OBX Helical Installed in S14. Ongoing Review.

[240sHorTy]

Finally got my OBX differential a couple of days ago. It's been about a month and a half, thanks to the wonderful folks at UPS. What can brown do for you?? Otherwise, I'da done this over a month ago.

INSTALL: I took 36 pics and was thinking of doing a writeup, but a differential install is a differential install. They are pretty much all the same, so I'll just point out the relevant stuff.

First it was installed into an open differential. There was some question as to which type it would work for. It appears to be designed for the open. The shafts fit in where they should be, flush with the housing, and the depth appears correct also.

I installed the unit myself. I checked the backlash of both the oem unit and the OBX. The OEM @ 140K miles had backlash measurements of .0045, .0055, and .0070. The latter being slightly out of spec. It worked well.

I removed the bearings with a puller and reused them. I used the original ring gear as well. Everything lines up and is cake to install on the OBX. Ring gear applied with red loctite.

BACKLASH: This is important. I DO NOT recommend installing one of these without checking backlash. Some people do it with the s15 diffs, but that is an OEM Nissan part. I tried the OBX with stock shims and the result was ZERO backlash. Spec is .0039 to .0059. The gears interlocked completely with no play whatsoever. I had stock shims of roughly .083 and .103 inches. I thought of swapping sides of the shims, but they would have moved the diff housing the wrong way. I did not have a shim pack, so I cut my own shims. I don't recommend this, but it works. I cut a ~.063 shim from sheet and 6 .005 shims from aluminum cans. Hoffbauer lager, to be exact. I used these shims in combination to eventually get the backlash within spec. I took many measurements ranging from .0035 all the way up to .008. Again, that latter is slightly out of spec, but it is close enough for me, and pretty much the same as the OEM unit.



I checked the tooth pattern with prussian blue. It was pretty heel heavy, but I did not intend to adjust the pinion, so it will have to do. This cannot always be adjusted properly anyway, as it depends on the pinion bore to housing alignment.

I should also note regarding bearing preload: I did not have a spring gauge to test preload. The OBX with stock shims, fell into place pretty easily. It required more shims than stock to create some preload. I simply gauged the tension on the OEM diff and tried to duplicate it as nearly as possible. I ended up using all 6 pop can shims as well as the homemade sheet shim, plus the OEM .103 and spacer. I discarded the .083 from the non-toothed side of the diff. I probably ultimately added somewhere between .010 and .020 shims total.

OBX with bearings and ring gear:



Including removal and replacing the housing there are several hours of work involved to do the job right, depending of course on working conditions and tools. I did it over the course of a couple nights, off and on, while taking pics and making notes.

REVIEW:

This is a preliminary, first impression type of review. I'll update my impressions over the next couple of days and add any relevant information regarding its performance. And of course, if it breaks.

After the install I took it out for a 20 minute test drive. Normal driving operation is, well, normal. Everything looks good so far. So I took it onto a dirt road first. I stopped in a few different spots, leaving one tire on dry gravel/dirt and the other tire in the ice and hard packed snow. I gave it a little brake and a little gas and let the clutch out to spin the wheels in place. I did this for a couple of seconds at a time to verify that the wheel with the most traction was spinning. The results are as expected. Both tires spun, and the tire with the most traction (dirt) spun continuously. Note: This is hardly scientific, as the application of the brake gives torque to both wheels, really negating the effect that might be experienced without braking. But it does prove that the differential is functioning and transfering torque.

Here is a pic showing the marks left by the tires on dirt and snow:



Next I took it to a paved road and parked it once again, half on pavement, half off the road in a snow covered gravel field entrance. I repeated the same methods used on the dirt road and once again the tire on the pavement broke loose. I did this only briefly as my winter tires smoke like the d!ck and they are almost new.

I also opened up the throttle a bit on snow covered gravel to compare its response with the open differential. Both wheels spin and the rear end steps out more dramatically and quickly than with the open diff (of course).

This is about the extent of the testing so far. I didn't want to flog the car so fresh off the swap, and I will post more when I do.

In summary. So far, so good. I will update as appropriate.

-Steve

[574-240sx]

Thats good to hear so far, over on the honda boards there is horror story after horror story.

[Shift_Oversteer]

Keep us updated man! good stuff!

