rice_classic

OBX, that was assembled with the Rbryant kit.

dirty19

iTrader: (1)

nods head..... hmmmmmmm

Kingbuiltscca

When I first started road racing, I had a obx diff in my high powered K series STL race car. Made it 2 seasons, when I took my Trans apart I had metal flakes all over the inside as well as a final drive looking exactly like that one. I've learned since then, I just finished a new full transbuild using a M factory 1.5 lsd and a wpc treated final drive. Next time around I would STRONGLY recommend treating the final drive and supplying yourself with a proper lsd.

rice_classic

The diff was a gift so I made the most of it. The OBX diff's most common shortcoming was the QC of the assembly line so I took strides to overcome that using the Rbryant rebuild kit. OBX_LSD Products

It looked great coming out but I sent it to SynchroTech already and I didn't do a runout check on it. I suppose if they want to they can do that. It may have played a part, or not.

But yeah.. My engine was also 4 years old and was getting soft so I'm having a new race engine built so I figured I'd upgrade to a "proper" lsd from Mfactory while I had the tranny out when I discovered this. I'm really really looking forward to this coming race season.

Kingbuiltscca

Good luck I too am looking forward to this season.

0parts@synchrotech

So the customer(Rice_Classic) decided to send in his OBX Differential in for a discount as part of the Refugee Program that MFactory offers. It was a perfect thing since it allowed us to get a better look at the root cause of the Final Drive wear. I wanted to be 100% sure before I made any statements and appear foolish if I was incorrect.

Many of you that know me personally know that I am never one to immediately point fingers and post a thread, pictures etc. the second I see something that piques my interest. I always prefer to deal direct with the manufacture if an issue arises or if I have a particular question with a product. In my years of doing this and being a racer myself, I have found that this goes a long way and builds better relationships with the companies I am involved with and adds to my knowledge base as well. Its a win win for everyone.

So we did a quick run down with a dial indicator to check for run out on the bearing spigot. Keep in mind, we can get extremely precise and check every angle but, I didn't feel it was necessary and the run out that we found just from initial inspection is enough to show cause. This is nothing new with OBX products. This goes beyond a repair kit of shims and bolts unfortunately. I cannot speak on the differential clearance and what the specs were set to since we didn't do the install. I can tell you that the differential bearing that was left looked like it was kicked around for a mile or two. The other differential bearing was not included in the package.

The OBX Diff had about 17 thou. of run out at the opposing end of the zero marking. Not acceptable by any means



This was not intended to be a call out rub it in your face Reply but, just wanted to show a very good reason for the wear.

We don't recommend the oil simply because we "sell" it. Anybody that sells fluids knows you are lucky to make a buck or two on a fluid sale if that LOL. We sell it simply because it works. We have tested this fluid in everything from record breaking high horsepower drag cars to endurance road race cars and it took lots of time and R&D to come to this recommendation. It works! That is why we recommend it.

Very good advice and the OP purchased a new FD(on its way!) and Plate LSD to compliment it. No more OBX!

rice_classic

I need to add clarity to that statement. I was attempting to remove the bearings without a bearing-puller before sending it back. I didn't bother borrowing a bearing puller since I didn't plan on reusing these bearings or this diff. I got one without issue, but on the other I gave up when I realized I had damaged the casing and the bearing wouldn't be salvageable even as a spare (and that explains the broken speedo gear too). Both bearings were mint condition coming out. I hope you weren't checking runout with a bearing that was mangled with a screwdriver and a hammer. I very much hope you used a new bearing before inspecting runout.
Thanks for doing this too because I thought about checking after I just shipped it off. This runout, assuming it wasn't done with my mangled bearing, eases my mind about the performance of the FD, especially since I will be combining a new MF FD with a new MF LSD. I will measure the runout on the Mfactory Diff during installation and reply.

It also lends itself to the reality that the macropitting may not have been solely attributed to the chosen lubrication but to an external input (the diff). I have corrected the input (assuming no runout on new diff) and have bought a case of Torco MTF.
No negative insinuation intended as it stands to reason you would sell what you recommend and recommend what you sell. However if you would address the questions about cSt and why your 100% synthetic gear oil isn't too thick while other "synthetic performance gear oils" are, even though they may have a lower cSt, that would be very appreciated.

Or in the case of the MTF, why going thinner would be better when the engineer recommended a greater film thickness. The Torco MTF, for example, has a lower cSt (thinner) than the Pennzoil Synchromesh.

0parts@synchrotech

Your bearing was not used and went straight to the scrap bin. We used a new bearing.


Torco MTF and RTF fluid is not thick by any measures. I am not a chemist and won't pretend to be one. If you want to get down to the chemical composures and comparisons, I would suggest contacting Torco direct and speaking with an oil expert. They are more than knowledgeable and can assist you on those specifics.

What I can say from personal experience is...it works!

Calif_Kid

As Kingofbattle909 mentioned on the first page, a lot of people are running a mix of Torco MTF and RTF. I use one liter of each when I change my trans fluid. The RTF is more expensive than the MTF, but the mix of the two works well for me and other drivers. The following thread has more info/comments. The main thing, is that if you're going to try the Torco trans fluid, is probably to try the 1:1 mix of the MTF and RTF instead of just using straight MTF assuming that you're comfortable with the higher cost. - Jim

https://honda-tech.com/road-racing-a...ation-2832037/

LightningTeg

I've had an OBX diff in my trans for 7-8 years. Original owner did the rebuild of the washers and I haven't touched it. Built my trans 2 winters ago and found some pitting on the ring gear / output shaft as well.

