Row2K

iTrader: (10)

Some forewords and prep:

Well, I know there was some interest in OBX LSDs on the forums and questions asked, but as far as I am aware no one has actually posted a successful install. Recently there was an un-used one for sale in the classifieds so I said f-k it, I'll toss some spare change at it and give it a go. This way I can let all you ungrateful schmucks know how it goes and maybe we can all find a new cheap option. I am here to report....things don't go as smoothly as one would hope.

As a pre-statement I should say I gave this some research and thought. OBX makes questionable quality parts, however the LSDs are a bit of a gem in the rough. The LSDs are approximate duplicates of Quaife Helical style LSDs for half the price. There are however two main issues:

1. The casing bolts are of inferior quality/low grade and should be swapped
2. The inner belleville springs are of poor quality metal and either disintegrate during use or arrive DOA

Both issues are easy to address and there are in fact now OBX LSD rebuild kits available from Rich Bryant:
http://rbryant.freeshell.org/obx_washers.htm

The previous owner of this LSD was aware of the two issues and took steps to rebuild it. He replaced the casing bolts with 12.9 grade bolts and attempted to replace the belleville washers inside per instructions found on Rich Bryant's OBX rebuild site.

There are however some complications. For reasons I don't understand the LSD comes not with belleville spring washers, but flat washers in between the main worm gears and to top it off they are a very odd size (45mm in, 55mm out, ~2mm thick):


There are no belleville washers available in this odd size, so the only solution was to install wave springs cut to size between the worm gears, like so:


With the Belleville springs taken care off or rather replaced with wave springs, the new casing bolts installed, and the LSD checked for any poor casting that might need to be cleaned up with a dremel it was ready for torquing down and installation:




Install:
This part starts easy; drop the diff, open her up, pull the old LSD:



Start unbolting the ring gear....my impact gun is boss btw


....hold on a moment
Here is where the interesting part starts. Looking at the VLSD I realized it looks a bit big compared to the OBX unit, so before I managed to ubolt the ring gear I stopped and did a test fit of the OBX into the diff only to have my heart sink a little. It doesn't fit

And by it doesn't fit I mean it's significantly shorter. I immediately stopped and started looking for resources. Luckily Quaife posts the dimensional drawings of all their diffs online, the auto, the manual, VLSD, or open diff options. They are all there and they are all 179mm in height bearing to bearing, which means the stock VLSD is 179mm as well. The OBX looks to be about 160mm (I will measure exactly tonight). The OBX was in fact so much shorter that the bearings did not reach the mounting locations/bearing caps on the sides of the differential.

Here's a picture for comparison:


Where to now:

I reached out to the original owner who was very helpful but wasn't really able to offer any additional info. I found contact info to OBX: peter@obxracingsport.com who didn't reply. Luckily I found his phone number and called him up. He confirmed I have the right part number:
20H10-LSD11276


I also confirmed the part number with one of the many ebay re-sellers who said its the same one he sees. This means one of three things:

1. The LSD I have is designed incorrectly / for the wrong car or was machined incorrectly.
2. The casing is miss-matched to the bottom of the diff (casing has part# engraved, bottom of diff does not)
3. There is another 350z differential I am not aware of that used a smaller LSD housing???

I spoke with Peter at OBX and sent a comparison picture of the heights. He is supposed to measure the ones he has in his warehouse to see if they too are ~160mm and not the ~179mm as the stock unit. Ill try to work with him and figure out what went wrong....I do really want to make this work seeing as how other platforms have made the OBX LSDs run very well after the rebuild kits.

Here's where I need the help of you folks; Can anyone tell me if there is a model 350z that uses a shorter differential assembly or specifically a narrower pumpkin (bearing to bearing)? My research points to No, but I'd like to double check this fact, maybe just maybe there is a 350z that this LSD is supposed to go into.

Update 1:
So I took a number of measurements of the OBX LSD I have and looked up the technical drawings for 240sx, 300zx and 280z LSDs that Quaife has on their website. Sadly I didn't know that Quaife has this info posted until today....it would have saved me a good bit of time pulling the stock diff.

The results are that I simply have a 300zx LSD. The dimensions of the OBX match up PERFECTLY to the dimensions of the Quaife 300zx diff and as far as I am aware the 300zx has the same 6 bolt pattern output shaft as the 350z making the package easy to confuse. The worst part is the OBX part number engraved on the LSD appears to be the associated with the 350z and not the 300zx when I checked with Peter and another ebay reseller earlier. I am hoping that there are two different diffs for the cars, otherwise what this means is that 300zx LSDs are being passed off as 350z to unsuspecting buyers. I've reached out to Peter@OBX with this info and I'll see what he says. Hoping here that there is a 350z version and I can swap for some restocking fee....

Update 2:
Peter got back to me today claiming the following:


I've checked with the LSDs that we have here for Nissan and based on the picture and part # you have provided IT IS FOR 350X!!!

