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Xray T4 18

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Old 07-17-2018, 03:49 AM   -   Wikipost
R/C Tech ForumsThread Wiki: Xray T4 18
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Welcome to the XRAY T4'18 Thread & Wikipost! Here you will find some useful info, tips and tricks as well as setups that are used by several team drivers. This wikipost is a work in progress and should continue to develop over time. Feel free to add anything you feel is useful to the community!

New for 2018:
Similar to 2017, the T4'18 kit comes available in the U.S. with either a Graphite chassis (Part no. XRA300024), or Aluminum Flex chassis (Part no. XRA300024A) along with all of the great features introduced last year. We recommend the Graphite chassis for starting on asphalt, and the Aluminum Flex for starting on carpet. The big changes for 2018 are much lower center of gravity, courtesy of the Ultra Low Profile (ULP) shocks/towers and narrower weight distribution by shifting the motor in towards the center-line of the car. In moving the motor closer to the center, the topdeck and layshaft bulkheads have been re-designed. Also new this year, the motor mount includes more holes which extend further toward the rear of the car to improve traction. With the new shorter shocks, the 2018 will use the same springs as previous T4 models.

What's NEW at T4 2018? Convert your '17 to '18 specs with these parts:

- NEW chassis plate (3 options to chose from, Graphite, Aluminum, Alum. Flex)
- NEW topdeck
- NEW ULP shocks (4mm shorter than 2017)
- NEW ULP shock towers (4mm shorter than 2017)
- NEW Motor mount (1mm narrower than 2017)
- NEW Motor mount plate
- NEW layshaft bulkheads
- NEW 51mm ECS ES driveshafts

301145 T4'18 CHASSIS 2.2MM GRAPHITE
301199 T4'18 UPPER DECK 2.0MM GRAPHITE
302084 ULP SHOCK TOWER FRONT 3.0MM GRAPHITE
303001-O T4'18 ALU LAYSHAFT BULKHEAD RIGHT - ORANGE
303002-O T4'18 ALU MOTOR MOUNT - ORANGE
303003-O T4'18 ALU MOTOR MOUNT PLATE - ORANGE
303085 ULP SHOCK TOWER REAR 3.0MM GRAPHITE
305221 ECS (ES) DRIVE SHAFT 51MM FOR 2MM PIN - HUDY SPRING STEEL(tm) (1)
305334 ECS ES (EXTRA STRONG) DRIVE SHAFT 51MM - HUDY SPRING STEEL(tm) - SET
308043-O ULP ALU SHOCK ADJUSTABLE NUT - ORANGE (2)
308308-O ULP ALU SHOCK ABSORBER-SET - ORANGE (2)
308324 ULP ALU SHOCK BODY (2)
308334 ULP COMPOSITE SHOCK PARTS
308354-O ULP ALU SHOCK CAP-NUT WITH VENT HOLE - ORANGE (2)

Tips & Tricks:

Alex Hagberg's Tech Tip Tuesday articles

How to mount your Protoform LTC-R Body
Setting static camber
How to mount weight on your chassis Part1
How to mount the rear wing on Protoform bodies
Simple troubleshooting guide
How to mount the battery on your chassis
How to glue your front tires for CRC Black carpet with Eric Anderson
Mastering the Sanwa M12S: Utilizing Exponential and RMode
How to mount weight on your chassis Part2
Mastering the Sanwa M12S: Utilizing TH-Hold

ULP Shock:

Building the new ULP Shock w/ Zero Rebound by Dominic Quek

Team driver Tim Wahl posted some very useful build tips for the T4'16 on Facebook as he worked through building a new kit. These tips will still apply on the current model.

1- Carbon Parts
2-Suspension
3-Solid Axle and Differential
4-Bulkheads & Drivetrain
5-Driveshaft (ECS & CVD)
6-Front & Rear Suspension
7-Tweak
8-Anti-Roll Bar
9-Battery Fix (OPTIONAL)
10-Bumper & Body
11-Shocks
12-Steering

Center Brace:
The manual indicates using a 2mm shim under the center brace when attaching to the chassis plate. The gap is actually 3mm, so a 3mm shim should be used here.