OEM LS final, running Torco MTF and Redline superlightweight shockproof. But this has been seeing 400whp+ the whole time.

Kingbuiltscca

Yea obx products are trash. Start it off right with mfactory parts all the way through!

rice_classic

:UPDATE:

-I put a dial indicator on the Mfactory Diff (new bearings) and measured runout was ~0.001".

-I emailed Torco about why a distributor (Mfactory) would say that competition gear oil is too thick but then recommend and oil (Torco RTF) which has a greater (thicker) cSt at temperature than equivalent competition gear oils (like Amsoil MT Gear lube 75w-90). That email was sent to Torco on January 21st and as of March 10th I have received no response. Frankly I doubt they will respond.

-I installed the diff, the FD, all new synchros, new main/countershaft bearings and a new 5th gear collar (needed it). I also spec'd all the clearances for the shims and thrust shims and everything was within spec. Buttoned it all up, grabbed the input shaft and it spins easily. I'm looking forward to installing this transmission when I get my new engine back. I can't wait to go racing. I will be using half MTF/RTF as others have suggested.


Thank you Synchrotech.

No18

Just to add some fuel to the fire (as a random engineer with gear/wear experience):

The root cause of the issue is almost certainly an insufficiently (insufficiently meaning not enough for how he was using it, not necessarily 'improperly') hardened spur gear.

Why?

• The wear on the spur gear is even and smooth. Look at the hard edges where the gear has been worn vs where it hasn't been touched. A pitting/fretting/stress failure doesn't cause wear like that. A material being too soft does.
• Uneven runout would cause significant wear/failure in a spot where the gear was binding. i.e. 'the high spot' tends to cause too much mesh penetration in the gear which *would* cause fretting/pitting/stress failure on the gear. I can't see perfectly, but it does look like the wear is pretty even all around.
• The pitting/fretting on the ring gear is likely a result of the wear on the spur gear. When the spur gear wears it's causing uneven pressure on the ring gear, leading to the pitting/fretting/stress failure you see in the ring gear. If it were the ring gear pitting initially, it would have chewed up the spur gear, not worn it down smooth.

Now it should be noted that this is not to say that the part is necessarily faulty. Without power figures, etc. We can't really judge how long this gear set should have lasted. And one might expect more wear on a higher ratio final drive set because the forces on them are higher (even for the same amount of power) And finally if he was overheating/breaking down his transmission fluid then he could wind up seeing wear like this. But if he's making anywhere in the range of stock power figures I would be disappointed to see wear like this, even after 4 seasons of racing. It should be well within the range of expectations to have a gear that's hard enough to not wear significantly at stock-ish power levels.

0parts@synchrotech

Let us bring light to a few things:

Think: RATIO

The countershaft spins 4.9 times to every rotation of the ring gear. So would a highpoint still exist after 4 seasons of race use? I don't think so personally...it would get to a point to wearing the complete pinion shaft and thus creating a more even looking wear pattern as seen. If both parts were somewhat equal in size or tooth count, that would bring more validity to your argument of a high point. Just imagine how many times this Final Drive spins under load during the course of an event let alone 4 seasons of Race use. Stock power or not, this car is not driven at a snails pace. It is going to wear the final drive down with the differential spinning way out of spec. With the 4.9:1 ratio...its going to happen that much quicker. I see contact all the way around and I see spots where it has even deeper contact.

With the differential being INSANELY and UNACCEPTABLY out of spec in terms of runout, there is also going to be some wear in the differential bearings which presents a whole different story. I think the wear seen is a combination of issues between improper runout and a worn set of differential bearings. I can't imagine them living to long and stayin within tolerance with that type of runout.

With 17 thou. of runout, what would you expect to see happen? I can tell you that a factory final drive would have more than likely broke a long time ago. A final drive that is overly hardened would also break with the introduction of more carbon to the surface. So, to see a final drive survive this long with that type of runout is pretty damn impressive in my opinion. MFactory goes a long way with their final drives and was amazed to see it hold up given the circumstances.



Mfactory Final Drives:
Made from SAE 8620 and 4320 Steel
Forged, Double Tempered and Super Sub-Zero treated for unsurpassed toughness
Advanced Shot Peening technology increases surface hardness

I may not be an engineer but, I am a Honda/Acura transmission specialist and have been in this industry for 16 years. One thing I can tell you is, it doesn't take an engineer to know when a part is 17 thou out of round...your gonna have some problems. Don't blame the part attached to it and come up with ways of how it should have worn in that type of situation. That's an unknown. That would be like putting an out of round/unbalanced wheel on your car with a new tire and complain about how the tire didn't last its 30,000 mile warranty period and arguing how the tire should have worn if it was made differently. That is an absolute waste of time. It would be obvious why the tire wore out...talking about a change of rubber compounds and tire assembly processes to appease yourself would be asinine at that point.

Had it been right and a quality differential been used from day 1, we wouldn't be having this discussion This isn't my first rodeo...especially with OBX products. Pay the least...expect the worst and pay the most in the end.

Lets stop beating this dead horse and let it rest. The issue has been resolved, we know what the problem was and lets move on.

Cheers!