OBX Helical LSD
#41
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
My buddy just installed one last week, initial impressions make it seem very similar to oem. The real test comes this weekend, we'll be at buttonwillow, I'm not driving said car but I can report back if it fails in any manner. With a few hundred street miles so far it's nice and quiet and seems just like oem, install was also a breeze.
#43
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
My buddy just installed one last week, initial impressions make it seem very similar to oem. The real test comes this weekend, we'll be at buttonwillow, I'm not driving said car but I can report back if it fails in any manner. With a few hundred street miles so far it's nice and quiet and seems just like oem, install was also a breeze.
#44
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Guess what arrived in the mail today:
![](https://lh6.googleusercontent.com/_T4-XMt0y3Z0/Taemhv74o-I/AAAAAAAAAMI/Uhi0n0k6F50/s640/IMG_20110414_185848.jpg)
I'm going drag racing this Sunday, and then again two weeks from this sunday. I don't have time to install it before this racing event, but it'll be in before the next one so I'll definitely be able to give a comparison on it. I'm also pretty sure my current dif is an open one, but I'll find out for sure once it gets taken out. I'll probably take the obx diff apart tomorrow morning. Pics to come.
![](https://lh6.googleusercontent.com/_T4-XMt0y3Z0/Taemhv74o-I/AAAAAAAAAMI/Uhi0n0k6F50/s640/IMG_20110414_185848.jpg)
I'm going drag racing this Sunday, and then again two weeks from this sunday. I don't have time to install it before this racing event, but it'll be in before the next one so I'll definitely be able to give a comparison on it. I'm also pretty sure my current dif is an open one, but I'll find out for sure once it gets taken out. I'll probably take the obx diff apart tomorrow morning. Pics to come.
#47
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Well I went to do the rebuild today, and everything has gone well so far. I would be done by now but I forgot to pick up some blue locktite, and will have to bolt it together tomorrow. But my impressions so far are good, except you definitely need to order the bolt/washer kit upgrade that was linked on the first page of this thread. The bolts were way over torqued, and the hex head on one of them was all fubar'd. I had to hammer my allen key into it, and took my time backing it out. The bolts are significantly thinner in diameter then the replacement ones. Also, the washer that came with the LSD are pot marked and of very cheap quality. None of them were cracked though.
What I spent the most time on was figuring out what washer combination I would put in. The company that sells the washers/bolts recommends certain combinations, but they were either higher or shorter then the stock obx washer configuration. The washers are curved, so I ended up just mimicking the stock configuration (from the bottom washer it goes Down, Up, Down, Up, Up, Up). I spent about 35 minutes on this part, because I really don't want to have to take this out. So I'm trusting OBX enough on their base configuration for this.
The gear work within the diff seems awesome. Very sturdy, and everything just falls back into place when reassembling it. It doesn't feel cheap at all.
Here's the pics:
![](https://lh5.googleusercontent.com/_T4-XMt0y3Z0/TaiGFqoKrmI/AAAAAAAAAMk/seTmdAXk1EY/s800/DSC01962%201024.jpg)
![](https://lh3.googleusercontent.com/_T4-XMt0y3Z0/TaiGHNACFsI/AAAAAAAAAMo/2Hr2LLyp0AQ/s800/DSC01963%201024.jpg)
![](https://lh6.googleusercontent.com/_T4-XMt0y3Z0/TaiGI5WaijI/AAAAAAAAAMw/aOeVrGIGoN0/s800/DSC01964%201024.jpg)
What I spent the most time on was figuring out what washer combination I would put in. The company that sells the washers/bolts recommends certain combinations, but they were either higher or shorter then the stock obx washer configuration. The washers are curved, so I ended up just mimicking the stock configuration (from the bottom washer it goes Down, Up, Down, Up, Up, Up). I spent about 35 minutes on this part, because I really don't want to have to take this out. So I'm trusting OBX enough on their base configuration for this.
The gear work within the diff seems awesome. Very sturdy, and everything just falls back into place when reassembling it. It doesn't feel cheap at all.
Here's the pics:
![](https://lh5.googleusercontent.com/_T4-XMt0y3Z0/TaiGFqoKrmI/AAAAAAAAAMk/seTmdAXk1EY/s800/DSC01962%201024.jpg)
![](https://lh3.googleusercontent.com/_T4-XMt0y3Z0/TaiGHNACFsI/AAAAAAAAAMo/2Hr2LLyp0AQ/s800/DSC01963%201024.jpg)
![](https://lh6.googleusercontent.com/_T4-XMt0y3Z0/TaiGI5WaijI/AAAAAAAAAMw/aOeVrGIGoN0/s800/DSC01964%201024.jpg)
![](https://lh6.googleusercontent.com/_T4-XMt0y3Z0/TaiGIZ0EyeI/AAAAAAAAAMs/yhJsg-j7SWE/s800/DSC01966%201024.jpg)
#49
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I really hope this works out. I'd really like something that I could beat the crap out of for fun. I baby the torsen by never doing hard launches.
I would buy one of these, a 3.636 R&P and an "open" pumpkin to install it all, making the swap super easy. This may have just devalued the torsen.
Oh, then we can sell the torsens over on m.net
I would buy one of these, a 3.636 R&P and an "open" pumpkin to install it all, making the swap super easy. This may have just devalued the torsen.
