So I recently bought a "Frankenstein" atv. The guy I bought it off of said it is a 350 rancher frame, 250 rubicon engine, and a Forman 400 rear end. I think the rear end is actually a 250ex or close to it at least because of the brakes.

Anyways the rear brake drum doesn't sit by the wheel but is part of the rear end housing. Sorry not sure what everything is called. I unbolted the cover for the brakes and oil started pouring out of it. I'm guessing it is the rear differential oil? but the brake drum and brake pads are covered in oil. I'm guessing this isn't supposed to be the case because the pads obviously can't get friction. Can someone tell me why the oil poured out? On top of the differential is a bolt that I guess is used to put oil in but I'm not sure.

I watched a video on the rear axle and brakes and the guy put everything back together but didn't put any oil in the rear differential. Should oil be in there? I'm just trying to figure this out and at least get 1 year out of this Frankenstein beast.

 

The Rubicon is a 500 Liquid cooled motor unless he meant a 250 Recon.
A Foreman rear axle will have twin dual shocks.
To change the read diff oil you just drain the oil out from the bottom bolt. The smaller top bolt is where you fill it,once its over flows you have the correct amount or it has a small middle oil check bolt like the video below.
Here is a vid on it,its a Rancher but there all done the same. There should be a hole on the skid plate to get at the drain bolt so you do not have to take it off.

 

So I was fed up with the rear end and trying to figure out the brakes. I planned on putting it all back together and buying the disc brake conversion kit for the front end and run without rear brakes. I've read about a lot of people just going that route.

I cleaned everything up and put everything back together, spun the axle and heard some grinding. I pulled it all back apart and noticed the outer seal opposite the brake was bad. I pulled the axle all the way out and picked ball bearings out of it. I'm guessing I need to replace all of the seals and then put it back together. I'm hoping that maybe someone can help determine the rear end.

The person I bought it from said it was an 08 350 rancher frame, 05 400 forman rearend, and a 250 rubicon engine. I've found that actually a lot of these atv's don't even exist so I have no clue what parts he pulled from what atv. The closest rearend I've found is the 400ex. Any chance anyone can confirm or deny that based off this pic?

 

400ex is chain drive...Is this photo your atv? 250 recon and 250ex is the only honda thats has drive shaft of that side. IMO. rubicon is an 500 water cooled an drive shaft on the other side, dual shocks like mention above post.this is an recon engine also in the photo

 

all foreman have dual shocks..Only one in this photo.

 

You can look at the base of cylinder an the cc is printed in cylinder base.