RCCrawler Forums

mikegigabyte · 12-31-2009, 08:21 AM

So I changed my chassis last week, and on my backyard course going down a steep rock it usually filps over forward using chisels and losi real beadlocks with stock weights in all wheels. The same day I bought my first set of flatirons and it still does it stock wheel weights. Since ive been working I only have around 1/2 hr per day to test and half the time is in the dark. Last night I tweaked the shocks and tightened them down and added 12 stick on weights on both front wheels. Im getting more today incase needed. I also changed the drag brake on the mongoose esc, it was set at 1, I went to the highest. Now this seemed to maybe help and I was wondering if the brake was set wrong before and im going down steep and super slow could the brake not acting correctly filp it over. Im thinking about adding rear weights to maybe keep the back down, or will it force more weight on the front when vertical and aid in flipping forward.

It never did this before with the stock chassis and lexan body, but my shocks were at a different angle, the tube chassis I use has a totally different layout and only 2 holes to adjust, both settings havent helped.

So my question is does it help to add rear weight for forward flipping going downhill, or adjust the drag brake more?

Changing to the tuber only the chassis and shock position was changed all electronics stayed in place. I dont know if the chassis really changed the cog, or the shock placement. The ground clearance changed a hair upwards, not even a quarter inch.
My course is pretty steep with river type rocks, I can drive the whole thing I just dont like flipping it on the rocks as I dont want to break a part.

Here is the area when going down it will flip forward. The pic helps show the angle.

JeepinOR · 12-31-2009, 09:09 AM

If you're rolling over forward, there is obviously a weight bias up front... How much weight all around?

If you're rolling down the decent OK until you let the drag catch, and then it flips you over: some weight in the back may help, but I'd try slowing down as gently as possible to see if it's the momentum that wants to flip her over. If you can adjust your style, or the drag, so that you don't flip, I'd say that your weight in the back is OK (this driving adjustment may include descending slower or faster). If you can't adjust, try adding a little weight in the back until you like what you can do. A balance for ascending/descending won't be perfect; you'll have to decide what you like better. One thing you might do is just "pose" the rig at the angle that is troubling you and see what gravity does: if she flips, I would worry about weight, first, then drag. You may even try lightening the weight up front (and see how she does climbing and descending).

That picture shows a pretty good angle. From that limited shot, I would assume my MRC would climb it fine, but descending may be a different story, as it does seem fairly steep.

Don't forget about COG. If she's too high more weight won't work as noticeably...you could try limiting your shocks a bit, too, so she sits lower.

I don't see your battery. Where are you keeping that thing? Lipo or Stock? You might simply try putting that battery on the back axle, as it'll lower COG if you're keeping the battery in the cab or on the servo, and it will add a little weight in the back.

Flat Irons are tall tires. The added elevation they give to your rig isn't going to help COG. How much they "hurt" it, I couldn't tell you, but logic suggests they aren't going to help it.

mikegigabyte · 12-31-2009, 09:24 AM

Im using the losi lipo on the front mount plate. It can climb up that huge rock great and when I go down its super slow almost stopping and letting the drag brake move it down. I also try using the steering to wiggle me down too. I may swap fronts and rears today before adding rear weight just to see. I was going to add rear weight because my course has very steep rocks and its hard to get a grip to climb, but if I barely put my finger on the roof it will add enough weight to climb to rock. The shocks are limited, but the way the chassis is the 3 link interferes with the lower bent rods anyways so it also acts as a limiter.
Im just thinking the shock position has screwed up my cog and im experimenting with the stiffness of the shock also at the same time, that has seemed to help it climb better for some reason. I was using chisels that same day and it flipped, then I bought the flatirons and same thing so I dont think it is the tires.

