Low C.O.G. XRC comp rig! XRC tech!

[insanerc]

Originally Posted by james

I love the shaved TLT-1 axle.

Yeah shaving the TLT axles is a must do under all occasions. They perform better and even look better IMHO.

David
Xtreme Rc Hobbies

[cblake187]

Although the truck is 3/4" lower now (this pic was before running it) with the tranny mounted slighly forward and the rear pinion angle raised this chassis provides nothing but slick delrin for the rocks.If the front wheels can bite it will drag the rear up 90% of the time.

[insanerc]

Originally Posted by cblake187

Although the truck is 3/4" lower now (this pic was before running it) with the tranny mounted slighly forward and the rear pinion angle raised this chassis provides nothing but slick delrin for the rocks.If the front wheels can bite it will drag the rear up 90% of the time.

Forward breakover would be good I am sure. With a high rig though I would think you would suffer badly in off camber situations because your roll center is so high.

Sincerely,
David
Xtreme Rc Hobbies

[revin9k]

Originally Posted by insanerc

Forward breakover would be good I am sure. With a high rig though I would think you would suffer badly in off camber situations because your roll center is so high.

Sincerely,
David
Xtreme Rc Hobbies

so is using shorter shocks the best way to lower your ride/lower cg?

[insanerc]

Originally Posted by revin9k

so is using shorter shocks the best way to lower your ride/lower cg?

On most shocks you can just limit them. I have instruction on my website as how to do so. There are several ways to lower you C.O.G. though. Getting any movable weight as low as possible, limiting your shocks, sometimw positioning your shocks different on your chassis, etc.

With the bent HC links I like to see them come off the chassis level with the chassis untill they reach the bend. When adjusting your shocks remember that articulation is very much over rated and you really only need about 45 degrees or so. Just look at all the torsion rigs and how well they perform to see this point driven home. Also keep in mind the you can lower your C.O.G. without actually shortening your shock throw. The way to do this would be softer springs, maybe a lighter shock fluid, and have some droop which is very desirable if your chassis is well balanced, and your link geometry is good.


David
Xtreme Rc Hobbies

[Rc EnthuSiasTs]

can droop be explained as "riding in the suspension".
It seems my tlt always is sitting on " top of the suspension", even though i losi soft springs and 25wt oil. My shocks are pretty soft, but they dont "ride in the suspension".
Thanks, this has been a great guide to everyone, even those w/o xrc chassis

[insanerc]

Originally Posted by Rc EnthuSiasTs

can droop be explained as "riding in the suspension".
It seems my tlt always is sitting on " top of the suspension", even though i losi soft springs and 25wt oil. My shocks are pretty soft, but they dont "ride in the suspension".
Thanks, this has been a great guide to everyone, even those w/o xrc chassis

It sounds like you have the idea and just need to apply it. It's just like a 1:1, if you jack a wheel up you will see the suspension droop down as the chassis weight is removed. Ideally you want some degree of this on your 4 link crawlers. When sitting in a static position it should not be sitting on top of the suspension as you say. Just like a 1:1 it should compress the suspension some with its own weight. This is how rigs called belly dragers works so well. They can have long suspension but very low C.G.s still. You say that your shocks are fairly soft right now but evidently you still have no droop or static suspension compression. Proggressive rates are good in that you can get your droop and also have a fairly firm footprint in the static position to help prevent chassis roll and torque twist when off camber. Remember as you change your ride height that you will more than likely change your link geometry. It's a good idea to note what you have before you start searching for those magic numbers.

David
Xtreme Rc Hobbies

[patrick_b]

Originally Posted by Rc EnthuSiasTs

Thanks, this has been a great guide to everyone, even those w/o xrc chassis

Just want to echo that statement. This thread has helped illustrate a variety of concepts about which I've been unclear. David, I LOVE your website too. Great tech info.

I'm new to crawling and am still reading/learning before I start my own build. I recently bought a used SW2 rig that's really helping me learn how to crawl and understand how all the parts go together (and I get to crawl while learning). It's also made me very anxious to build my own as well.

After searching & reading build threads and hundreds (if not tousands) of tech posts on most of the well known chassis'...I think I've made my choice.

An XRC is in my future. Do I understand this correctly...the XRC Roller kit will give me everything I need minus the electronics? That'll save me some time...

