SWB on 35s - Wheel alignment tuning Q's (1 Viewer)

[clintnz]

Hi All, I'm hoping for a little knowledge from the hardcore here on my plan for improving the setup in my heavily modified LJ71 to get her driving a bit nicer on the street. 4 years ago I swapped in an 80 series rear axle & a Y60/GQ Nissan front axle, using the donor axle suspension setups (or fairly close to it) also. So a 4 link + panhard in the back & 2x radius arm + panhard in the front. This has all worked fairly well but we've been doing more longer distance touring lately & I know there are aspects of the wheel alignment that can be improved fairly easily so why not.

#1 Caster. Currently about 2.1 deg, I want to use 2deg offset kingpin bearings to change this to 4deg. Can also get 1.5 or 2.5 deg bearings. The current 2 deg is actually just in spec for the Nissan but well under the 3.8deg listed for the LJ71.

#2 Thrust angle. Now 0.5 deg. Would like to correct this with adjustable arms one side as they are fairly inexpensive for the 80 series. I've found varying opinions on this from 'more than 0.1 is bad' to '1 deg is nothing'

These numbers came from an alignment report I got just after I had done the axle swap, but the shop gave me no interpretation of it, I think I'll get another alignment check from the specialist (not a tyre shop) before diving in & then get the same guy to dial in the adjustable arms once they're in.

Cheers
Clint

 

[74fj40]

I would suspect your rear axle is pretty crooked having 4.3* of toe in on the left side and -2* toe out in the right side. This in itself would cause a pull. You will need all 4 rear arms to be adjustable. This way you can get your pinion angle dialed too.

Bigger tires love more caster. 4* would be great. 6* would be even better. If you can’t get 6* with offset bearings, you may be able to install offset bushings in the radius arm like an 80 series.

sounds like your on the right track. Sweet looking ride

 

[clintnz]

I would suspect your rear axle is pretty crooked having 4.3* of toe in on the left side and -2* toe out in the right side. This in itself would cause a pull. You will need all 4 rear arms to be adjustable. This way you can get your pinion angle dialed too.

Bigger tires love more caster. 4* would be great. 6* would be even better. If you can’t get 6* with offset bearings, you may be able to install offset bushings in the radius arm like an 80 series.

sounds like your on the right track. Sweet looking ride

Thanks! When I looked back at that alignment report the 4.3 number did give me a shock as 4.3 degrees works out to about 2.5" of misalignment of the axle & I'm sure I'm not THAT rough. Then I realised it is most likely a measurement in mm (no degrees sign) front to back on the 16" rim, which computes to around 1/2" out at the mounts. Which still seems a lot compared to the ~2mm difference side-side on my tape measure between the front arm & rear lower arm chassis mounts I made. Apart from the rear upper arm to axle mounts that were relocated pretty carefully in a jig the other arm mounts on the axles are std.

A new, more reliable alignment report is definitely required.

OK, 2.5deg bearings for the front caster will be on the shopping list. The pinion angle is pretty good there so I'd like to avoid offset bushes. One day I may build up another axle housing for the front & rotating the knuckle balls for 6deg could be on the cards then, but there are a few long road trips coming up before that will happen.

Cheers
Clint