[Dano]

hmmm, watching...

-Dan

[Jookmasta]

also watchin...........................

[skylinedreams]

watching, and waiting patienly for more results.

[sileighty85]

also watchin...........................

[eds13]

i know what an lsd does, but i didn't understand most of the stuff you said in there.

[projectka-t]

waiting also!!!

[ORL240]

Thanks for the write-up 240shorty. A lot of people like to write reviews of parts with out ever owning of actually testing the part. Let us know how obx diff works out for you. Maybe a street and launch review for the diff. when you have some time. How much did you pay for the diff. and whom did you buy from?

[240sHorTy]

IIRC, $450 shipped. Bought it on Ebay, don't know who else sells OBX stuff. Guys name is Danny Wong. I think his seller ID or company is Sparktec Motorsports. He initially sent one, which got lost in shipping. A month later, after I contacted him and he dealt with UPS, he sent a new one. His feedback is pretty good. He also mentioned the possibility of offering a discounted rate to the forum(s), if indeed I found it worthy of a good review. I have not pursued this idea and will not, without more time.

Price has already dropped. I know there are a few different sellers already. Seller 'tuning-depot' has them listed @ 415 shipped, which is more in line with pricing on other make OBX diffs.

Oh, and there is also an important factor that I forgot to mention in my install. I chose not to install the c-clips that retain the output shafts into the obx differential and there are none installed in the obx as it is shipped. I do not anticipate any issue with this, but I figure it should be noted and I will update also if this causes any issues. This was the most common issue with these differentials in FWD applications. The shafts could be installed, but stuck due to lack of beveling on the diff teeth. This should not be a problem for us, as the clips are retained by the differential and the beveling is located on the OEM output shafts. I am not recommending the diff to be installed in this way, but it's just an FYI.

I've got a little bit of intercooling piping to do this morning, but I expect to have the vehicle driving again by around noon. We just got a pretty good snow here in mid-Michigan, so I'll get some good adverse weather driving in and post an update hopefully this evening. Thats all for now.

-Steve

[1WheelWonder]

Awesome, i'll be waiting on more news.

[Aworkinprogress]

You sound like you really know your stuff but just a reminder take it easy on the diff for the first few hundred miles when you get it on the road, no hard launches. I binded the gears in my Galaxie when I swithed to a 3.73 because I was pedal friendly. Deffinetly let us know what you think though very interested for my 240. Ps the gears didnt bind till about 10000 miles on the diff, made a grand howling sound for a few miles then BAM! and I didnt read the artical about proper break in from car craft till a week after lol! That was when i was really into american muscle, still have it, but now my s13 has caught my heart! I LOVE DRIFTING!

[si1via]

Wow I'm watching this thread. There should be a way to subscribe to this thread. Like automatic emails once somebody replies to this thread.

edit:

Disregard just figured out how to subscribe.

[95lstegman]

i've been planning on getting one of these for myself. perhaps in a month when my b-day comes around again. i still need to iron out some ongoing electrical/wiring issues in my S13 first . . . but i have full faith in the OBX piece. from first-hand knowledge i've gathered (so now it's second-hand, to you), it's simply a Quaife unit for the application listed that has been 1) marked down due to not selling as a Quaife, and 2) made with slightly inferior metallurgy and machining. that said, the tapers, out-of-rounds, diameters, etc. are only off by a couple thousanths of an inch, so it's not that big of a deal, and i've seen 500whp Hondas eat transmissions all day long without a sign of trouble from the OBX diff.

glad to finally know for sure that the OBX was designed for cars with the stock open diff. and i've seen a lot of people just swap around differentials in 240's, and was tempted to do the same (i mean not bothering with checking bearing preload, backlash, and gear interactions), but now that you said you found the backlash to be zero, i'll make sure and check it and order up some shims. they should be available from Nissan if i can just get a **** part number. trying to find a Nissan part number for obscure parts [like shims] is a PITA compared to other makes i've worked with.

[slpr240]

I would put those c clips in there man

[drifter_for_life06]

waiting.........watching........

[Shift_Oversteer]

Hey I didnt even realize you were in michigan! Roadtrip to Owosso to see if its the real deal

[240sHorTy]

^^Yes there are a few of us representing in this salt infested hell-hole. I was done with this whole 'winter' thing like the day after it started.

