Xpresso K1 K-Chassis Build Guide

Xpress Xpresso-K1 Build Guide Written by : KK Chung @ 2016.09.01 (Translated by Xpress)Source: http://www.rc-magazine.com/bbs/forum.php?mod=viewthread&tid=320

After a long break, Xpress is coming back swinging! To kick things off we are releasing a never before seen K-Chassis fun car! The Xpresso K1 takes the form of a K-Chassis which is smaller than the M-Chassis! The chassis layout bears resemblence to modern day RWD Drift cars and also balances the center of gravity towards the center. Even though this is a fun-car, the materials and designs used in the making of this car has taken no shortcuts and rivals the quality seen on 1/10 normal sized competition grade touring cars with aluminum bulkheads and carbon fibre bottom and topdecks!

The most outstanding feature is the carbon fibre suspension arms which uses a pivotball mounting system which fits without a problem! The transmission takes on the tradition tried and proven pulley and belt system with a full sized Touring Car Gear Differential which can also be built as a solid axle for easy drifting through the use of the locker! The front steering geometry can be easily changed

Upon opening the box, you will see everything is neatly organized into different plastic bags. The lugs found on the aluminum bulkheads fit snugly into the bottom deck and allows for a straight mounting without much work.

Full aluminum bulkheads machined through high precision CNC process.

Belt tension can be fine adjusted through the tension adjusters.

Full Carbon Fiber Bottom Deck, Top Decks, Shock towers and Suspension Arms.

You will see the chassis plate is about the size of your palm.

Space used efficiently to mount all items to bottomdeck.

One piece motor mount and rear bulkhead keeps the rear flex to a minimum and allows for more on-power grip.

The kit comes pre-packaged with gear and shock oil.

S3M189 rear belt which is a common size in the 1/10 Touring Car World.

The shocks uses the industry standard of o-ring sealed cartridge with plastic shock bodies.

Oversized O-Rings used in the gear differential which will keep it sealed and prevent leaks.

Gear Differential Bevel Gears and Lockers in one mold for easy locating.

Body post extenders are included in the kit for a wider range of usable bodies.

Drift and Racing Ackermann holes come standard in the kit.

Plastic front and rear suspension knuckles, there should be aluminum upgrades in the future.

Suspension pivot holders, secured by E-Rings for secure mounting and easy suspension changes.

Kit comes with both servo saver and servo horns.

Ball-ends come with open ends for easy maintenance without the need of snapping ball-ends off.

Aluminum 12mm hex adaptors.

Kit comes with universals with no slop whatsoever.

好！開完箱便開始組裝啦！因為我沒有說明書，所以會以我「自己方法」經驗+設計風格去判斷安裝這車行為。因此不一定和正式說明書所作法相同，而我安裝次序也會按我經驗去組裝。一開始我會先安裝差速器！說說如果 XRay 差速器有 100分，這 Xpresso K1 的差速器我會比 80分。這 K1 差速器可以完全不用後期加工，便可組合出不錯流暢的效果。而且皮帶齒輪轉動時也沒有明顯搖晃及內齒虛位控制也算OK。而 K1 原裝差速器的鋁合金差速柸是用細直徑球頭，如果打算用來代替 XRay 差速需要同時更換差速柸。

Apply Grease to the gear differential outdrives.

Apply grease to o-rings as well.

Small amount of grease applied to gasket as well.

Sand the gear diff gears to ensure a flat surface and a smooth gear differential.

Make sure all burring is sanded down in plastic parts.

Add gear differential oil up to the center of the gears only.

Pay attention to match the locking knob of the differential casing.

Tighten the gear differential lightly and do not over tighten.

Clean molding marks on the suspension holders to ensure perfect suspension movement.

Add some light grease to the balls but do not add too much as it may attract too much dirt to the suspension components.

Install the suspension balls before screwing onto chassis for easier mounting.

Pay attention to the suspension balls used and the top and bottom orientation of the suspension arms, the e-rings can be installed at this point also.

A tip if you want stiffer suspension arms: sand the edges of the arms and apply a thicker and slow drying CA glue to the sides and let it sink in.

The droop screw is screwed in from the bottom.

Note that the rear suspension mounts require spacers underneath.

A tip for installing the arms: when installing flat head screws, the screws may have some fine play which might lead to un-even install of the mounts. To avoid this, apply some force from the top with your hand whilst installing the suspension mounts to the chassis will allow for a more precise build of the suspension mounts. xpresso k1

Having a flat surface whilst installing the suspension mounts and arms will make things easier. If the arms cannot move freely (Lift them up and they should drop down freely) then re adjust the suspension mounts on each side. Removing the bulkheads will make this process easier as well.

As usual, make sure to remove all molding marks from plastic parts to ensure a smooth drivetrain.

Note the orientation of the bearing holders with the bulkheads.

Apply small amounts of CA glue whilst building the drivetrain pulley, take note of the curved side needs to face inwards. Place something heavy onto the pulley whilst waiting for the glue to set to ensure a flat and straight pulley build.

Do not overtighten the bearing screw on the belt tensioner as you will risk damaging the small bearings. It is advised to use minimal force combined with Loctite when building this.

Note the bulkheads must be square for a smooth and balanced drivetrain.

Here the pulley assembly is installed and will be adjusted when the whole rear end is assembled.

The spur holder will also be adjusted again when the whole rear of the car is assembled.

Assemble the upper bulkhead and shock tower on a flat surface to prevent introducing any tweak to your chassis.

The rear toe-in geometry is adjusted through a turnbuckle attached to these two ballstuds and the effect of the dynamic rear suspension is also adjusted through adding spacers to this ballstud.

The front bulkheads sit flush with the bottom deck, so we advise strongly against sanding the bottom deck as this may cause the installation of the front bulkhead to be out of alignment.

After installation of the rear end, it was found that without any work the transmission system builds nicely with the right amount of free play to compensate for chassis flex.

Pay attention whilst installing front suspension mounts that the arms will not hit the front bulkhead.

Install servo mount before installing the front upper bulkheads.

Make sure all bearings are pushed into the suspension pieces fully and nothing will hit the universals.

The rear universals must be built with Loctite otherwise the pin will fall out.

You can also use some cleaner to clean out the oil applied to the universals from the factory and apply your favorite lubricant.

Normal 1/10 sized hex adaptors.

Whilst building the steering components, make sure the ball stud installs straight and do not over tighten as it may strip the plastic.

Take note of the camber link ball end lengths.

A tip here for racers, is that you can add more caster to allow for more straight line stability and faster turn in reaction. But pay note that this may introduce understeer at the middle of the corner. Caster can be adjusted through adding/removing spacers underneath the camberlinks.