XRAY - Model racing cars

How do I break in my differential?

When you rebuild your diff, even if you use the same diff rings and diff balls, or start using a new diff it is best if you take the time to run it in before tightening it beyond a loose setting. A well run in diff will last many weeks racing without needing a rebuild. Moreover it will run smoother throughout that period. In fact if well broken in the XRay diffs will feel smoother than some of the one-ways on other cars...

So how do you break in a diff?

Well the trick is to run the diff very loose the first time you run it. If your first run is during a qualifier then try and aim for the loosest possible setting where the diff does not slip ON THE TRACK. The latter is in bold because a diff that is set so that you can still push through it a bit manually will usually not slip or only slip the first two laps on the track!

If you have the luxury of running in the diff during practice you may want to run the diff slightly more loose still so it slips slightly throughout the run. Don't overdrive the car.

Ideally for the second and third run you only tighten the diff a little bit compared to the previous run to allow the diff to get fully seated in. After that you can tighten it further to medium or even tight settings if necessary.

What tips are recommended for building new shocks?

Here are a few tips, some of which are reminders of what is already included in the FK05 instruction manual:

Composite parts preparation:

• Use a hobby knife or small wire cutters to remove the composite parts from the nylon frame. This will prevent small chunks of material from being removed if you twist the pieces off of the frame.
• Carefully use a hobby knife (at a perpendicular angle) or a fine file to gently scrape off the excess composite material that connected the composite parts to the nylon frame. This is a critical step for the shock pistons and they must be smooth and properly rounded on the sides. Too much extra material remaining will not let the piston slide through the body free. Too much material being removed will allow the shock oil to flow through the new crevice and change the dampening characteristics of the piston.

Lower shock ball joint installation:

1. Install a metal ball into the lower shock ball joint before you pre-thread or mount it. This will allow you to use pliers to grip the lower ball joint and screw it on without having fingers like the Hulk.
2. Pre-thread the lower shock ball joint using an M3x8 button head screw. Once you have the button head screw threaded in straight for a few turns, use your left hand to hold the ball joint with pliers clamped onto the metal ball and your right hand to tighten the screw in with a hex wrench. As you tighten the screw into the ball joint, be careful to leave approximately 1 to 2 millimeters of thread showing between the button head and the ball joint. You should be able to feel the screw getting harder to tighten as it pushes against the bottom of the hole in the ball joint. DO NOT over tighten or you will strip the inside of the ball joint.
3. Use a small pair of wire cutters to clamp onto the shock rod in the first groove just below where the top of the thread starts, while you tighten the lower shock ball joint onto the rod. Make sure the flat side of the wire cutters is facing towards the bottom end of the rod where the rest of the threads are (as seen in the manual). This will allow you to tighten the ball joint all the way against the flat side of the wire cutters which will leave the ball joint approximately 1 millimeter below the start of the threads on the rod.
4. Use a pair of vice grips to clamp onto the end of the wire cutters and provide more force to keep the rod from turning and slipping free from the wire cutters grasp. This will also alleviate the need for you to hold the wire cutters in place with your hand (ala Hulk ) and further prevent slipping.
5. While holding the rod with the wire cutters and vice grips, screw the ball joint on a few turns until there is too much resistance to screw it on with a light hold from your fingers. Then use the pliers to clamp onto the metal ball inside the ball joint and tighten the ball joint all the way until it is tightly pressed against the flat side of the wire cutters.
6. Remove the vice grips and wire cutters. You may have to use your hobby knife to remove a little bit of composite material on the top side of the ball joint near the rod, where it has been lightly shaved off of the inside lip by the wire cutters. This is normal since the pressure of the rod being threaded into the ball joint flares the composite material up and out at the top. It is critical that you remove these shavings so they do not change the height of the lower spring retaining collar as it sits on top of the lower ball joint.

Shock filling and bleeding:

• You can use procedures #3 through #14 in the of this thread.

How do I prevent and fix stripped screws in the chassis?

