Suspension Setup

[Hammertone]

Coming from a racing background, if you've got your head around ride height, spring rate, piston size, shock location and limiters, then you're pretty well on your way to having a well set up car.

But looking through this forum, there's very little chat about setting suspension for a crawler which makes me think that it's not nearly as important as it is for a racer.

So i'm hoping you blokes can pitch in and give me a clue as to how all the many suspension settings do affect crawling and to what extent.

It seems to me that the purpose you're going to put your truck to will greatly affect what you want out of your setup. I've got a massive rock wall in the back yard that no truck has yet managed to scale, so i'm modding my night crawler with the aim of getting it to the top. I've never been to a comp, but i guess my truck is much like a front heavy comp crawler.

So first of all, is there a good crawler suspension resource on the web that someone can point me to?

Failing this, i'm hoping you guys can answer my questions regarding each component.

Shock Oil - I've read on this forum that shock oil affects speed of travel and slower (heavier) oil allows better assessment by the driver of what the truck is doing. Will lighter oil allow better contact with the ground when traversing large obstacles at slow speed?

Pistons - Having never read a single mention of pistons on the forum i assume everyone uses the stock ones and rely on oil adjustments instead.

Shock location - I have no idea how standing up or laying down the shocks will affect handling. Please enlighten me!

Ride Height - I'm guessing that there is a balance to be found between having a high under-carriage clearance and raising your centre of gravity too high. The wall i'm trying to get up is very steep, with large rocks jutting out which the truck regularly gets hung up on, so i want high clearance with low CG! Any advice on this or is it down to experimenting with ride heights?

Spring rate - Really soft springs will allow more flex which is what i need, but are there downsides to this? I guess the springs need to be heavy enough to hold the weight of the truck???

Any help with this would be fantastic guys. Looking forward to finding out where i've gone wrong!

 

[Norton]

Quote. (But looking through this forum, there's very little chat about setting suspension for a crawler which makes me think that it's not nearly as important as it is for a racer.)

I don't have enough time at the moment to get into all of your questions.

Suspension setup is one of the most important aspects of a crawler, by far!
I'll try to get back after dinner but I'm sure other people will chime in.;-)

 

[Hammertone]

No worries, look forward to hearing from you

 

[Szczerba]

Shock pistons, springs and oil are all a test and tune with crawlers.

Start here to check out some suspension chatter.

http://www.rccrawler.com/forum/general-crawlers/472065-another-4-link-thread.html

Each type of crawler has a different setup. Ie, comp crawlers are setup one way, scalers another, go-fast racing crawlers, another. But at the basis of all of these is weight placement, center of gravity, suspension link setup, shock mounting and axle type.

 

[MRCrackhead]

Shock Oil - I've read on this forum that shock oil affects speed of travel and slower (heavier) oil allows better assessment by the driver of what the truck is doing. Will lighter oil allow better contact with the ground when traversing large obstacles at slow speed?!

Everything has a fine balance for all of your questions. Tuning to your rigs specific setup is the number one rule, of course.

Slower suspension gives predictability like you said. It also helps keep the suspension from unloading to quickly and tipping you over when you are in a very steep, strange spot.

If your oil is too light, the rig will move fast when you don't want it to. You have control of the throttle, so you can go slower, if need be, in a tricky spot while the suspension "settles". Better if you're in control, I think.

Pistons - Having never read a single mention of pistons on the forum i assume everyone uses the stock ones and rely on oil adjustments instead.!

I wonder this too, and haven't seen much mention of it. I run 2 hole pistons in my shocks with a lighter oil instead of 3 hole and heavier.

My only reason is that the lighter oil will be affected less by the cold weather here. Just theory.

Shock location - I have no idea how standing up or laying down the shocks will affect handling. Please enlighten me!!

Standing the shocks up gives a more stable feel to the rig, but can limit travel.

Laying them down softens the feel, but can make the rig "twitchy" and less predictable. The axle has more leverage against the shock and you lose some control in that manner.

Finding that sweet spot is dependent on the rig.

Ride Height - I'm guessing that there is a balance to be found between having a high under-carriage clearance and raising your centre of gravity too high. The wall i'm trying to get up is very steep, with large rocks jutting out which the truck regularly gets hung up on, so i want high clearance with low CG! Any advice on this or is it down to experimenting with ride heights?!

This is a very difficult question. I like a about 75mm of clearance, give or take.

I don't like to be too high, for obvious reasons; but bottoming out all the time for the sake of CG doesn't seem to pay off as often as you'd think.

When you're on the skid plate, you're not truly in control of the vehicle. I've been pushed off my line too many times in this manner and feel I'd rather sit a bit higher and be in control.

Sometimes, it hurts me; but it seems to help many more times than it hurts.

Just my opinion.

Spring rate - Really soft springs will allow more flex which is what i need, but are there downsides to this? I guess the springs need to be heavy enough to hold the weight of the truck???!

You want them as soft as what it takes to hold up the rig, kinda.

Stiff springs will unload the suspension at the worst possible times, and flip you over sideways, or backwards.

Softer springs don't seem to do that.

Also the softer springs will compress fully when the rig is upside down. This gets your tires on the ground and a better chance for recovery.

I'm still learning, but these are some thoughts I have. Hope it helps.

 

[Hammertone]

Thanks for that link Szczerba, Dude really knows his stuff.

And cheers to Cracky for the effort you put into that post for me. Gives me a good starting point. I'll start with 30w and see how that feels, then sit at the bottom of my wall with spanners in hand to adjust shock location, ride height and springs on the fly.

My night crawler is pretty much stock apart from beefing the speedy and servo and mounting the battery on the links, but i've just gotten hold of some comp crawler shock mounts which gives me much more options over where to locate the shocks, hence, all the questions. So i'll get to work and see how far up this hill i can get.

Thanks guys! "thumbsup"

 

[Odd-M]

I've read that several "scaler guys" run their shocks without oil, or with very little just to keep them lubed. The purpose is to make the shocks soft. This is very wierd to me. Perhaps the most important function of a shock is to controll rebound. Then again, my first impression is that these guys just go for looks and know little about how suspension works. This might be a plausible explanation to why there's little talk about this topic.

 

[Hammertone]

So i've made some good progress on scaling my wall. with adjustments to the suspension as advised i've been able to scale the whole thing except one particularly steep section where the tyres are unable to get enough traction to pull the rear wheels over a protruding rock. The car is really well balanced for hill climbing though and is not far off vertical before she wants to tip, so it's been pretty successful. now for some new rubber!

 

[lagerratrobe]

So i've made some good progress on scaling my wall. with adjustments to the suspension as advised i've been able to scale the whole thing except one particularly steep section where the tyres are unable to get enough traction to pull the rear wheels over a protruding rock. The car is really well balanced for hill climbing though and is not far off vertical before she wants to tip, so it's been pretty successful. now for some new rubber!

I realize this is a pretty old thread, but curious if you have before and after pics of how your rig looked when you were tuning the suspension setup? Would love to see them!