The ECX Boost: The buggy with an identity crisis

[i_r_beej]

I've spent the last few weeks on a (fool's) quest to prep my Boost buggy into a race-capable vehicle. One major sticking point is the front suspension: The Boost's front suspension set-up is a TRUCK set-up. Not for a buggy!

The main problem is that with the shorter suspension arms the front suspension doesn't sag the necessary amount (or maybe only a millimeter or two depending on what aftermarket springs you might be using). Sag is better with a heavier NiMh battery, but with a lighter weight LiPo? Forget it. The problem is that the suspension arms just don't have the proper leverage on the shocks.

Since the ECX Boost appears to be something of a clone of the Associated B4 buggy I'll be experimenting with installing a B4 shock tower and shocks on my Boost.

 

[xlDooM]

Sounds like you just need softer springs?

Also, I found on my amp that moving the shocks to other mounting holes on the tower and arms so that they were more vertical had quite an effect on the effective spring rate. I take it yours are already as horizontal as they will go?

 

[i_r_beej]

Yes, softer springs might help. Might. I've already spent a fair amount on different springs. Part of the problem is that so very few are not labeled with an actual spring rate. Typically springs are "soft" "medium" or "red" "blue" which is completely unhelpful. I found a pair of Axial-branded springs that were a little short (not a problem with threaded preload collars) and were acually labeled as having a 1.43lb rate. They seemed that they were a little softer than the ECX-branded red/soft replacement springs but it's impossible to tell for sure since the ECX springs don't have any rate information (and I haven't cobbled together a testing jig).

As for setup of the existing shocks, yes, I've tried every available mounting. Currently they are inboard tower hole and outboard A-arm hole for indoor "off-road" carpet racing with a 3mm internal limiter and are performing sufficiently well. True off-road the stock and aluminum shocks just bounce around and are not very compliant. There is virtually no sag (maybe 1mm?).

The issue is that the tower and shocks are actually designed for a truck's longer A-arms (AMP, Circuit, etc.) and I think the shocks were originally designed for the weight of a NiMh battery.

My AMP sags quite nicely in the front with minimal pre-load using the middle hole on the tower and inboard hole on the A-arm. It sags less with a LiPo battery, but I can remove ALL preload spacers and still get sag.