Preventative measures:

• Use Hudy wrenches or wrench tips. They are much more durable and resistant to rounding of the hex edges on the tip.
• Use a Q-tip to apply a thin layer of CA glue into all counter sunk screw holes in the chassis and top deck where they are mounted to the bulkheads or standoffs. This helps the screws to grip the carbon fibre plates better with less applied torque, and subsequently allows them to be unscrewed without as much force. Make sure you wipe away any excess glue from the top and bottom planes of the chassis or top deck around the counter sunk holes and let the CA dry well.
• Patience is certainly a virtue here. Take your time to apply controlled pressure at a perfect 90 degree angle while breaking the seal of the screws free initially. If your wrench handles are not thick and easy to grip, you may want to use vice grips to clamp onto the allen wrench handle in order to provide more torque in the same manner that a four way tire iron wrench is used.
• Before tightening down the chassis or top deck screws, check the condition of each screws head by holding it with one hand, inserting the wrench tip fully and twisting the wrench to look for play. If the tip rotates free inside the hole more than a quarter of a millimeter, then you should replace that screw with a new one.
• Team drivers use the black coated screws (Part# 309322) which are more resistant to a hard to break seal with the carbon fibre

http://www.teamxray.com/teamxray/produc ... kategoria=

Removing stripped screws:

• If you can remove all of the other screws that hold the bulkhead on, twist the bulkhead in a counter clockwise rotation around the stuck screw to loosen the tension. This normally will loosen the stripped screw enough to remove it with the 2mm allen wrench cocked to the side. If the head is stripped too much to use the allen wrench, you can also use a small flat head screw driver that is slightly wider than the stripped hole by lightly tapping it into the stripped head with a small hammer.
• Use a thin dremel cutting wheel to cut a slot in the stripped head and use a flat head screwdriver to unscrew it.
• Use a drill set to a slow speed with a metal cutting bit slightly larger than the diameter of the screw threads. Drill into the stripped hex hole until you have completely cut out the center of the coned head. The outside perimeter of the head should fall off. Remove the chassis plate or top deck from the bulkhead or standoff and use pliers to grip the remaining shaft of the screw that is hanging out and twist it off.
• Place a drop of CA and your wrench tip into the stripped head and let it dry well. Then use vice grip pliers to securely hold the wrench handle and apply more controlled torque while twisting the screw out
• Use a small screw "drill out extractor" kit with a reversible slow speed drill. Drill the screw head out slightly with the drill tap bit and then use the reverse threaded removal bit to back the screw out.
• For button head screws (very uncommon) use a dremel cutting wheel to completely cut off the head of the screw and remove the shaft with pliers.

Why do you put shims underneath the outer steering rod ends where they are mounted to the steering blocks?

Shims are used to get rid of the undesirable handling effect called "Bump Steer". This effect happens when a cars front toe changes, as its suspension compresses or rebounds, from the position that was pre-set using a setup station. The change can cause the front wheels to either increase or decrease in toe. To eliminate bump steer, it is necessary to change the angle of the steering rods using shims in between the outer steering rod ends and the steering blocks.

Here is a simple process to figure out if a car has bump steer and how to minimize or eliminate it:

1. Make sure the car is fully setup, has been de-tweaked, aligned and is race ready. Only the tires, body and clips should be removed.
2. Set up the car on a setup station
3. Press down and quickly release the front shock tower to get the suspension to settle
4. Use the setup stations toe gauge to check the front toe while the suspension is at rest and reset it to the desirable amount of front toe
5. Press down on the front shock tower until the front of the chassis is approximately 1 to 2 millimeter's above the surface and use the setup stations toe gauge to see if the front toe has changed
6. If the front toe has changed, then add or remove shims underneath the outer steering rod end in 1 millimeter increments
7. Repeat steps 5 and 6 until the front toe is the same with the suspension at rest or compressed. A barely noticeable change is acceptable, but you may need to use .5 millimeter increments to completely eliminate it.

