Ok, so I've been sitting on this information for a while just because I've been WAY too lazy to actually post something about it. Part of it probably is because I don't have the right tools to accurately measure the runout that several other people have mentioned with the latest generation of OBX 40mm LSDs from Chinaland. So what I will tell you is what I found and what I did to 'fix' the problem. This included brand new hardware and springs
Straight out of the really crappy packaging that didn't really protect the unit. It's a solid chunk of steel so I wasn't too worried about it.
Shot of the spring washers like they came from the factory
Starting to unscrew the SHCS. Right off you notice that a few of the screws were way harder to get out than others
As you can see, a couple of the screws seem cross threaded. I marked which holes the hard ones were on the case
Close up of the worse ones
Bevelle spring comparison. A typical problem with these LSDs is that the springs fail. So, I found some from MSC that were a bit thicker and felt way better. Factory installed are on the right
Ok, so here is the money shot. Those screws are not cross threaded. When I was looking over the unit after pulling out the screws, a few of the holes in the top half of the case didn't really match up with the threaded holes in the bottom half. Oddly enough, the ones that looked like they didn't match up too well were the ones that the screws were hard to get out. There was just enough room so that when you fooled with it a bit, you could get the screws started, but they were not happy being tightened down. So what to do? The easy solution was to drill out the upper half to make the holes a little bigger so that the poor machining wasn't as noticable. I did this with a drill bit that was just a size or two bigger than the hole was to begin with. Now it was much easier to get screws in and out and it didn't take enough material off the top half to hurt being able to hold the case together
Here is the thing. With the LSD straight out of the box, I was able to clearly notice the runout wobble with the unit installed in the clutch half of the transmission case. When I took the unit apart, and installed just enough screws to hold it together in holes that were 'good' the run out wobble went away. I'm not saying it was completely gone, but I couldn't see it with my eye and I looked really closely. After the above modifications, I tested it again after locktiteing all the screws, installing the upgraded springs and re-tapping the screw holes for good measure. Same thing, no wobble. The screws went in much easier now that they were not having to deform themselves to get in the hole. Now I don't have a nice dial gauge with magnetic base to test things and get real numbers, but I was more than happy with the results of my modifications. LSD got installed, and I've put about 1600 miles on it, no problems with the modifications. Even snapped a half shaft at the drag strip. I also did the same thing for a unit that went in Dr. D-Series' car and he hasn't had any complaints. Only thing we both noticed, which had been documented by other people on the interwebz, was that one of the axles is snug and could use a little bit of loving from a brake hone to make it easier to get in and out.
So I submit this post to you, RHMT. Take it or leave it, maybe someone will find it useful. I also have a bunch of extra beefier bevelle spring washers and one grade stronger SHCS bolts that fit these suckers cause MSC sells bulk, so if anyone wants to just buy enough to do one, I got you covered for nog cheap.
Author
Topic: What I found with the new generation OBX LSD (Read 11746 times)