Regarding the C-clips. I am questioning whether I should pull it and install them. To be quite honest, it was initially an oversight on my part and when I got ready to install the diff, I opted not to go back and install them. I really cannot forsee them causing issue. While the rubber boots do have a little give to them, which could allow a little movement, they certainly do not have enough to allow the shafts to come a significant distance out. They actually have pressure holding them inward. If you think I'm crazy, please explain why, and I will seriously consider pulling it to install them.

Now, I did a small amount of driving yesterday, but my intercooler piping kept popping off (3 times). It was late in the evening so I had to wait till today. I redid some piping and welded lips on the trouble pipes.

Today it held boost for some heavier throttle runs under boost. I have not gone hard right out of the gate, I eased through the start of first gear, but uncorked it a bit through the higher gears. The diff held up and provided decent traction.

Regarding break in. I know clutch disks require break in and ring gears too, neither of which apply here. My diff came with no documentation, so what is appropriate break in for a hlsd? I'll search for some Quaife documentation.

I'm waiting for some dryer roads and maybe some tracks to open. I'd like to get some cornering tests as well as some 1/4 mile runs in. Both would probably be somewhat helpful in showing the grip this diff can provide in a more demanding situation.

[240sxOwner]

nice mod...when i snapped my stock rear end, i picked up a s15 helical and i love it.....Good luck man

[blairellis]

My brother is up there in the Grand Rapids area with his S13SR. He just picked up a S15 HLSD for his open diff.

Isn't there a figure 8 driving pattern you can do to break in the diff quickly?

[lrb_2000]

any updates?

[Edub1]

Sounds like you have a lot of places to drive fast where you live. I'm about 20 miles N of Detroit. I like that that diff is a direct bolt in. I'm considering the Q45 though. The taller gear isn't for drag racing but I think it might be nice for a street car.

How is the OBX different from the viscous? Have you noticed that it locks up better.

[240sHorTy]

Never driven a viscous 240. But as a general rule, I don't like them. I don't think they transfer enough power to the wheel with better traction soon enough and I don't have faith in the longevity of the fluid.

Differences: I would start with the fact that the viscous can't work until there has already been slippage. The fluid doesn't heat up till you've slipped. The helical transfers traction prior to slipping. I like the way the OBX locks so far. I have noticed no situation where I don't think the diff did it's job.

What I don't like: There is a delayed shock when applying power and when shifting. I attribute this to the moving parts in the differential and I am not sure if it happens with other HLSD's or not. I had attributed this to my failing clutch before, but after changing it, the condition remains. It is momentary and I only notice it occasionally and in certain driving conditions. It does not affect the diffs performance.

It's been in for 2 or 3 months now maybe. Still happy with the purchase, but it still hasn't been tested with too much power or in a road course environment.

[Shift_Oversteer]

Have you done any donuts/sliding/burnouts yet? If so, how did it perform?

[bigo181979]

Anything new with this? 1/4 mile runs yet?

[H8tred]

First off, first post, and I would like so say hi to what seems like a fairly knowledgeable community.

What I don't like: There is a delayed shock when applying power and when shifting. I attribute this to the moving parts in the differential and I am not sure if it happens with other HLSD's or not. I had attributed this to my failing clutch before, but after changing it, the condition remains. It is momentary and I only notice it occasionally and in certain driving conditions. It does not affect the diffs performance.

Do you have your stock two piece drive shaft? That could be what is causing this delay/jolt you speak of. Just food for thought. Keep us updated.

[AeonTorpor]

Have you changed your subframe bushings lately, or maybe the differential mountings (not sure if it has bushings/ though i'd assume so)? I have the same sort of jolt once you shift and put on the gas a little. And since all my bushings are stock I'm pretty sure that's what it is. Then again, I have the stock 2 piece driveshaft too.... Just thought it's a possibility, throwin' that out there.

EDIT: Man.. I need to start paying attention to how old the threads are. < owned

[H8tred]

Yeah, it is pretty old, but I figured this horse would be ok to beat as it is valuable information. Kinda sucks that he would just let everyone hang like that.

[Edub1]

The post isn't that old considering it's a rear end. I guess no news is good news.