Note: Bump steer is a suspension tuning option commonly used in off-road RC racing to change steering characteristics over rough and loose terrain. However, it is recommended to eliminate bump steer in touring car suspensions.

Why are my T1's left and right rear toe readings uneven?

It is extremely important to first examine and confirm that the setup station used to measure the rear toe is accurate and properly functioning. Check for binding chassis support block bearings, a warped setup board, or pieces of debris/glue in the clear gauge slot that the chassis support block bearings slide along in. The clear gauge should be able to slide freely to each side until the bearing is fully seated in the end of the slot.

Other than an inaccurate setup station or worn/bent/broken parts, there are two reasons for a small uneven toe reading. First, plastic suspension holders and/or rear hubs have manufacturing tolerances which allow for minute dimension differences. Secondly, when torque is applied to these plastic parts from the various mounting screws they also deform slightly. Even though the tolerances and torque deformities may allow for differences within the tenth of a millimeter range, the end result of all the parts involved may be a noticeable difference in toe angles between the two sides. This difference is commonly found and corrected by team drivers by changing the total width of the shims in between the bulkheads and suspension holders of each side as necessary. However, the difference between the left and right toe angles should never be more than one degree.

In order to correct the small amount of rear toe difference without increasing the possibility of more differentiation inherent with the use of plastic parts, Xray now offers NEW aluminum shims. In order to minimize the left and rear toe angle differences, we recommend using aluminum rear hubs, aluminum shims to equalize the left and right toe angles and the high quality Hudy All-In-One Set-up Solution.

• Aluminum Rear Uprights

0 deg http://www.teamxray.com/teamxray/produc ... goria=1297
1 deg http://www.teamxray.com/teamxray/produc ... goria=1297
2 deg http://www.teamxray.com/teamxray/produc ... goria=1297

• Aluminum Shim Sets

0.5, 1.5, 2.5mm http://www.teamxray.com/teamxray/produc ... goria=1297
1.0, 2.0, 3.0mm http://www.teamxray.com/teamxray/produc ... goria=1297

• Hudy All-In-One Set-up Solution for 1/10 Touring Cars

http://www.hudy.net/xhudy/products/prod ... tegoria=64

What is the correct way to implement anti-dive and anti-squat?

This has been a topic of discussion lately in the RC industry. Some view anti-dive as the rear part of the arm being mounted lower, as is in the Hudy Setup book, and others view anti-dive as the front part of the arm being mounted lower. The meaning of the term anti-dive is sometimes misunderstood. This may be due to the resemblance of wording with the term "anti-squat", which angles the rear arms backwards in the same manner as you would for front "kickup". In fact, when looking at a car from the side, the angle for anti-dive is actually opposite of anti-squat as it limits compression in the front end under deceleration, and not acceleration.

Here are a few definitions from scale automotive sites that clarify the meaning of "anti-dive":







"anti", means to partially or fully prevent or restrict, and "dive" means to move or plunge downward together. When put together, they simply mean to prevent something from moving downward. In a vehicles case, anti-dive is a suspension tuning option that prevents the front suspension of a car from compressing under deceleration.

In the automotive industry, anti-dive is used as a tuning aid primarily when vehicles need to run a soft front spring rate and they have a tendency to dive downward too much in the front under braking. In order to prevent 100% of the cars weight transfer force from being exerted onto the softer springs anti-dive is used to allow a certain percentage of the weight transfer to be absorbed by the front lower arms motion. This is accomplished by angling the front arms to where the rear hinge of the arm is higher than the front hinge when looking at the arm from the side of the car.

Anti-squat is used as a tuning aid primarily when vehicles need to run a soft rear spring rate and they have a tendency for the rear end to squat down too much under acceleration. In order to prevent 100% of the cars weight transfer force from being exerted onto the softer springs anti-squat is used to allow a certain percentage of the weight transfer to be absorbed by the rear lower arms motion. This is accomplished by angling the rear arms to where the rear hinge of the arm is lower than the front hinge when looking at the arm from the side of the car.

