Robitronics Scalpel 1/18th Pan Car?

[InZane]

You can eliminate most of the bump steer by mounting the servo upside down in an angle as most 1:12 pan cars have (see pic)

[heretic]

thank you all for responding;

Actually this is the way i mounted my servo. I didn't like the original design because the servo was in a stupid place imho. So I installed it like every 12th amateur would have !( i have the 150mm chassis, but it is possible also in the short one) Now, among other benefits, my servo head is centered.

But my servo is mounted flat, shoe gooed. No way to put it on posts like the pic of the xII, there is no room left under the body.

I am sorry can't take any picture of the car.

To say things differently, could someone decribe the best angles of the steering linkages (horizontally and vertically) to obtain the very least bumpsteer ?

Also, which hole to use in the steering arm ? and such things to get a nicer steering geometry...

[heretic]

Originally Posted by DBBIndy

The bumpsteer is inherent in the basic fron suspension design. A completely different front end is required to really eliminate the bump steer.

I was wondering about the same thing, but I still have hope.

I would like to see introduced by RobiTronic or any aftermarket manufacturers, a front end similar to the sp12g2 and g3 from corally.
( http://www.kimihiko-yano.net/Image/Pc300001.jpg )

It was also possible on the sp12M to use one metal part instead of the two separate arms. I loved it when i tried it.You could swap from one front end type to another , and so could you on a scalpel.

This kind of front end ( old) offers more caster loss when compressing, but also offers very little camber gain, which could help with the bumpsteer. Also the antiroll effect is nice (to me at least.) Maybe one day i'll try to make a part like that myself...in a few years !

[Micro-Man]

I HAVE MY CAR PRETTY MUCH DIALED IN AND I HAVE MOST OF THE CAMBER GAIN TAKEN OUT....I HAVE 2.5MM SHIMS UNDER THE BALL STUDS WITH THE LINKS IN THE REAR POSITION AND THEN I ADDED BALL STUDS IN THE FRONT POSITIONS AND USED A THREADED PIECE OF TIE ROD WITH BALL CUP ENDS ON THEM TO CONNECT THE TWO TOGEATHER...THIS TAKES OUT THE BUMP STEER.......I AM WORKING ON A NEW FRONT END THAT TAKES OUT ALL THE CAMBER GAIN AND LOSE THIS WEEKEND....IT SHOULD BE THE TICKET FOR THE SCALPEL AND THEN IT WILL BE UNTOUCHABLE .....

[InZane]

I've been running the Scalpel with the servo mounted "backwards" from day one (nearly two years ago).
With 2,5mm spacers under the knuckle studs there is nearly no bump steer at all.



There shouldn't be a problem to mount the servo like in the XII pic - maybe depends on the body though.

This is what my old 4-cell config looked like

[heretic]

Originally Posted by Micro-Man

I HAVE MY CAR PRETTY MUCH DIALED IN AND I HAVE MOST OF THE CAMBER GAIN TAKEN OUT....I HAVE 2.5MM SHIMS UNDER THE BALL STUDS WITH THE LINKS IN THE REAR POSITION AND THEN I ADDED BALL STUDS IN THE FRONT POSITIONS AND USED A THREADED PIECE OF TIE ROD WITH BALL CUP ENDS ON THEM TO CONNECT THE TWO TOGEATHER...THIS TAKES OUT THE BUMP STEER.......I AM WORKING ON A NEW FRONT END THAT TAKES OUT ALL THE CAMBER GAIN AND LOSE THIS WEEKEND....IT SHOULD BE THE TICKET FOR THE SCALPEL AND THEN IT WILL BE UNTOUCHABLE .....

Thank you all for you answers and pictures.

I saw a picture of what has to be your car, (can't remember where) and i have to say it surprised me a bit. I thought it was a bit "anti mechanical" and that it was only an empirical way to getting rid of the backlash (play?) in the steering linkages. What I don't understand is how does this eliminate bump steer? I don't see how it could make a difference. could you show us some pictures? And also a picture of your new front end... of course !

About the pictures, it is very similar to what I did , from day one also, i didn't even try the standard way of mounting the servo.

The angle described by the steering links is similar too, but it has quite obviously not the same consequences since there is a noticeable amount of bumpsteer remaining.

