OBX Helical LSD
 

Well I took the plunge and finally ordered the OBX helical LSD that keeps getting tossed around on this forum. I'm pretty sure my "Torsen" rear end that my mechanic from years ago sold/installed for me is an open diff. I did the parking lot test and it failed miserably. Once I get it I'll replace the bolts with something stronger (as I've read this is a failing point on Honda versions of the OBX LSD). I'll post pics once I get it and feedback when it's installed.
http://www.racingpartsdepot.com/pictures/10523.jpg

******************Update - 04/29/2011
The OBX Diff is installed and functioning perfectly. Here's a quick how to:

1. Buy the OBX Helical Differential
2. Order the bolt and washer kit from here:
http://rbryant.freeshell.org/obx_washers.htm
3. Open up your new OBX differential.
https://lh6.googleusercontent.com/_T...958%201024.jpg
4. For some reason OBX appears to sometimes assemble rear wheel drive differentials in a FWD configuration. Here is the wrong and right way:
http://batou1.googlepages.com/obx_gears.JPG
5. If your gears look like the WRONG picture, you need to swap the gears on the top with the gears on the bottom. This is easy to do.
Mine when I first opened it
https://lh3.googleusercontent.com/_T...963%201024.jpg
And with the gears swapped (top to bottom)
https://lh4.googleusercontent.com/_T...425_210521.jpg
6. If your gears are in correct orientation, then just remove the top gears and remove the stock OBX washers. The configuration that worked well for me was all new 6 washers in this orientation: )()()(
7. Reassemble, put blue thread locker on the new bolts, and install in a diagonal pattern. Torque to 28 ft/lbs.
8. To install into your 1.8 diff you will need two new bearings, and a couple of seals. Direct from Mazda cost me $200.
9. BEFORE YOU INSTALL - you might want to take your shiny new differential to a machine shop and get them to measure the tolerance on the surface that the differential ring mounts on. Mine was not machined properly from the factory and was out 0.007, which caused the ring to pop out of the pinion. $100 of machining later and it was perfect.
10. Use the same gear oil that you use in the regular miata diff. I put in Royal Purple Max Gear.
11. Enjoy your new diff.

Cost breakdown:
Differential: $250
Bearings & Seals: $200
Bolt kit: $15
Gear oil: $20

That sits at about $485. If you need to machine the unit true then your cost might vary, but mine was $100 which is probably on the higher end of the price. If you consider that if you install a used Torsen or any other diff you will still need the new bearings and seals, then this actually turns out to be quite a sweet deal.

* One misconception to note. This is not a direct copy of the Quaife differential. It actually appears that OBX used some sort of in-house design, and it is unique.

I would inspect the conical pre-load washers, a lot of the Honda guys replace these right away. They also found the backside of the side gear splines aren't tapered so it's extremely hard to get the stub shaft or axle out.

Interesting, never heard of them making a diff. At $290 it's actually something I can afford. Although googling "OBX LSD" comes up with the first link of a "buyer beware" thread from a Honda forum, something about an axle not coming out a week after installation. If that's the worst part of the unit, it's not too bad. They damaged transmissions while attempting removal, something we don't have to worry about.

I'd just be concerned with it actually performing as an LSD.

Given that I'm considering buying one in the near future, I am curious about how it is. Will be watching this thread closely...

A friend of mine is a fabricator for Morris Tuning in new york. They do ridiculous Honda builds, and for people on a budget they have used the OBX lsd's before with success. I'm hoping the same goes here.

I don't see how my Torsen can possibly last much longer.

From what I understand about them, they're basically a copy of a Quaife.

A copy of a Quaife with shitty washers then? Doesn't sound too bad if new washers and bolts are $32 shipped.

I think I'll have to try this when I feel the urge to spend $280.

It's quite possible these are a copy of the Quaife, albeit with sub standard quality control. I worked as a machinist for three years, specializing in gear cutting. So all this information is common knowledge to me. It's interesting that he said honing with a brake cylinder hone helped, as most good splines are a major diameter fit. Aka the diameter centers the two pieces, where as the spline only locks it in. The bevels are merely a by product of not checking your parts enough. Anyone here know how to properly measure a bevel on a shaft? It's not a very precise measurement.

Where did you buy this and do they come in 1.6 diff size?

Ebay.

No. Sorry dude :(.

it would be nice if someone like emelio or sav looked into these. buy them, overhaul as necessary to make it reliable, then upcharge a little to resell

in for results!

So can this withstand more torque and abuse than a torsen?

I've seen a side by side teardown of a quaife & obx LSD, they are the same design but the fit and finish on the quaife was considerably better. I'm going to give the obx a shot regardless.

I have no experience with these, but I have seen numberous Honda builds with 500+whp using these. If you use that rebuild kit it should be great.

Thanks for that link. I just ordered the bolt/washer kit.

