HPI Hellfire SS Kit Build & Long Term Review
04-10-2007, 06:45 PM
#61
Originally Posted by MadHacker
Do you have a link for that company?
04-10-2007, 10:24 PM
#62
Tonight I had the chance to run the truck for a few tanks... and after some quick examination have found that the nubz tires are almost treadless! LOL. I guess that's to be expected as they really weren't intended for pavement running! Hahaha! I guess I've got myself a set of "street tires" now!
I washed the truck up, and blew it off with compressed air, then lubed the engine, and pulled the rear diff out to wash out the diff oil and replace. I like to do the first oil change after a few tanks so that all the metal flakes from the break-in process will be replaced with clean oil.
In the first picture, you can see that removing the diff is fairly simple. 8 screws and you're in. The diff slides out the back of the bulkhead. It took all of about 30 seconds for me to remove the rear diff.
After I'de cleaned everything up I re-assembled the rear diff. When I mated the ring gear to the diff case, the bevel gear on that shaft slipped off... I didn't know this had happened, and one of the bevel gears cracked when I started to torque the ring gear onto the diff case... Doh!
I washed the truck up, and blew it off with compressed air, then lubed the engine, and pulled the rear diff out to wash out the diff oil and replace. I like to do the first oil change after a few tanks so that all the metal flakes from the break-in process will be replaced with clean oil.
In the first picture, you can see that removing the diff is fairly simple. 8 screws and you're in. The diff slides out the back of the bulkhead. It took all of about 30 seconds for me to remove the rear diff.
After I'de cleaned everything up I re-assembled the rear diff. When I mated the ring gear to the diff case, the bevel gear on that shaft slipped off... I didn't know this had happened, and one of the bevel gears cracked when I started to torque the ring gear onto the diff case... Doh!
Last edited by MadHacker; 06-03-2007 at 11:55 AM.
04-10-2007, 11:04 PM
#63
I compared the Hellfire bevels against the Savage ones. They're slightly different, not by much, but probably just different enough. 
I'll try putting the Savage gears into the Hellfire diff cup and see if everything lines up ok... will let you all know...
I'll try putting the Savage gears into the Hellfire diff cup and see if everything lines up ok... will let you all know...
04-10-2007, 11:14 PM
#64
Good news! The Savage bevels work! I used everything from the Hellfire, including the shims, and just replaced the 4 bevels with Savage gears. The diff is together and feels nice and smooth!
In the picture, the gear on the right is the Savage bevel.
In the picture, the gear on the right is the Savage bevel.
04-10-2007, 11:22 PM
#65
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I'm curious to see how it runs for you at the track. I just bought a couple of Hellfire SS's for my brother and me a few weeks ago (wish I had waited! They are only $260 now!). I'll be racing mine for the 1st time this weekend. Let's see what happens!!!!
04-11-2007, 09:30 AM
#67
I did the center diff this morning. Everything's good. Was super easy to take out... 4 screws.
When I got to the front diff, I noticed something interesting... A broken dog bone pin (see photo). I wasn't driving the truck very hard, mostly just ripping around on pavement, with a few minor jumps off some small snow banks. No crashes. I have a hard time believing that any vehicle could break a pin like this with just basically driving around. It must have been a fluke.
- Update - I've been running the truck for quite a few months now, and have had no further issues with broken dog bone pins. I'm certain this was a fluke.
When I got to the front diff, I noticed something interesting... A broken dog bone pin (see photo). I wasn't driving the truck very hard, mostly just ripping around on pavement, with a few minor jumps off some small snow banks. No crashes. I have a hard time believing that any vehicle could break a pin like this with just basically driving around. It must have been a fluke.
- Update - I've been running the truck for quite a few months now, and have had no further issues with broken dog bone pins. I'm certain this was a fluke.
Last edited by MadHacker; 07-10-2007 at 01:52 AM.
04-11-2007, 09:41 AM
#68
I've started looking around for parts to see who's got what... Great Hobbies has a pretty full list of in stock parts for the Hellfire. There's lots on Ebay, and the local hobby shop has a few parts. The parts don't appear to be all that expensive either.
With regards to the steering servo... as I mentioned earlier in this thread, the instructions recommend a servo with a minimum of 160 oz in of torque. I dug up and installed a Hitec 925 (108 oz in @ .08 sec). I found out that at high speeds, 108 oz in isn't enough to turn the wheels. The gyro effect of the high rpm wheels want to keep them pointed straight and the 925 just doesn't have enough grunt to turn them.
With that in mind, the Airtronics 94758 servo (115 oz in @ .06 sec) that I ordered will not have enough grunt to turn the wheels either. I might have to throw in an Airtronics 94359 (200 oz in @ .10 sec). I've got one of these in another vehicle (that probably doesn't need the torque), so I'll do a servo swap today.
With regards to the steering servo... as I mentioned earlier in this thread, the instructions recommend a servo with a minimum of 160 oz in of torque. I dug up and installed a Hitec 925 (108 oz in @ .08 sec). I found out that at high speeds, 108 oz in isn't enough to turn the wheels. The gyro effect of the high rpm wheels want to keep them pointed straight and the 925 just doesn't have enough grunt to turn them.
With that in mind, the Airtronics 94758 servo (115 oz in @ .06 sec) that I ordered will not have enough grunt to turn the wheels either. I might have to throw in an Airtronics 94359 (200 oz in @ .10 sec). I've got one of these in another vehicle (that probably doesn't need the torque), so I'll do a servo swap today.
Last edited by MadHacker; 04-11-2007 at 10:08 AM.
04-11-2007, 04:45 PM
#70
Originally Posted by MadHacker
...With that in mind, the Airtronics 94758 servo (115 oz in @ .06 sec) that I ordered will not have enough grunt to turn the wheels either...
04-12-2007, 08:44 AM
#71
Will do Brad. It only takes 5 screws to change the servo so it wouldn't be a big deal.
The Airtronics 94359 is now in the Hellfire. I'm just in the process of painting up the body, so I might take it for a run today if I'm done. Will see how much of a difference 200 oz in of torque makes to the steering.
The Airtronics 94359 is now in the Hellfire. I'm just in the process of painting up the body, so I might take it for a run today if I'm done. Will see how much of a difference 200 oz in of torque makes to the steering.
Last edited by MadHacker; 06-03-2007 at 12:00 PM.
04-12-2007, 10:17 PM
#73
I got a chance to take the Hellfire out for a spin this evening. The Airtronics steering servo definitely helps out in the steering department, so HPI wasn't joking when they said in the manual to use a servo with 160 oz in of torque, or better.
04-13-2007, 12:52 PM
#74
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looks briliant!