I have a digital scale and the overall truck weight is 59 oz
front weight is 33.3 oz
rear weight is 23.80 oz
this is with the truck put together on the scale all built overall weight not wheel weight

wheel only weight
rear 6.85 oz
front 9.55oz

I think after a few more tests I will add more limit to the shock to drop it a bit more

JeepinOR · 12-31-2009, 09:55 AM

So, I think you're saying that you can descend down that steep angle if you go at it super slow, and perhaps let the tires help wiggle you down? Sounds about right man!

If you have a few stick on weights you might try adding just a little to the rear to get a taste of that "finger weight" you suggested, and then see if she still climbs OK. Swapping wheels is quick and easy, too. Don't forget to also try climbing to see how less weight influences the front.

It sounds like those Flatties are spinning when you have to add your finger to help them grip? Are you using PL's monstrous foams?

For kicks, if you have time, you may even remove those springs from the shocks and see how she does full droop. You may not like it at all, but seeing rigs suck to rocks while drooping is convincing enough to experiment more with shock setup and COG.

toyw/me · 12-31-2009, 12:03 PM

Im with JeepinCA, I like mine setup to go up great and then really have to drive it to get down. Is your belly clearance the same as your old setup? If it is then your new setup has a high cog due to the tube work. I think this is why most over the counter tube chassis recomend short shocks or full droop. I say put straight links back on and slam it, but thats just me and how I like my crawlers. I love this hobby (addiction).

mikegigabyte · 12-31-2009, 12:29 PM

Quote:

Originally Posted by toyw/me

Im with JeepinCA, I like mine setup to go up great and then really have to drive it to get down. Is your belly clearance the same as your old setup? If it is then your new setup has a high cog due to the tube work. I think this is why most over the counter tube chassis recomend short shocks or full droop. I say put straight links back on and slam it, but thats just me and how I like my crawlers. I love this hobby (addiction).

After installing the tube chassis it was less then a quarter inch higher then the setup I had on the losi chassis, which was way lower then the stock losi setup originally.

Im going to test it now, I added a little more shock limits, and swapped tires so the heavier ones are in back.

mikegigabyte · 12-31-2009, 12:51 PM

Well swapping the tires around and limiting the shocks more seem to keep it from flipping over, even going faster then before, and going super slow. It seems to be around the same height my old stock setup was because now it drags on the higher rocks. Still have the problem with crawling up the steep rocks so I may add more weight to the empty fronts now as the finger on the roof trick still helped it climb those steep rocks.

Ground clearance is 2-1/4 high
And wheel limit is 3-1/2 of articulation

jason yates · 12-31-2009, 03:49 PM

You have way to much weight up high that a tuber for you.My bug body only weighs 1.1oz. Whats the tuber weigh?

JeepinOR · 12-31-2009, 03:54 PM

Quote:

Originally Posted by mikegigabyte

Ground clearance is 2-1/4 high

That's about the highest number I think I can recall reading for an MRC setup. Most don't surpass 1 7/8", let alone 2". That's not necessarily bad, of course, but will sure make you drive that rig, considering that extra weight from the tube work (as suggest above).

I whipped up a quick little ramp out of some scrap plywood and carpet...it's not as fun as testing on the rocks, but it's a quick (clean, dry, indoor!) way to see how she's doing with the angles: forward, reverse, and "posing" for COG.

mikegigabyte · 12-31-2009, 04:14 PM

Well im pretty sure the stock losi height was around 3 inches, thats the only reference I had to go by. My shock have about 3/4 of the shaft showing, but I figure the tires may have raised it up some. I may also put on the stock suspension arms because my bent ones hit the 3 link. If my shock get any lower there wont be anything of them left

mikegigabyte · 12-31-2009, 09:54 PM

Just put on the stock losi bars and they dont hit the 3 link anymore, and now I have 4-1/2 inches articulation. 2 inches ground clearance

mikegigabyte · 01-01-2010, 01:23 PM

Well problem solved, it was adding weight in the rear. Now the front and rear wheels weigh the same and no more problems.
Made my own lower rods as the straight ones dont hit the 3 link like the bent ones did.