Nice one. Does it fit straight in the 1.8 diff?
Please do a report on the installation!

It should fit straight into the 1.8 diff, and I'm on the fence whether to do it myself or just get a transmission shop to swap it out. I'm busy with a bunch of garbage and I'm lazy.

I actually have one in my c60 (6spd) that is swapped into my corolla. works just fine. I did replace the bolts and Belleville springs before install with the ones from the posted link. I arranged the springs for max preload, a pattern like this ()()(). also torque the new bolts down to 40ft-lbs in a star pattern, kinda obvious.

It has gotten it's fair share of abuse since its install. I have no complaints

The diff arrived today. Now I just have to wait for that rebuild kit. First impressions are fine. It looks like a differential and it didn't fall apart in transit. Now let me take you through a journey of unpacking it.
https://lh4.googleusercontent.com/_T...953%201024.jpg
https://lh4.googleusercontent.com/_T...954%201024.jpg
https://lh6.googleusercontent.com/_T...955%201024.jpg
https://lh5.googleusercontent.com/_T...957%201024.jpg
https://lh6.googleusercontent.com/_T...958%201024.jpg
https://lh4.googleusercontent.com/_T...959%201024.jpg
https://lh5.googleusercontent.com/_T...960%201024.jpg

Man, I could really use some tarmac control.

That got me excited too.

I am looking forward to seeing/reading results. It would be sweet if you could get a comparison of how in tracklike conditions vs a stock torsen.

I'd love to, but there is no track on Vancouver Island. Well there's one track, and it's a tiny oval, and it's not open to the public. They basically do hit to pass. Yes I'm a sad panda.

I can't wait to see how this goes over...

I'm sure someone will start offering OBX diff rebuilds soon if its good news.

I have high hopes for this. Now take it apart!

That sucks man. Perhaps some side by side driving impressions to sway others to do a more in depth look then?

Other than the regular autocrosses with the Victoria Porsche club, VMSC, and Victoria MG club there isn't much track time for the public. The VMSC does hold 2 solosprint events a year where it's pretty much the full track with no cones and includes the hairpin. June 26 and July 23 are the dates for those events, you'll need a solo1 license though.

Have to say the finish looks nice. Mine is plain steel. So they are at least trying to improve. Waiting on the results in this thread before I order the new springs.

Guy at work bought a semi-riced out 2002 Civic for better mileage. Seller included all the paperwork on the mods (small wing, splitter, etc.) Turns out it has an OBX diff, and has run it for about 12k with no problems.

:drama:

I'd be really interested in one of these if someone can get some track time with it and show that it won't blow up or malfunction.

This OBX diff....... Is it merely a cost effective option for those that have an open diff, or a busted torsen, or is this an upgrade like an OSgiken?

*

I Will be doing some serious drag racing with this differential. I Am launching at 4500 rpm at 5psi of boost. I Can put up 60 foot times and it's definitely a stress test.

This may be my next upgrade assuming your install isn't horrific. Not looking forward to my own install, Someone needs to make a pnp diff. Page LEGO.

install it quick!

Fuck yeah! I was hoping that this would come back up. I looked at this the last time it was brought up. WANT CHEAP DIY LSD for my open!

This is what I'm thinking. If it's better than the stock torsen, then I may get one of these when I do the 3.6 ring and pinion.

Interested, provided it's more locked than not.

Dustin
can you weigh the OBX

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.

It's about 16.5 lbs.

That is good to hear. How much power is said car pushing and how hard is it being driven?

Guess what arrived in the mail today:
https://lh6.googleusercontent.com/_T...414_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.

I want the pumpkin from your old one!

I'm just swapping the internals so I'll still need the pumpkin.

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/_T...962%201024.jpg
https://lh3.googleusercontent.com/_T...963%201024.jpg
https://lh6.googleusercontent.com/_T...964%201024.jpg
https://lh6.googleusercontent.com/_T...966%201024.jpg

I'm conflicted on the washer configuration, so I just emailed the guy who sells the kit to give me some advice.

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

its pretty easy ()()()()()()()())()()()()()()() come on!


do we know what the torque ratios are for these things?

Those washers squish, you know that right? And were they too short or too long? As in the washers were loose once tightened, or there weren't any threads to screw in?

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.

I do know they squish, but there is a warning saying that they can't be too high. The guy has already gotten back to me and suggested a few combinations to try.

We have no idea.

Can you post the guys email response for future reference?

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

^???/ so confused. basically there will never be a cheap/simple solution to get me into the LSD lifestyle.

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?

No kidding, that's what I'm thinking. No more "Want my torsen for $700?"

Not that I really need one, but I've spent so much money already, what's another $300 when I swap gears.

Just and update. The diff is going in Tuesday, but I might not get the car back until Wednesday. Normally if I didn't need my car I would just do it myself, but I need the minimum amount of downtime.