Tuning Note:
On Carpet we have found that adding screws or doubling up the graphite brace will make the car react quicker to steering input, & change direction faster. Raising the graphite brace off of the aluminum bulkheads by placing a shim under it on the front and rear holes will reduce response. Using the tie-rod will reduce initial response to input, but will generate more in-corner traction or 'side-bite'. Using no brace will generate even more of this 'side-bite' but all of this is at the expense of corner speed. Best to use the tie-rod or no brace only in low-traction conditions. Additionally, the center brace increases forward traction, so removing it will potentially increase wheel-spin out of low speed corners.

New Graphite Hubs:
Xray have recently released some additional Graphite hubs for the T4 lineup. The 4° Graphite C-Hub has been out for some time and is known to improve steering on entry, and in general makes the car turn better. This has been the go-to c-hub on asphalt for many on the Xray team, though it is not needed on high bite carpet. The Graphite rear hub tends to make the car more stable, especially on corner entry. We are still working on gathering input on the new Graphite steering block, but for the moment feel that it should improve steering response. All Graphite parts are approximately 1g lighter than the Hard or Medium options.

ARS Tuning courtesy of Ed (TryHard):
If you set the ARS up with no shims under either inside or outside ball positions, it actually adds toe-in under compression, at around 1° at 5.2mm ride height (how much it adds depends how much the car compresses, obviously )

Adding shims reduces the amount added (1mm under one of the links gives about 0.5°), until the link has 2mm worth of shims (1mm either side, or 2mm on one side) makes the ARS neutral. Adding more shims then turns it into reducing toe in under compression.

Whilst that might sound a bit backwards, it's actually not quite as simple as it sounds. By having the links to add toe, you gain forward traction. Also consider as the car rolls, the inside wheel is in negative compression, and the outside in compression. So the inside is toe-ing out, and the outside toe-ing in, so the whole rear is then 'steering' in the direction of the turn. Obviously the inside wheel has a lot less influence than the outside as it's far less loaded, but the effect is still there.

Optional & Tuning Parts to consider:

XRA301146 T4'18 ALU CHASSIS 2.0MM - SWISS 7075 T6 **For very high traction** (Approx. 108g)
XRA301147 T4'18 ALU FLEX CHASSIS 2.0MM - SWISS 7075 T6 **For high traction** (Approx. 93g)
XRA301169 T4'18 UPPER DECK 1.6MM GRAPHITE
XRA302254 Composite Steering Block - Graphite
XRA302334 Aluminum C-Hub Block - Caster
0° - Orange **Only for ARS**
XRA302383 Composite C-Hub Right – 4
° - Graphite (ECS) **Not recommended for high traction**
XRA302384 Composite C-Hub Left – 4
° - Graphite (ECS) **Not recommended for high traction**
XRA302711 Brass Front Lower 1-Piece Suspension Holder - Front - FF
XRA302803 1.3mm Front Anti-Roll Bar

XRA303360 Composite Upright 0° Outboard Toe-In - Graphite
XRA303802 1.2mm Rear Anti-Roll Bar

XRA305137 Steel Solid Axle Driveshaft Adapters - HUDY Spring Steel **Highly recommend**
XRA305242 Composite Drive Shaft Replacement Cap 3.5mm – Orange – Strong (QTY 4)

XRA305351 Aluminum Wheel Hub – Offset “-0.75mm” – Black (QTY 2)
XRA305352 Aluminum Wheel Hub - Offset
“+0.75mm” - Black (QTY 2)
XRA306191 T4 Graphite + Aluminum Fully Adjustable Battery Holder
XRA308029 ULP ALU PROGRESSIVE SHOCK SYSTEM - SET (2) **Only for asphalt**
XRA308264 4S Spring-Set Progressive C=2.5-2.8 (QTY 2)

XRA308276 4S Spring-Set C=2.7 (QTY 2)
XRA308286 4S Spring-Set C=2.6 (QTY 2)

Recent Setups:
7-Oct - Alexander Hagberg - IIC - High Traction Carpet - Mod Q2, P2
7-Oct - Craig Xavier - IIC - High Traction Carpet - SuperStock Q5, P5

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Old 10-14-2018, 08:45 PM
  #871  
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Could not buy a 1.3 front bar, so I dremelled the kit 1.4 bar with a stone bit to around 1.32 then sandpaper to 1.30. Took about 5 minutes, not as hard as I thought.
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Old 10-18-2018, 05:32 AM
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Where’s everyone mounting their transponder, pics please. Not much room, I’ve seen some on top of the servo mount bracket
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Old 10-18-2018, 05:49 AM
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Originally Posted by Hundo View Post
Where’s everyone mounting their transponder, pics please. Not much room, I’ve seen some on top of the servo mount bracket
I mount mine on top of the servo.
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Old 10-18-2018, 11:48 AM
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Originally Posted by Hundo View Post
Where’s everyone mounting their transponder, pics please. Not much room, I’ve seen some on top of the servo mount bracket
Been running like this for 2+ years on 2 different cars. I spread some CA glue on the back of the bumper and let it kick before mounting the holder with servo tape - tape sticks better than to raw foam.

