ARC A10 ‘25’ Review and Racing a Major meeting with the car

I wanted to add something different with this review as we had our state titles less than a fortnight after getting the kit. So why not do both and while I am at it only race the event with the kit setup. This means kit oils, ride, height, camber, etc.  The only things I played with were flex settings and droop.


Let's get started with the review.

Changes to this year's car:

Well just about everything is probably 90 percent new and this wasn’t promoted as such. All the alloy parts were changed, shock mounts, all new carbon apart from the top deck. New Arms, Alloy knuckles - I had endless people asking me if this was coming, so it was a nice thing to see.

So it's basically an A11. Even the new parts start with R14 coding.

Let’s start and download the manual which can be found here: https://www.arc-rc.com.tw/image/a10-25_instruction.pdf

The New A10 25 has the shocks carried over from the A10 23/ It's said that you need the 17mm springs for the new car as you won't be able to get ride height in all settings. I haven’t yet found a setting where the 20mm springs can’t be achieved and one of the tracks I race at where you need to run a ride height in the 7mm range, I have to use 20mm springs to gain the height. So don’t sell off your old 20mm springs or feel you need to buy the new ones straight away.

I used all the normal tricks with building them. The main ones were to put a slot on the shock adjustment nut to make it easier to count turns and use SIMSpec Red Jam o’ring V2 grease to prevent leaks and air from getting into the shocks.

The new shock mounting system is great, I never really thought this was a needed feature or could see how active rear shock towers would help. Actually, I think it's now a must on all kits. The difference in fine-tuning it gives you with the different flex options really is noticeable on track.

The next big change was the redesigned arms and Alloy knuckles.

The arms have changed in length and gone slightly longer in the rear vs the 23 car but not as long as the 22 car. They use an updated alloy lower mount for the shocks and new outer pivot balls which take an M3 screw to help remove the likelihood of the ball pulling out of the socket.

The new Steering Blocks are now made from aluminium. The new steering blocks are very much like the Mugen and AMX ones. There is no play between the steering, bearing, and wheel hex adaptor. Also allows you to use mechanical limiters for endpoints.

The geometry is different compared to the plastic ones so I do not recommend just retrofitting them into the other A10 models.
When building these, the grub screw that goes into the lower knuckles I feel is too short, so I installed M3x10mm ones to get more thread engagement with some blue Loctite. The M3x4 screw on the bottom still fits fine.

Like with all kits running carbon arms, I highly recommend running our brass screws to protect the chassis. These are stronger than alloy screws but still break before the chassis.

The Front DJ CVD drive shafts have changed as well, with a new big bore alloy DJ CVD case with 2mm pins.

So far I haven’t seen any wear issues yet, but I highly recommend servicing these every 2 race meetings and replacing the pins. This reduces wear on the alloy parts.

Like always, I rebuild these before running the car as they only have a light oil on them and the clips are installed one in each direction. It's always best to have the clips installed in the proper direction so they don’t catch and come off.

I chose to run the A10 23 rear horizontal body mount plate with the SIMSpec Rear Body Mounts. This lowered the COG and regained the most downforce possible over the kit setup.

Some more tips when building the car:

The spool goes together nicely, but pay attention to the direction the pulley goes on. Can be a little tricky to see in the manual.

With the rear diff, a tip here is I always sand the backs of all the plastic gears flat with some wet dry 800 grit paper. Some kits have 3 shims and some have 4 shims to go behind the spider gears. ( I don’t know why) but I recommend using 3 shims for touring cars and 4 for a FWD.

I like to drill 4 small (1mm) holes to allow any diff oil in the threads to escape. Stops leaks as sometimes you can't tighten the screw in properly if the hole is full of oil.

Use SIMSpec Red O'ring Jam V2 on the o'rings to help stop any leaks.

I like to use some paint on the eccentric hubs to make it super easy to see they are in the same position. I use a silver Sharpie for this.

This goes for all the A10 design kits - always pay attention to the way the inserts go in the arms before gluing. If you look closely in the pics I made this mistake building this car which I was able to fix without damaging any parts.

Extras used on this build:

ARC R132044 Aluminium Steering Bellcranks
ARC R114023 Low Friction Rubber Belts

SIMSpec Upper Stainless Screw Set

SIMSpec Brass Screws for the lower side

SIMSpec Carbon Front Bumper Brace

Electronics:

REDS ZX PRO 160A 1/10 GEN2

REDS Racing VX3 540 PRO Stock 21.5t

SRT CH712s Servo

Sanwa RX482 RX

SIMSpec GEN2 40mm Fan and Duct

MYLAPS RC4 Transponder

Let's get to the fun bit racing this new ARC..

I did a couple of runs with this car leading up to the 2024 Victorian State Titles at Boronia. Straight out of the box on the first run I was instantly in love with this car. I was honestly shocked by how good it was and I made the decision I wanted to race this car at the Vic’s with the car as close to completely kit as possible just to show how good this car is straight out of the box.

In seeding the car was better than I could drive it, it's rare I felt I was about 2 tenths a lap not good enough to get the most out of this car. I also felt like I didn't have any bottom end out of the motor, which is normally not the case with the torque-based REDS motors.  I put the 2 tenths down to not feeling well all weekend and not being used to racing 21.5t as I stepped up to 17.5t and 13.5t after entering this race meeting.