Ive abused my HF for aprox 3 yrs and only stripped the spider gears once. I still had the grease in the diff when it stripped. Once you put the diff oil in you should solve that problem. The spiders do have small shims behind each one so make sure they are there or add more ir required.
Thicker centre diff oil gives more all wheel drive and better accelleration/topspeed but less turning ability. So if you are gunna race on a track try the 7/10/3, 7/15/2 or similar. This should limit the front tyres pizza plating. The stock tyres are only ok for bashing and wont grip very well on most tracks. The also pizza alot.
Remember shim the pinion and crown.

I will be blunt. The HF is heavy and poor quality. It takes alot of maintanence. I still love mine though.

well question for ya all I just got my oils in and they sent me 2k, 3k, and a 7k............So I'm guessing 7k middle and the 3k front and the 2k rear?

ok now will hpi send me just one cog? or the whole set plus shims? or do i have to order the shims?

Yes. The heavier oil goes in the center diff, then the front and then the rear.

today i went to my local track to drive my hellfire and i had just drove it at my house the other day to make sure everything was working and when i went to pull start my truck it pulled very hard and it worked fine the other day. any suggestions on what may have happened

What do you mean it pulled hard?
The engine wouldnt turn over? Or the pull start slipped?
If you can clarify what you mean we can help you out

the engine turned over (i had it going until it died) it was the pull cord that pulled hard. it sometimes wouldnt wind it self up and half of the cord would be out until i tugged it a little and then it wound back up

It sounds like the spring is going. You can try to rebuild it but to be honest its easier to just buy a new one.
Make sure the engine isnt flooded when you try to start it. It puts extra stress on the pull start

Unfortunately most pull starts dont last long. Remember only short pulls and it really helps ease the stress on the pullstart if you loosen the glowplug slightly when the engine is cold. Even better if you can heat the engine up with a heat gun or hair dryer. Also make sure the the piston is at bottom dead centre.
I now only use a starter box as pullstarts and rotostarts sux.

it mite have been flooded because i did pull it a lot.

i was pulling it out all the way but now i know not to. i have a heat gun but for got it at the house!! and i would have used my starter box but my battery doesnt work anymore and i am still waiting for my new ones to arrive.

thanks for all of your help

hey guys im going to a hobby shop this week what parts would i need to rebuild my rear diff. and what kind of shock oils should i use?

Need some help looking to buy a Savage 25 X XL any suggestions? heres the add: Up for sale is a hpi savage w/ LST shock conversion,fastlane machine frame, bulk heads, mugen mid tank conversion,throttle servo relocation upgrade, integy steering hubs front and rear, 3 speed transmission, Sh .28 8 port engine that is still a killer along with a brand new still in the box XTM 457 pro engine. Proline F 650 body proline wabash wheels w/ big joes. This is a killer truck and I will also include all of m nitro accessories such as wrenches 2 glow ignitors both rechargeable, a box full of savage 25 and x plastic parts also comes equipted with XTM sure start w/ 4500 mah battery and much more.

The shock oil is going to depend on where you run. If its bumpy you want to go with a lighter oil to have better control. If its mostly smooth then heavier oil is better.
Mcrazy that sounds like a good set up. How much is he asking?

asking is 400 how ever it does not include any electronics. So I am racking my brain I am looking to get a truck, do I go with the Savage X or the Savage XL, Or do I go for the Revo? And I think the T Maxx is over rated.......but dont know anyone with in put?

I dont have any real experience with Traxxas. I have a Savage and I love it. The XL is a little bigger then the X so its a matter of preference on the truck. You cant go wrong with either one though.
Seeing as you guys have unlimited room to run there have you thought about a Baja 5T?

ok so what weight range of shock oil should i get and do i have to use different weights for the front and back?

Again thats really going to depend on what you are driving on. Is it mostly smooth or is it really bumpy?
Im using 70 weight fluid in mine and seems to be working well for me. I run mostly on grass, and some fairly smooth dirt/sandy fields.
I use the same weight all around. You could run different weights front and rear to really customize the truck to your driving style, along with changing the diff fluids.
Some of it is just trial and error. The temps where you are will have an effect on the oil choices too. If its really cold you might want to go with a slightly lighter fluid.
Hope this helps

im either running it on grass, gravel/dirt/sand all pretty flat and lots of parting lots.  so i would go with a heavier weight if i was jumping it? like 80?

Ya the Baja 5T has crossed my mind how ever I heard that the Engines aren't as strong, they dont get up and move very quick and they are more tempramental as far as adjustments and getting them tuned in..........The only reason I got into this hobbie is I am building a Sandrail (DuneBuggie) back home so I'm just trying to pass the time........Thanks for the help, I should be getting my oils in today so hopfully I can run the hellfire on the track, and I will turn the Pixels down on the camera and load them up...

zviper, 70 should be a decent weight. Thats what Im running. You can always try it and then try the heavier and see what happens. 1 bottle is more then enough to do all 4 shocks.

Mcrazy I think the gas engines are actually less temprarmental then the nitros since you are using a regular sparks plug rather then a glow plug. I know the newer 30cc engines have some massive torque too. If you check out you tube there are some interesting videos of the bajas.
Good luck with the pictures.

when should i first change oil in the shocks. i have ran about 2 gallons through mine since i got it.

whats the lowest weight to highest weight should i get because i cant go to the hobbies shop often like 1 every 2 months because of work. im thinking about just getting 6 or 7 different weights and suggestion what i should pick.

K-man there is no real time table. If the shocks are still working well then there is no need to change it. If you notice they are not operating smoothly of if you want to change the handling then you should change it out.

zviper I would say between 50 and 80 should give you a good spread. Any lower and its going to be too thin for the weight of the hellfire. Any heavier then 80 with the temps you get up there and it will probably slow the damping too much.

Ok so im wanting to sell me hellfire and wanted to see whats a good fair price im thinking 200? what do u think it has a modded mach427 only about 3 tanks ran on it new body never even ran 40's axial wheel and also stock wheels and tire as well no steering servo and a cheap rx and tx and two spare bodies

Post up some pictures and we can give you a better idea of what its worth