OBX LSD for 240sx R200

[JMortensen]

Helical by far.

There are some, like me, who would say clutch by far. This is an argument that we have gone through many times.

 

 

Here is one of them: http://forums.hybridz.org/showthread.php?t=93879

[alexideways]

I tought that by "distributing the torque better" you meant wich one will send torque from one wheel to the other better. So what I meant was helical will be smoother thus making it transfer torque "better".

 

I did'nt meant that helical was better than clutch. To me, I think the clutch type makes for a bit more twitchy car on the street but as "jmortensen" said, it's a bit of a personal preference.

[NZeder]

As to which is better again like others have stated driving style or how you like the rear end to feel will be a personal thing. As I have not installed it yet (and my car has been off the road for almost 9 years) and I have not driven my CLSD for years I can't compare. Having said that I believe a local circuit racer changed from a CLSD to a Helical center and his lap times were lowered by just over a 1's a lap (takes 57 seconds to 1:20seconds - depends on the car/driver on this track) so 1's is quite a bit just by changing the center. In this case the drivers style might be better suited to the Helical center.

 

In circuit racing the helical unit will put more torque to the outside wheel on a turn but the CLSD will just drive both. Drifters don't like the helical units as they try and prevent the drift from occuring - so they want CLSD or lockers. I am going the helical as my car will be a road car that will take to the track on the odd club day so this will be a better setup than the CLSD with a high torque setting.

 

I am not a diff expert but from the research I have done the helical is the solution for me and my application (personal choice) as jmortensen this has been discussed to death ie

[NZeder]

NZeder just wondering what pattern are you going to put those washers in?

Not sure yet - depends on the preload I will want on the setup. I believe these washers will determine the preload and thus if some torque will still be transferred to a wheel when no load ie wheel off the ground etc. Most of the info out there on how to set these up on the OBX relates to the Honda centers which are smaller FWD units (they have 5 helical gears on each alxe where as the R200 has 6) also the Honda's have 6 belleville washers mine had 8. Another local (NZ) 240z owner has ordered a OBX unit so I will discuss with him what he thinks is best - he is an engineer and will have a much better idea on how to setup the preload etc as his work has him designing custom manufacturing systems/machines.

[alexideways]

Another local (NZ) 240z owner has ordered a OBX unit so I will discuss with him what he thinks is best - he is an engineer and will have a much better idea on how to setup the preload etc as his work has him designing custom manufacturing systems/machines.

 

That is great news, and would be priceless info. for us less. wealthy guys.

Looking forward to hear back from you. keeps us posted.

[NZeder]

Ok finial got off my butt to do something about my OBX unit. I ordered some new Belleville Washers from mcmaster today. The original belleville washers in the OBX units already had the black coming off them. I did the normal trick measure twice then measure again to be sure I was ordering the correct part.

 

Here is the specs of the original washers (I took the measurements in mm so I have converted to inches as this is what mcmaster had in stock)

 

Max Outside Diameter = 31.75mm (1.250")

Min Inside Diameter = 16.0mm (0.629")

Thickness = 1.6mm (0.062")

Height = 2.33mm (0.092")

 

So looking over the mcmaster online catalog the high carbon steel belleville washer that is the closest match is part number 9712K83 which as the following specs.

Max OD = 1.250"

Min ID = 0.63"

Thickness = 0.062"

Height = 0.092"

 

Perfect just the same

 

When I get them I plan to install in the following order.

)) (( )) (( this will provide more preload than what was installed on my OBX center which was ((( )( )))

 

Hope this info is of use to others.

[NZeder]

UPDATE: Well looks like mcmaster don't ship to individuals outside of the US - I got an email today to inform me of this and that they will cancel the order for the belleville washers

 

So back to the web and phone to see what I can find locally again. Still no luck locally in New Zealand - most stock stainless steel ones that are a bit smaller or larger and only order in lots of 100 = $$$$$$$ when I only need 8.

 

I have found a place in Australia that has the correct size - the total height is 2.80mm so I rechecked one of the originals and given the curve it is hard to get the true height using my calipers (as you can move it around at different angles to get different heights) but the height is between 2.33 and 2.8mm so once I get confirmation that they will deliver and they are the correct part I will post the info here.

 

For those state side the belleville washers from mcmaster will be fine and most 5/8 belleville washers should do the trick if the thickness, max OD is correct.

[Tony D]

Big Stretch, but if you want, I can will call them, or you can have them sent to my place, and I can forward them. McMaster's L.A. warehouse is only about 35 miles from my house, and I go by there on a regular basis whilst in town. Maybe pisk up another set just in case I bid on that one on e-bay currently (forewarned is forearmed!)

I have forwarded stuff for people in the past before, how much can it be to ship some Bellville washers to NZ?

I lost track of this thread, here it is! LOL

[Guest Mike]

You can always count on your friends here at hybridz

[NZeder]

You can always count on your friends here at hybridz

You certainly can - thanks for the offer Tony and if I don't have any luck with these guys from Australia I will PM you as I need to get this OBX unit back together and into my diff (wife is telling me I need to tidy up the garage and finish my projects - I have my motorbike in bits in there too and I am looking after a 240z for our club prez, so wife wants this gone soon so my car is not sitting in the driveway)

[260DET]

Good for you Kiwi for trying the OBX unit, got my fingers x for you.

[frank280zx]

Good info !! Me and Xander also gave up qaife so lets see what it brings !