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Old 10-18-2018, 12:30 PM
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Thats what I was thinking, as far forward as possible and low. Putting it in the middle that could cost you a position at the line if your side by side.

Thanks



Originally Posted by belewis01 View Post
Been running like this for 2+ years on 2 different cars. I spread some CA glue on the back of the bumper and let it kick before mounting the holder with servo tape - tape sticks better than to raw foam.

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Old 10-18-2018, 09:05 PM
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Originally Posted by Hundo View Post
Where’s everyone mounting their transponder, pics please. Not much room, I’ve seen some on top of the servo mount bracket
I mount mine on the rear of the servo
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Old 10-19-2018, 11:49 AM
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The link didn't work.



Originally Posted by dvaid852456 View Post
This is one of the pages I read that summarised roll centre well:

Understanding and Tuning Roll Centre

Especially usefull was this part:

Rear Roll Center
The lower the rear roll center is, the more off power and low speed corner grip the rear end will have, but the less on power corner exit the car will have (and it will get worse the harder the car is pushed out of the corner). The higher the rear roll center is, the more it will be able to be pushed on corner exit and maintain grip, and the more willing it will be to rotate in low speed corners or any time the rear is unloaded under corner entry or mid corner transition. An extremely high roll center will make for a car that can punch out of any corner extremely hard but will slide around willingly in low speed corners. An extremely low roll center will make for a car that is too hooked up and unwilling to rotate in the infield and very difficult to exit corners with any speed, causing you to wait on the car to get moving or else it will come around on you.

If you are unsure as to which direction you need to go on rear roll center tuning to address an issue, ask yourself this: When I apply throttle, does it get better or worse? Applying throttle will cause more weight to transfer to the back and more chassis roll. If the throttle improved the situation, and more grip was had, you likely needed to lower the roll center to get more roll. If it made it worse, and the additional roll from throttle application broke the car free, it was probably rolled to far to begin with, dictating a higher roll center to prevent the excess roll.

If you have trouble finding a balance on rear roll center, another setting is likely to blame. On a recent track change, I found that I needed to lower my rear roll center for better traction in the infield technical sections, but it hurt my ability to maintain grip at the end of a sweeper's on power exit to a straight away. My rear spring choice was as stiff as I felt I could run, so my solution was to add another limiter to my front shocks to reduce total weight transfer to the rear on acceleration.

In my opinion, if you have to err on the side of high/low in the rear, pick high. This will leave you with a car that doesn't punish you if you drive it too hard out of corners and at worst has a little more rotation at low speed, which can be fast in and of itself. There is nothing I hate more than a car that breaks free in the rear once it feels hooked up and you get on the throttle."


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Old 10-20-2018, 04:45 AM
  #878  
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Originally Posted by outlandr91 View Post
The link didn't work.
That's odd? I just clicked on it and it takes me to here:

http://www.rctech.net/forum/electric-off-road/703926-understanding-tuning-roll-center.html
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Old 10-20-2018, 08:24 AM
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I’ve seen a couple of set up sheets with only 1 screw in the motor mount, is this correct? Just the nut + 1 other screw?

Also diff position ‘Up’ - does this refer to the tab on the eccentric bearing carrier being in the ‘up’ position and therefore the diff being low, or the other way around?

Cheers!
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Old 10-23-2018, 02:10 PM
  #880  
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Default T4 spur gear options

I am looking for a 102 tooth 64p spur. Any other brands work with xrays?
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Old 10-23-2018, 02:23 PM
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Originally Posted by kwb0748 View Post
I am looking for a 102 tooth 64p spur. Any other brands work with xrays?
axon works, I use their gears all them time.
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Old 10-23-2018, 02:24 PM
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Originally Posted by kwb0748 View Post
I am looking for a 102 tooth 64p spur. Any other brands work with xrays?
i really like the ARC spurs.
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