i'm sorta new to the hobby about 4mos andI have recently purchased a savage xl. was a previouse savage 25 owner.

My issue I am having is that when I hit the throttle front wheels will spin but back wheels don't move. But if i spin wheels by hand all the wheels will move as normal. I have takin the transmission apart but didn't find any flaws no shredded gears everything seems to work as it should please help...

9/10 times its the grub screw missing in the pinion hub, look at the front of the rear diff bulk head and see if the hub turns when the car is running off the ground and if so then that is the problem the drive train is working fine but with out the grub screw holding the hub to the pinion the rear diff just wont turn over.....good luck

And use a good thread locker, the HPI blue thread lock is not holding it tight enough.

im having the same problem no diff gear is shred no tranny gear either yesterday i was pushing it and the rear wheels would lock.. this morning i took rear diff out see if anything inside was broken.. didnt see anything broken now the wheels dont lock.. but when i start its only front wheel drive what does this grub screw look like?

For people with the Savage Xl or similar. I have had the same problem with my Xl and it was the screw shaft part #86094. I'm looking at my Savage Xl manual now and if you look at page 51 at the bottom you'll see it by the cup joint. I broke the screw in half and i would only have front wheel drive and my back wheels were locked up. Hope this helps.

You need to knock that broken step screw out dude.
And replace with a new screw.

I use a heat shrink tubing over that little step screws now, it should hold on well.