The 5 cell solution is clever, and must be an excellent compromise between 4 and 6( weight and power), allowing you to put the servo in the right position, and use a not-so-tiny ESC. good idea!

I never tried it since i use lipo. I definitely should post some pictures so that you could give me a more precise advice.

[bigb11]

With the new foam tires that are out and front end improvements, this will make the car great.

[HVAC25000]

Originally Posted by bigb11

With the new foam tires that are out and front end improvements, this will make the car great.

I must have missed it, where are these new tires?

Thanks!
Chris

[bigb11]

Originally Posted by bigb11

We finally have our foam tires in stock. Fronts are 1.225 dia. and rears are 1.250 dia.

Fronts come in the following: white, blue, black, pink, xxpink, purple, xxpurple, pearl white, purple/orange, grey, xxpink/orange.

Rears come in the following: white, grey, pink, pearl white, xxpink.

Fronts are $15.00, Rears are $16.00.

Also here is our new lipo chassis.

we are going to RC Madness tommorow for the race, weather is bad here today.

Happy Holidays to all.

YES NEW FOAM TIRES AT www.browneng.org

[HVAC25000]

Ah.

I'll definitely be ordering some of those.

Are the colors listed from softest to hardest (excluing the dual compounds of course)?

[bigb11]

For the scalpel onwers that missed our news flash about the new foam tires. here it is again.
we have the following for the front.
white - 30+/-
blue - 55/65 +/-
black - 45/50
grey - 40+/-
pink - 30+/-
purple - 40+/-
xx pink - 35+/-
xx purple - 45+/-
purple/orange
xx pink/orange
pearl white - 25/30

we have the following for the rear.
white - 30+/-
grey - 40+/-
pink - 30+/-
pearl white - 25/30
xx pink - 35+/-

the cost are $15.00 for front which are trued to 1.225 dia. and $16.00 for the rear which are trued to 1.250 dia. they are on white rims.

Thanks and happy holidays.
www.browneng.org

[heretic]

eye candy...
it is a shame that the car was never released by laje, it seems to be a lot better than a scalpel, to me.

[all4fun]

Originally Posted by heretic

eye candy...
it is a shame that the car was never released by laje, it seems to be a lot better than a scalpel, to me.

heretic.......Now this chassis looks awesome and looks like it would work. Does it use any of the Scalpel parts, like the rear axle, front and rear tires, etc? Is this car available to purchase now, and if so.... where and price?

[ShadowAu]

Originally Posted by bigb11

For the scalpel onwers that missed our news flash about the new foam tires. here it is again.
we have the following for the front.
white - 30+/-
blue - 55/65 +/-
black - 45/50
grey - 40+/-
pink - 30+/-
purple - 40+/-
xx pink - 35+/-
xx purple - 45+/-
purple/orange
xx pink/orange
pearl white - 25/30

we have the following for the rear.
white - 30+/-
grey - 40+/-
pink - 30+/-
pearl white - 25/30
xx pink - 35+/-

Ok... I admit I am not a big foam tire user so I am not sure about the compounds, but what is the difference between whites and pinks if they are both 30+/-... purple & grey @ 40 +/-

[Micro-Man]

ATTENTION ALL SCALPEL DRIVERS........

IF YOU ARE LOOKING FOR THE BEST SCALPEL TIRE ON THE PLANET, THEN LOOK NO MORE.......

ONE HUGH WOW!!!!!!!!!!!

I HAVE HAD THE SURE PRIVILEGE OF TESTING THE BROWN ENGINEERING TIRES THIS WEEKEND AT "THE TRACK" IN GAITHERSBURG, MD....

THESE TIRES ARE #1 IN MY BOOK FOR BEST AND GREATEST....GREAT LOOKING WHEELS WITH THE EASY TO SEE WHITE RIMS AND THESE TIRES HAVE UNBELIEVABLE GRIP AND SUPERB TIRE WEAR.....UNDOUTIBLY THE MOST BANG FOR YOUR HARD EARNED BUCK......

SO MAKE SURE YOU GET YOURS...GIVE BROWN ENGINEERING A CALL OR CHECK HIM OUT ON WWW.BROWNENG.ORG