So I just installed a LSD in my FB. I noticed when driving yesterday (on my way home from work) that I had some gear whine. I went to check my gear oil level, and the plug was stuck. I soaked it in Aerokroil (think PB Blaster from hell and you'll start to understand the strength of this stuff), and let it sit overnight. Drove to work and back, picking up 2 quarts of Royal Purple 75w90 gear lube w/ LSD addative, and got home. Attempted to remove fill plug, and again, it didn't budge. I heated around the fill plug with a propane torch, and pulled. No dice. I then heated it again, put in the ratchet, and used my foot to push on the ratchet. The hole stripped. I am wondering if this is a fix I can do, or if I should take it to a trusted mechanic and have them remove both plugs, re-tap if necessary, and fill with my royal purple).

 

You can repair it yourself by putting a heli-coil in it. There are also some over sized self threading oil drain plugs that you can get and may be a easier way to fix.

 

your talking about the square hole that the 3/8ths drive goes into is stripped right? You will need to weld an extension piece to the plug and get a new plug. should fix the problem. I had a hard time getting mine out also. I used my feet, and had my girlfriend hold it in place.

 

^ If that is the case their is a thread on this already from around a month to 2 months ago.

https://www.rx7club.com/showthread.p...highlight=diff

 

Could he just remove the entire rear cover, then replace it with the one from his old rear end? Just woke up, and I'm having a hard time picturing the rear cover, but I can't think of why that wouldn't work.

Anyway, congrats on the lsd dude, you're going to love it. Also, I used the RP w/additive when I did my conversion, and ended up with horrible chatter. Had to get an additional tube of additive, and that took care of the problem.



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Yes.

So the only way with the 3/8" hole stripped is to have another bolt welded on and break it free that way, or drill it out?

Kentetsu- There isn't a removable back cover, just the pig is removable.

 

Best bet is to weld a socket extension on there and then pop it off. Use an impact if it is really stubborn. Replace with new plug.

If you drill it out, you'll get a bunch of metal in your rearend and that isn't very fun at all.

When I was a total newb, I made the mistake of draining the rear before checking to see if the fill plug would come out. Fill plug was stuck. Luckily there was a truck stop not far and drove the car down there with only whatever oil was still stuck to the gears/housing. Real tall/skinny dude slide under the car (without jacking it up at all) and hit it with the impact. Didn't even charge me for it. Now, I know better.

 

If the housing is stripped, then why not just drill it out and replace with a 1/2 NPT plug? You can pop the axles out, remove the chunk, and get on the back side of the fill plug to catch the shavings.

 

I don't think the housing is stripped. I think just the 3/8" square drive hole is stripped because the plug was too tight and is now rounded out.

If it is not too bad, you still might be able to get it out using an impact wrench without welding the extension on there if there is enough meat for the impact wrench to grab. Otherwise, weld the extension on there and pop the plug off.

 

I had the same problem not too long ago. I would take it to a shop and they can heat it with an acetylene torch which is way hotter than propane. Should come right out. If it is stripped so bad that you can get any tork on it (which is how mine was) drill out the plug starting with a very small drill bit and getting bigger and bigger so that you are more likely to drill right in the center. Don't drill out the whole plug and go and buy the biggest, baddest easy out you can find, find a 1/2" socket that will fit on the end of the easy out, then bring to the shop, heat with acetylene and it will spin out with such ease you won't even believe it was stuck to begin with!

 

Drill it and use the appropriate-sized (very large) extractor on the remaining shell of the plug.

You might also try freezing the plug with dry ice, rather than heating the housing... as heat makes metal expand, but cold makes it contract, and what you want is not an expanded case (making the hole smaller), but a contracted plug. You can also try heating the whole affair, then freeze-shocking the plug with the dry ice. Dry ice works best for this because you can't get a steam explosion from it like you can with water ice, and it's much colder (-100f)

Last ditch you can have it bored out thin enough that you can collapse the remaining plug... but you're off the car and disassembled at that point, so it might be easier/cheaper to just get a new housing.

 

I'm going to pick up an IR impact gun on my way home from work, and I'll pound in a 3/8" extension into the fill plug and see if I can break it free with that. If not, then I'll try a 1/2" extension pounded in. My neighbor has a welder, so I may also ask him if he can put a bead around the extension so it doesn't slip out of the plug. I'll let you guys know how it goes.

 

So the impact gun stripped the fill plug the rest of the way.

I took my dad for a ride (he was an engineer for Ford's rear axles from 1987-1992) and he said that I have nothing to worry about. It sounds like normal gear whine under acceleration, and since there is no whine under constant load, that I have no issues.

Next time I go to my Grandpa's place, I'm going to have him weld something onto there and we'll hit it with my Uncle's impact gun (he has an impact gun that's good for 1800 lbft of torque, and he carries up to a 4" impact socket on his work truck at allt imes) to blast it off.

thanks for the suggestions.