MRC Pro - Impact of Length and Position
 

I have an MRC Pro that I've upgraded. And I am puzzled about how best to setup the front upper links. :?: :?: :?:

I installed the RcBros front servo mount, along with RcBros zero ackerman knuckles and steering link. In this setup the steering link splits the three axle posts giving me OTA steering. This also means that the front upper links must move back from the stock mounting location.

General upper link questions:
1. What is the impact of the different mounting positions on the front upper links?
2. Is the purpose of the upper links only to set the angle at which the front axle sits?
3. What do I need to consider when positioning the front upper links, just that they don't bind on the lowers or shocks?

MRC Pro specific questions:
4. I currently have the front stock upper links mounted in positio 10, the lowest rear hole in the chassis. In this position the axle is tilted slightly more forward than stock is this okay?
5. On the RcBros servo mount there are link mounts to the rear that would require much shorter links, would I be better off making new links to use those mounting locations?
6. Has anyone tried shortening the stock links? Could I cut them off with a dremel tool and simply cut the threads with a die? I just like the fact that all the links match.

Thanks,
Eric Porter

There has been a lot of discussion in the AX10 forum about link positions etc. I will not pretend to understand the intricate details of how upper link positioning impacts the way a truck handles but I will say it does. Someone drew a really cool illustration of how wheel lift effects handling based on link position. You might try and find that diagram. I do not have a MRC so I cant answer those issues specifically but this is what my logic would tell me.

1. Length and position impact the way the axle will twist or swivel under articulation. If you push directly down on your truck the axle will twist equally from left to right but under driving conditions that will surely not happen which can effect performance.

2. Angle of the upper links fore and aft can also have an impact on actual length but also impact the handling when a wheel whats to hop or lift under load. (look for the diagram on the ax10 forum and apply accordingly.)

Hope that logic helps a bit. If you are wanting to play with length some you might just pick up some all thread and mock up a temporary link and install to see how it effects handling. If you are keeping stock links I would also recommend moving them around some and hit the exact same climb and see what handles better.

Rick,
Thanks for the suggestion. I will checkout the AX10 forum while I wait on other responses.

Eric

Here's the same setup in put on this losi I have the links in farthest forward and turned the "C"s up http://i1177.photobucket.com/albums/...e/148dc3ac.jpg

badman,
Why did you choose to connect the steering link in front of the axle rather than on the axle, was it simply because you wated to maintain the stock link geometry?

Yep the pro works very well so why mess with the links? I wanted to try some caster anyways so I turned the knuckles to put the steering next to the servo.
The chassis is a juice that I just build for a friend and he ran it for the first time this last weekend and its every bit as well as my pro. I tried the links shorter at first and didn't like the way it cycled thought it's travel.

I have replied to your pm. Every bit counts. The pro works good in stock form because it is tuned for that setup. Changing your links can have ill affects if you do not change the surrounding setup to compensate for it.

I run a true BTA setup because approach angle often means making or not making a gate with these little guys, and I want full contact with my tires before the axle ever interferes. I have changed my shock positions, shock oils and spring rates to compensate for both the front suspension change, but also my eletronics locations. These are small rigs and every gram added can effect its performance. You may find it very surprising that placing your Speed Control on one side can have ill effects, but placing it on the other can greatly increase its abilities. Its all about weight placement and suspension tuning. I spend more time tunning the mini then my 1/10th.

I plan to next experiment with caster changes, but that'll be a whole new ballgame!

Thanks for all the help.

I assembled everything tonight and it appears that with the stock front upper links and the RcBros servo mount, knuckles, and steering link I was able to achieve OTA steering with near zero caster and a good pinion angle that keeps my driveshaft up out of the way.

Nice lookin' truck!8)

Thanks it came out very nice I'm proud to have built it for a good friend. Like I said if my pro didnt do so well I'd build one for me.