Rear axle clocking for max 4WS tie rod clearance

[Mesozoic]

I recently decided to upgrade to the 3Racing aluminum axle housings since I was really smashing my axles crawling around my backyard in Arizona (big rocks everywhere). I also picked up some KM Racing knuckles and hubs. The new parts went together nicely, but I'm a bit confused about the rear axle and how to clock the knuckles correctly.

The instructions say to setup the rear axle with 25 degrees of caster and the fronts at 15. What I've found is that with the 4WS setup in the rear, my rear steer tie rod is making contact with gnar and getting chewed up and bent. A tie rod over knuckle would help, but I think I might just not have the axle clocked correctly. Does anyone have any photos of their rear steer setup to share?

[Mesozoic]

Alright, well I managed to get my rig back together properly and in order to obtain some additional (and much needed) clearance on the rear axle with 4WS, I performed a tie rod over knuckle conversion. This conversion is quite popular among fullsize crawler enthusiasts as a bent tie rod could result in a fully incapacitated rig in the bush.

The procedure simply relocates the tie rod from the traditional attachment points below the knuckles to above them. On fullsize 4x4s, many times the drag link is attached to the tie rod for some reason... thankfully, with our CR01s that's not the case. Another popular mod for fullsize rigs is to get better drag link angles by attaching directly to the knuckle for proper crossover steering.

In any case, here's the steps:

1. Detach the tie rod from both knuckles.
2. Detach the knuckle end of the drag link from the knuckle.
3. Replace the left rear side tie rod end with a non-threaded rod end.
4. Replace the knuckle end of the drag link rod end with a threaded rod end with the nut side facing down towards the knuckle.
5. You may want to use a washer between the 2 stacked rod ends and another between the rod end and the top of the knuckle (I did to preserve the aluminum knuckle).
6. Insert the original bolt (screw) from below the knuckle going up through it and then through the tie rod end and drag link rod end.
7. Tighten to spec and you're done.
8. It may be necessary to adjust the drag link length as well as modifying/replacing the steering servo arm to make it shorter for a better drag link angle (not required, though).

[OSRC]

Interesting - I've never really given any thought to rear caster. I don't use 4WS generally, but I'm curious - do you have positive or negative caster on the rear? Looks slightly negative to my eyes.

[Mesozoic]

Originally Posted by OSRC

Interesting - I've never really given any thought to rear caster. I don't use 4WS generally, but I'm curious - do you have positive or negative caster on the rear? Looks slightly negative to my eyes.

The rear axle appears to have a slight amount of negative caster.

[new2rocks]

The rear axle has a natural positive caster due to the pinion angle. I have my chubs rotated forward to reduce the natural caster. Here's what mine looks like:




The steering link sits a bit below the centerline of the axle, but it's close enough to the axle that it doesn't hang on rocks. From your pictures, it looks like you may have the knuckles reversed, because the arms for the steering links are sitting very low. Did you try flipping sides?


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[Mesozoic]

I tried every combination to find the best positioning. As I have it set now, the rear axle steering linkagehas much more clearance than the stock setup. I have, as I previously indicated, performed a tie rod over knuckle conversion.

I'm running KM Racing hubs and knuckles, though... maybe that's where the difference is.

[new2rocks]

That's probably the biggest difference. Looks like the arm on those knuckles is offset all the way to one end instead of roughly centered on the stock knuckles. That's probably intended to give more clearance for the steering link. If you were to swap them L to R, the steering link would probably be fine mounted under the arms. But if what you figured out works, might as well roll with it.


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[Mesozoic]

Originally Posted by new2rocks

That's probably the biggest difference. Looks like the arm on those knuckles is offset all the way to one end instead of roughly centered on the stock knuckles. That's probably intended to give more clearance for the steering link. If you were to swap them L to R, the steering link would probably be fine mounted under the arms. But if what you figured out works, might as well roll with it.


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I examined the stock knuckles and the KM Racing knuckles and the only difference I see is that they lack forward ears. Dimensionally, they appear to have all the same offsets as the stockers.

[OSRC]

There are 4 caster settings on the axle. If you move the A and B knuckles to the opposite side, you get slightly different caster angles. Didn't realize they worked this way. Working on steering on mine as well. I flipped the knuckles so the steering arm is on the bottom, and mounted the steering links on top of it (exactly as you did in the rear) - was still too high, so I swapped C's. Much better.

Love tinkering with these rigs - so many adjustments you can mess with.