The anti-dive section on page 46 of the Hudy Setup Book actually reflects how to implement front "kickup" or "pro-dive". It will be revised to reflect the correct information for anti-dive.

Here are the effects:

1. Anti-dive - the FRONT arms are angled DOWNWARD from the center forward with the rear suspension holder mounted higher than the front suspension holder:

• The front suspension will resist compressing on corner entry. Off power steering and front end grip is reduced by transferring less weight forward on corner entry.
• The front suspension will take longer to reach its maximum roll point allowed by the springs in the corner. Mid corner steering and front end grip is reduced until the throttle is applied.
• The front suspension will promote compressing on corner exit. On power steering and front end grip is increased immediately after the throttle is applied by transferring less weight rearward on corner exit
• Usually reduces the ability for the front suspension to handle large or successive bumps. But this can be countered by using softer front springs.
• Works well for cars with a forward weight bias like the FK05 when grip is medium to high

2. Pro-dive or "front kickup" - the FRONT arms are angled UPWARD from the center forward with the front suspension holder mounted higher than the rear suspension holder:

• Off power steering and front end grip is increased on corner entry by transferring more weight forward on corner entry
• Mid corner steering and front end grip is increased until the throttle is applied
• On-power steering and front end grip is reduced on corner exit, immediately after the throttle is applied, by transferring more weight rearward on corner exit
• Increases the ability for the front suspension to handle large or successive bumps

3. Anti-squat - the REAR arms are angled DOWNWARD from the center rearward with the front suspension holder mounted higher than the rear suspension holder:

• The rear suspension will resist lifting up on corner entry. Off power steering is reduced by trasferring less weight forward and increasing rear end grip on corner entry.
• The rear suspension will reach its maximum roll point quicker. Mid corner steering is reduced until the throttle is applied.
• The rear suspension will want to lift up on corner exit. On power steering is increased immediately after the throttle is applied by trasferring less weight rearward and reducing rear end grip on corner exit.
• Increases the ability for the rear suspension to handle large or successive bumps

4. Pro-squat or "rear kickup" - the REAR arms are angled UPWARD from the center rearward with the front suspension holder mounted lower than the rear suspension holder:

• Off power steering is increased significantly by transferring more weight forward and reducing rear end grip on corner entry
• Mid corner steering is increased by reducing rear end grip until the throttle is applied
• On power steering is reduced immediately after the throttle is applied by transferring more weight rearward and increasing rear end grip on corner exit
• Decreases the ability for the rear suspension to handle large or successive bumps
• Works well for rubbers on low grip smooth asphalt

All of these options make the cars steering more responsive to throttle changes in the corner. Keep in mind that if your rear ride height is higher than the front, then your arms are already tilted in relation to the track surface which gives you a small affect similar to anti-dive and pro-squat on corner entry only. The more rear droop you have, the more the effect. But since the rear springs are usually softer and compress more under acceleration, there is no mid corner or on power affect that you would have with actual anti-dive and pro-squat.

What do I need to know about using foam tires?

General tips:

• Make sure you rotate the front and rear pair from side to side after one or at the most two runs on the track. This will allow them to wear evenly throughout their life as most tracks cause one side to wear more than the other. Uneven wear is common since most tracks have either a high speed sweeper or more turns in one direction.
• Use a micrometer to measure the diameter of your tires before and after each run. Taking measurements will help you to make sure that any handling problems are not caused by unequal tire diameters. Taking measurements of the inside and outside edges of each tire after a run will also help you to diagnose setup problems, such as improper or unequal camber or camber gain settings.
• Mark each tire with its original position (LF, RF, LR & RR) on the car with a permanent marker. Include its compound if there is more than one compound being used at any given time and they are not already marked. This will help you to keep track of what is happening with each tire concerning the tips below and also minimize mounting the wrong compound on the front or rear.