12-31-2009, 08:21 AM	#1
mikegigabyte Quarry Creeper Join Date: Nov 2009 Location: San DIego Posts: 219	Changed chassis, now rolls over forward So I changed my chassis last week, and on my backyard course going down a steep rock it usually filps over forward using chisels and losi real beadlocks with stock weights in all wheels. The same day I bought my first set of flatirons and it still does it stock wheel weights. Since ive been working I only have around 1/2 hr per day to test and half the time is in the dark. Last night I tweaked the shocks and tightened them down and added 12 stick on weights on both front wheels. Im getting more today incase needed. I also changed the drag brake on the mongoose esc, it was set at 1, I went to the highest. Now this seemed to maybe help and I was wondering if the brake was set wrong before and im going down steep and super slow could the brake not acting correctly filp it over. Im thinking about adding rear weights to maybe keep the back down, or will it force more weight on the front when vertical and aid in flipping forward. It never did this before with the stock chassis and lexan body, but my shocks were at a different angle, the tube chassis I use has a totally different layout and only 2 holes to adjust, both settings havent helped. So my question is does it help to add rear weight for forward flipping going downhill, or adjust the drag brake more? Changing to the tuber only the chassis and shock position was changed all electronics stayed in place. I dont know if the chassis really changed the cog, or the shock placement. The ground clearance changed a hair upwards, not even a quarter inch. My course is pretty steep with river type rocks, I can drive the whole thing I just dont like flipping it on the rocks as I dont want to break a part. Here is the area when going down it will flip forward. The pic helps show the angle.

12-31-2009, 09:09 AM	#2
JeepinOR Rock Crawler Join Date: Mar 2009 Location: West of Eugene, OR Posts: 942	If you're rolling over forward, there is obviously a weight bias up front... How much weight all around? If you're rolling down the decent OK until you let the drag catch, and then it flips you over: some weight in the back may help, but I'd try slowing down as gently as possible to see if it's the momentum that wants to flip her over. If you can adjust your style, or the drag, so that you don't flip, I'd say that your weight in the back is OK (this driving adjustment may include descending slower or faster). If you can't adjust, try adding a little weight in the back until you like what you can do. A balance for ascending/descending won't be perfect; you'll have to decide what you like better. One thing you might do is just "pose" the rig at the angle that is troubling you and see what gravity does: if she flips, I would worry about weight, first, then drag. You may even try lightening the weight up front (and see how she does climbing and descending). That picture shows a pretty good angle. From that limited shot, I would assume my MRC would climb it fine, but descending may be a different story, as it does seem fairly steep. Don't forget about COG. If she's too high more weight won't work as noticeably...you could try limiting your shocks a bit, too, so she sits lower. I don't see your battery. Where are you keeping that thing? Lipo or Stock? You might simply try putting that battery on the back axle, as it'll lower COG if you're keeping the battery in the cab or on the servo, and it will add a little weight in the back. Flat Irons are tall tires. The added elevation they give to your rig isn't going to help COG. How much they "hurt" it, I couldn't tell you, but logic suggests they aren't going to help it. Last edited by JeepinOR; 12-31-2009 at 09:15 AM.

12-31-2009, 09:24 AM	#3
mikegigabyte Quarry Creeper Join Date: Nov 2009 Location: San DIego Posts: 219	Im using the losi lipo on the front mount plate. It can climb up that huge rock great and when I go down its super slow almost stopping and letting the drag brake move it down. I also try using the steering to wiggle me down too. I may swap fronts and rears today before adding rear weight just to see. I was going to add rear weight because my course has very steep rocks and its hard to get a grip to climb, but if I barely put my finger on the roof it will add enough weight to climb to rock. The shocks are limited, but the way the chassis is the 3 link interferes with the lower bent rods anyways so it also acts as a limiter. Im just thinking the shock position has screwed up my cog and im experimenting with the stiffness of the shock also at the same time, that has seemed to help it climb better for some reason. I was using chisels that same day and it flipped, then I bought the flatirons and same thing so I dont think it is the tires. I have a digital scale and the overall truck weight is 59 oz front weight is 33.3 oz rear weight is 23.80 oz this is with the truck put together on the scale all built overall weight not wheel weight wheel only weight rear 6.85 oz front 9.55oz I think after a few more tests I will add more limit to the shock to drop it a bit more Last edited by mikegigabyte; 12-31-2009 at 09:29 AM.

