timorous

The HSP94180 metal diffs worked fine for me until the steering hubs broke so I went ahead and got an all metal front and rear axle from Ali but the diffs in it are rather slack so I again upgraded to Axial AR44 metal diffs + pinion which is actually pretty solid and the truck has been working fine for a good while now. I was going to ask in the owners thread but since this is actually alive I hope it is okay to ask here. I have made several upgrades as parts broke over the time I have had it and my son now wants it to go faster. I have purchased a cheap 3900KV motor + esc combo and installed it which has done the trick and just about doubled the speed but 8-10mph is still pretty sluggish for what he wants to do with it. Looking at the gearing charts and advice many suggest starting with a rollout of 1 and working from there based on temp but the gearing required to do that is a 1:17 ratio and it calcs to around 30MPH which is faster than I want for my son. I was thinking more around the 20MPH using a 72t spur and a 30t pinion (48d) since that calcs to 22mph on a 2s with an FDR of 1:24 and a rollout of 0.72. The other reason to use that combo is the centre to centre of the spur and pinion stays about the same as current (less than 1mm further away and there is 2/3 mm of adjustment available in the motor bracket) so I don't have to worry about getting a good mesh between the two since that won't be changing by any significant amount. So my questions are is that kind of FDR and rollout number okay for a 4x4 kind of offroad but more on road truck that might go up a hill / over tree roots now and again but is not used for any challenging or extended crawling? If so what 72t spur gears are compatible with it because there does seem to be quite a bit of variety compared to pinions which are find your bore size and go.

If I reverse it on the transmitter it still only goes backwards.

Am I just really unlucky or is this typical RC ownership? 1) diffs strip making it effectively 1 wheel drive, replace with alu diffs and all good for 1 day then. 2) screws strip on front axle steering hub so car wont steer. Replace both axles with metal wraith ones. All good for 2 days then. 3) Steering servo pin bends a fraction jamming up the servo. Replace that with a 25kg one. Good for 2 hours then. 4) 2 in 1 esc/rx does something and now car only goes backwards. Checked transmitter and it is not batteries or a fault there.

Yea as others have said HSP 94180 or RGT 18000 (Rock Hammer) based parts are the same for the axles/diff. The metal diffs seem pretty sturdy, unfortunately with the new axles on order they were a total waste of money for me since the new axles use different diffs. If only the screw had stripped out 1st. Oh well I have a wood screw holding it together for now until the axles arrive in a couple of weeks.

This is a year later now but same thing happened to mine. Saw that the FTX aluminium replacements were £28 a pop and found some on Amazon that worked for £10 each. Unfortunately the following day the screw stripped out of the front left hub carrier and again the FTX aluminium replacement is around £40 which is crazy so I have spent most of the day looking at Wraith axle sets to replace the entire thing with but lead times are pretty crazy.