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Old 03/31/2012, 06:04 AM   #1
Dj Technick
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Default 4.625 ring and pinion swap.

Had a few issues come up with the car over the past couple days. Started to make a strange "clicking" noise coming from the rear on the driver side of the car under deceleration. Not sure as to what it was I crawled under her to check it out. Found that my axle wasn't in the best of shape. Kept driving on it for a day and the noise increasingly became worse until the axle finally said "I don't like you anymore, time to commit suicide."

Simple fix right? Bought a brand new axle from the part store and threw it up in there. Only this made the noise far worse...Now it was doing it on both decel and accel...This really concerned me of course, so I check it out again only this axle felt a lot more stable. This made me decide to drop my differential to get a look at her, maybe that's where the noise was coming from.

Pulled the rear end, opened her up and well, everything was perfectly fine, not a single mark anywhere on it.

Went back to the new axle I had just installed to find out, it was junk too...So I had to order in a new one which was going to take a day. I also needed some gear oil now, and decided I would wait to put the diff all back together when I picked up the new axle and got some gear oil. The same day me and Leon went out the junkyard to get some parts for a customer car and stumbled across a shit load of early 90's Nissan Pathfinders, and it just so happened that there were a few out there that were AWD with the 3 speed automatics. Now for those of you who don't know, the frond differential in those cars is also an R200 diff which comes factory in the 240's, silvias, and a lot of other nissans. However, these in particular pathfinders come with a 4.625 gear ratio where as the 240 has a 4.08. My diff was already torn apart so why not have a little bit of fun right? Unfortunately we had gone out there a little late in the day so we had to wait to head back out there. Sure as shit, it of course has to rain on the one day I need it not to.

Determined to do this, we said fuck it, loaded up the tools and set sail to Car Country! Had them lift the front of the car in the air, threw a couple spare tires underneath to hold it up, and snagged some carpet out of the surrounding cars and went to work.

It looks like it's a cake walk to get one of these out at first glance, all the bolts came loose as if the car was brand new. Everything was going well until it was time to pull it out. We spent a good hour trying to pry it out but it wouldn't budge. Right on the edge of defeat Matt Cossel showed up out of NOWHERE! Literally, dude came straight out of nowhere! Thanks to his quick thinking and with the aid of an exhaust pipe as a prying bar we were able to get it out. Then he even helped carry the thing from the back corner of the lot all the way to the front!

Anyway, onwards we go. Switching out the ring and pinion is rather simple, a bit time consuming and a slight pain in the ass, but simple. 4 bolts and the passenger side outlet pops right out, then a single bolt on the driver side and that oulet pops right out. 4 bolts holding the the actually diff itself, and one nut holding the pinion on. After you get that all taken apart there are 10 bolts holding the ring gear.

And wala, she was all taken apart.

Here's a comparison of the stock 240 ring and pinion and the Pathfinder one. The 240 is the top one and the pathfinder the bottom one.

Here's a shot of the gear ratio's just to show you it is a 4.625. In case there is anyone that has no idea how I got 4.625 out of looking at this, you simply divide the number of teeth on the ring gear by the number of teeth on the pinoin. In this case 37 divided by 8.

Then you simply bolt the ring gear onto the diff, mine is an s15 HLSD for those of you who are wondering.

Also install the pinoin in the casing, takes a little bit of work to do. I reused my bearings because they were all in beautiful shape, plus I like to be cheap when I can.

Thew the diff into the casing and installed new output seals while I was at it.

Add some RTV and bolt up the casing, also slip the outputs in place and she's ready to go back in!

I spent a total of 125$ to change out the gears. The junk yard charged me 75$ for the differential and the gear oil was 20$ per bottle. I used Royal Purple 75w90, a bit on the pricey side but well worth it especially when you have LSD!

The change in gear ratios isn't as ridiculously dramatic as you might think, but there is quite the difference. After doing just one quick pull through 4th I could really tell.

I would again really like thank Leon Wilson and Matt Cossel for helping me with this, not sure if I could have done it without you guys!


Damn that's a good lookin' pixel car ;)
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Old 03/31/2012, 10:22 PM   #2
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Lee_MA61 is offline
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Posts: 152

Default Re: 4.625 ring and pinion swap.

nice write up nick and yes this swap was well worth the time and effort.


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Old 04/01/2012, 07:47 PM   #3
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Default Re: 4.625 ring and pinion swap.

Gear changes are your best bang for the buck mod, hands down!


Romans 6:23 - "For the wages of sin is death, but the gift of God is eternal life through Christ Jesus our Lord."

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