260z, suby lsd, wolf creek adaptors, driveline bind/popping noise, HELP!

[evoog]

Hey guys, need some help with a little issue I have been encountering, and havent really come across a answer in the search section

 

 

SPECS

early 260 w/ sr20det light to mild mods(stock turbo)

suby 2004 3.9 lsd rebuilt

240z axles

wolf creek racing axle adapters

 

MY BACKGROUND

degree in automotive science

six years working for Benz as a master tech

 

ISSUE:

popping noise & vehicle hops in tight turning reverse, forward motion turning, or taking off(normal load driving)

breaking u joints

 

HISTORY

About seven months ago I decided it was time to replace the stock 260z diff after blowing up its guts, After much research I picked up a 04 suby lsd off ebay used, had the diff rebuilt at known shop(seals , pinion and ring gear replaced), and installed it into my 260z using wolf creek racing axle adapters and stock 240z half shafts with new u joints. The diff was filled with motul 90pa, fluid specifically made for that diff.

 

After being proud of my swap, it was off to testing the diff out and performed the break in procedures including the 20 or so mile drive with letting the diff cool to harden the metal. Everything seemed ok, but after 50 miles I started to notice a clunking/popping noise coming from the rear end & and the whole car would hop(during clunking noise) as if you were driving with a flat tire. This would happen when reversing down hill from my drive way and turning, or making forward turns from a stop, or when starting to move under low/normal load, or making large 180 degree freeway off ramps turns. 

 

 When I inspected the diff I found the side seals leaking oil, and wondered if their was something wrong with the rebuild. I took the car back to the diff shop, who actually started yelling at me and swearing when I told them the car wasn't right and I wanted them to check it out. I asked them to inspect not just the diff, but the drivetrain for binding. Before the rebuild the shop was told to spend extra attention to the clutch's, due to the cost of replacing clutches vs just picking up a new diff. Talking with the diff shop about the problem, I asked again about the clutches, turns out they did not torque test the clutches or test the clutch adjustment, just visually looked at them and demand them ok. After a week at the shop, it was time to pick up the car. the shop said they drove the car all over and said the noise was due to no lsd additive and the wrong fluid. I showed him the suby recommended fluids and the motul site indicating that it wasn't needed, and he basically told me to GTFO and that he was perfect.

 

Leaving the shop, heading home, within 20 miles, the diff starting popping around the corner and I lost the passenger side half shaft at the inner U-joint. The car ended up sitting for a month or two due to my schooling and work demands keeping me out of the garage. Last week I finally found time to swap the axle with a spare one I had laying around. The car seemed to drive ok for about 15 Miles, until I reversed out of a parking space making a corner....then the infamous popping noise came back. You can spin the tires free hand in the air, and you feel light resistance then a little moderate then light again, but I think thats just from the brakes(doesnt look like the axles causing it)

 

MY THOUGHTS:

I don't know if the clutches are causing the wheels to lock up and cause this issue, but that seems kinda unlikely. I am leaning more to an issue with the axles coming out of the diff at to much of a angle causing them to bind when rotating. The adapters seem to stick out a little far for my liking, but I have not seen a photo of them installed on another car to see if this distance is normal. However other people run this set up and haven't mentioned this concern. I would love to swap the axles out to cv joints, but have not found a shop that builds custom axles( I want the axle to have a suby inner to eliminate the adapters and reduce the angle), and honestly I'm pretty over spending a crap ton of money on this thing(I'm a paramedic student, poor as hell lol). I am also reluctant to spend over a grand on axles, knowing that this may not fix my issue....sooo hard to justify that one just yet.

 

CALL TO ARMS!:

This whole situation sucks, I spent days swapping the motor, and building the car, and now this issue, ugh. I'm ready to kick this car to the curb, but before my last straw breaks, I am humbly requesting assistance. Any ideas would help, any experience with this swap, any pictures of adapters installed, ect. I am located in the bay area and the only real rear end shop near me happens to be the one that told me to GTFO. I can try and get pictures or a video over the next few days if that will help anyone whos interested in this challenge.

[evoog]

Heres some pictures of it resting on the ground

[malibud]

I am no expert but this what happened to me ... I hit the axles with a hammer to get in. one would not go in, I hit it harder and no go .. then I Put the axle and diff in a press and it went in. Then I had the same problem you are describing kinda like drive a truck in 4x4 on dry pavement. Took the diff out brought it to my guy who rebuild a lot of sti diffs for people all over. Turns out I broke the C clip when i put it in press . the clip fell into the gear and locked it . the diff acted a if it was welded. got lucky no damage . it still whines I think because I did not cut enough off of the RT mount ...hope this might drop some insight  

[johnc]

Add 8 oz. of frriction modifier. That's the cheapest thing you can do right now. I would also get away from the Motul 90PA. Over the years I've heard a lot of complaints like yours on Nissan, BMW, and Porsche CLSDs.

