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XRay T4 2019 Review Part 1 - Build and Tips for Mod Racing


The Xray T4 2019 is the latest incarnation of the popular 4wd touring car platform. This T4 is a special car because it’s the car with which Bruno Coelho won the IFMAR 2018 World Championship.

Xray started building touring cars back in 1999, and it’s the first time they won this most coveted title in the R/C industry. Let’s have a closer look at the innovations Xray used to win this title.


BPA or body post adjustment. With this clever design, you can use one body and mount it neutral, 2mm to the front or 2mm to the back. The body position is a very important tuning aid. Before this innovation, you had to use different bodies in order to put them more forward or rearward. Now you can use a single body and adjust it. Beware that you will need to cut the wheel arches as otherwise the wheels might touch the body.

An innovation that comes from the 1/8 scale cars is the new front flex stiffener. This alloy part allows you to make the front stiffer and give the car a more direct steering feeling. According to Xray it’s best to use it in low to medium grip conditions.

In order to make the steering assembly more direct, Xray also included a new steering bellcranck with pressed-in bearings. The 19 car also uses bushings that you can mount into the steering arms to get less slop.

The dampers mounts have been updated as well. The shape remains the same,but they now have two extra holes to accommodate two pins that come out of the bulkhead. This is a neat solution to avoid tweak in case of a collision.
Adding the pins however adds weight, and as the weight is quite high up, Xray wanted to avoid this. That’s why they omitted two camber link holes. By doing so, the weight of the 19 part is lower than that of the 18 car, which is quite positive.


Objective.. Marginal gains = Performance

I didn’t just want to build a car out of the box. We all know the T4 is a great car that will suit a wide range of drivers from club racers to world champions. Out of the box it gives plenty of performance. I wanted to try and build the ultimate T4. By doing so, I sourced some parts that will give more performance, a lower weight and also a cooler look. (If it looks fast, it must be.. right?)

In this article I have built this car for modified racing. In the next part I will show which parts I would chose specifically for stock racing.

Presentation

As always, the Xray kit is well presented. It comes in a cardboard box with a nice colorful sleeve which shows the built car.

All the parts are nicely packaged and the color manual is imho the best in the industry. Xray is also one of the only R/C companies that still manufacture their cars in Europe. This is also a very positive part for me.

Preparation

This is perhaps the most annoying part of it all, as you have to prepare the parts before you can even start to assemble them. If you however take some time to do it, it will be very rewarding as it will make the maintenance afterwards easier.

The manual states that you can apply CA glue to the carbon parts. This will prevent the carbon parts from splitting in case of a crash. You can however make your damper stays and carbon chassis look really smart by following these steps:

Apply some CA glue to the carbon part. I put some glue on a plastic can and then apply it with screwdriver. Let it rest and dry. It’s possible that the part will look horrible, but don’t worry, it’ll get better!

Take 400 grit sandpaper and sand the carbon part so that the bead is even.

Apply glue again and slightly sand with 400 sandpaper again, then 1000 and then 2000.

I also sanded the sides of the damper mount with 1000 sandpaper to get a matte finish. This contrasts with the shiny glue bead. You can polish the glue bead with some automotive polish.

I also used the polish on all the hinge pins and damper shafts. This will make them ultra smooth and you will have a perfect suspension.

Working on the Differential.

Before mounting the bevel gears, I slightly sand the bevel gears with 400 and 1000 sandpaper to make them smooth.

After the underside has been wet-sanded, I put them in a small cleaning container, like this one from PN racing distributed by MARKA.

The lube you use on the diff o-rings is very important. I recently discovered a nice range of products from 1up Racing. Their Blue Grease is great stuff to put on the shock and diff o-rings.

Before filling the diff with silicon oil, I put some Tamiya Ceramic grease on the satellites. I then closed the gear diff and ran it in by hand.

Once finished, I put 6000 Tornado oil in and filled it with 1.4 grams of oil.

For the front spool, I used the Xray Solid axle driveshaft adapters in spring steel (item 305137). This is really a must have if you are doing modified.


Servo preparation

Well, there basically isn’t much you can do about a servo :)

I used a PowerHd Storm 7 servo. We've used this servo for over a year now, and it gives Florian a very connected feel. I used to shorten the servo leads, but that resulted in some DNF’s in the past. The aftermarket connectors I bought weren’t so good as the original ones, and they sometimes jumped out of the receiver.

