SOA and pinion angle.... Help!

[Heimeken]

I started my SOA this weekend and have a problem with my pinion angle. Check out these pics:

http://snow.prohosting.com/heimeken/TractorSOA.htm

I'm installing wide track axles and stock springs from a chero.
I welded the SO perches parallel to the stock ones.

Problem: Looks to me like the original perches had some angle to them. As you can see from the pictures the pinion seems have a negative angle thus my front drive shaft and pinion will not meet. Now I had planned on installing 3 degree shims. My question is: Given the current angle, can I go 5 or 6 degrees without steering problems?

Any Suggestions?

[JeepFreak]

If it was me I would cut off the perches and set the pinion angle you want then cut and rotate the knuckles to bring caster back into spec. But that's allot of work isn't it. This is what I am going to do to mine. Now another option is to re-weld the perches to get some pinion back then use some aftermarket caster adjustment sleeves. These will give you back around 1.5 degrees of negative caster.

[ July 10, 2002, 03:07 PM: Message edited by: JeepFreak ]

[JeepFreak]

Also another thing to think about is that ideally you want the pinion to point at the transfer case. If you did this you would to much negative caster which can bad thing. Another thing to consider is that you stock driveshaft will be to short. If you did get it to bolt up then you risk the chance of it coming apart when the suspension is at full drop.

[ July 10, 2002, 09:03 PM: Message edited by: JeepFreak ]

[River Beast]

IF you welded them parallel, you can use a 3 degree shim... I would'nt go more than that or you will start the wandering all over the road.

IS your front shaft in full droop in that 2nd pic?

[Hump]

Uhhhhmmmmm...I just had my home made perches welded on last week, and I have my pinion in line with the driveshaft. Now you guys are telling me that this is a bad thing???? I need to know more and how to fix it please.

[Heimeken]

More details: My driveshaft is hitting the exhaust at this point so it will go down a bit more, maybe an inch at the end. It is long enough because I had lengthened it before, it still has plenty of extension from the pic. I used to have 4.5 inches of lift(spring and shackle), now I have about 6 but my old axle had 3 degrees. It seems to me that this axle had some angle because I can tell the old perches are not parallel to the ground, hence positive degrees underneath means negative on top.

[Heimeken]

Is there a method for measuring caster? That would clear up some things... I think.

[ July 09, 2002, 03:00 PM: Message edited by: Heimeken ]

[Panther]

Heimeken, you can try and run it as is and see how it works. Keeping the original 4 degrees of pinion angle basically means the ujoint at the axle pinion is operating at a steep/tough angle. For a part time tcase and off road only, it might me just fine. Ideally you want 3 more degrees like Todd said but I'm not a big fan of shims. Looks like you need a longer driveshaft also so maybe grind off the perches and reweld with the added 3 degrees and measure your driveshaft at that angle and be done with it. Personally, I don't think redoing the ball joint yokes is necessary, if you are doing a SOA will seriously lifted springs, then yes, otherwise 3* should be fine.

Hump, I would have that redone. That is way too much angle if the pinion is pointed directly at the tcase. With that you will probably have bumpsteer of death! Like I said above, you can use 3* and be in good shape. All I did was take an angle finder and added the 3 degrees. There was another discussion on this recently that is very detailed. I investigated all the different angles before going SOA on a J20 axle in my CJ before welding. I did a quick search but couldn't find the site that explains all the variables of alignment.

When doing SOA there are 3 basic alignment angles to keep in mind.
First with the axle flat on the spring perches you have the pinion angle. This should be 4 degrees. Then you have the angle of the ball joints that is turned back 4 degrees and this is your return to center for the steering wheel. With the knuckles removed, I placed a rod through the ball joints and measured the angle, it's been a while but I think it was 4 degrees. You do not want to raise the pinion angle so that it exceeds the angle of the ball joints and I would think that if the pinion was pointed directly at the tcase, it's more than 4*. The last thing is caster but you probably don't have to be worried about that.
Lee

[River Beast]

I knew the Y pipe must be in the way... ;) if you went parallel to the OEM perches... your caster should still be at the factory setting of -4*... this is measured thru the centerline of the upper and lower balljoints. It is VERY difficult to measure with everything assembled.

The way the OEM perches look now look OK... a 3 degree shim should do just what it needs.

I don't have a direct shot from my pinion to the T-case either... cuz I didn't want to cut and rotate my knuckles.... not with a 44 anyway... :D
If and when I get a 60 I will most likely go that route.

Hump,

IF you have the pinion pointing straight at the t-case you have angled it too much and need to back it off to a max of 3 degrees or rotate your knuckles...the steering geometry is altered too much with anything over 3 degrees from specs...

[Heimeken]

I'll try the 3* and see how that turns out. I see your poing Panther. I'm running a NP208 and will only engage when 4WD is needed so the 'bad' angle may not be that big of a problem if I can get it hooked up.

Thanks guys.