rbryant

Most of the recent orders for my kit have been the newer version of the LSD over the past couple of months. The new one with the Taper/cone/curvy shape should be superior to the old version. My customers have reported 50mm long bolts (shank length without the head) and the ones pictured in this thread also look like 50mm to me based on the threaded length. The 40mm is probably a typo. This unit should be superior and should solve the center retainer issues that required the larger center washers to hold everything together in my kit. I still highly recommend replacing the bolts and washers but this is good progress from OBX. -Rich http://rbryant.freeshell.org/obx_washers.htm

All, I just wanted to add a note that I have been shipping kits with two different diameter washers for a few months now with very good success. The big problem I have had with the R200 OBX LSD was that there is a large space between the center washer retainers which can allow for the washers to slip outside of it and then misalign. Picture this: [)()()()(] If the () washers in the center aren't surrounded by the edges of the retainer and there is space for them to move then they will.... The solution is this: [)()()(] I ship 4 larger washers that go in the center so that they keep everything aligned. The larger washers are actually retained by the diff case its self instead of the washer retainers. They also cup around the smaller washers so that they hold the smaller washers in place. I took care to make sure that they are very close to the same spring rate as the smaller washers. (because they are larger they have to be thicker too) I have been shipping 4 larger washers and 7 smaller washers. This is because the machining hasn't been that consistent and some of the LSDs require more washers. I don't expect people to require all of the washers and in most cases only 2 of the larger ones will be needed but on some of the newer units they seem to be a deeper pocket where all 4 larger washers can be used. Originally the first R200 diffs only needed about a 14mm stack of washers and I have recently heard of them being ~20mm (based on customer feedback) so that is the reason that I can't just give people a one size fits all configuration. The larger center washers should only be used if they are sufficiently spaced by the outside washers to where they won't ever touch the normal washer retainers. If they compress and touch the retainers then the small washers will be loose, rattle, and not do their job. If anyone has feedback on the latest kits it would be great to hear it here. I am also interested to see some pictures of your installs. Thanks, Rich

Based on this feedback I am going to change the washers I supply for the R200 LSD to 7 identical washers. They can be installed )()()(( or )()()() which allows for different heights depending on the needs of the particular unit. -Rich

They really shouldn't flatten out. They will look pretty flat in that configuration because the gaps are on the inside. I will take a look at making the stack a little taller in the future. If you feel that the stack that you got was not correct just send me an email and we can talk about how to improve it and I will give you a refund or replace them. I am honestly more worried about my kits being correct than I am profits from them. -Rich

Detailed measurements were taken of the stack a couple of years ago and the stack height was determined then. It is possible that something could have changed since then or there could be some variances. Please keep me posted. If there is something that you need to make it work right I will provide a different stack at no charge and I can also update the writeup or change what I provide to avoid any future problems. -Rich

If you look more closely at my writeup you will see that there is a mention of checking the preload with the amount of compression from the time the case touches the washers to when it is fully torqued. I admit that I could have been more explicit with this. The problem is I can't personally check the tolerances of every differential from OBX. If they machined yours 2mm deeper than normal I have no way to know that and change my stack recommendations. My comment of: The overall goal with the washers is that they get ~.8-1.5mm of preload. The bolts are a 1.25mm pitch so you can tell the preload based on the number of turns on the bolts. From the time that the washers become snug to the time when the case is fully clamped by counting turns on the bolt. One full turn is 1.25mm. This means we want .5 to 1.25 turns from when the washers start to compress until the case is fully clamped down. If you had checked the preload on install then the stack configuration could have been changed to account for the machining differences. A simple change to )(())( might have worked or we could even go with ()()() or )()()(. The preload should really be about 25-50% of the compressable portion of the stack. With my recommended stack height 4 washers are compressing and 2 are spacers. The working washers have .6mm of compression to full flat each. That means to get to 50% compressed we have 1.2mm of compression. That is just under 1 full turn to get to 50% compression which is well within the text above. Half a turn would give just over 25% compression and 1.25 turns would give something like 65% which is also fine. I will add some text that indicates that it is always necessary to check the preload of the stack. Note that my records show about 25 R200 kits sold and you are the first to say that the stack height didn't work for you. Either that or the rest of the people are actually changing the stack height based on checking the preload. I honestly haven't gotten feedback or I would have changed my suggestions. Complaints about the recommendation or questions about the install can always be sent to me in a PM here or to the email address that you used to pay for them via paypal. I was never contacted about a problem with the kit and therefore I feel posting negative remarks here is not really the right way to approach the problem. Thanks, Rich