I therefore apply some black shrink tube to the servo wires and hide them. It’s not so neat, but it works better!

Shock preparation

I've already polished the shock shafts, so I didn’t have any extra work to do on them.

I slightly sanded the pistons with 2000 grit sandpaper to remove any blemishes.

I slightly coat the O-rings in 1up blue grease, which makes them leak and sweat-free.

I also put some Tamiya Fluorine coating fluid on the suspension balls to make them mover more freely inside the plastic cups.

When the piston is mounted on the shaft and the shocks assembled, I put some 1up clear oil on the shock shaft before inserting it in the o-ring. It is also important not to tighten the shock collar as this might damage the o-ring.

Once done, I filled the shocks with Tornado 500 oil and let them rest for a while. 

If you want to know how you can build the perfect shock, have a look at Dominic Queck’s excellent video on Youtube. Dominic is an Xray factory team driver and made great video especially for the super short shocks.

In order to have the shocks at the exact same length, I used these digital calipers that Wouter Ferreiro showed me during the Ifmar Worlds in South Africa. It is a simple trick, but gives you the perfect shock length. (Check the video on our Facebook here)

Drive train

The spur gear is held with 3 steel screws, which weigh in at 1.03 grams.

I replaced them with 3 Hiro Seiko 3 x 5mm screws which only weigh 0.34 grams. It might not seem much, but as it is rotational mass, every weight saving is important.

That is also the reason why I use the composite 20T pulleys (Xray item 305577), as they are 0.26 lighter then the stock parts. Just with those 2 parts I almost shaved 1gram off :).

The diff pulleys sometimes develop some play. That’s why I put some 1up Gold grease inside the pulleys where the axles sit.

I also used the 1Up red oil when mounting the drive shafts. I used to put grease on them, but ever since Jilles Groskamp showed me how he builds his, I limit myself to a very light oil.

Suspension

On a suspension, it is important to limit the unsprung weight. Unsprung mass includes the mass of components such as the wheel axles, wheel bearings, wheel hubs, tires, and a portion of the weight of driveshafts, springs, shock absorbers and suspension links. On our cars, you can’t really shave a lot of weight off. That’s why I decided to use some products that are designed by Avid.

Avid is a USA based company that specializes in real cool lightweight stuff. In the UK, you can buy their products via MB models etc
The stock arm weighs 8.84g. A saving of 1g per arm
Instead of the stock droop screws, I use Avid’s titanium domed droop screws. A set of 4 almost weighs 1 gram less then the stock parts. The Xray graphite parts are also lighter then the plastic parts. The ARS graphite arm is for instance 1 gram lighter than the plastic part.

Avid also makes some rather cool titanium ball studs. I didn’t buy the complete kit, just the outer parts and the ones for the stabilizers. By using these parts, I managed to shave 4 grams off of the un-sprung mass (Roughly 0.5g for each ball stud). The Avid products also come in handy containers, so you can store your original parts in the container and reuse the plastic bag the Avid products came in.

Steering

The previous Xray T4’s were sometimes criticized for having slop in the steering arms. Xray addressed this problem in two ways. First they made a steering bellcranck with an improved design and pressed-in bearings. Secondly they added washers between the two ball bearings in the servo saver arm.

I bought the aluminum dual servo saver arm as it gives you a bit more steering throw.

On the black servo saver holders I put some Bittydesign liquid mask. This will remove the play caused by the ball bearing on the servo saver holder. I then used some small shims to put between the screws and the servo saver arm. You will have to mount and disassemble the steering system to see where you need to put the shims.

This way however you can remove most of the play. To be honest, we had a bit of play on the T4 18 car, but it was never dramatic nor did it have an influence on the performance. In the past I built other cars with much more play in the steering system.

Main chassis

It was like Christmas when I got the T419 alu flex chassis (Xray 301150), because I could start building the rest of the car.

The 19 chassis is the same as the 18 chassis, except for the front section. There are two more holes which will allow you to mount an alu flex bar.

This bar will increase initial steering in low to medium grip conditions. The front opening also seems to be slightly bigger.

