Rear end

2001 Pete approaching 1 million miles. C-15 that I just in framed. 404 axles.

I started noticing a vibration that was accompanied by what felt like a slight engine miss. Not so much a miss but it almost felt like I was lightly letting on and off the fuel. Noticed it if I was running right around 70mph. If I let off the fuel it immediately disappears. Now I think it's getting worse. Any time I'm in the fuel pedal hard I can feel the vibration in my feet in the pedals. I only notice a very slight surge in power if I'm doing 70 or more and it's so slight I might be imagining it.

So the driveline all looks good. All u-joints are tight and the hanger bearing looks good. Haven't actually measured the ride height but I know how the truck acts if that is off and this isn't it.

The input shaft on the front drive axle does have a fair bit of up and down movement and when I checked the oil level this morning there is a fair amount of fillings on the magnetic plug.

Could this be the cause of my vibration? I assume there are some bearings on the input shaft? Is it worth just replacing those? Or should I prepare to replace the whole power divider assembly?

When I first noticed the vibration and possible surge at high speed I thought it may have been engine related ( injector was my thought but I'm not sure I'm on that path anymore)

 

I would tend to agree with swaan. It bothers me greatly knowing there is something that could leave me sitting on the side of the road. The oil in the rear diff looks great and has little to no metal on the plug. So I won't touch that. Buy the front has me concerned. I don't know a lot about differentials but was hoping I could get by a little cheaper than replacing the whole thing at the moment.

 

Oil is probably about due for a change. The rear rear looks pretty good yet. The front is not good.

My first thought was an injector causing the vibration. But I'm not sure how to check it out. Injectors were replaced this summer.