[insanerc]

Originally Posted by patrick_b

Just want to echo that statement. This thread has helped illustrate a variety of concepts about which I've been unclear. David, I LOVE your website too. Great tech info.

I'm new to crawling and am still reading/learning before I start my own build. I recently bought a used SW2 rig that's really helping me learn how to crawl and understand how all the parts go together (and I get to crawl while learning). It's also made me very anxious to build my own as well.

After searching & reading build threads and hundreds (if not tousands) of tech posts on most of the well known chassis'...I think I've made my choice.

An XRC is in my future. Do I understand this correctly...the XRC Roller kit will give me everything I need minus the electronics? That'll save me some time...

Thank you for the kind words. Yes the XRC Roller Kit includes everything that you need to get up and running a legitimate comp grade crawler, other than the electronics and a body.

Sincerely,
David
Xtreme Rc Hobbies

[revin9k]

cant wait to see the updates to the website

[insanerc]

I'm adding to this thread and pulling it back to the front page because I have so many people that are new or fairly new to crawling, and are asking for setup info. Other than the above there are only a million things left that you can do to make your XRC more capable. Maybe some of you have seen some of the torsion rigs lately rolling their rear pinion angle upwards. This is something that you can do every bit as well with your 4 link setup as long as you keep your link geometry correct. I advise you to do so to keep the rear driveline out of the way on breakovers. The point is that on a 2.2 comp machine your going to have to lock out your rear steer anyway. Other than helping to move your pinion up out of the way you are also straightening out your driveline angle which eases stress on the components and makes for smoother crawling. I'm going to leave any illustration here that I drew up real quick so you may see the difference.

David
Xtreme Rc Hobbies

[Rc EnthuSiasTs]

As i understand the best way to make this axle angled upward it to move the upper links longer. I have a sw2 but i think i can just adjust the upper links so they push the axle upward. What are some problems that may be seen while doing this? You said to make sure the link geometry stays the same. Thanks i appreciate it alot.

[insanerc]

Originally Posted by Rc EnthuSiasTs

As i understand the best way to make this axle angled upward it to move the upper links longer. I have a sw2 but i think i can just adjust the upper links so they push the axle upward. What are some problems that may be seen while doing this? You said to make sure the link geometry stays the same. Thanks i appreciate it alot.

What I wouldn't do is change the angle/pitch of the links if they are setup correct just to roll the pinion upwards. Providing you have your links set at the optimal setting you wouldn't want to change your "Instant Center" or your "Anti-Squat". This can spell disaster if you get it wrong. There are some excellant discussions on here about link geometry. It can be very compicated to understand. What you need to remember is that if you draw lines through your rear links toward the front of your vehicle the point of convergence is very important and in most cases has much to do with the above mentioned settings and ultimately the performance of your rig.

Here is a very good thread that you may want to read: Anti Squat and Suspension Tech

David

[cblake187]

This settup works extremely well.Stock xrc chassis,xrc 5/16 links.R2j 110mm shocks limited with fuel line.




Note no rear drive line exposed.Only slight tilt in rear end is needed.

[cblake187]

With a stealth and a lightweight brushless cog would be even better,but it's already better than a lot of trucks.

[Rc EnthuSiasTs]

thanks insane, i will defeinently read that thread. i am dieing to learn how to set up links the correct way.

Blake that xrc looks good!!

[insanerc]

Originally Posted by cblake187

This settup works extremely well.Stock xrc chassis,xrc 5/16 links.R2j 110mm shocks limited with fuel line.




Note no rear drive line exposed.Only slight tilt in rear end is needed.

I love to see an XRC slammed with good link geometry and an upward rotated pinion. It looks like you have a very nice range of anti-squat (A.S.) following the geometry. We normally run ours with overkill "A.S.". Nice job on the setup. I'b be interested to see if you have any droop with this setup and how the side-hilling works.

[TLTCrawlin]

Just thinking, if you took some HC links, eight of them, and turn the top ones upside down, it'd be lower COG.

[mobil1syn]

Originally Posted by cblake187

This settup works extremely well.Stock xrc chassis,xrc 5/16 links.R2j 110mm shocks limited with fuel line.




Note no rear drive line exposed.Only slight tilt in rear end is needed.

you mind snappin a shot of your rig from the top. im intrested how much room there is around the trans and motor. thanks

[revin9k]

any updates?