Marc P

My front u-joint angle is just a little to much right now...I dont think it will need much of a change, maybe 2-4 degrees would make me more comfortable with the angles.

Can I safely add angled shims to the spring perches?

Offered by 4crawler

Robinhood150

I used 11 deg shims from 4crawler for my rear. Welded them to the perch. I would think that as long as they're welded they'd be fine.

getitdone

The thing to worry about is your caster will change. If you do change the angle, do very little. I have heard of death wobble as a result of messing with the caster too much. Search pirate or do some trial and error.

rockota

Caster is definitely the issue. check that first; it will determine how far you can go. If you are currently w/in spec (I *think* it's 1-2 degrees, but please don't take that as fact), then you'll want to find another solution; High Pinion or cut-n-turn.

AxleIke

yeah, you mess with the caster you'll get mad deathwobble, among other problems. a quick fix is the hp diff, not so quick or cheap- cut and turn.

Flygtenstein

To reiterate, the front spec to be concerned with is caster.

IIRC, you are low pinion with single cases. That is going to be hard to get shafts perfect any way.

FROR had a rule of thumb comparing castor to pinion angle and lift height so a person could set caster with optimal pinion on the Diamond housings. Worked well on mine.

4Crawler

iTrader: (3)

Yes, measure your caster angle first (find an alignment shop that'll just check it for you) and then you can shim the pinion angle to the limit the caster angle allows:
- http://www.4crawler.com/4x4/ForSale/Shims.shtml#FAQ1

Shims work fine on the front axle, I've run them (bolt-on) for many years (none with my current setup), and if you weld them on, they are part of the spring perch.

As long as your front shaft/u-joint is not binding and you don't need it for high speed 4WD operation, forget about it. Otherwise, cut and rotate the knuckles:
- http://www.4x4wire.com/toyota/tech/rotated_housing/

Or pop for a high pinion front diff, that's take 4" of drop out of the front shaft, or put in dual cases, that'll lengthen the front shaft and lessen the front shaft angle. I run dual cases and HP diff and have an almost ideal angle up front.

rockota

Any more info on this? Sounds very interesting.

Flygtenstein

A stock housing has a 14 degree difference between castor and pinion.

My truck, with 5 inches of lift, dual cases and a high pinion front. Using Brian's "formula" my housing has a 12 degree difference between castor and pinion. So, castor being optimized between 2 and 4 puts my pinion right on the nuts for a dual CV shaft. There is some Enron math in there making it close, but using all the variables, he optimizes it for single versus dual, high versus low, CV versus stock.