I was under the car and noticed that the passenger side half shaft and areas all around it had a oily grime all over it. Feels like it could be a heavy gear oil, with years of road grime embedded in it. Driver's side was completely clean & dry - see pictures below for comparison. I took the pictures after I started cleaning up the passenger side.



Here's a shot of the filthy passenger side half shaft

And here's the relatively clean driver's side half shaft

My 1st thought was that the boot was ripped, and the grime is from the CV joint grease. Since taking the picture, I completed cleaning the mess so I could get a good look at the boots - they are fully intact with no tears or breaks anywhere on them, so the CV joint is probably fine. Next suspect is gear lube leaking from the diff/half shaft seal, So plan is to just observe what happens after the cleaning. Are there any other possibilities here? Are the FD diff mount bushings/mounts above filled with any fluid that could leak out?

 

yes, your suspicion is accurate. the diff bushings directly overhead are oil filled. could be that. now that its all leaked out, it should remain dry unless its a diff seal.

 

Yep, it’s likely one of those. I’ve dealt with both. Seems like when my bushing started leaking it got onto the exhaust as well. Looking up with a good light and checking the bushing might tell you more. Cleaning and re-checking is the right thing to do. But with the picture and your suspicion of gear oil my money would be on the differential side seal.

https://www.rx7club.com/3rd-generati...-seals-517073/
(Let me know if you need any pics...I think I still have them)

https://www.rx7club.com/3rd-generati...hings-1128159/

 

There's a thread within the past week or so on the diff mounts, that's a strong possibility or the diff seal where the half shaft goes in on that side. If that seal leaks it flings gear oil all around the place.

I think you're on the right track, clean everything up and go drive around, see where it's coming from. if it's the diff bushing it may not come back, it's a relatively small amount of fluid in that bushing so if it's all leaked out that's the end of the mess.

Heck, may just be worth replacing both diff seals, putting new diff bushings in, and filling the diff with fresh fluid. Obviously something is/was leaking, might as well go through everything.

Dale

 

+1 on the slippery slope. I personally think it's the diff, but if you're in there, you may as well change out the bushings (if they are original) and the fuel filter as well (if that has not been changed). And if you're pulling the axles, may as well change any loose rear suspension bushings. And if you're changing your rear suspension bushings, front....

 

If it’s the side seal leaking I might change them both...they’re cheap. And maybe when the right axle is pulled it would help access the fuel filter.
But you don’t have to drop the differential to change the side seals. And those diff bushings are a much bigger job and more expensive.

 

Thanks guys, this FD is becoming a slipperier slope every day Good thing I have a lift in the garage and more shop time thanks to this freaking zombie virus quarantine to work on it!

It will be quite a while before my FD is back on the road again - I just started the Link ECU rewire job, and will be pulling the motor to make it easier to do the oil pan brace and a bunch of other things under the hood, such as add the 2nd oil cooler, restore a working AC system and figure out how I want to handle the radiator/IC & condenser packaging. Speaking of which, does anyone know what kind of FMIC this is and what it might be worth? It's a really nice piece, but I'm probably not going able to make it work in a FMIC or SMIC config with A/C, so it may be up for sale soon.

 

That's an Apexi front mount, I used to have one in my car. It's a quality front mount.

Dale