12-31-2009, 09:55 AM	#4
JeepinOR Rock Crawler Join Date: Mar 2009 Location: West of Eugene, OR Posts: 942	So, I think you're saying that you can descend down that steep angle if you go at it super slow, and perhaps let the tires help wiggle you down? Sounds about right man! If you have a few stick on weights you might try adding just a little to the rear to get a taste of that "finger weight" you suggested, and then see if she still climbs OK. Swapping wheels is quick and easy, too. Don't forget to also try climbing to see how less weight influences the front. It sounds like those Flatties are spinning when you have to add your finger to help them grip? Are you using PL's monstrous foams? For kicks, if you have time, you may even remove those springs from the shocks and see how she does full droop. You may not like it at all, but seeing rigs suck to rocks while drooping is convincing enough to experiment more with shock setup and COG. Last edited by JeepinOR; 12-31-2009 at 10:00 AM.

12-31-2009, 12:51 PM	#7
mikegigabyte Quarry Creeper Join Date: Nov 2009 Location: San DIego Posts: 219	Well swapping the tires around and limiting the shocks more seem to keep it from flipping over, even going faster then before, and going super slow. It seems to be around the same height my old stock setup was because now it drags on the higher rocks. Still have the problem with crawling up the steep rocks so I may add more weight to the empty fronts now as the finger on the roof trick still helped it climb those steep rocks. Ground clearance is 2-1/4 high And wheel limit is 3-1/2 of articulation Last edited by mikegigabyte; 12-31-2009 at 09:54 PM.

12-31-2009, 12:03 PM	#5
toyw/me Pebble Pounder Join Date: Dec 2008 Location: Eastern, Oregon Posts: 109	Im with JeepinCA, I like mine setup to go up great and then really have to drive it to get down. Is your belly clearance the same as your old setup? If it is then your new setup has a high cog due to the tube work. I think this is why most over the counter tube chassis recomend short shocks or full droop. I say put straight links back on and slam it, but thats just me and how I like my crawlers. I love this hobby (addiction).

12-31-2009, 03:49 PM	#8
jason yates Rock Stacker Join Date: Oct 2008 Location: gainsville Posts: 58	You have way to much weight up high that a tuber for you.My bug body only weighs 1.1oz. Whats the tuber weigh?

12-31-2009, 04:14 PM	#10
mikegigabyte Quarry Creeper Join Date: Nov 2009 Location: San DIego Posts: 219	Well im pretty sure the stock losi height was around 3 inches, thats the only reference I had to go by. My shock have about 3/4 of the shaft showing, but I figure the tires may have raised it up some. I may also put on the stock suspension arms because my bent ones hit the 3 link. If my shock get any lower there wont be anything of them left

12-31-2009, 09:54 PM	#11
mikegigabyte Quarry Creeper Join Date: Nov 2009 Location: San DIego Posts: 219	Just put on the stock losi bars and they dont hit the 3 link anymore, and now I have 4-1/2 inches articulation. 2 inches ground clearance

01-01-2010, 01:23 PM	#12
mikegigabyte Quarry Creeper Join Date: Nov 2009 Location: San DIego Posts: 219	Well problem solved, it was adding weight in the rear. Now the front and rear wheels weigh the same and no more problems. Made my own lower rods as the straight ones dont hit the 3 link like the bent ones did.

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