Oh, then we can sell the torsens over on m.net
#52
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I wouldn't trust what OBX had on the washer orientation. Incorrect washer orientation was one of the big issues I saw frequently on other Honda installs. I used this orientation
)()()( when I did one for a friend's civic. I also lightly filed and sanded the raw sharp edges from the end of the worm gears and edges inside the case. It's probably not needed but it made me feel better.
I'll be going the OBX route in my Miata as soon as I sell off the S2000 lsd I have.
)()()( when I did one for a friend's civic. I also lightly filed and sanded the raw sharp edges from the end of the worm gears and edges inside the case. It's probably not needed but it made me feel better.
I'll be going the OBX route in my Miata as soon as I sell off the S2000 lsd I have.
#56
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Good idea. Here it is:
Here is my question:
I've torn the thing apart, and I guess I'm having difficulty trying to understand how to get the height right on the washers. My obx diff had 6 washers in it, and came in this configuration (if looking from the top down, I am starting with the very BOTTOM washer): )()(((. So it is in the combination of down,up,down,up,up,up. I'm really torn as to how to configure this. If I go with your sites recommendation, it seems to end up higher (if using 6 washers, even with the two top washers facing the same direction.
Could you please give some clarification on this? Should I just follow the OBX configuration? Thanks for your time!
Reply:
Dustin,
I wouldn't use the OBX configuration it really forces 3 washers to do all of the work. Additionally my washers are thicker so they are taller when you stack them (((
If you visualize compressing a stack of )()((( stack the right side of ((( is 3 times stronger than the left side so it just won't compress.
Here is some math. It is interesting to me but might bore you. If you don't like it just skip to the bottom bold sentences.
Given that configuration I would expect their stack height to be something like 9.9mm (assuming their washers are 1.2mm thick and 2.15mm tall)
My washers are 1.5mm thick and 2.15mm tall so...
I would probably try a )()() configuration. (that makes it 5*2.15mm = 10.75mm) so it is slightly taller.
It does however use an additional 2 washers that can compress.
We want between a 25% and 75% compression....
My compression height is (height - thickness) which is .65mm each. = 5*.65mm = 3.25mm
Assuming a 50% compression 3.25mm* 50% = 1.625mm
Assuming a 75% compression 3.25mm*75% = 2.4375mm
Their compression height is .95mm each = 3*.95 = 2.85mm
Assuming 50% compression 2.85mm * 50% = 1.425mm
Soooo the overall heights would be.......
9.9 - 1.45 = 8.45mm
10.75 - 1.625 = 9.125mm
10.75 - 2.4375 = 8.31mm
So if they were around 50% compressed then the )()() config should work for you if they were compressed more than that then go with )()((
Just count your turns from the time the case is suspended by the washers until the two halves touch (just touch not torqued to spec). If it is under 2 turns on the bolts then you are good. If they don't touch or it takes more than that then I would go with a )()(( configuration.
-Rich
Here is my question:
I've torn the thing apart, and I guess I'm having difficulty trying to understand how to get the height right on the washers. My obx diff had 6 washers in it, and came in this configuration (if looking from the top down, I am starting with the very BOTTOM washer): )()(((. So it is in the combination of down,up,down,up,up,up. I'm really torn as to how to configure this. If I go with your sites recommendation, it seems to end up higher (if using 6 washers, even with the two top washers facing the same direction.
Could you please give some clarification on this? Should I just follow the OBX configuration? Thanks for your time!
Reply:
Dustin,
I wouldn't use the OBX configuration it really forces 3 washers to do all of the work. Additionally my washers are thicker so they are taller when you stack them (((
If you visualize compressing a stack of )()((( stack the right side of ((( is 3 times stronger than the left side so it just won't compress.
Here is some math. It is interesting to me but might bore you. If you don't like it just skip to the bottom bold sentences.
Given that configuration I would expect their stack height to be something like 9.9mm (assuming their washers are 1.2mm thick and 2.15mm tall)
My washers are 1.5mm thick and 2.15mm tall so...
I would probably try a )()() configuration. (that makes it 5*2.15mm = 10.75mm) so it is slightly taller.
It does however use an additional 2 washers that can compress.
We want between a 25% and 75% compression....
My compression height is (height - thickness) which is .65mm each. = 5*.65mm = 3.25mm
Assuming a 50% compression 3.25mm* 50% = 1.625mm
Assuming a 75% compression 3.25mm*75% = 2.4375mm
Their compression height is .95mm each = 3*.95 = 2.85mm
Assuming 50% compression 2.85mm * 50% = 1.425mm
Soooo the overall heights would be.......
9.9 - 1.45 = 8.45mm
10.75 - 1.625 = 9.125mm
10.75 - 2.4375 = 8.31mm
So if they were around 50% compressed then the )()() config should work for you if they were compressed more than that then go with )()((
Just count your turns from the time the case is suspended by the washers until the two halves touch (just touch not torqued to spec). If it is under 2 turns on the bolts then you are good. If they don't touch or it takes more than that then I would go with a )()(( configuration.
-Rich
#58
Cpt. Slow
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (25)
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 14,360
Total Cats: 1,184
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
What doesn't make sense? Buy the $270 OBX LSD diff, the $32 washer and bolt kit, skip the math of the above post and orient the washers as described, reassemble, install, done.
What part of a $302 diff is expensive?
What part of a $302 diff is expensive?