Weight Distribution - Acts nose heavy but isn't... Is it?

[zanoob13]

Hi there everyone. I am having an issue that may just be me being only 6 months or so into crawling and trailing, but either way I can't seem to figure it out and can't find any good info on the problem. My Deadbolt seems to act pretty seriously nose heavy. When descending even mild slopes, if I don't keep an extremely even throttle (in places that aren't steep enough to coast, drag break is currently at 50% on my stock Axial esc) if I ease off the throttle a little it will almost flip over forward.


Info that I'm sure would be helpful in solving my flip-over-ness

3-4 oz in each front tire
Rear tires aren't weighted
Tires are Proline TSL XL 1.9 on Axial 8 holes
Battery is pretty heavy and in stock location over the rear axle - 5,000mah 2s
Made homemade links and when doing so 4 linked the front
All scale items I have added on in the rear but amount to >1oz for sure

I just don't know. Should I weight the rear tires a little, say 1.5 oz or so? Should I weight them as much as the front tires and then leave weight distribution up to electronics placement? Sorry I know most of you figured this stuff out through trial and error, but I am a Dad with very limited spare time and those 8 holes take FOREVER to undo all those tiny dang screws lol. So any help would be greatly appreciated

ALSO: sorry if I left out key info, just let me know if I did and I'll post it here asap.

[TacoCrawler]

with your battery in the rear...
I'd think the weight would be more biased towards the back side.

I use tire weights both front and rear...
and I mount my batteries atop my sliders.

Are you sure it not because the incline/traction is excessive
and your trigger finger does not utilize smooth transitions ?

I run 100% drag brake...
but don't seem to have endo issues unless...
the incline is excessively steep...
and I abruptly let off the throttle engaging the drag brake.

Not to be offensive...
but this may be more of your fault
then the chassis's layout/arrangement.

[zanoob13]

No offense taken, as I said I'm very new to this genre of the hobby. As a test though, it sounds like it would be useful to just switch to 100% drag brake and ease down one of the hills that I know I have this problem on, then let off entirely. If it endos when it's just the drag and not me at all, then maybe what I'm thinking shouldn't be steep enough to cause it actually simply should. It very well could just be that I'm expecting too much of the truck. Then again though... A friend of mine's truck can be pinned heading down one of these hills, grab full break, and doesn't even begin to endo. Hmmm.

[zanoob13]

I just was thinking, too much weight in the rear may be actually causing it to basically push itself into an endo couldn't it? With that and the amount of grip like you mentioned.

[meatmonkey]

We need vids to be able to really tell you what's going on.

My $.02 is ditch half of your front wheel weights and give it a try.

Have you had the truck on scales to determine actual F/R bias?

How about the "balance test" as a judge of F/R bias. You ussually want the balance to be withing 1/2 of where the front links attach to the skid.


Where is your ride height set at? Do the upper links go "up" to the frame at ride height?

[Eric0424]

Originally Posted by zanoob13

I just was thinking, too much weight in the rear may be actually causing it to basically push itself into an endo couldn't it? With that and the amount of grip like you mentioned.

If the weight is up high, yes it can.

[sf2000xj]

Originally Posted by zanoob13

I just was thinking, too much weight in the rear may be actually causing it to basically push itself into an endo couldn't it? With that and the amount of grip like you mentioned.

I bet this is the case, a 5000mah 2s lipo although lighter than nimh is still pretty heavy and that weight is going to want to keep moving given a steep enough incline will pull the backend over the front. I'd move the battery to the front cross-ways behind the tires this can be done easily by using a premade plate like the one from Howler Customs or the Jevne Racing. The same thing could be accomplished using the stock axial tray or a piece of steel or aluminum and some creativity.

Sent from my SM-G920V using Tapatalk

[TacoCrawler]

Originally Posted by zanoob13

A friend of mine's truck can be pinned heading down one of these hills, grab full break, and doesn't even begin to endo. Hmmm.

did you inquire with your friend about their set up ?

It's possible they have overdrive gears in the front axle
and under drive gears in the rear axle !?

Doing this would allow the front tires to roll farther (delayed drive engagement)
while the under driven rear axle would engage or brake prior to the fronts.
Meaning: the front tires will spin faster, roll farther then the rear tires.
the freer spinning front tires won't engage the drive line before the rear tires do.
This arrangement could reduce that chance of doing endo's
when abruptly releasing the TX's trigger.

I gear equally... but then I crawl my rig (3-4 mph max = trail).
But more commonly I roll 1 mph or less when precision crawling.
Going fast is not on my agenda.
Torque and low end grunt is what I prefer.
Tho' wheel speed is sometimes critical...
it can be controlled by motor wind selection and gearing.

^ don't confuse wheel speed with top end speed.
they are not the same deal.

For those wishing to roll faster...
they would likely do better utilizing the OD/UD gear set up.
Doing so will net improved steering response as well.

It's possible the battery weight out back/up high could cause issue...
But it would mostly be caused by weight, COG and forward momentum.
So once the rear of the chassis starts to lift on a decline...
follow thru momentum of the battery's weight could occur.

btw... higher end TX's have more fine tuning capabilities
allowing for drag brake lock up reduction,
thus offering a smoother transition when letting go the TX's trigger abruptly.
Drawback is that the drag brake cannot hold position.
And I personally find that to be critical for a precision crawler.

Other options would be to eliminate the drag brake option altogether
and revert to shunt style braking instead.
Would also require that reverse be delayed slightly
so that the brakes would apply before reverse engages.

Dialing down the drag brake to a lower percentage...
can reduce DB lock up when abruptly releasing the TX's trigger.

Moving up to 100 % DB and releasing the TX's trigger abruptly
would likely upset the chassis more so and increase the endo probability
that you'd wish to avoid.

It seems purchasing crawlers is a popular thing...
but if someone is wanting to go fast.
I don't really get why ?
It must be because of popularity
rather then what a crawler chassis was designed/intended for.

For go fast rock bashing RC's
there are so many better chassis options available
then what a crawler chassis offers...
so I don't really get why folks select a crawler
when going fast is what they want from it ?

to each their own...
but I don't get it.

last note:

If you like how your friends rig rolls
why not ask them what they've done !?
Only way to know why theirs does better then yours...
is to ask them

[snapon boy]

I run a 7 cell nihm up front in my sons dingo and acasonaly in my deadbolt or 2s hard case as you do and very rearly flip forward. I do have over drive in the front. I also moved my electronics to the rear. When going down steep inclined slopes it will take some practice to get the hang of it. In one of our favorite spots to crawl one side you have to Gass it to keep a 4 tires on the ground the other I go as slow as possible. I'll put a few pictures up to give you ideas.