charl mac

Hi Guys, would like to knowwhich is quicker FGX or F109.

I know F109 or new F113 is wider but how is the suspention on FGX.

might start a F1 class but want to keep it easy, would Jonson motor with tamiya rubber be good choice. I have raced F104 before with 18t b/l on rubber tire but for most newbies its just to much power.

Thanks.

InspGadgt

Well that depends on the rules under which you will be racing and the surface you will be racing on. If grip is good and foams are allowed the F109 will be faster. If grip is poor and the track is bumpy most likely the FGX will be quicker. If the rules limit the width to 180mm than neither car is legal...if the limit is 190mm then the FGX is legal but the F109 (stock) is not.

Team Lotus

Very nice!!!
I can't wait to see pics of the finished car!! Please post pics when done!!

howardcano

iTrader: (37)

No, Rick, my statement is correct. The "line of the lower arm" is immaterial because it does not move. One could change the shape of the arm or its attachment point on the chassis with no effect on the roll center as long as the pivot ball is not displaced from its original location.

Check John Stranahan's discussion of the strut suspension in his Pantoura thread; here's a quote from post #1949:

"The instant center on this inverted strut (inverted McPherson Strut) is determined by extending a line at right angles to the kingpin at the lower pivot. A second line is extended on the upper A-arm axis. Where the two meet is the instant center. A line from the tires contact patch to the instant center meets the roll center at the vertical center line of the car.
Because of this when you change camber you change the angle of the kingpin and thus the lower right angled line. This changes the instant center and thus the roll center."

A quick internet search will reveal a plethora of drawings illustrating the geometry used to find the roll center. Search for "MacPherson strut roll center"; John misspelled it in the quote above. You will indeed find that the line must be drawn perpendicular to the kingpin. Here's one example: http://www.miracerros.com/mustang/t_rollcenter.htm

Edit: I should have made my statement regarding the steering knuckles more clear. Camber may be changed by using different steering knuckles having an angle other than 90 degrees between the axle and kingpin. (Check Stranahan's Pantoura thread, post #1981 for an example.) This will not affect the roll center as long as the ride height remains constant. I was not referring to changing ride height by shimming the knuckle on the kingpin.

robk

iTrader: (22)

What you said about the kingpin angle on camber change is true, as illustrated by the reworked drawing i made based on the 1/12 front end. However, i can tell you by actual experience, changing the link on top of a kingpin front end acts exactly the same as changing the link on a sedan. A longer link lets the car roll more, a shorter link is more reactive, etc.


As far as different knuckles, now you're getting into kingpin inclination which is a whole nother ball of wax as well. You're also going the wrong way on kingpin inclination if you camber the tires in without changing the kingpin "camber"

fleetmaster

iTrader: (16)

There is NO such this as FAST ENOUGH !

I'm happy with my EFX . This is for another project car I'm looking at building in a couple of months time.

Racing more than once a month would surely make me faster

I'm just happy to get out and do my best. Where I finish isn't paramount - good , close, fair racing is..........
I know a good paint job is worth .2 per lap , heaven forbid I bolt a faster motor in it

P.S : I reckon there are 28 laps in the 540. I was approx 3 seconds off it last week, with lap traffic .

fleetmaster

iTrader: (16)

Thanks, just what I needed to know

NewWestF1

iTrader: (5)

got the adjustable front arms, rear upper link and hubs on . painting the helmet when i get my hands on a nice gold and getting the red done tonight for the rear wing panels and front wing panels .. even with white primer coat it'll take a few coats of red to get it just right .. total labour of love . should have images of the finished car this weekend .. then off to some racing

fleetmaster

iTrader: (16)

I used red vinyl on mine , after the red paint started to peel off ( after a couple of race meets ) . Just a thought for you .......

NewWestF1

iTrader: (5)

hey that's a great idea .. i feel a trip to Michael's coming on if the peel starts ..

howardcano

iTrader: (37)

Yes, it certainly is a "whole nother ball of wax", as it drastically increases the number of permutations possible when seeking the optimum setup! Too many possibilities can often reduce the probability of finding the best one!

Changing the angle between axle and kingpin is used more on oval cars to add positive camber to the inside tire while maintaining the same roll center and preserving the symmetry of the rest of the suspension geometry on left and right sides. It is not often used on road course because of the lack of off-the-shelf parts (and the effort involved, as I mentioned above), although it is still a valid option.

As an aside, modifying the steering knuckles for different kingpin/axle angles was also used on the "old school" Associated front end to change the roll center without changing tire camber, as Frank Calandra alluded to in the same Stranahan/Pantoura thread. One could change the knuckle, then shim under one side of the suspension arm to maintain the same camber. Leaning the kingpin in at the top would lower the roll center, and vice-versa.

You might consider modifying your drawing of the strut-style suspension during cornering roll, as neither spring has changed length. A more accurate representation would show the kingpin on the outside suspension slid upwards through the lower ball pivot, with the spring compressed. I think that's what Marcus was referring to in post #3360.

NewWestF1

iTrader: (5)

Here's some quick ones I snapped this morning before work .. obviously still need to get a few things done.

Upgrades put on, all the basics rebuilt .. you'll notice I cut out the side pod vents to draw air in for the ESC Tornado fan and generally cool under the body when the girl is moving around .. I cut off some plastic bits so the receiver would fit more tightly under the upper deck .. and I need to get the glue off the tyres .. but other than some minor stuff I think she's looking good for my first RC build ever ........

to do: paint on front and rear side wings, driver's helmet, cockpit detail and clean up the wiring.

JayL

Have we tried any off-road front knuckles? the kyosho and HPI Blitz ones look close and are metric.

Team Lotus

Very nice job, so far!!

Matt Howard

iTrader: (6)

anyone know of a shop that has the rear swaybar kit in stock?


*edit, speedtechrc has them in stock