looking great


i would also cut out the rear of the body, it will greatly reduce drag

Man, that looks bizzare- like 1/8 buggy shoes on a mini erevo... *hmm, interesting idea...*

Should be alot more controllable now, but I wonder how many runs those tires will last?

Yea, they are definatly different looking and I could of run buggy foams or still small truggy foams but I would lose gear ratio and the big monster truck wheel look. BTW They are 1/8 scale CEN monster truck wheels cut on a lathe. They are the purple foams and supposed to be the hardest compound available. So I imagine they should last longer than most. Theres not much on the back of the body at least not a real tailgate or anything. I do think the slipstream will be ideal though, thanks Neal for the recomendation.

Looks nice river.
 

It really does look nice river. I hope the tires hold up for you. I still think a more solid tire might be the ticket for the speeds you want to go. You may have to run your own rubber on a lathe to get a trustworthy set of tires forgetting much over 100mph. So lets see it with the body on there. I sure hope your setup gives you some aerodynamics that will keep the wheels on the road. Once you get up around 80mph it will want to lift up if you do not have some kind of down-force included. Good luck with your testing.

The foam these tires are made out of are the same purple type Nic Case uses in his 160mph car. I am sure John at bsr knows what he is doing. He is the best tire mounter around and multiple guys with speed cars use him. A solid rubber tire would be too heavy and probably cause other problems. We will see how it tracks at speed. I noticed alot of the blow overs were from either a wheely or a tire balloning(growing) causing a lift off. I have the punch control set at 90% to help with the wheelies and obviously no tire balloning. The test body is going to be different from the run body as I dont want to have to buy another if I thrash it. Once I know everything is good I will start using the actual run body which I will be painting next week.

Heres some pic with a messed up body that I bought off ebay that the holes were not drilled in the right spots. I guess it will work for this project as I am going to use clear packing tape to hold it on for now. The slipstream body is longer and will fit alot better.
http://i153.photobucket.com/albums/s...s/CIMG2630.jpg
http://i153.photobucket.com/albums/s...s/CIMG2631.jpg

Awesome! Yes. I would install the monoblock. Very exciting!

Cant, I am running a extended rear titanium skid. It is a little longer than with the mono also. I wanted it as light as posible also. Mono would of added some unwanted weight. Notice the narrow old school rpm arms and pillow blocks. It has aluminum pillow balls all the way around. Ti cvds, ti centers,ti turnbuckles,ti skids, UE 1/8 scale 6 spider diffs. I put all new avid ceramic bearings in the tranny and new bearing in the pillow blocks.It weighs 9.4 pounds with 2 6s 3300 batts without a body.

anxious for more testing now that you've got the right shoes. Looking awesome..........

OH now I see what you meant, You are thinking about moding(lengthing) the chassis and installing the mono block shaft only. Gotcha.

Those BSR's are quite amazing aren't they

If you ran without punch control & a front splitter I'm sure the effect would be the same just a little kinder to the MMM

Are you revealing any pics of the aero setup? I'm assuming vertical stabilisers?

So your saying if I run without any punch control it would be easier on the mmm.? I could be wrong but i thought it was the opposite. As far as a splitter not sure how I would go about doing it. I didn't have a chace to test it this weekend. Maybe today. If I need vertical stabilizers I think a modded 1/8 scale wing will suffice.

Well Punch control is limiting current IIRC. Limiting current, i.e. not running full throttle also, tends to build more heat since the ESC has to work harder.

So rolling into the throttle with no punch control is easier on the esc than without?. I really dont see how it will make a difference since I have to roll into no matter what . Unless the combination of punch control and rolling into the throttle is worse than no punch control and rolling into the throttle. I figure the PC will help out with amperage spikes from me getting to throttle happy. Theres no way I can just punch it full throttle from a dead stop. I am using the punch control too prevent wheelies and help smooth out accleration and prevent parts breakage more than anything. I am sure without it the tires may cut loose if I acclerate too fast. I need to play with it and see.

You guys act as if running punch control is putting the MMM past its operating envelope


Punch control is not physical current limiting. Nor does it limit full throttle opperation.

It is just a ramping of PWM value, it does exactly what pulling on the trigger slower would do. just dampens the increase of change from the throttle input. doesnt change anything at WOT

Punch control will be fine... the ramping will deaden the large amp spikes from jerky trigger movement and will help your batteries stay cool.

That my Understanding of it also. I knew it didnt affect full throttle is just make it get there a little smoother. I personally think it an awesome design and I am glad this esc has the option. I wonder if I should adjust the linear graph curve or just leave it alone. Any recommendations?