[lbhsbZ]

Well, I just broke down and bought an OBX and it showed up today. There are 12 holes that appear to be for bolts to hold it together. One of those holes look like they forgot to counterbore it and put the bolt in, but its actually for a dowel pin. My diff had 8 of the correct bolts, 12.9 strength, and 3 incorrect bolts, about 10mm too short and only 8.8 strength. I took it apart and it looks OK on the inside. I tried to reorganize the bellville washers like NZeder showed ))(())((, but it won't work. Even with the diff fully reassembled, the outer washers are not contained by the collar and fall out of position. At least the 2 outer washers must be assembled (), and probably the outer 2 on each side. The only thing you can do to get more preload out of them is to possibly add a spacer between them in their exsiting positions. I'll update as soon as I take it apart again.

[NZeder]

I have finial got my replacement belleville washers and I did try and install them in the ))(())(( order but ended up installing them in (())(()) which has the same load and deflections - I am just waiting on a new diff gasket and breather thing to come from Nissan - should be here tomorrow of the next day - then I will be painting the casing before I install the center but all looking good so far.

[lbhsbZ]

I took the diff apart again last night, and I was able to assemble it with the washers ))(( ))(( . I made a pin on the lathe to drop through and keep the washers centered properly during assembly and it seemed to work. I didn't put a torque wrench on it but I seem to have about 40ft/lbs of preload. I am still using the original washers. I'll try it like this and change out the washers if I have a problem.

[frank280zx]

Well me and Xander have jumped the OBX bandwagon aswel ..

here is my diff

 

 

Her is my helical madness.

As stated before you do not only get the diff but apparently the factory gets rid of there grind waste in the carrier .

 

Funny thing is that my diff had no holes on one side of smaller gears while Xanders had holes on both side.. I guess Xander got lucky on the weight savings there!

 

Apart from that the OBX factory is not to keen on cleaning there casting molds, as you can see imprints of all sort of 'foreign' parts in the casting, it does not look to bad.

Also the skirt of the unit has some broken off edges because the bolts are close to the edge and the casting inst great. Sadly i don't have a before picture .. however i just ground the edges round making sure no casting parts will come loose there

The metal used i pretty hard though as numbering some castings was harder than it is on other metal i use my number kit for.

 

 

I will use a 3.3 gearing with diff cooler to compensate the heat that comes with these units( stock on euro turbo's).

As far as wheel lifting ... well a z should not lift or better, none rear wheel drive car should lift a traction wheel in my book!

 

Unlike the powerbrute fitments does not seem an issue sofar, however that leads me to a question.

how do you remove the bearings of the original unit ? as you can see in the right side of the picture? I can apply gentle force like.. but im hoping for some tips here. ( edit bearing puller!!)

 

 

 

So lets see who will have the first one to explode.... I have faith in it sofar however nothing like road testing i guess

 

So all in all im still happy (however old gear oil stinks!!)I dropped in the washers ))(())(( however i did not use a pin, they seem to line up fine. We went this way so you have two of the stock washers ( witch are crap) backing each other up . piece of mind and enough preload i think. if not after some runs it will have to come out agian

[NZeder]

What did I start when purchasing one of these units (there are at least 3 here in NZ with these units now ) ok given a number have installed the belleville washers as I first stated I will be pulling mine apart one more time and I will change from the current install of (())(()) to ))(())(( however as the replacement washers I have a little thicker (should give more preload) I will need to use something to line them up correctly while torquing the halfs together

 

Re the question about the bearing - not sure how you would remove the old ones from the original center - I have new bearings that I will be installing on the OBX center.

[wheelman]

I got into the PowerBrute group buy but it's starting to look as if they aren't going to honor the agreed to price so I'm evaluating these OBX units.

I've looked at several other automotive websites where they are discussed and these are my concerns.

 

1. Tolerances: One guy specifically mentioned he had disassembled an OBX and a Quaife side-by-side and found the gear mesh tolerances and worm gear pocket sizes to be of poor control.

 

2. Axle removal: It was reported many times that axles had gotten stuck in the units.

 

3. Poor material quality: The metal of the OBX outer casing is not as hard as the Quaife units.

 

Have any of you guys who've purchased these units noticed these issues?

I saw some posts that said the negative aspects regarding the tolerances and stuck axles were on early production units and had been resolved. If this is true then these OBX units might be worth a try otherwsie I wonder how long they'll last.

 

Quality issues aside, how big an issue will diff cooling be with either a helical or clutch pack unit? I have a stock 280Z long nose diff case with it's original rear cover, should I plan on adding a cooler or finding a finned cover? I don't race the car much, Auto-X about once a month and occasional street drives but no long duration road racing, at least not yet.

 

BTW: I'm cheap, really cheap, which occasionally bites me, but I'm trying to make the correct decision on this without money being the primary factor. I want to get the best setup I can for Auto-X which might be the PowerBrute, if so please slap me upside the head and let me know.

 

Wheelman

[JMortensen]

For autox I'd go Power Brute for sure. One thing to keep in mind is that the Quaife and the OBX knock off rub the sides of the worm gears directly on the case to create friction. If the case is made from a softer metal, that ***might*** lead to increased wear.

 

You can always call Reider's competition and see if they'll match the price that the guy at Reider made. I think http://www.differentials.com carries that Power Brute...

[lbhsbZ]

I bought the OBX and simply reorganized the bellville washers to get more preload. It was so cheap, that I figured its atleast worth the amusment I'll gain from disassembling it with a magnet after it explodes. If it doesn't explode, even better. I'm looking to have the car running in by the end of March (all my parts are in) and there is a track day in early april that I'd like to attend, so that will be the test. The casting was not as clean and polished as the QUAIFE unit I ran in the VW, and the bolts that hold the assembly together were of very poor quality...I ordered replacements from McMasterCarr. We'll see what happens.