Anyone tried the GRC steering knuckles?

[Inspector86]

I installed a set of these GRC steering knuckles on my #1 TRX4 and have been very pleased with the result, so much so that I plan to install them on my other TRX4s. They provide ackermann which improves over all steering. Note the extra outboard tie rod mounts.



Ackermann steering geometry is a geometric arrangement of linkages in the steering of a car or other vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out circles of different radii. Read more about ackermann here.


https://en.wikipedia.org/wiki/Ackermann_steering_geometry


Prior to installing these knuckles I noticed the outside tire rolling under in a tight turn which just did not look right to me and always bothered me. After installing the GRC knuckles the tires follow the inner and outer radii more closely and the outboard tire no longer rolls under in a turn. I have also noticed a tighter over all turn radius.



I have seen these knuckles for sale on ebay for $85 but RCMart has the same part for $45. To be honest the RCMart product description sucks and does nothing to explain the benefit of ackermann in the steering that these provide.


for Traxxas TRX-4 #GAX0032BT, ,(GAX0032BT) by GRC Aluminum Portal Cover & Titanium Steering Link Set Silver

 

[soze]

Nice. I'll have to keep these in mind.

 

[HumboldtEF]

Interesting!

Is the main difference where the links mount? And which set of holes do you use for the steering links? I assume one set is like stock and the other set adds more ackerman.

 

[Inspector86]

That is basically correct. It all has to do with the tie rod mount location relative to the kingpin pivot point. These are the only aftermarket TRX4 knuckles that I have seen that offer improved ackermann. A simple approximation of perfect ackermann steering geometry can be generated by moving the tie rod pivot points inward so as to lie on a line drawn between the steering kingpins and the center of the rear axle or in the case of the TRX4 with front steer moving the tie rod mounts outboard to fall on the same line.

Here is a link to the ebay sale of these knuckles, way over priced. But scroll down to the description and it helps visualize what they do to improve ackermann even if you can't read Chinese. BTW, I would love to see a translated description.

https://www.ebay.com/itm/ponton-craft-steering-gear-box-base-tie-rod-drag-link-for-TRAXXAS-TRX4/263210694154?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20150817211623%26meid%3D83f9596288cb44c88d937b9efc9da05e%26pid%3D100505%26rk%3D1%26rkt%3D1%26%26itm%3D263210694154&_trksid=p2045573.c100505.m3226

 

[Inspector86]

Here is another good article explaining ackermann in RC Cars.

RcTek - Radio Controlled Model Car Handling - The Ackerman Steering Principle

 

[kevman1]

do I need the other side of the knuckle as well ? the portal cover ? or will this work without that ?

 

[Inspector86]

This is the inner part of the the front portal, you still need an outer portal cover or portal weight.

 

[kevman1]

This is the inner part of the the front portal, you still need an outer portal cover or portal weight.

thanks , the stock TRX4 outer portal cover should work with this right ?

 

[83trekker83]

If i didnt just buy these in brass i would have to try them out,.

 

[redemon]

I will have to try these out on the budget build truck.

 

[kevman1]

found them on ebay as well for $40

 

[JatoTheRipper]

They look very nice and I dare say Vanquish-like. How's the slop between the knuckles and the C-hubs on the axles?

I always thought you wanted zero Ackermann for crawling?

 

[Inspector86]

In my RipRap crawling I saw a dramatic improvement in the way the truck turns on the rocks with these knuckles. It became especially apparent when I drove the #1 rig with ackermann and the #2 rig without ackermann back to back over the same obstacles.

 

[redemon]

Im going to try and get the english version of all of the pictures.
I have a guy working on it right now.
Will post up when i get it, if I get it

 

[kevman1]

Are those links intended to replace the stock links? one looks too short.

 

[Inspector86]

The kit includes a longer tie rod and longer drag link for attaching to the ackermann steering holes.

 

[Inspector86]

They look very nice and I dare say Vanquish-like. How's the slop between the knuckles and the C-hubs on the axles?

I always thought you wanted zero Ackermann for crawling?

I have slow crawled with and without these knuckles and I find that the trucks just turn better at low speed with ackermann. Without ackermann, the outside front tire just rolls under and scuffs across the rocks. As speed increases, you need less steering angle to make a turn and ackermann becomes less important.

 

[JDM74]

I found this. The same knuckles?

https://www.ebay.com/itm/1Pair-Allo...481437&hash=item1a5b062ce9:g:jF4AAOSwAllbbp8n

 

[Ola.]

I have slow crawled with and without these knuckles and I find that the trucks just turn better at low speed with ackermann. Without ackermann, the outside front tire just rolls under and scuffs across the rocks. As speed increases, you need less steering angle to make a turn and ackermann becomes less important.

Does the max steering angle increase on the inner wheel with these knuckles, or is it only the outer wheel getting less angle?

 

[G60nut]

I believe the outer wheel is getting less angle. The hubs can only turn so far.

I'm waiting on the GRC G2 Axle set currently and will post up when they make it in but. I did find these for Yeah Racing's brass knuckles looks like they have the ackermann mounting points.

For TRX-4 - Yeahracing - (#TRX4-031-1) Aluminum Replacement TRX-4 Steering Mount For TRX4-031 Brass Knuck