i_r_beej
Well-Known Member
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I thought I'd break this discussion off into it's own thread. I had been going back-and-forth with @rob5059 regarding the use of RPM's 2-stage shock pistons in the aluminum ECX "upgrade" shocks.
There are a few issues that are preventing a "bolt-on" upgrade:
The first difficulty is that the design of the RPM piston requires 2.5mm between the E-clips on the shock shaft and the ECX shaft only has 2mm.
The second problem is that I measured the diameter of the stock ECX pistons at 9.9mm and the RPM pistons at 10.02 mm. That's just enough of a difference to cause some problems. The stock plastic bodies appear to have some taper that causes the RPM piston to bind about halfway through a stroke. The aluminum shock bodies are more consistent, but the RPM pistons *just* barely fit and there is some drag the full length of the stroke.
Finally, I have not yet found a compatible shaft for the front ECX shocks. Traxxas produces a 51mm long shaft (part number 2765) that is a direct replacement for the ECX rear shock shaft.
So it seems that the only really "serious" performance upgrade in terms of spring and damping adjustment is system from another manufacturer such as Losi, TLR, Traxxas, or associated.
For the time being I will continue to experiment with different springs and shock oils in the ECX aluminum shocks.
If you have any experience swapping out the shocks on your Boost (or other ECX car) please share your experience here (with part numbers!).
There are a few issues that are preventing a "bolt-on" upgrade:
The first difficulty is that the design of the RPM piston requires 2.5mm between the E-clips on the shock shaft and the ECX shaft only has 2mm.
The second problem is that I measured the diameter of the stock ECX pistons at 9.9mm and the RPM pistons at 10.02 mm. That's just enough of a difference to cause some problems. The stock plastic bodies appear to have some taper that causes the RPM piston to bind about halfway through a stroke. The aluminum shock bodies are more consistent, but the RPM pistons *just* barely fit and there is some drag the full length of the stroke.
Finally, I have not yet found a compatible shaft for the front ECX shocks. Traxxas produces a 51mm long shaft (part number 2765) that is a direct replacement for the ECX rear shock shaft.
So it seems that the only really "serious" performance upgrade in terms of spring and damping adjustment is system from another manufacturer such as Losi, TLR, Traxxas, or associated.
For the time being I will continue to experiment with different springs and shock oils in the ECX aluminum shocks.
If you have any experience swapping out the shocks on your Boost (or other ECX car) please share your experience here (with part numbers!).
Dimensions of stock ECX Boost shocks:
REAR: Total length - 95mm center-to-center; shaft - 3mm diameter, 51mm long
FRONT: Total length - 85mm center-to-center; shaft- 3mm diameter, 42.25mm long
Piston diameter: 9.9mm; 2mm thick
SPRINGS:
REAR: 14mm ID, 74mm (2.9") long
FRONT: 14mm ID, 58mm (2.28") long
Stock spring rate: not provided by ECX (based on my experiments with Associated springs, I guess around 2ft/in rate for the stock springs)
REAR: Total length - 95mm center-to-center; shaft - 3mm diameter, 51mm long
FRONT: Total length - 85mm center-to-center; shaft- 3mm diameter, 42.25mm long
Piston diameter: 9.9mm; 2mm thick
SPRINGS:
REAR: 14mm ID, 74mm (2.9") long
FRONT: 14mm ID, 58mm (2.28") long
Stock spring rate: not provided by ECX (based on my experiments with Associated springs, I guess around 2ft/in rate for the stock springs)
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