XRAY - Model racing cars

Dear fellow T2 racers

As nobody seemed to be to enthusiastic about posting T2 measures I had to do myself. Here's my simulations and personal findings based on T2 measured data. Discussion welcome.

Please have a look at the following picture. It shows the 4 possible options of the T2 ackermann settings. Inner position forward refers to the servo saver shaft mounted in the forward position (not the indicator). To have a common reference for comparison I adjusted each setting to set the outer wheel at 25 degree angle. The difference in wheel angles and the angle necessary to set the outer wheel at 25 degrees are shown.



From looking at the pictures I conclude the following:

1. Using the outer forward position regardeless of the inner position setting inreases the ratio servo input to steering angle (less servo input required to set the same wheel angle). By using this setting you will notice that you need to reduce servo throw significantly. This in effect reduces the system resolution, means your servo has to be far more accurate in setting a given angle (especially repetition accuracy).

2. There is effectively only three usable ackermann settings

a. Inner position backwards, outer position forward resulting in the highest ackermann ratio
b. Inner position backwards, outer position backwards resulting in medium ackermann ratio
c. Inner position forward, outer position forward results in just the same ackermann ratio as b., but has the negative effect described in 1.
d. Innerpostion forward, outer position backwards has just a little bit less ackermann ration than b. (and c. of course)

3. Reading 3. I concluded there is no point in setting c.

4. Changing the inner setting to the forward position does not change ackermann significantly. May be that's the reason why other brands didn't bother to offer this option and stayed with the outer position option.

5. The Kit basic setup is well selected. You can easily go in both directions changing a single parameter.

What I haven't done so far is looking at the overall characteristic (servo saver angle over wheel angle). The kit setting (b.) seems to be fairly linear, don't know about the others yet.

Have fun interpreting ...

Hi Jilles and Joep,

Looking at the list from the EFRA, I don't see IB3800 approvement. Can we use these cell's for NK 2006 (by NOMAC rules)??

And Jilles good luck.

Peter

Hi bmw

Does this means that in forward and out forward is a bad option??

Peter

Hi Peter,

The EFRA list is till april. After april 1st they will allow also IB3800 and I think also IB4200. For the dutch nationals I heard that only the 3800 is allowed and 12t limit.

Jilles

All cells listed on the Efra Battery list will be allowed IF the cells have the right size !!!

Hi Peter

I wouldn't say it is a bad option. As in real life there is often more than one way to reach a goal. If you have the option choose the one with the least side effects.

As I said I am convinced that in-f/out-f results in the same ackermann ratio
(goal) as in-b/out-b but has the side effect of having to limit servo throw with the effect of reduced steering resolution.

To understand what I mean by reduced steering resolution try to imagine increasing the lentgh of the servo arm dramatically. To reach the steering end stops the servo now would only have to travel a few degrees. In this case you would have to limit the servo throw to a few percent. But as in any technical system (in our case the tx/rx/servo combination) the resolution is limited, leading to inaccuracies and small signal jitters having disproportionate effects.

Selecting between b. and c. is surely not that dramatic, but if you have the option why not choose the better one.

Hi bmw

It looks like inboard and outboard front gives the fastest reaction on steering. I will give all the options a try on the track of HFCC in the Netherlands. Let's see what looks good on paper works in real life. I've been giving that option (in and out front) from Tony. I'll let you know how all the options worked.

Peter

I just got my new T2 in the mail yesterday, and was really excited to build it. I had a race to goto last night so I didnt have a chance to start on it untill this morning. First I started on the chassis prep, and then started to build the car. As I went along the car I measured everything to make sure it was all aligned perfectly. The car ended up going together very nicely, and everything fit perfect. I never had to hone out a single part to make it fit or align. I was happy after reading all this stuff on the net about everything, and also hearing everything at the local track about the car. I got my car all built today, and I have no tweak issues with the car at all its flat as a board, and the rear toe problem is no exsistant on my car. Once again I am very pleased with this car.
Xray did a awesome job on it.
Thanks
Jason

People were asking for a list of parts which can be used on the '05 and T2:
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Item Description
302551 SERVO SAVER PLASTIC COVER - ECCENTRIC (2)
302580 COMPOSITE SERVO HORN - KO, JR, AIRTRONICS, MULTIPLEX
302582 COMPOSITE SERVO HORN - FUTABA, ROBE
303060 GRAPHITE MOTOR GUARD
305002 BALL DIFF. WITH LABYRINTH COVERS™ - (FACTORY KIT)
305040 SCREW FOR EXTERNAL DIFF ADJUSTMENT - SPRING STEEL
305050 DIFF PULLEY 34T WITH LABYRINTH DUST COVERS
305082 DIFF WASHER 17 X 23 X 1 (2)
305102 XRAY MULTI-DIFF
305131 INNER DRIVESHAFT ADAPTER - SPRING STEEL (2)
305150 TIMING BELT PULLEY 34T FOR FRONT ONE-WAY DIFF.
305240 DRIVE SHAFT REPLACEMENT PLASTIC CAP 3 MM (4)
305431 HIGH-PERFORMANCE KEVLAR DRIVE BELT FRONT 3 X 507 MM
305442 HIGH-PERFORMANCE KEVLAR DRIVE BELT REAR 3 X 180 MM
305575 FIXED PULLEY 20T (2)
305784 SPUR GEAR 84T / 48
306131 SET OF BATTERY BACKSTOPS T1FK'05
306200 ALU SERVO MOUNT (2)
306300 ANTENNA MOUNT
306310 ANTENNA TUBE (2)
308035 COMPOSITE PISTONS - ADJUSTABLE + NON-ADJUSTABLE (SET 2+6)
308040 SHOCK ADJ. NUT ALU + O-RING (4)
308080 SHOCKABSORBER MEMBRANES (4)
308090 SHOCK FOAM INSERTS (4)
308380 ADDITIONAL XRAY ULTIMATE RACING SPRINGS (20)
308390 XRAY SELECTED ULTIMATE RACING SPRINGS (24)
309319 UNIVERSAL SET OF PLASTIC SHIMS
309500 SILICONE GREASE 00
309530 SILICONE OIL 30W
901304 HEX SCREW SB M 3 X 4 (10)
901308 HEX SCREW SB M 3 X 8 (10)
901408 HEX SCREW SB M 4 X 8 (10)
902305 HEX SCREW SH M 3 X 5 (10)
902306 HEX SCREW SH M 3 X 6 (10)
902308 HEX SCREW SH M 3 X 8 (10)
902310 HEX SCREW SH M 3 X 10 (10)
902312 HEX SCREW SH M 3 X 12 (10)
930120 CARBIDE BALL 2.4MM (12)
930138 CARBIDE BALL-BEARING AXIAL F3-8 3X8X3.5
930407 BALL-BEARING MR74ZZ 4X7X2.5 (2)
930508 BALL-BEARING MR85ZZ 5X8X2.5 (2)
941015 HIGH-SPEED BALL-BEARING 10X15X4 RUBBER SEALED (2)
960030 NUT M3 (10)
961032 WASHER S 3.2 (10)
963030 CONE WASHER ST 3X8X0.5 (10)
963041 CONE WASHER ST 4X12 (10)
965019 E-CLIP 1.9 (10)
965023 E-CLIP 2.3 (10)
965040 E-CLIP 4 (10)
965050 E-CLIP 5 (10)
966080 CH-CLIP 8 (10)
970050 O-RING 5X1 (10)
970100 O-RING 10 X 1.5 (10)
970121 O-RING 12.1X1.6 (10)
971031 SILICONE O-RING 3.1X1.6 (10)
981210 PIN 2X10 (10)
981212 PIN 2X12 (10)

And off course the pinions.
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Part number 303401 is indicated as the T2 rear swaybar, and includes all 3 sway bar sizes (1.2, 1.4, 1.6).

The T1 rear sway bar was 303400 and included the 2.0mm bar as standard, with the 1mm (303421) and 1.5mm (303422) bars being optional