Help! Possibly blown rear diff? Car being towed now.
 

Okay I just changed my rear diff fluid with redline 75w90. Drove about a mile when the rear locked up and caused a stall. Now the car won't move and the rear shudders when I try and drive. Worried the diff is gone. Could I have screwed something up changing the fluid? Thanks for any help. Car was running like new yesterday.

2009 R3 60K KMs

Alright. I just realized i'm a total idiot. I forgot to put the drain plug back when I was refiling. So my diff is probably dry. When I get it back home i'm gonna refill it. What are the chances i've done permanent damage?

Thanks.
And. Reminder to always triple check you work.

I'd say pretty good.

How do you not put the plug back in? When you were refilling did you not see it coming out?

Pretty much full blown idiocy. Plus being distracted.

So i'm planning on refiling it properly and then seeing how it is. It it ok to try and drive it after I refill?

Am I gonna need a new differential?

Quite frankly I don't know. I have never heard of anyone doing that before. My "guess" would be that if it locked up while driving, it's already toast and all the oil in the world won't help it. Will it hurt to try, I don't see why it would. The worse that can happen is exactly what's happening now, nothing. Probably not what you want to hear, but a new ring and pinion is on your shopping list, maybe you can find a good deal on a whole pumpkin somewhere. It would make the job a little easier. Good luck bro.

Ugh I feel sick right now. I can't believe myself. I'm young, my car is my baby and after all the work i've done on her I slip up like this. Anyway I really appreciate the insight. Thank you.

Alright, so I just topped up the diff fluid, it's better but the there's definitely damage done. I'm honestly at a loss for words right now but I just need to figure out how to fix this.

So I guess my question is, what needs to be replaced? Just the ring and pinion? And is it feasible for me to do the repair myself?

I'm really sad and in shock right now but I just want to know what I can do to fix this.

Thanks a lot

You can get one here for a couple grand. Unfortunately yes yours is done.

The most expensive lessons are usually the most painful and wont be repeated.

I definitely won't forget this. Is it just the ring and pinion that I need to replace? Or the whole pumpkin itself? And I assume it's best to have a shop do it? I was looking on mazmart and it looks like they are around 700$ for just the ring and pinion.

Thanks for the advice, I feel like I killed her, and I need to fix her asap.

I would do the whole box you might have some trashed bearings. Or at least go to a transmission shop for the rebuild.

Alright. Thank you. I'll look around here and try and buy one. Would you happen to know any other places I might be able to get the whole box? If it was you how would you approach this?

Anyway I really appreciate the help, my Rx-8 means the world to me and I just want to see this damage undone.

Ring and pinion is all that will be needed (shims and bearings maybe, but the casing will be usable), if I was you this would be a great time to invest in 5.12 gears :cool:

As much as I would love 5.12, i only DD my car and the gas already kills :P So let me get this straight. If I just buy a new ring and pinion and then have it rebuilt I should be ok? What if the bearings and shims are bad? I'm sorry I wish I was more experienced but all this stuff is a level above me. Is there any possibility that the damage is so bad that I need to replace the whole axle(worried about axle bearings)?
Thanks guys, this really means a lot. I'm practically depressed here and all I can think about is the best way to fix this.

Won't know that till you get it out and opened, ring and pinion for sure. Shop will tell you everything else and should be able to source it.

Buy a good used diff and replace it. Not going to be able to salvage a lot of that one I wouldn't imagine