First thing you have to do is mount the bulkheads. Even though with modern technology all the machined parts would give a perfect fit, it is always recommended to use some kind of jig to align the bulkheads. You have two options. You can either buy the RC Mission bulkhead jig, or you can use 3 suspension axles.

Just fit them in and slightly tighten the 4 screws on the lower bulkhead. At any time, they should move freely, and almost drop out by themselves. Repeat this procedure for the front and rear bulkheads.

Instead of the aluminum motor mount plate I used the Xray brass one (Xray 303004) as it adds a bit of weight on the right places.

New for the 19 are also the smaller ball bearings (they don’t interfere with the top deck flex anymore) and the neat graphite battery stopper.

I also mounted the front graphite brace to see how it would work. The screws used are steel satin grey Hiro Seiko screws. For the lower chassis I always use steel screws and the Hiro Seiko ones just look a bit better!

The suspension mounts underwent a cosmetically change and now feature rounded corners. Personally I also think that this would give less risk of breakage in a high speed crash.

With the suspension mounts added, it’s now time to mount the suspension arms. I use 0.5mm shims up front instead of the 1mm shims. This gives you a bit more room to fine-tune the wheelbase.

In this picture I mounted the ARS suspension with the optional aluminum c hubs, but I will take them off for the carpet races.

I also cut the front part of the servo mount graphite bar off. We don’t use it and it’s weight that is relatively high placed.

Instead of the 5mm wheel hexes, I used 2 sets of the -0,75 hexes to give the car a sharper feel. It will have faster directional changes with these hexes (Xray 305351).

Suspension with the Avid titanium ball studs.

Xray have a really neat system to mount the stabilizer bars. Instead of using the 1.4 front anti roll bar, I installed the 1.3 one (Xray 302803).

There is also a new front battery stopper that you can adjust to any kind of Lipo pack.

With the main chassis finished, it’s time to mount the top deck.

On carpet, most team drivers run the 1.6 topdeck, so we decided to install it as well (Xray 301169), mounted on 1mm shims.

Before installing the top deck, I quickly put the HiroSeiko motor pinion on as well. I didn’t know Hiro Seiko made pinions, but theirs are hard anodized, so we had to give it at try as well.

When Florian started racing, we opted to use Hobbywing electronics. Hobbywing not only makes great motors and speedo’s, but they also have the easiest and more intuitive app to program the esc. You can virtually change all the different parameters in super small increments. The best thing about it, is that you can actually feel the difference, so the software is really top notch. In a future article, we will make an in-depth review of the Hobbywing ESC and Wifi module.

The Hobbywing XR10 pro comes with a really beautiful fan protection. It sits however quite high, so I decided to take it off, together with two steel screws. This saved me 1.85 grams.

As a servo horn, I choose the PowerHD one. It is specifically designed for the Storm 7 and has 2 fixing screws to fix it to the servo.

By now, you probably know I’m quite biased to keep the weight of the car as low as possible. That’s the reason why I decided to buy some brass weights of 7075.it, an Italian company which makes some really neat stuff. One of their great products is the servo mount insert. This part weighs 8.5 grams and sits quite low. I gave it a quick polish to make it look even better.

Also from 7075.it is the brass battery mounting system. It features an aluminum angle coupled to a brass weight. This weight not only allows you to use shorter battery tape, but also to move your battery forwards or backwards to give more steering or more traction. It’s a really clever design.

So, with the build of the car done, here are my first thoughts.

It is true that the car is not cheap and that there are many options for it. You don’t need to buy all of them however. I think that the parts mentioned in the article are the main ones for mod racing. I hope to finish the stock car soon and make a small article on those specific parts.

For the price however, you get a great racing car. It truly is a pleasure to build. All the parts fit perfectly and the quality of the aluminum and other components is top notch. Xray also manages to improve the T4 year after year.

It is true that other car manufacturers have more innovative designs, but the T4 remains one of the class leaders, supported by its success after winning the Worlds.

In a next article, we’ll give you the first race report, the need-to-have stock options and setup sheets, so stay tuned!

Special thanks to:
#Teamxray
#Rcconnect
#Hobbywing
#PowerHD
#GensAce
#Avid
#HiroSeiko
#7075it
#1upRacing
#TornadoOil
#RacingArenaLimburg
Xray 4855975917953182511

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