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R/C Tech Forums Thread 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 high traction**
XRA301147 T4'18 ALU FLEX CHASSIS 2.0MM - SWISS 7075 T6 **For very high traction**
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 12-06-2017, 04:09 AM   #451
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Originally Posted by R Dodge View Post
No issues with the o-rings. Thinner oil just seemed to generate more traction. It also worked for those of us using '17 shocks, we went from 450 to 400 after he went from 350 to 300 and went faster.
Yup, I thought it was crazy too, but his car was good and as mentioned above, lighter oil worked well on '17 shocks as well. Traction was not very high and temps were not high either, so maybe that's why.

On black carpet this past weekend I found that I liked 550 front oil and 450 rear oil in ULP. Traction was high (higher than Indoor Champs) and the car was a bit tippy so I may tweak that some more. Another guy with an '18 tried 600 front oil and really liked it, but he was also running more front glue than I was.

We were running Gravity Type C at 180 Raceway getting ready for Stock Wars this coming weekend. Here is video of the main; I have the white car starting P2

https://www.youtube.com/watch?v=HIwGHB2jGBc&app=desktop
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Been running the ULP shocks here on low-medium grip asphalt out here in Australia (it's summer time).

In mod, combined with the PSS inserts, 450 seems on the money. With the SLP's, I would tend to run 550 everywhere, so the lighter oil in the ULP's seems to be about right. I think in part it's down to the PSS inserts being a little more aggressive in the damping rate increase, as they are shorter. I have noticed that the new PSS also seems to prefer less droop than the old SLP/PSS combo... 5.6/4.6 is my new go to instead of 5.2/4.2. Running more, and the car just locks up in the turns.

For the Stock car, with standard shocks, 400 has seemed pretty good, but in cooler times, can deff see 350 working well.

Our tracks aren't super smooth, but so far have been just as fast with the ULP than the SLP. One thing I have noticed with the ULPs is that they seem to give the car more mid-corner rotation. Haven't yet figured out why this is yet though.
Were these thinning of the oils combined with using softer springs, or were the springs kept the same whilst using the thinner oil?
I assume you at least started with 2.5-2.8 etc?
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Old 12-06-2017, 04:19 AM   #452
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Were these thinning of the oils combined with using softer springs, or were the springs kept the same whilst using the thinner oil?
I assume you at least started with 2.5-2.8 etc?
Johnee, the guy that ran 300 in his ULP had Axon 2.55 front and 2.65 rear. I ran Xray 2.6 front and rear on my SLP w/ 400. I think we all tried every spring combination possible over that weekend. Including 2.5 front and 2.9 rear
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Old 12-06-2017, 06:29 AM   #453
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Were those the springs you would both have used/tested, even before going soft on oils?

Will be running Volante tyres on ETS carpet this weekend. SO I might rebuild my ULP's with 300-350 to start with
Usually run 2.5-2.8 with 2.6 springs etc. But no idea on what traction will be like as we haven't run Volante's there before.
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Old 12-06-2017, 07:22 AM   #454
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Dear cognoscienti

Can someone please explain in layman's terms why are SLP's presumably better on bumpy tracks, whereas ULP are better when grip is high and surface is smooth?

It isn't because the ULP's pistons would "bottom out" on the bumps, or is it?

Thank you,
Paul
(T4 '17 for med-grip club racing, and currently no intention to go to '18, unless convinced otherwise)
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Old 12-06-2017, 09:31 AM   #455
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Johnee, the guy that ran 300 in his ULP had Axon 2.55 front and 2.65 rear. I ran Xray 2.6 front and rear on my SLP w/ 400. I think we all tried every spring combination possible over that weekend. Including 2.5 front and 2.9 rear
Sounds like max was involved!
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Old 12-06-2017, 09:33 AM   #456
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Dear cognoscienti

Can someone please explain in layman's terms why are SLP's presumably better on bumpy tracks, whereas ULP are better when grip is high and surface is smooth?

It isn't because the ULP's pistons would "bottom out" on the bumps, or is it?

Thank you,
Paul
(T4 '17 for med-grip club racing, and currently no intention to go to '18, unless convinced otherwise)
In the most basic way I can try and explain it-all has more fluid, and larger volume, thus making them more consistsnt throughout compression and rebound. Ulp is smaller in size and volume and can be more effected by changes and bumps, vs. slp shocks with the larger volume of fluid.
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Old 12-06-2017, 11:39 AM   #457
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Were those the springs you would both have used/tested, even before going soft on oils?

Will be running Volante tyres on ETS carpet this weekend. SO I might rebuild my ULP's with 300-350 to start with
Usually run 2.5-2.8 with 2.6 springs etc. But no idea on what traction will be like as we haven't run Volante's there before.
I have no real idea what the grip level is like on ETS carpet, nor do I have any experience with Volante tires. I don't think I can really be any help here. Your guess would be better than mine.