The other LSD has "tapered" housing, which is for 300ZX/240SX/Silvia with R200 axle.

After calling him and discussing the sizing and how simply it is impossible to install this LSD into a 350z diff as it is the WRONG size he had the nerve to tell me he doesn't have time for this. After asking about refunding or returning under warranty he said I have to contact the seller (Racing Parts Depot) and they can do the warranty claim (their phone number btw is the same as his ). He won't warranty the LSD even though he represents the manufacturer. At this point the conversation conclude with him hanging up. So that's all folks....DON'T BUY THIS LSD. It's not meant for the 350z even though its sold and advertised as such. Honest mistakes are one thing, but it's rather clear this man is misrepresenting the parts he is selling for incompatible vehicles.

Sorry to disappoint folks


Also for reference, contact info to Peter and Racing Parts Depot:

Peter@obxracingsports.com
(510)-568-2244
6195 Coliseum Way, Oakland, CA 94621
kenneth@obxracingsports.com

Racing Parts Depot:
(510) 568-2244
6195 Coliseum Way Ste F, Oakland, CA 94621
http://www.racingpartdepot.com

Also he appears to have an ebay store, I will report the OBX LSDs he has listed to ebay and hopefully no 350z/G35 guy will get burned by this.

ebay:
http://www.ebay.com/usr/racingpartsd...p2047675.l2559

dcains

iTrader: (15)

No offense, but saving several hundred $ for such an inferior product hardly seems worth the trouble, as swapping a diff properly is fairly labor-intensive. FYI, all the Z and G diff housings are dimensionally the same. I love my Quaife diff's, in my Z and Alfa Spider's.

Row2K

iTrader: (10)

no offense, but it's my money and my car and changing out the diff requires relatively little work if you have the tools.

With that kind of thinking there would be no progress in this platform and we would all just use the same one or two part manufacturers. Besides these diffs after rebuilding have worked quite well in a number of other platforms.

Frankly I don't care about the money, for the chump change I spent on this it's no big deal (I didn't buy it new). If it can't be done I'll pursue the Quaife or the OS Giken, but if it works out people like you will have another alternative.

dcains

iTrader: (15)

I understand what you're saying and doing, and I really didn't mean to be offensive, so I hope you didn't take it that way. Nothing at all wrong with trying something new, but a Quaife can be bought for $1K (+ labor), and as a proven product, that's going to be much cheaper and easier for maybe 90% of the guys looking for a great aftermarket. diff. In any case, I hope you can get the OBX to install and operate as intended.

Row2K

iTrader: (10)

Understood and none taken.

However this goes I will keep the thread updated. This will either be a cheap alternative or spectacular failure. At least Peter@OBX is answering my calls...for now.

Row2K

iTrader: (10)

Gents, one final update. In short; do not buy this LSD. Sorry to disappoint, but it looks like the LSDs being sold as 350z units do not fit the car. I've gone over everything thoroughly with a digital caliper and all measurements match 300zx LSD size per Quaife tech drawings (even the bearings are 300zx sized)...seriously.

Peter is as expected unwilling to warranty the item...no surprise there

2004Black350z

iTrader: (37)

Unfortunate to hear but thanks for the review.

350zjason350z

iTrader: (15)

Thanks for contributing something worth reading ...

ApexEight

First off, sorry for the massive thread bump.

Second, thanks for doing this.

Now, in the picture you have showing the height differences between the OEM diff and the OBX unit, the height difference appears to be made up on the two circular bearing things on the top and bottom of the OEM LSD.

In this eBay ad: http://www.ebay.com/itm/OBX-Helical-...9SolrL&vxp=mtr

It appears that those bearings are separate from the diff and do not come attached. Is it possible that yours just didn't come with the two bearings when you bought it second hand from that guy?

I'm researching LSD options given that OEM VLSD is not all that great but am not crazy about spending ~$1K or more for a Quaife, OS Giken, or Tomei unit.

jdm-v35

iTrader: (7)

It won't make up the height difference. the bearings are not extensions. they get pressed onto the end flush with the ends of the diff.

I would just stick with the OEM untill you can afford one of the diffs proven to fit. Not worth the headache.

ApexEight

Ah, I see. That makes sense.

I'm thinking a Quaife would be the way to go for a spirited daily driver/occasional autocross car over a clutch type LSD.

Thanks for answering my question.

Emski

Thank you for the contribution OP. OBX is in Oakland. I shouldn't be surprised.

Row2K

iTrader: (10)

Not possible:

and also:

+1 , stick with OEM. There are nice deals that come up in the classifieds as well. You actually just missed a never installed Quaife diff that was available in the FS section.

Browse the FS section and something will come up again, just don't go for the jokers that want to sell a used LSD and charge a premium because it's in the pumpkin....installing a diff is easier than you think...besides LSDs especially clutch type are a wear-item, sometimes quickly if oil is not changed regularly.