The )()()( configuration is what is mentioned for FWD differentials which is about 90% of the kits that I sell. The writeup also includes the following text: In general washers should be stacked )()()(. The 240sx R200 differential is an exception and should be stacked () )( () with the two thinner washers in the center. . The RWD washers should be stacked in this manner in order to hold them together since they aren't fully enclosed like the FWD, AWD, and MR washers are. Note that some FWD diffs are now coming with 5 washers. My washers are the same overall height as the OBX washers so they can be stacked )()(). The overall goal with the washers is that they get ~.8-1.5mm of preload. The bolts are a 1.25mm pitch so you can tell the preload based on the number of turns on the bolts. From the time that the washers become snug to the time when the case is fully clamped by counting turns on the bolt. One full turn is 1.25mm. This means we want .5 to 1.25 turns from when the washers start to compress until the case is fully clamped down. I can't control the tolerances from OBX so the last paragraph is important. The tension of the stack should be checked to make sure that the compression is correct. I can update the article to be more explicit about this but I do believe that the information about checking the preload was there. I do admit that it could be more explicit. -Rich

Just make sure that there is a reasonable amount of preload. Sometimes the FWD diffs come with 5 washers instead of 6. The washers shouldn't compress over 75% to keep a reasonable spring rate and I would generally say 50% or slightly less is a better target. The kits that I provide use two different springs so that you can adjust it to whatever you want. If you are getting over 1.5 turns from the time the case is flush against the washers then it might be too tight. Less than 1 full turn is probably too loose. This is based on the threads having a 1.25mm pitch (one turn is 1.25mm). -Rich

I have looked into the washers quite extensively. I have actually sold hundreds of sets of them to the FWD guys and ~15 sets for the R200 diff. Quaife mainly put the washers there to take up the slop and keep things quiet. They should have some preload but it won't do much as you can usually turn the wheel over by hand if you leave the other side on the ground on my FWD OBX LSD. I suppose you could argue that it might give a faster response or give you some traction if one wheel is totally off the ground but it wasn't the main purpose to use them like a phantom slip sytle differential. I provide a set of 6 washers (4 thick and 2 thin) that can be stacked in various combinations to yeild the desired preload. If they are stacked ())(() then they yeild the stock height as they were carefully measured compared to the stock height. Overall they vary some so you can change them to various combinations like )(())( which will give more height because of the way they sit in the retainer. Be careful with the )()()( type combinations because from what I heard the retaining gears don't surround the center of the washer stack on the R200 differential so unless the stack is cupped in the center they could slide out and either lose the preload or jam things up (very bad). I suggest the ())(() because the retainers cover the bold (thick) washers and the curve of the thick washers holds the center washers (mainly spacers) in place. The actual preload comes from the compression of the thick washers. They will compress more and more evenly than the ))))((((( parallel stack combo. The parallel stack also uses a much thinner and lower load washer. I also agree that you want to get about a 50% load on the washers and not fully flatten them out. Anywhere from 25% to 70% is probably ok but the loads change (increase) with the compression amount and we don't want to go past 75% compressed in this application. Also be careful that you don't go over 30ft*lbs on the case bolts they are only a M8 bolt! -Rich

