View Full Version : Kyosho MR-03 optional spring set

2010.11.18, 07:52 PM
quoted from Mini-Z development blog:


"New front springs for the MR-03 will be released.

MZW423 Front Spring Set (Soft & Short)

The springs in this set are softer than the existing MZW401 spring set and also the spring length is 0.5mm shorter.

The order of spring rate is as follows from the hardest one,

Lemon Yellow
Dark Orange
Light Green
Deep Purple


The spring rate of the red spring (Softest) of the MZW401 is the same as the lemon yellow spring of this set.

Why do you need softer springs?

It is because of the characteristics of the upper arms of the MR-03.
The standard plastic upper arm deforms to a certain degree and soften overall spring rate.
So, if you like firm suspension set up, you need a hard spring.
(Springs for MR-03 are much harder than those of MR-02)

However, ideally the upper suspension arms should be hard and stiff.
Soft suspension arms works flexibly but not accurately.

The MZW415 Aluminum Upper Suspension Arm was released to achieve more accuracy.
However, existing springs are bit too hard for this arm.

Also, the MZW416 Inner Tube Shock applies preload to the spring
and this makes the suspension work harder.

The soft and short springs set is fine-tuned for the aluminum upper arm and the inner tube shock.

I recommend you use the dark orange springs if you use the plastic upper arm and the inner tube shock,
And if you use the aluminum upper arms, my recommendation is light green ones.

You will experience silky smooth driving feel!"

2011.01.21, 05:37 AM
Anybody used this MZW416 Inner Tube Shock Set?
I found no information about this optional front suspension upgrade on the forum.
Anybody tried it out? Does it work with the Front spring set from Kyosho (MZW401)?


2011.01.21, 07:59 AM
I will be using that system shortly on a MR-03 build that I am doing for the Reflex points series and can give feedback shortly. This system is a way to add dampening to the front suspension. Most guys just use diff grease on their knuckles/kingpins. This is more like an elegant version of doing that simple thing.

Also, please read above post for your answer on springs. Yes, they are compatible however as noted above, they are suggesting the softer spring set.

2011.01.21, 08:35 AM
Thanks. I'll appreciate your feedback.
As for the springs - yes I read the first post, but I was wondering if this shock preloads as much the spring that the suspension becomes way too hard. Or it could go with the softest (red) springs from the Kyosho spring set.

2011.01.21, 09:13 AM
They certainly add stability to the front. The front is much less nervous at high speed corner entry. Steering feel seems smoother. Said another way though the steering could feel numb.

It eliminated the front chatter on a couple of my cars that were running 30 degree rears with 40 degree fronts. Probably less understeer as well but the tire combo will favor understeer no matter what.

For sure more grip and less understeer on the LM cars that have it installed. Lessened the tendency for the front to dive into the apex of the corner when lifting the throttle on entry.

This is on a carpet track with a fairly stiff wood base layer. I would assume that the improvement on RCP would be less. Saying that though all of the top cars in the Kyosho sanctioned cup series run on Kyosho RCP tracks have them installed.

Overall I recommend them if you have money to spend, they're 1,750 yen here which I think is overpriced, I'm guessing over 20 bucks in the states. A rear damping system is certainly more important as are the SS kingpins, flouring balls and SS upper arms shafts.

BEWARE: These parts put a limit to the suspension arm travel. You can only have about 2mm worth of spacers in any combination below or above the knuckles or above the arm, even with the long kingpins. So if you use the long kingpins to induce camber with spacers above the knuckle and to adjust bump stop it is very limiting.

2011.01.21, 09:21 AM
@iruninsoga Are you refering to the soft/short spring set (MZW423) or the Inner Tube Shock Set (MZW416)?

The spring set in the US retails for $20 which it too steep in my opinion. Not sure what IT Shock Set sells for here.

2011.01.21, 03:31 PM
The Inner Tube shocks sell for about $25-30 here. I have them installed in a couple of my cars. As said above, they limit the suspension travel a bit, and you have to use a softer spring than you would without them.

2011.01.21, 07:57 PM
I'd like to know how these feel as well. Not looking to stray away from RR Long pins just yet solely because PN's MR Low Down springs currently feed ALL of my cars and paying 30-50$ for a new setup for just one isn't something I'd do unless its miles better.

2011.06.02, 04:13 AM
I just got the inner tube shock set and the softer and shorter spring set.
Can you give me some recommendation for the oil/grease to use on the shocks?
I currently applied the Oil that I have from the Kyosho Oil Shock. But I think it needs more dampening.. What do you use?

2011.06.02, 07:29 AM
I use 5000W kyosho diff grease (red colour). As for springs and spacers, I can't remember- will have to look at my car this weekend. I should get around to documenting my setup, it's pretty kick-arse actually. I'm running with guys using 48t atomic round can (yellow) and xspeed 50t, whereas I'm using reflex 70 turn.