Best I can tell, grip at ETS is lower than what we see in the U.S. I think you can probably run thicker oil than that and be okay, and I would think those springs are fine. Jan and the team ran 450 oil instead of 400 here at IIC for more stability. But they also ran 1.6mm topdecks. IIC is usually not super high traction, so maybe that is comparable to ETS, I don't know.

Quote:
Originally Posted by Boostinswifty38 View Post
Sounds like max was involved!
Maybe
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Old 12-06-2017, 06:52 PM   #458
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Originally Posted by Skiddins View Post
Were these thinning of the oils combined with using softer springs, or were the springs kept the same whilst using the thinner oil?
I assume you at least started with 2.5-2.8 etc?
Usual... 2.5-2.8 Front, and 2.6 or 2.5-2.8 rear.
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Old 12-07-2017, 02:15 AM   #459
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In the most basic way I can try and explain it-all has more fluid, and larger volume, thus making them more consistsnt throughout compression and rebound. Ulp is smaller in size and volume and can be more effected by changes and bumps, vs. slp shocks with the larger volume of fluid.
Thanks, I'm still struggling though... the wheel travels 5 or 6mm max when runinng normally (unless you hit a dot on just one side, even when rolling, the wheel doesn't travel that far ) meaning the piston moves, say, 3 to 4mm max in the shock body... what do the oil volumes linked to the other 8mm (mostly) above and (a little) below that have to do with performance when running?

Not trying to be a smarta$$, but just to understand! and if layman's terms explanation isn't enough, feel free to go to proper technical language

thanks!
Paul
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Old 12-07-2017, 07:58 AM   #460
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For 25.5 VTA are guys running the same setups as 17.5TC?
Would love a good VTA setup for this weekend, Black CRC carpet
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Old 12-07-2017, 09:09 AM   #461
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Originally Posted by Lonestar View Post
Thanks, I'm still struggling though... the wheel travels 5 or 6mm max when runinng normally (unless you hit a dot on just one side, even when rolling, the wheel doesn't travel that far ) meaning the piston moves, say, 3 to 4mm max in the shock body... what do the oil volumes linked to the other 8mm (mostly) above and (a little) below that have to do with performance when running?

Not trying to be a smarta$$, but just to understand! and if layman's terms explanation isn't enough, feel free to go to proper technical language

thanks!
Paul
I don’t think it’s actually an issue with piston position or oil that has some concerned with running the ULP shocks on bumpier tracks. I believe it’s basicallly all about droop and ride height. When running higher setups 5.5-6mm rh and wanting to stilll get 3mm or more over ride height of droop, the shocks physically aren’t long enough.

I personally think the SLP shocks would be better in those situations, they’d probably be better in low bite situations as well, where you are trying to get the car to roll more.

Ethan
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Old 12-07-2017, 09:46 AM   #462
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Originally Posted by Lonestar View Post
Thanks, I'm still struggling though... the wheel travels 5 or 6mm max when runinng normally (unless you hit a dot on just one side, even when rolling, the wheel doesn't travel that far ) meaning the piston moves, say, 3 to 4mm max in the shock body... what do the oil volumes linked to the other 8mm (mostly) above and (a little) below that have to do with performance when running?

Not trying to be a smarta$$, but just to understand! and if layman's terms explanation isn't enough, feel free to go to proper technical language

thanks!
Paul
Paul, 2 things to note on the ULPs:

1. The design is so that the piston does get up in the bladder. This is partly because the shock body is probably 1mm too short. This creates a bit of extra rebound that is not always great on bumpy surfaces. I do feel they make the car roll more, surprisingly and ran them on my Gizmo at the asphalt nats in 17.5. I kind of wished that I had in mod too. As others noted, they feel like the car rotates more with them, I think this could be part of the reason.

2.The lower volume of the shocks does affect the damping characteristic of the shock. There is simply more turbulence inside the chamber and this can cause the shock to pack up more. I think of a smaller capacity shock as one that has more reactiveness to it, whereas a higher volume shock usually gives a more plush, lower oscillation feeling. I think that volume can be used as a tuning aid. Perhaps on smooth surfaces or subfloor tracks where bite is higher there can be an advantageous use to these "faster reacting" shocks.
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Old 12-07-2017, 09:47 AM   #463
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I don’t think it’s actually an issue with piston position or oil that has some concerned with running the ULP shocks on bumpier tracks. I believe it’s basicallly all about droop and ride height. When running higher setups 5.5-6mm rh and wanting to stilll get 3mm or more over ride height of droop, the shocks physically aren’t long enough.

I personally think the SLP shocks would be better in those situations, they’d probably be better in low bite situations as well, where you are trying to get the car to roll more.

Ethan
You can always unscrew the lower eyelet to get a little more length on the shock to get extra droop.
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Old 12-07-2017, 03:39 PM   #464
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They explained it better than I. I woulda gone all technical.
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Old 12-07-2017, 04:38 PM   #465
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Originally Posted by Adamska27 View Post
For 25.5 VTA are guys running the same setups as 17.5TC?
Would love a good VTA setup for this weekend, Black CRC carpet
+1. I'm gonna start with kit setup.
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