XTM Mammoth ST thread
#19
Tech Master
Joined: Jul 2003
Posts: 1,508
From: indpls,ind
Originally Posted by mountaindr3wz
in the first video there were testing the mammoth at palomar raceway.thats weird. anyway i want this truck so bad but my lhs doest not like xtm.
#20
Tech Master
Joined: Jul 2003
Posts: 1,508
From: indpls,ind
macnkitty, today my wife left me along so I sneaked out and ran my St for the first time. I have a ramp in my backyard which it cleared without any problems it seemed to glide thru the air unlike my zilla that falls like a stone when I ramp it. I think this truck is gonna be a good jumper at least compared to the zilla. And it turns on a dime too.
#22
Joined: Aug 2001
Posts: 4,385
From: NW Indiana
The wheels on the ST are 17mm hexes correct. They should fit the new 17mm hex conversion that HPI is releasing soon. Does anyone know if the offset for the wheels is close to that of a Savage wheel.
Thanks
Thanks
#24
Tech Master
Joined: Jul 2003
Posts: 1,508
From: indpls,ind
Thats a good question jonski!! So far my truck has held up, I feel that the throttle servo is weak and needs to be replaced with a stronger one. And possibly the steering servo could stand an upgrade to a slightly stronger servo. Also I wished they had put a slipper on the spur gear assembly because if you jump it and forget to get off the gas you hear a grinding sound when you hit the ground I suspect this is the sound of the spur gear wanting to shave off some teeth. So don't forget to let up off the gas when you jump.
#26
I bought this truck as well. I couldn't believe the value. But like most things, you get what you pay for. I'm not saying it's terrible by any means, I just think it needs a little TLC before it's ready for primetime. I think I'll disassemble and rebuild it before making a final judgement. I'll bet they sell a lot of these for that price.
#28
I took the truck to my local track (Palomar Raceway) on Saturday. I wanted to test it stock out of the box (after brake-in) to see how it performed. I have to say it did pretty well. My Revo will handle circles around the stock ST, but that's a different story.
I made a couple laps, checked the temp, all was fine. The brakes were very weak, and the steering seemed off a bit as well. Then I discovered the EPA on the Hitec radio (duh). Setting the steering to turn all the way helped quite a bit, but it was no superstar and the brakes were getting worse with time. Handling left a little to be desired, but a few tweaks on the camber, toe, and suspension should fix things up a bit. A couple laps more and a hard landing... Now I have front wheel drive only. Time to go home.
I took it all apart. I fixed the rear wheels getting no power. The setscrew holding the rear outdrive to the primary gear assembly came loose. I put some thread lock on it and tightened it down, problem solved.
I took a look at the brakes and noticed that the rear brakes were engaging before the front brakes. So much so that the front brakes weren't able to really grab the rotors in front. I adjusted all of the brake linkages so the fronts grab first and the rears come in for back up. Problem solved (maybe, I'll test it this coming weekend).
I tried my best to eliminate some of the slop in the steering linkage, but I'm not sure I helped it all that much. I do think I got rid of some binding that was occuring with the servo horn, and possibly a little bit from where the axle carriers mount with the front uprights. I'll be testing again this coming weekend but I'm going to guess that the steering setup (not the servo) is the weak link in this vehicle.
One other thing I noticed is excessive chassis flex at the rear of the vehicle. The front seems fine, but I think a different rear brace setup is in order. If I get a chance, I'll share my findings from next week.
I made a couple laps, checked the temp, all was fine. The brakes were very weak, and the steering seemed off a bit as well. Then I discovered the EPA on the Hitec radio (duh). Setting the steering to turn all the way helped quite a bit, but it was no superstar and the brakes were getting worse with time. Handling left a little to be desired, but a few tweaks on the camber, toe, and suspension should fix things up a bit. A couple laps more and a hard landing... Now I have front wheel drive only. Time to go home.
I took it all apart. I fixed the rear wheels getting no power. The setscrew holding the rear outdrive to the primary gear assembly came loose. I put some thread lock on it and tightened it down, problem solved.
I took a look at the brakes and noticed that the rear brakes were engaging before the front brakes. So much so that the front brakes weren't able to really grab the rotors in front. I adjusted all of the brake linkages so the fronts grab first and the rears come in for back up. Problem solved (maybe, I'll test it this coming weekend).
I tried my best to eliminate some of the slop in the steering linkage, but I'm not sure I helped it all that much. I do think I got rid of some binding that was occuring with the servo horn, and possibly a little bit from where the axle carriers mount with the front uprights. I'll be testing again this coming weekend but I'm going to guess that the steering setup (not the servo) is the weak link in this vehicle.
One other thing I noticed is excessive chassis flex at the rear of the vehicle. The front seems fine, but I think a different rear brace setup is in order. If I get a chance, I'll share my findings from next week.
#29
Tech Master
Joined: Jul 2003
Posts: 1,508
From: indpls,ind
I noticed the soft steering response too especially when you get up to speed. I replaced the steering servo with a unit that puts out more torque. The steering is more responsive now. I took the steering servo and used it as the throttle servo. I have very strong brakes now. After completing break in of the .24.7 motor when I started running my Mammoth St I noticed it was very slow on the take off!! So I also reversed the clutchshoes the orientation of the shoes are just the opposite of the way they are displayed in the manual. The clutch engages faster with the shoes reversed. Throttle response coming out of the turns is alot better.
#30
What servo did you use to replace the stock one? I think the stock unit is a Blue Bird 630MG. The stock servo is unmarked but if you look at the case and the wiring, they are identical. Also, they claim 195oz/in of torque which is what the Blue Bird unit puts out. Not sure why the mags didn't point this out, they are all saying the servo is made by Cirrus (which it may be, but then, they would also be producing the Blue Birds).