 

Redline 75W/140 is what I used with the aforementioned friction modifier.

[evoog]

malibud---that sounds like a rough go, ill pull the adapters out again and check

 

johnc---i had good luck with the fluid on my 06 sti and the shop added some friction modifier at its last visit with no real change. but at this point, changing the fluid out wouldn't harm anything, I also want to inspect the fluid coming out for debris. Sounds like redline is the next fluid i will try

 

thanks for the responses guys,

[RebekahsZ]

Your diff sounds a lot like mine-that jumping and flat tire feeling is a great description. What you are feeling is what car guys call "chatter." Chatter my ass-it feels like your world is getting rocked! Anyway, what is happening is that your diff is locking. Welcome to the world of high performance CLSDs. If you were selling this diff in a catalog you would simply say this diff is "aggressive." And of course you would say that it is a "must have for any serious enthusiast." But I know from experience that an aggressive CLSD sucks ass to drive on the street. Hell, they suck ass to drive thru the pits! You need to set the pre-load and clutches back to factory specs. It may still chatter some, but should be less problematic. This is probably something you can do yourself. After the last bit of work I paid out for, Im done paying people to work on my stuff. If I can't fix it myself, I'm buying a new car. I'm just tired of paying sociopaths to fucx me over. However, this shop may have simply done what you asked them to. But, I doubt they test drove the car before they gave it back to you, that's just a thing of the past. And johnc-I'm down on doctors right now, and I am one. Finally, the leaking at the axle seals may be just spillage coming from the vent up top-these diffs create heat and oil comes out the vent hole. That's why they are all greasy in the junk yard. Nothing's gonna fix your diff but you. You need to find a cheap, grungy $75 Datsun diff to stick in there while you tear this one down yourself: figure out how it works, and do it yourself. Search this forum for my thread and video on this subject. If you can't find the video, go to YouTube and find my channel: RebekahsZ. Tell your girlfriend that gear oil smell is male musk: the hottest new aphrodisiac cologne and get out in the shop and get smelly and greasy. Just like Im telling my wife that the white powder Im getting all over her new floors and that itchy feeling she gets when I climb in bed with her isn't fiberglass dust from building an airdam-it's fairy dust-designed to keep our marriage strong, and to make me more sympathetic and a better listener.

Edited May 24, 2015 by RebekahsZ

[TimZ]

 

MY THOUGHTS:

I don't know if the clutches are causing the wheels to lock up and cause this issue, but that seems kinda unlikely. I am leaning more to an issue with the axles coming out of the diff at to much of a angle causing them to bind when rotating. The adapters seem to stick out a little far for my liking, but I have not seen a photo of them installed on another car to see if this distance is normal. However other people run this set up and haven't mentioned this concern. I would love to swap the axles out to cv joints, but have not found a shop that builds custom axles( I want the axle to have a suby inner to eliminate the adapters and reduce the angle), and honestly I'm pretty over spending a crap ton of money on this thing(I'm a paramedic student, poor as hell lol). I am also reluctant to spend over a grand on axles, knowing that this may not fix my issue....sooo hard to justify that one just yet.

 

 

This is kind of what I was thinking as well, especially given your observation that you get varying resistance when you rotate a wheel by hand.  U-joint halfshafts don't like high deflection angles, and they don't like forces that result from bottoming out the telescoping shaft.  I'd take another look at your deflection angles throughout the suspension travel and especially around your normal ride height, and also make sure that the shafts don't come close to their minimum length at any point in the suspension travel.

Also, I believe that the right and left shafts are different lengths - could they be in backwards?

[NewZed]

 

 When I inspected the diff I found the side seals leaking oil, and wondered if their was something wrong with the rebuild. I took the car back to the diff shop, who actually started yelling at me and swearing when I told them the car wasn't right and I wanted them to check it out. I asked them to inspect not just the diff, but the drivetrain for binding. Before the rebuild the shop was told to spend extra attention to the clutch's, due to the cost of replacing clutches vs just picking up a new diff. Talking with the diff shop about the problem, I asked again about the clutches, turns out they did not torque test the clutches or test the clutch adjustment, just visually looked at them and demand them ok. After a week at the shop, it was time to pick up the car. the shop said they drove the car all over and said the noise was due to no lsd additive and the wrong fluid. I showed him the suby recommended fluids and the motul site indicating that it wasn't needed, and he basically told me to GTFO and that he was perfect.

 

 

I'd go with you picked the wrong shop to work on your diff and they screwed it up.

