New addition to the stable – Yokomo MRTC-MD “Mini” touring car

I’ve always fancied one of these… managed to get two of them in a cracking deal – both were in good condition with a couple of hop-ups, this one is the better of the two and has been my informal racer for the last few weeks.

Yokomo MRTC-MD

The body is brand new, a good find in XRAY packaging (XRAY used the Yokomo body for their own T1M). It’s sporting my new race colours, pretty simple as painting is not my strong point.

Yokomo MRTC-MD

Under the hood we have a Yokomo S-World handwound 9-double (similar to a Reedy Ti), 4-cell IB4200 packs, Keyence Rapida Pro ESC, Futaba S9550 low-profile servo and a Futaba R133F mini receiver.

The whole setup works very well on 4.8V, I did have a couple of miniature 6V 1/3AAA receiver packs built up just in case, but actually the servo copes perfectly, motor power goes off before you get any slowdown in the responses.

I’ve been running indoors on a 23T pinion¬†(7.46:1 overall), overall a similar pace to a 19-turn motor on 6-cells. A shade less punch but also a shade more top end, and since we race on low-grip “slippy floors” locally (hence the spiked tyres) the¬†decreased punch is not a disadvantage.

Yokomo MRTC-MD

This car is fitted with some relatively old Yokomo alloy shocks and wheel hexes, still work well as far as I can tell. Apart from that it is basically standard.

The transponder plate on the top deck is cut from a bit of scrap lexan and attached with servo tape, there is nowhere else to put it really.

Yokomo MRTC-MD Rear view

Rear suspension uses the standard shock mounts and hubs to good effect. I have found that you need a lot of shock length (63mm) to get even droop with the front. I also like to run the camber link in the inner middle hole on the tower, this gives a raised roll center compared to the front and keeps the car handling well balanced. I’m also running 5.5mm rear ride height, 1 degree negative camber, #400 shock oil on standard 3-hole pistons, and TOP Racing 1.5×6.50 springs (316gF/mm).

Yokomo MRTC-MD Front

I’m still pursuing the ideal setup for the front end. One of the problems is that the shocks are mounted a long way inboard on the wishbone, so there is a huge amount of leverage from the wheel. This means you need to run a very stiff spring to limit roll. The second issue is that the wishbones are very soft, so you get a lot of wishbone flex before the spring starts getting compressed, and this problem becomes more marked the stiffer the spring.

Currently I am running a TOP Racing 1.5×5.75 (379gF/mm) spring with #500 oil, standard pistons, 1 degree negative camber and 5mm ride height. Shocks are 60mm long (shortest setting) and are leaned in one hole on the tower (when in the outer hole the shock goes through a strange angle under compression). Also using the inner middle hole for the camber link. I think the front end needs heavier damping as it is twitchy when the grip is good.

Yokomo MRTC-MD

Electronics install is pretty tidy, the low profile servo helps as the Keyence is a relatively large speedo with buttons on the side.

Yokomo MRTC-MD Chassis

Finally a view of the carbon chassis, wonderful quality as you expect from Yokomo, really sets the car off.

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