Do that once you get the truck running. If there is one particular range of throttle where the truck pulls the wheels, then tweak the curve a bit

I don't see you punching the throttle off the line with or without punch control, you'll need to feed the throttle to about 60 before you can WOT

After driving my Rustler with a 1515 1.5, my punch control is my throttle finger

Edit: My reference to the splitter is that if set up right, it can keep the vehicle composed across the entire speed range & allow you to pull more throttle earlier by creating downforce

You really need your cells to be as warm as possible (65-70 degrees C) before a run. You'll get one full power run before most cells loose the window. If you run them cold it'll take a few runs to warm & by then you'll lost the best of the battery

To much down force and speed will suffer not enough and its flying. What funny is I am running 2 6s 3300mah batts in parallel not 2 3s in series so I think I have alot more capacity and be able to do way more than 1 run without too much speed loss. After I came home after the first speed runs(like 3 good ones) my batts were still ~ 4volts. Yea I heard about warming the batts for best results. And as always the first run will be the best. Going out in a bit for a speed trial I will try to get some video.

trinity makes an excellent battery warmer, it wouldn't be a bad idea for the speed challenge,where you wait in line to do a run and can't warm the packs properly.

only if the batteries are pre warmed, otherwise your 2nd or 3rd run will be the best. And lipos holding power allows multiple passes with identical performance(once they're warmed up), not one first good run like nimh's

Saw this in a magazine, said something about warming to 140 degrees.. seems a bit odd doesnt it?

nope, that's the temp the electrons like to flow at. An inherent trait of lithium polymer technology:yes:

Took the truck out tonight before it got dark and the tire seem to be doing their job. Obviously no balloning and I got it up to 67 mph a little over 1/2 throtle but it starts too drift and is really hard to control and I had to let off. It definatly has alot left in it as I gave it about 3/4 throttle going 50mph and you could hear the tires break loose and it started sliding sideways so there is lots of power still availiable.The hitec servo has a little play in the gearbox and it hard to get it to go perfectly straight I checked 5 hitech servos and all had a little play. I wonder if I should have some toe in or toe out maybe to help with stability a little. I also think I am going to have to put verticle stabilizers and/or low down force wing. I think a giro is in order also. I am not going to do any vids until I get atleast 80 mph and I know it can do it but need to figure how to control it some how. It did do a 50 mph power slide and it fliped it over wheels got a little scuffed but nothing else was hurt glad I used this jacked up body, the packing tape held it on good lol. After about 6 60+ mph passes the batts still have 4 volts left in them.

like 1 degree rear toe-in will help track straight. for straightline speed fronts should be neutral

I actually have about 1* toe in in the rear the fronts are neutral also but it is still hard to control. The road crown probably didnt help at all either. I notice under acceleration it started to pull to the left. Whats up with that? If I cruise about 20 mph it goes straight.

That's all good news

The drifting or slewing may be as simple a fix as vertical stabilisers off the 1/8 wing end plates

Toe in/out? assuming it's at the rear - I'd run a max of 1.5 deg, any more starts to scrub off speed

If you use a gyro they take a little getting used to, wind the gain right down so that it is only noticeable under brakes...you don't need it hunting under acceleration

Sounds like torque steer

sounds like torque steer to me. only thing you could try is flipping diffs and reversing motor operation, but I suspect it may go to the right under acceleration then.

also sounds like you are traction limited, you have a pretty small contact patch with the road. Needs more downforce!

The left pull may also be a further sign of wheel spin, once moving forward but without traction, a vehicle will follow the natural camber of the road...it may be this??

I've posted this elsewhere in reference to an excellent mini revo custom build, it may be of some benefit? Apologies for being lazy....

"I see there are 4 basic elements to an open wheel design...1st is the splitter, 2nd is the body, 3 is the rear wing & 4 is wheels

http://i703.photobucket.com/albums/w...CFDracecar.jpg

You can adjust everything except the wheels fairly easily & this is the splitter function...

http://i703.photobucket.com/albums/w...ySplitter1.jpg

but in your case I think something more exaggerated in terms of length & perhaps even reducing the high pressure area by smoothing the splitter to body area - which increases the downforce...& then if you need to, you can reduce this effect by reducing the size of the splitter. I hope that makes sense?"

In most cases, the splitter can be mounted directly to the chassis via a simple CF or alum plate using the existing diff screws

I also think a 1/8 rear wing might be too aggressive & reducing the near vertical elements will work well to decrease drag but maintain sufficient downforce. Combined with the enlarged vertical end plates, it should work perfectly with some fine tuning

Whats funny it pulled toward the crown not away so it might be torque steer. I thought a gyro would help correct this problem. Now i have to find a gyro thats will work and reasonably priced. As my budjet is through the roof.