Tire truing/sizing tips:

• Use a tire truer to trim all new sets of four tires down to 60mm to start with and use them for practice only, if you can, until the smallest one of the set reaches 58mm
• Then lightly skim the other three tires down with the tire truer until they are all exactly 58mm and use them for qualifiers until the smallest one reaches 56mm
• Then even them out again with the truer and use them for main races only, until they reach the ROAR minimum diameter of 55mm or even smaller if your local club rules allow it

Note: If your setup causes your rear tires to wear faster than the front tires, then add .2mm to .5mm of diameter to the rear tires when truing them down. This will make sure that they do not wear down to a smaller diameter during a race and cause the rear end to abruptly lose traction. Even diameters on all four tires throughout an entire run is the goal, but larger rear tires are always better than smaller ones.

Preventative tips for chunking:

Aside from hitting things, your tires will chunk more often if there is not enough negative camber in the middle of the turns at full chassis roll to keep them from riding on their outer edges. This happens more often on the rear tires than on the front.

• Check the diameters of the inner and outer edges of each tire after each run. Pay particular attention to the side of the car that wears the tires down the fastest as this side will shoulder the greatest amount of cornering forces for any given track. Treat both front and rear tire pairs separately, even if they are the same compound. If either tires outer edges within a front or rear pair have a smaller diameter than their inner edges, then increase the static camber in .5 degree increments, rotate the tires from left to right and track test them again. Keep increasing the static camber until the tires wear evenly flat on the front and one or both of the rear tires wear just a little bit more on their inside edges (no more than 0.1mm after two or more runs). If you follow these steps and reach 3 degree's of negative camber on a set and one or both of them are still wearing the outside edge, then you need to increase the amount of negative camber gain (explained as "camber rise" or "camber intake" found on page 19 of the ) on the outside wheel as the suspension compresses during cornering. This is accomplished through shortening the camber links by moving the inner pivot point out one hole on the shock tower. If you are already using the outer holes on the shock tower, then you can use shims underneath the outer pivot points to raise them up so that the camber link rods slant downward from the outside in towards the center of the car. Slanting the camber rods also increases negative camber gain. However, increasing the slant angle of the camber links will raise the roll center at that end of the car as well.
• Place a semi-thick coat of CA glue on the entire outer sidewall of the tire, from the edge of the rim to the top of the sidewall and let it dry sufficiently (20 to 30 minutes). You can speed up the drying process by wrapping the outer/bottom surface of the tire with a paper towel, and spraying instant cure onto the wet CA glue. Wrapping the surface keeps the instant cure spray off the tires contact patch and possibly minimizing grip. Mount the tire on a tire truer and use a file or sandpaper to round off the inner and outer edges of each tire and remove approximately 1mm of the CA glue from the top edge of the outer sidewall. This will allow the outer sidewall of the tire to flex some while cornering and keep the CA from cracking. You will need to round off the edges every two to three runs as well.

If anyone has more information to add, please PM me and I'll add it accordingly. Thanks!

2.0mm chassis for asphalt and low grip

<img src=http://www.teamxray.com/teamxray/show.php?img_id=14941&crt=2419822e9c0e9b994a1cc4b66f6c7eab>

XRAY T1FK'05 Rubber Set-up sheet for Carpet

This article is a have to read for all T1FK'05 owners running with rubber tires on carpet.

Should I cut every other tooth on the belts or the pulleys?

No.

While some believe the drive-train will be even more free than it already is, testing has shown there is no noticeable advantage. In fact doing this will make your belts wear much quicker and often leads to the belts skipping. To counter the skipping effect you could run the belt tighter but this will increase the drag instead of decreasing it.

The best way to reduce friction in the drive-train is to run the belts as loose as possible without them skipping. It is also possible to make the belts more flexible by rubbing them lightly in WD40 or soaking them in WD40 for a couple of minutes. This will also lead to more wear on the belts, but they can still be run loose without them skipping.