How Much Resistance?

[Vvajk]

I'm just curious. I'm wondering how much resistance should be in the drive train with the brake off. For example, when I turn on my Savage XL, (engine off, electronics on) and I apply throttle, how easy should the truck roll forward? I can give it a little shove with my foot and the truck maybe goes a foot and a half ... seems like a lot of resistance. Is this normal for the Savage, or do I need to do some tweaking somewhere?

 

[Jam Racing 1]

ya that aint good, maybe check the gear mesh and see if it is too tight.....

 

[Vvajk]

It's not the gear mesh. It was the same way when I had the engine completely removed. I wonder if it has something to do with the brakes.

 

[Vvajk]

It's not the gear mesh, the brakes are loose when not engaged. The diffs are pretty free flowing. I pulled the main gears out of the top of the transmission and they are all smooth. The only thing left is that gear down in the bottom of the transmission that is hooked directly to the drive shafts. It appears smooth ... I'm just not sure how much resistance is supposed to be there. Do I have a gummed up bearing maybe? Here's a little video I made if anyone cares to watch:

 

[Jam Racing 1]

Could be as simple as a wheel being too tight on the axle... My MMT will roll freely across the floor if I give it a push, and my Savage is about the same as it is..... Looking at your vid it looks as if the inboard brake disc is dragging more than the outter one is, try adjusting the caliper screws a turn out and see if that helps....

 

[Vvajk]

I'll have to do some tinkering for sure. I don't think it's the brakes or a wheel too tight. It's gotta be something to do with that gear at the bottom of the transmission I think. I will do some digging. Thanks for the input. I'll update when I can get some more bench time in with it.

 

[fz1dave]

When you turn one wheel you should be able to get all four wheels to turn some at least with little to no pressure on the other wheel on the same axle. my guess is the one of the differential bevel gears.

 

[Vvajk]

I just barely installed new bullet proof diffs in the front and rear. I wonder if I did something wrong. Maybe I'll try removing both the drive shafts and see how that effects the drag. Maybe narrow down which end is causing the drag.

 

[fz1dave]

Nice idea.

 

[fz1dave]

What did you find?

 

[Vvajk]

Okay, I have been able to track down the source of the drag. I first removed the brakes entirely so that I could rule that out. Then I removed both front and rear diffs. When I turned the spur gear with my finger, the drag was still there. So, I decided I would remove the pinion gears and driveshafts as well. When I went disconnected the the rear driveshaft from the pinion gear ... voila! The drag was gone! Long story short: upon removing the bearings from the rear bulkhead or bearing block that serves the pinion gear, I found that inside the bearing block there is a plastic burr sticking out just enough that the bearing (closest to the pinion) can't be seated properly. Because of this small gap (I think) when you connect the driveshaft to the pinion gear shaft, it causes the gear to be forced up against the bearing creating the drag. That's my theory anyway. I still need to scrape that burr off with a blade and then reassemble. Hopefully that fixes it. I'll update this when I know. Then I'll probably be on here asking how to put the brakes back on!
I'll see if I can post up a pic of it: