View Full Version : GPM Rear Double Damper

2011.02.24, 09:42 AM
I found this (http://gpmracing.com.hk/catalog/product_info.php?products_id=640) part on the net.

I've seen similar damper design in the MR-01 section of the forum.
This part is designed for MR-02 - so it can be used on MR-03 too.
It works with grease.
The question is - is it worthed a try?
I haven't seen anybody using it on MR-02/03.
Is it bad suspension design? It costs almost nothing. I found it for $9.10 without shipping.
Of course it has less adjustment capabilities compared to the tri-damper setup for example..

2011.02.24, 10:00 AM
I am pretty sure a friend used this set in our last cup races for a GT1 with PN motor mount. The only difference seeing it unassembled is that his shocks are yellow. Worked pretty fine for him - he won 2 of 4 races and finished the cup as #1, me close being close behind (in points that is, not on the track though).

DJ Rattray
2011.02.24, 10:15 AM
you got the part number for that?

2011.02.24, 10:19 AM
No, but a link with pictures.


Seems to different from the GPM part.

2011.02.24, 10:27 AM
This is kind of different suspension setup.
The GPM part I mentioned looks like this assembled:
Note the picture is from the MR-01 pictures thread. And the part is not the GPM one. Just works the same way.

2011.02.24, 11:07 AM
Looks like the Kyosho roll shock I described HERE (http://mini-zracer.com/forums/showthread.php?t=28227). The stock version wasn't very good :(


2011.02.24, 12:52 PM
Back when I was going from the Xmod scene to the Mini-Z scene in mid '06, And I didn't even know how a Disk Damper Plate System worked:confused:, I remember the general consensus on Roll-Shock setups like the GPM dual Roll-Shock & the Kyosho dual Roll-Shock was NG - No Good.:eek:

Racers said about the Roll-Shock setups the design suffered from inconsistent damping/spring action from the left/right shocks, stiction issues, poor bump absorption in the design, and more fuss making sure the left/right shocks were even (And performed exactly the same as each other). The solution was to dump the Roll-Shock setups for a DDS.:)

Even when Reflex was selling their Side-Damper System, it was important to note that there was one main damper tube. This design was simple and just plain rocked. You did not have one left damper tube + one right damper tube, because then you have to make sure each tube is set up and greased identically. And if there were 2 shocks instead of one main damping tube shock it would be harder to diagnose problems because one side shock might be overcompensating for the other side shock, one shock might be smoother, or have different damping feel, etc., etc....

When I first saw the PN Tri-Damping System prototype on a car I said, "Why are we going backwards?" because the TDS reminded of a Roll-Shock system, just with different angles for the shocks. Anyone else kinda feel this way? I like my PN TDS, even though it is a lot of work compared to a DDS and RR Side-Damper; And with the PN & RR TDS the position of the shocks does make a huge difference I know. But still I wonder if Disk Damper systems or Single Damper Tube systems like Reflex's are simpler and just plain work better and more consistent overall, and are easier to tune and use???

2011.02.24, 02:07 PM
The difference is in the geometry and build quality. The old "roll-shock" setup involves two springs with minimally adjustable collars, imprecise joint connections (look at the GPM part... screw joints!) and the fact that the springs affected both roll and bump, so there was a trifecta of disadvantages. The springs did not work directly against each other but rather through the T-plate, so suspension centering was not perfect; because the motion ratio was so high (wheel movement to spring movement) you'd also run into problems making sure the spring rate was even side to side.

Fast forward to 2010 and with the tri-shock, we have proper ball joints, thumbnut adjustable spring collars, and the springs affect roll and bump separately. The roll springs work directly against each other instead of going through the T-plate; and the motion ratio is increased so the small spring rate differences are not as important (you can tune it out with the spring collars if needed). Better tuning and better control is what sets the RR and PN tri-shocks apart from any older designs; the same reason is why competitive 1/12 cars have defaulted to the tri-shock setup for the last few years (granted, their springs are usually on the pivot balls).

2011.02.24, 02:20 PM
the biggest thing for me running the tri shock is how it recenters itsself perfectly every time... the confidence it gives me to mash the throttle outta every turn wit a mod car is the best part of the set up... it takes away the exit torque steer the dps gives you... like when you exit the last turn onto the straigh ands you wanna go straight but the car wont come outta the turn so good... this is exactly where the side shocks come into play and why i love it and its on every single car i own...

2011.02.25, 01:34 AM
Thank you all. It was helpful :cool: