Stuck differential cover

[Mike B]

I picked up a used Nissan Comp R200 LSD yesterday, but I can not seem to get the rear cover off it. I removed the eight bolts that should hold the cover on and tried pounding it with a heavy rubber mallet, but the cover won't come off. I even tried putting the mustache bar on it and wacking that, but it didn't help. I also tried using a razor blade to cut the edge around the gasket. That didn't have much effect either. It looks like there is a small notch on one of the bottom corners that I may be able to insert something to pry it with, but I am afraid if I do that the aluminum cover will be damaged. I sprayed the edges of the gasket with some kroil hoping that might soak in and loosen it, but nothing yet. Any suggestions? Should I just take it to someplace that works on differentials to see if they can get it off?

-Mike

[geezer]

The gasket is more than likely cemented on both sides bonding it very securely. I usually use a 1" wide, very thin blade putty knife and tap it with a hammer around the circumference until it breaks loose.

Start off with a few good whacks on the top of the case, just in case you do knick the mating surface a bit, so it is less likely to leak.

Edited November 1, 2010 by geezer

[Zs-ondabrain]

Put some Muscle into it Mike, Beat the hell out of it and show it who's boss.

[Darrel]

just beat it, we are just talking about the diffy cover right?

[Mike B]

just beat it, we are just talking about the diffy cover right?

Yeah, just trying to get the diff cover off. I know it should be easy, but its really stuck. I was pounding on it with the rubber mallet and it wasn't budging. I thought putting the mustache bar on and pounding on that would do the trick, but that didn't help either. I'll have to see if I can get a really thin putty knife in there like Ron suggested. If that doesn't work I'll take it over to he-man Dave's and he can show me how to muscle up .

-Mike

[Darrel]

After the putty knife, you can use a brass drift/punch and hit at the thicker portions of the cover, areas similar that is on the transmissions to separate the halves.

[Zs-ondabrain]

If that doesn't work I'll take it over to he-man Dave's and he can show me how to muscle up .

-Mike

I got 5 kids over here, Pretty sure I can show a diff who is boss too.

But seriously though, a solid oak or similar wood or a solid lip with a dead blow should knock it loose without any real damage to the aluminum.

And the real this putty knife may work, if you can get it between the metals without the knife bending.

Good luck.

[FastWoman]

Here's an idea: Adapt an air hose to the drain plug hole. Shoot compressed air into it.

[RIP260Z]

Mike B,

I use the window putty knife method, works well, but does take a bit of effort. I usually find going in from the top of the diff where the diff casing and cover are at different heights, that way you know you are cutting through the gasket. A combination of using the point of the knife and curve blade, keeping the knife vertical and hitting it with a hammer.

Just hitting the cover does not work, on all the diff covers I have taken off, they are very well stuck.

[Mike B]

I was finally able to get this cover off last weekend. I bought a set of putty knives from Harbor Freight that have metal ends so you can hit them with a hammer http://www.harborfreight.com/4-piece-stainless-steel-putty-knife-set-94325.html. There is a hole at the top left corner that I was able to use to insert the edge of the knife and then then tap with the hammer to get through the seal (circled in red in the first picture). This cover was really on there tight and there is no way it would have come off without a putty knife, so thanks for the tips Geezer and RIP260Z. It looks like the gear ratio is 4.375. I may see if I can get a 3.90 ring and pinion to put in it. I was also able to get a Mallory Unilite and an early Nisan 2400 OHC valve cover from the same car for another $100 .

-Mike

[jmortensen]

Don't put the gears in that diff. Put the LSD into the diff with the 3.90 gears. MUCH easier job. I did a write up on hybridz.org in the FAQ section.

[geezer]

Glad it worked out. Is the lsd destined for any particular car Mike? I'm kind of curious because it doesn't seem like a modification you would make on any of your '69 build cars or such a low milage, original '72.