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Precision Gear unit installation for 4.37 R180... Pics!


Leith280zlt1

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This installation was kindof tricky because the ring gear for this R180 has a larger diameter than any other 180. The ring gear was about .2" larger than the LS carrier. What I did was make a sleeve that fit over the carrier and inside the ring gear so that it would be perfectly centered. I made it right on size because the ring gear is a 0" tolerance part. I machined a piece out of aluminum so that it had about a .010" lip underneath the ring gear so that it has no chance of comming off inside the differential and causing problems. The ring gear has a large chamfer on the inside that made this possible. So now it's pressed on and has a lip that will be underneath the bolted ring gear to keep it from ever comming loose.

 

Here's some pictures of the process...

 

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I mounted the differential on an engine stand so that I could rotate the differential as I needed to...

 

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The old open differential carrier, new ls carrier, ring gear and sleeve...

 

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Sleeve in the ring gear...

 

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Heated the sleeve and dropped it on the carrier. Now that the sleeve is on the carrier, the ring gear will have to be heated also to fit over the sleeve. I turned the heads of some old 10mm bolts down so I could use them as guides while I dropped the ring gear on over the sleeve and carrier. That was the easiest way to make sure the bolt holes lined up...

 

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The Precision Gear unit with the ring gear torqued down. Should look great in it's housing.

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VERY nice install.

 

The carrier changed in the mid 70's and they went to the larger diameter ring gear. You can probably order that same Power Brute diff for the front of a mid 80's Nissan truck (720?), or even just a later model Z and then you won't have to make the spacer, but it looks like you did a hell of a job on the spacer.

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  • 1 year later...

A few weeks ago I installed a PowerBrute LSD (I think it's the same as Precision Gear) in my 4.11 diff from a 720 4x4. At first I was not happy at all as it was locking all the time. With a lot of driving, especially some figure 8s in parking lots, it has settled down A LOT. So far all my experience with it is on the street, but we have one more track day this weekend so soon I'll know more.

 

Pros: the rear end is much more stable now. I can apply the throttle sooner when cornering. Also, when the rear end does break loose, it is so much more gentle and easy to control. Before about all I could do is lift. Now I can add some opposite lock and bring it back in. (Keep in mind I have a N/A L28, no massive torque like some of the V8 guys here.) Plus it's fun to see 2 black stripes out the rear view mirror if I dump the clutch.

 

Cons: even at mild street speeds (say 35 mph), when going around a bend, I can feel the front end does not want to turn in as well as it used to. If I let up on the throttle, the rear end "unlocks" and the front suddenly turns better. It's not enough to make the car unstable at all. The steering responds better to bigger inputs now, before it was more finesse. I'm exagerating this to make the point: I suspect if someone who didn't know my car well drove it, they might not notice it if I didn't point it out. I am getting used to it. Also, now and then at slow speeds making sharp turns, like in a parking lot, there is a clunk as the diff locks or unlocks. Not a big deal.

 

I'd say that for my style of driving which is mostly street, and without the torque of a V8, I may have gone overkill on this. A less agressive unit would probably have given me most of the goodness of the LSD without as much of the comprimise.

 

Any of you more experienced with LSDs, please chime in and let me know what you think of my experience with it so far.

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The PowerBrute LSDs are not like a Detroit Locker, where it's either locked or not. They have the clutches that breakaway with a preloaded amount of pressure. As for turn in properties, if you went from an open diff to a LSD, it will feel like and probably won't turn in quite as well. If you are letting off and it turns in better, that's just a weight transfer thing and is natural. You need to run the car on the track and play with the balance of the car. If you want a little better turn in, go with a rubber endlink bushing set on the front bar to get a little more front grip, if you are running a larger bar with poly bushings. Hope that helps.

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Gary, thanks for the comments - the previous car I had with an LSD had a setup where it was totally transparent, so I'm not sure what's normal with this one. I can say that the change in willingness to turn based on throttle is far more than just weight transfer. It happens at speeds slow enough (35mph) where all 4 tires are completely within the limits of their grip.

 

The diff I have came from a 720 pickup, so I can't vouch for the early R180 and this LSD. Of the 2 that Powerbrute sells for R180s, I ordered the latter. The ring gear fit perfectly on the LSD.

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