[evoog]

rebekahsZ--- I expected the clsd to be aggressive and have some noise, but this one shouldnt be locking up like this around the corner. The shop was supposed to measure, inspect, and reinstall the clutches to factory spec, but sadly I think they may have over tightened them. Which explains the way over aggressive locking, but they are too egotistical to realize they made a mistake. I would love to rebuild the diff myself, but I do not have the special tools associated with the adjustments for this diff, nor the time due to school and work. What makes life even worst, my DD blew up a month after this all happened....fml right?

 

oh and the side seals are leaking, its not coming from the diff vent tube, already cleaned it, drove it, and reinspected.

 

TimZ--Others run this same swap with the same axles and don't seem to have an issue, which leads me to think the angles should be ok, but im not 100 percent on that one. The car is running pretty much stock suspension besides poly bushings and some lowering springs, but otherwise the suspension is stock. I haven't really found anywhere indicating that the left and right half shafts are different lengths for a 240 or 260z, but I could be wrong.  What is odd though, Subaru half shafts are different lengths, and when I measured it out, there was a slight difference from diff to wheel hub, but not that much. That brings me back to other people running the same set up and not having this issue...so...again....fml right?

 

NewZed---So far, every time my car goes to a shop, it comes back jacked. This shop was very reputable though, and had everything from classic trans, muscle cars, 4x4s, ect present in the shop when I came by. There work did look to be clean as heck, and they said they specialized in this diff, were most other shops wouldn't even touch the sucker. So it was a risk that ended up bending me over and stealing my wallet. I should have just taken it to the Subaru dealership for repair, but they were even hesitant over the phone.

[evoog]

So I wanted to update this for peoples further searches

 

My differential clutch chatter was present no matter what type of fluid was installed, some fluids made it more pronounced then others, but always present, especially warm. I removed the rear diff, measured the break away torque to be under 15 ft lbs, found backlash, run out, and gear pattern in spec, removed the lsd unit, and broke it down. The clutches measured .3mm under spec, had edges, and were glazed. A new stock sti lsd unit was installed, break away torque increased to 25-35ft lbs(no fluid), the clutches were broken in following kaaz's recommendations, and the chatter is gone. Life is all good now, and the car actually performs like she should.

[RebekahsZ]

Congrats! Man, I'm so sorry that was such a pain. In the end you will LOVE your LSD. Way to stick to it.

[BluDestiny]

So you were getting aggressive chatter because the clutches were worn down? 

[evoog]

So you were getting aggressive chatter because the clutches were worn down? 

 

 

They wore in a odd pattern, which caused incorrect angles between the clutches, which caused issues with the clutches engaging, hence the chatter

 

 

Congrats! Man, I'm so sorry that was such a pain. In the end you will LOVE your LSD. Way to stick to it.

 

 

Thanks man, it was a rought go, but the car gods smiled upon me! Thanks for your input on my problem too!

[RebekahsZ]

No sweat! I'm really only still a Datsun guy for the friends hybridz has given me. I'm a street rod guy at heart.

[bigbore468]

Add 8 oz. of frriction modifier. That's the cheapest thing you can do right now. I would also get away from the Motul 90PA. Over the years I've heard a lot of complaints like yours on Nissan, BMW, and Porsche CLSDs.

 

Redline 75W/140 is what I used with the aforementioned friction modifier.

Sorry to chime in a bit late on this thread, but thought to share my experience with Kaaz 2-way LSD and gear oil / additives.

I posted the Kaaz LSD installation in another thread.

The unit is at least 6 years old, and initially followed their break-in procedures and used their gear oil.

All was good after initial break in; very minimal chatter around sharp turns at low speeds.

Have since driven about 2,000 miles, and have changed the oil every year.

 

Little over a year ago, it was time for a gear oil change and a buddy recommended to use Royal Purple 75-90 gear oil.

Found out this was a major mistake, as after about 20 miles of driving, that popping, chatter, banging, feeling like something is broken in the drivetrain started.

I went through the drivetrain several times, swapped half shafts, checked stub axles, etc., and eventually talked to a tech a Kaaz about the problem. They told me the synthetic oil probably caused the clutches to wear unevenly and the unit will need to be rebuilt to solve the problem.

 

Since then, went back to mineral gear oil and tried several different LSD friction additives; adding up to 12oz.  The car would drive fine when the diff was cold, but act up when once the oil warmed up. 

I was ready to swap out the diff last week and rebuild the Kaaz LSD per RebekahsZ instructions...

Another buddy who works at a Dodge dealer said they have been using BG LSD additive to tame chatter on their trucks.

So I put two tubes of that stuff and topped off with 75-90, and it was like a miracle.

No more hard chatter, banging, wheel hop.

 

Would have never thought the type of gear oil / additives would adversely affect the operations of the LSD clutches!

For what it's worth guys.