Here my wing:
http://i153.photobucket.com/albums/s...s/CIMG2643.jpg
I need to get rid of some of or all the down force kick up in the back. I was thinking of just removing kickup near the side of the stabilizers (see pic) or just remove the center leaving the rear side kick ups to help support the side stabilizers.
http://i153.photobucket.com/albums/s...s/CIMG2642.jpg
I could also remove the whole thing all the way across as I think I need the stabilizers more than the rear downforce as too much will cause the front to lift and I dont want that. even with the rear removed the front part of the wing still has a small kick up also(see first pic). What do you guys think?

Pull the wing off completely for a run and see how it acts. That will give you "data" at both ends of the spectrum, and you may be able to make a more precise "guess" at where you need to be.

I agree that you probably saw torque steer. Might want to change diff fluid.

Another thing you might try once you get to the fine tuning stage is some sort of mud guard on the A arms. You could possibly shape it so its not just a flat surface. May or may not make a difference.

Great diagram PBO - that's exactly what I was trying to explain in one of my earlier posts. I personally think its all about that front wing or spoiler with the body shape, height, extended arms and wheels that a MT has.

Never ran it with a wing at all . The diff has thick fluid and is pretty tight but I was told the front could be spooled or locked with diff grease. You think it would help with torque steer. Working on figuring a front splitter now , I will let you know what I come up with.

Test data
 

Good test data so far River. My 2cents. Unfortunately I believe the only way you are going to reach your (speed)goal is from a lot more testing and trying different effects. Running a 1/8 scale vehicle at those speeds takes a lot of tweeking to get all of the variables just right. The ones I have seen up to now that do very well were running with a body that covers the entire vehicle, including the wheels, which prevents or elliminates alot of the turbulance and push that you will see. Take a good look at todays "Funny Cars" and see what you can use from that technology. You might try fabricating your own wedge type body out of thin lexan sheeting. This type of body will give you more control and also give you more protection for your equipment in the event of a roll over at high speeds.

Your steer pull issue does sound more like natural torque steer from your drivetrain. This is something that is almost impossible to over come completely. A strong servo setup and the Gyro may help though. It is good to see what you what are going through in order to learn what (to do & Not to do) when my project gets to that point. Good effort River, and good luck.

Jerry - per the MT speed rules your body cant cover the wheels, so he's stuck with something close to standard width. He may be able to extend one out to almost touch the wheels though.

River - I would almost think that a light diff fluid may help with the torque steer. If not, you may have to get good at setting up your chassis to compensate. I'm going off memory here - can you adjust the maxx arms front to back at all? You may have one wheel sitting slightly forward of the other which could cause a slight drift.

Maybe also try adding a shim to the spring on the uphill/crown side of the truck.

I agree you need the vertical stabilizers more than anything. I would also remove the "kickup" but I would dremel it down bit by bit across the entire length. I would expect you'll remove up to 1/4" of height by the time you're finished tuning

I would add some bigger end plates though...each 5 mph increase over 70mph changes the way your vehicle will behave & the vertical end plates will have a positive effect on each issue you have described the closer you get to 100

I'm not sure a gyro will be able to correct torque steer (if this is the issue) because it may end up "hunting" (over correcting itself), this is bad at any time but under acceleration it can obstruct additional throttle input. You'll need to spend some time getting it setup correctly - I tried to tune both a Dbox & Ace gyro on my Rustler & I got to a point where it was doing almost nothing under acceleration but would keep things tidy under brakes (this enabled me to run stock sliders to > 85mph because I could slow down slowly, without snapping the yokes off first dab of the brakes)

The body cant cover the tires in the open wheel class. I was told by Nic Case that a spool or locked front diff is what I want thin dif fluid will have the opposite effect I want. The front will unload one tire quicker causing drift or torque steer. If its locked or close to it, both tires have to spin the same speed no matter what causing the truck to pull itself straight. I dont know if you guys noticed the arms are the short old style rpm arm so they are not adjustable. I did put some more toe in in the front to help with high speed stability, I will lyk how it works out. Not sure if a shim will help either the truck is pulling toward the side with the most traction. It was pulling toward the crown so if I shim that side it will put more pressure down causing more traction and more pull now if I put it on the other side it might help. My springs are adjustable so no need for shims just preload one side more than the other.
Jerry, I have seen plenty of open wheel cars go fast. Look @ the fastest top fuel cars, 230+ mph indy formula 1 cars, and outlaw cars. I also have seen a few open wheel buggies go 100mph+ and a few 80mph revos, and 1 that went 91.2mph . So I know it can be done it just getting everything set up just right and lots of testing like you said. Remember this is my first real test with the proper tires and I allready am doing 67mph. How many maxxes have you seen, heardor read about going that fast on radar? I know I might have read about 1 or 2 and thats it.
How do you guys like this open wheel design? I am thinking of stealing the front wing design. Will more smaller stablizers front and rear be as good as big ones on the rear. Kinda like a indy car.
http://i153.photobucket.com/albums/s..._1-470x352.jpg

Go with spools all the way around. Maximum power transfered. and your not turning much.