock suspension set up (lift shackles, lift springs, etc) both the pinion and caster angles will change. Usually the pinion will be pointed downward more than it should be. And what's the result? CV joint binding, DS vibes, and poor tracking/steering.

That's why correcting the pinion angle will correct the caster angle on a Toyota solid front axle in most cases.

[ryan]

I have an 85 pick up with chevies in the rear and rears up front with double cardan on both the rear and front drive line. The rear pinion is pointing right at the t case. the front one I did shim a hair, but it is not far from 90 degrees from the ground. Whithout the shims, it would be 90 degrees form the ground, and that didn't work, because the cardan was binding (It is flat bottomed). So, that is why I added the shims, but now I have problem with my passanger side leaf hitting my drag link, because my arms on top of my knuckles for the highsteer are slightly pointed down.
Your picture looks right, those arms should be about parallel to the ground. As for the pinion to be pointed straight at the t case. That would put my steering arms on the knuckles pointed alsmost straigh down. And that makes it kind of difficult to steer.

[TRunner]

That's why correcting the pinion angle will correct the caster angle on a Toyota solid front axle in most cases.


In "MOST" cases. That is my point. Setting your pinion angle will get you close, but with a large lift if you try to maintain the stock pinion to DS angle your caster will be negative (like ryan stated). That is why it is better to use something that accurately represents the caster angle such as the steering arms.

You made a gooid point about DL vibrations. That is why they do "rotated housings", where they cut the axle just inside from the spring perches and rotate it about 6 degrees (+- depending on amount of lift) and weld it back on. so that the pinion angle is 0 and caster is correct.

I am not trying to argue here, but this is a point that needs to be made so some kid out there with a 10" lift doesn't shim his front axle to have 0 degrees between pinion and DS and wrecks or breaks his rig because the caster was way negative. hopefully anyone reading can see all points brought up here and make their own judgment on what is best...

[bodo]

So if I have a stock rear DS I should pull the wedges out between the springs and perches? Sorry for the hijack but I might have figured out why I can't keep ujoints.

[fourwd1]

I am not trying to argue here, but this is a point that needs to be made so some kid out there with a 10" lift doesn't shim his front axle to have 0 degrees between pinion and DS and wrecks or breaks his rig because the caster was way negative. hopefully anyone reading can see all points brought up here and make their own judgment on what is best...

Caster is more important than pinion angle. If you can't steer a straight line down the road, who cares about drive line vibes. And a 10" suspension lift is going to have more problems than that. :grin:

[kemosabee]

what is SAS. i won't learn if i don't ask questions.

[ryan]

Solid Axle Swap. Swaping out the independent suspension for a solid axle.

[kemosabee]

i really want to get rid of my IFS; THANKS FOR THE HEADS ON THE SAS. I understand now ; i cant wait toget in the position to hook my truck up.

[fourwd1]

SAS also stands for Solid Axle Suspension, as opposed to IFS - Independant Front Suspension. Depends on the context.

[fourwd1]

So if I have a stock rear DS I should pull the wedges out between the springs and perches? Sorry for the hijack but I might have figured out why I can't keep ujoints.

Depends on which way you have the "wedges" aka degree shims, mounted.
Thick side facing front points the pinion downward, facing rear points it upwards. Many suspension mods, such as longer shackles, point it upwards.
So the shims would need to be mounted so as to get the pinion in the same plane as the t-case output (ie, parallel to the ground, typically). Having the pinion and t-case in the same plane/parallel minimizes driveline vibes, which can cause premature u-joint failure. (I don't mean the vibes themselves cause the u-joints to fail, but the same fctors do.)

Make sense ?

[zig80toy]

So if I have a stock rear DS I should pull the wedges out between the springs and perches? Sorry for the hijack but I might have figured out why I can't keep ujoints.

bodo, theres some good info in this thread...
http://www.wildyoats.com/vbulletin/showthread.php?t=14070