Ok I read it over again (and more carefully this time). I agree that they are there to take up the slop. Stacking them )((()))( as you mentioned will fully compress the outside washer which isn't what we want because only one washer on each side is doing the work and it is too tall of a stack that makes the outside washers compress flat... Stacking )()()( like the FWD cars will allow them to fall out and cause problems. The washers should give a stack height of 13-13.5mm if stacked ))))((((. This will take up the 1mm of slop perfectly when only compressed about 25% and not fall out. This will let them seat in the retainers properly and hold the stack together since they are all interlocked. It is almost like the )spacer( setup that was mentioned in a later post except a bit stiffer and it shares the job accross 4 washers on each side rather than just a single washer on each side. I doubt that the bolts are streaching but I also provide new 12.9 certified bolts in the kit. -Rich

Hmm I will look up the measurements I have but I didn't think they compressed flat when installed. I agree that the cup shape is the only thing that will hold them together. From the measurements I had there should only be about 1-1.5mm (.040"-.060") of compression on the whole stack when the assembly is tightened. This can be confirmed by checking to see when the stack gets loose relative to the turns on the 1.25mm pitch bolts. The stacks start to get loose after a little over a turn so that means they are only compressed 1mm. The washers have .030" of compression each before going flat (height-thickness). This means that they shouldn't be anywhere near flat in this configuration. They should actually only be about 1/4 compressed max which is about where a belleville should be. Alternatively we could start using larger bellevilles in the center so that they are centered by the housing rather than the sleeve but it makes things complex and shouldn't be needed. Were your flattened washers the replacements or the originals? The originals from OBX will flatten out or crack in just a few whacks from a hammer which is similar to what is happening inside of the diff. So that in its self will cause the problem you describe real belleville washers won't do that. -Rich

No major problems. We have a minivan that runs low 13s in a FWD car that doesn't have any problems. If you ran 600+ HP at one it might break (who knows) but hey that is probably quaife land anyway. -Rich

I posted some info in another thread aswell so hopefully this isn't too much of a double post. I have been working with the OBX FWD diffs for over a year now and provide kits to replace the bolts and washers to make it easy for everyone to rebuild them. I don't actually own a 240 diff since I have a FWD project car (sorry). I have worked with some 240 owners closely to get the washer setup right though. From what I found the washers should be arranged ))))(((( so that they stay in place in the 240 diff. Unlike the FWD diff the washers are not enclosed in a sleve and should be in this config so that they are held together and don't come loose in the diff. )( doesn't hold together as well as ))) does. The stack should be about 13mm tall. I can offer stacks that are either 35% or 55% stronger if more preload is desired. Overall the bellevilles are just for taking up slop and keeping things quiet. This has been confirmed by quaife designers. Let me know if you want a replacement kit. Here is some info: http://rbryant.freeshell.org/obx_washers I think the honda link earlier verifies that I have been selling them to peopel for quite a while now. If I am out of line for offering them forsale in this post then I am fine with the moderator killing the last section of this post and I will be sure to do it the right way. Thanks, Rich

The 240 differential should use 8 washers stacked ))))(((( This is because the center of the housing doesn't enclose around the washers and this configuration is needed so that the force on the washers holds the stack together! I have been providing bolt/washer kits to Neon, Honda, and 2GNT eclipse guys for over a year now. I did the 240sx research a while back but haven't gotten any demand. It seems that this board might actually be more interested than the 240sx forums are! BTW: The early OBX 240sx diffs actually came with 8 washers with 6 of one thickness and 2 of another... If people are interested I can provide the bolt/washer kit for the same $32 shipped that I offer for the FWD groups. I keep things in stock so they always ship the next day via priority mail. The big savings is that you don't have to buy the full box of bolts and get cheap fast shipping! The diffs are actually pretty nice if you take the time to clean them up and replace the bolts/washers. Here is my OBX LSD writeup for FWD cars: http://rbryant.freeshell.org/obx_washers Let me know if I am out of line for mentioning this here rather than the forsale forum. I will happily follow whatever rules the forum has or move it there if desired. Thanks, Rich