82 XJ750 maxim

Hi fellow riders.
- Is it ok to use a synthetic 80w-90 in the final drive?

-My final drive vent does not resemble the illustration in the manual. In fact it does not resemble a vent in the least. It looks like a plug that someone stuffed in the hole. It is conical, hard as a rock, doesn't move and has no visible vent relief mechanism or even a hole in it. I also have no idea how to remove it. (can't find it in the manual) any feedback would help.

- The wheel drive hub o ring shows signs of heat damage and there must be a build up of pressure and heat cause the molly is seeping through. Got me figuring it is not venting.

 

Is there more than one style of vent cap? Mine looks like what you are describing instead of the mushroom shape in the book. In either case I believe they are pressed into place.

But here you can see there is a hole near the top, leaking from laying upside down on the bench. Maybe yours is plugged with dirt.

Regarding the synthetic oil, I'm guessing its fine, but can't qualify that with experience. These are spiral bevel gears rather than hypoid, so there shouldn't be any exotic requirements.

 

For the final drive, I would just use whatever the manual calls for exactly, synthetic for synthetic, non for non. There are some forums on the topic, some people say its fine to run the synthetic, some people say that there is a metal in the drive, brass I think, that doesn't play well with the synthetic. Either way, I don't see a point in taking the risk when you can just put in the called for stuff. Just my 2 cents

 

Thanks.

I'll use what the manual recommends. Thanks for the input.
I found a small hole on the inward side of the breather finally.

 

For what it's worth, I looked again when I got home at my 2 different '82 XJ750J's and one has the mushroom cap and one has the cone. Both original as far as I know. Probably one of those small parts that changed design and they just used up all the old stock??

 

Thanks lots. Big relief..