1972 FJ40 SUA Suspension Setup (1 Viewer)

[kvanoort]

I've spent a considerable amount of time searching and learning about my FJ40 suspension and thought I'd share my current setup as it might be helpful to others on the forum. I would also like to hear from the experts to confirm pinion and caster angle setup.

Specs
- 1972 FJ40
- Spring Under Axle
- OME Dakar Leaf Springs - CS002F & CS002R (Medium/Heavy Duty 2" - 2 1/2" Lift)
- OME Poly Spring Bushings - OMESB30
- OME Steering Stabilizer
- Front Shocks: Bilstein F4-BE5-6251-H5
- Rear Shocks: Bilstein F4-BE5-6252-H5
- Cool Cruisers Greaseable Tri Shackle Kit (3 1/8" length pin to pin)
- Cool Cruisers Greaseable Spring Hanger Pins (15 mm pins)
- 4 Plus Products U-Bolt Flip Kits Front & Rear
- BF Goodrich KM2 Tires (31 x 10.50 R 15)

Weight Considerations
- 4 Plus Products Bull Bar Front Bumper (no winch yet)
- 4 Plus Products Rear Full Tire & Cooler Carrier
- Metal Tech Full Profile Roll Cage

Replaced original suspension last fall which increased the front ride height by 1" and the rear by 2 3/4". No more saggy leafs and the stance was perfectly level. Ride quality is great in comparison to the 46 year old original equipment.

So, after driving and wheeling the rig since last fall and to give things time to settle I thought I'd better check the pinion angles front and rear. Additional reading and researching was required as I know nothing about pinion settings and I'm still learning...

At this point I could use some confirmation and direction from the experts.

Current Rear Settings
Trans Output: 2.0* Down (Engine is also 2.0* Down as measured from valve cover)
Drive Shaft: 9.0* Down
Axle Pinion: 7.0* Up
Based on these measurements and from what I've learned it looks like I'm going to need 5.0* Shims in the rear to bring the pinion down to 2* Up? As strongly suggested on the forum I will be purchasing Steel Shims.

Current Front Settings
Trans Output: 2.0* Up
Drive Shaft: 11.0* Down
Axle Pinion: 1.0* Up
The front is a bit more complicated given caster.
From what I've read, stock caster is positive 1*-3* or 2*
Could use some help here to determine correct setup.

Happy to add pictures if it would be helpful.

Thanks!

 

[pjohnson]

How is the ride?
Any vibrations at speed?
Is the steering slow and sluggish or quick and twitchy?
Do the front wheels return to center easily?
If you don't have a drivability issue, what are you trying to fix?

All that being said...
Your pinion angles should be such that your u-joints are as close to parallel as possible. But if you don't have vibrations, you are probably just fine.
Your caster can be directly measured at the top of the knuckle. I would doubt it's off based on your specs. If the steering feels good and you don't feel like it's fighting you, you are probably just fine.

The only variable you didn't mention is if you have non stock power steering.

 

[kvanoort]

How is the ride?
Any vibrations at speed?
Is the steering slow and sluggish or quick and twitchy?
Do the front wheels return to center easily?
If you don't have a drivability issue, what are you trying to fix?

All that being said...
Your pinion angles should be such that your u-joints are as close to parallel as possible. But if you don't have vibrations, you are probably just fine.
Your caster can be directly measured at the top of the knuckle. I would doubt it's off based on your specs. If the steering feels good and you don't feel like it's fighting you, you are probably just fine.

The only variable you didn't mention is if you have non stock power steering.

Any vibrations at speed? - Yes. Slight vibration around 30-40 mph. Tires have been rotated and balance.
Is the steering slow and sluggish or quick and twitchy? - Yes. Steering seems a little light.
Do the front wheels return to center easily? Yes. Steering returns to center.
If you don't have a drivability issue, what are you trying to fix? No real drivability issues but before rebuilding my transmission and transfer case I want to make sure the driveline angles are correct. Not having the suspension dialed in correctly with cause new bearings and seals to wear out prematurely.

All that being said...
Your pinion angles should be such that your u-joints are as close to parallel as possible. But if you don't have vibrations, you are probably just fine.
Your caster can be directly measured at the top of the knuckle. I'll take more measurements up front. I would doubt it's off based on your specs. If the steering feels good and you don't feel like it's fighting you, you are probably just fine.

The only variable you didn't mention is if you have non stock power steering. Steering is stock with the exception of a Man-A-Fre Super Heavy Duty Tie Rod Kit.

 

[pjohnson]

Land Cruiser Professional shop guys please chime in...

I assume the vibration is in the rear as you are probably not driving 30-40 mph in 4wd, so you could have some u-joint wear or the u-joints are slightly out of parallel due to the lift. There could be other factors too.

The front steering 'seems a little light' could be a number of things. Are you afraid to take your hands off the wheel? I would make sure your tire pressure isn't too high, and measure the caster. You 'might' be a degree or two out of spec due to the lift. Also, measure your toe-in, although this has more affect on return to center than anything else. Your steering box may need to be tightened up. The 'feel' you perceive could be normal.

Not having the suspension dialed in correctly with cause new bearings and seals to wear out prematurely.

This is a myth. The bearings and seals are behind output flanges that have universal joints attached to them. Any misalignment of the driveshaft for any reason is going to be 'absorbed' by the u-joint. The bearings and seals never see the misalignment.