CLSD Identification

Engine, Transmission and related drivetrain.
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Byron510
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CLSD Identification

Post by Byron510 »

So I have acquired a CLSD of unknown origin.
It’s obviously a later style diff case, but the clutch pack is definitely not the same as the Precision Gear part.
I was able to engage a stock 510 stub shaft spline in one side (pictured) but not the other. It almost appears that the internal section of the spline is off centred, not allowing engagement.
I didn’t try tapping on the stub shaft, and may have to look into it more for sure. Took only these photos for now.
The gears are 4.375, making me think it’s a 720 diff, but I don’t recognize the CLSD unit.
And the last thing was the lack of lock tabs on the ring gear...
Maybe someone out there can identify this?
Thanks.
Byron
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iceman510
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Re: CLSD Identification

Post by iceman510 »

The case markings S60 757 and the K are the same as the 720 case I used except mine also has a N on it. LSD unit definitely different than the Subaru type at least on the bolt mounting end.

Interesting unit. Did 720s ever come with an LSD front?

You can see my pictures in this thread if you care to reference it.
viewtopic.php?f=30&t=31734&start=15
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Byron510
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Re: CLSD Identification

Post by Byron510 »

No 720 ever received and LSD new from Nissan.
I can not identify this one at all - anyone else out there recognize this thing?

Byron
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Tedman
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Re: CLSD Identification

Post by Tedman »

My 720 R-180 case has the big K and 757 as I recall. I wonder if that's a Detroit Locker in there. I've never seen one, but they were available in the Comp catalog. I would guess most were likely installed in 4x4 trucks.

Edit- Went and looked at my Comp catalogs. Looks like the Detroit Lockers were only for the solid axles, so that's probably not it.
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Byron510
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Re: CLSD Identification

Post by Byron510 »

I did a bit more checking yesterday on this diff as it’s still sitting in the middle of the work bench.
I confirmed the threaded buttons are installed in the diff, so it will accept bolt in style stub shafts.
The.
I looked again at why a stub shaft will slide into one side, but not the other. With the telescoping gauges and a mic, I can now determine a problem. The stub shaft seat, outboard of the spline, it I board of the seal seat, is .06mm smaller than the other side, and measuring the set of stub shafts I have on hand, .01mm smaller than the stub shafts themselves. So that issue is noted. I’ll take out the CLSD unit and see if I can fix the issue. There doesn’t appear to be any damage or fretting, it agora time the problem had been identified and should easily be rectified.

Coming back to the lack of lock tabs on the crown gear - what’s the consensus today:
New lock tabs installed?
Use of loctite?

I’m curious to take out the ClSD unit anyways, and confirm the break away torque setting.
I’ll keep you posted.

Byron
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JordanTr
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Re: CLSD Identification

Post by JordanTr »

I would ditch the locking tabs in favour of Loctite.
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Re: CLSD Identification

Post by icehouse »

Also interesting that there isn't any clearancing on the housing. I had to remove a bit of material to fit the Precision Gear LSD.
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Byron510
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Re: CLSD Identification

Post by Byron510 »

So, I finally got back to this project today. Mostly because I wanted to clean up the bench!

I went back to look at photos of my precision gear install back in 2009 - a unit I bought in 2007 when working in the US.
Jeff - interesting you mention the grinding because I just went to look at photos of when I installed my precision gear diff in the Bronze, and I show that I also did a little grinding.

So, comparing photos of the precision gear unit I installed in 2009 to the unit currently on the bench - apparently the same design, same casting numbers; they sure look identical to me.
So I guess I solved my own question - it's a precision gear LSD.

I can't remember if I noted above, but the thing is set at 130 lbs breakaway - that's HUGE! In a 2200 lb car, it's basically a spool. I have my current diff set at 45 lbs, and it's stiff. When it's cold, it's nearly a spool. If the LSD works cold, it bangs still - after 10 years of use. So 130 lbs break away... yeah that's too much.

So....

How does one go about adjusting these down?

I spent the day trying to find any video of this - nothing. Found a couple of YouTube videos on other brands, but nothing on this particular diff.
I assume that I need to remove shims, but I wouldn't remove 1 shim from either side - would I. It seems like too much as the clutches are a good 1.5mm thick. And I would assume that I would have to adjust on both sides of the differential gears to keep pressure even. I know I shimed up the R190 I had, but in this case I need to shim down. Anyone out there down this?

Are different thickness clutches available?

Bee good to hear your thoughts. Here are some pics

Byron
Attachments
Precision Gear LSD from 2007 1
Precision Gear LSD from 2007 1
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Precision Gear LSD from 2007 2
Precision Gear LSD from 2007 2
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New Diff
New Diff
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New Diff
New Diff
IMG_3940 (Medium).JPG (255.88 KiB) Viewed 1261 times
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Byron510
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Re: CLSD Identification

Post by Byron510 »

The cool thing about this diff is that it must be Zero or near-zero miles.
The LSD units is definitely zero miles - there isn't a mark on the clutch plates.
And the gears themselves have no wear at all noticeable.

If someone can pitch in on reducing the breakaway pressure and/or availability of parts if I need to find a thinner clutch plate.

It would be an idea to get some clutch plates cut out of similar material - likely something hardened in the spring range. The surface grind down to the thickness required. Maybe this is already available? Does anyone know of a source?

Byron
Attachments
I was enjoying this toy I bought a few weeks ago - damn it's powerful - 600 ft/lbs isn't playing around!
I was enjoying this toy I bought a few weeks ago - damn it's powerful - 600 ft/lbs isn't playing around!
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Loctite definitely used at last assembly
Loctite definitely used at last assembly
IMG_3942 (Medium).JPG (189.9 KiB) Viewed 1258 times
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Byron510
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Re: CLSD Identification

Post by Byron510 »

Some more photos of the condition of the parts...

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Confirmed 4.375
Confirmed 4.375
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butters68
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Re: CLSD Identification

Post by butters68 »

hey byron, you should give andy a call. thats were it came from.
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Byron510
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Re: CLSD Identification

Post by Byron510 »

Onward with the diff today. It was Molly Maid day - I spent 2-3 hours cleaning parts today from the diff.
But I had a bit of a pucker moment early on. I went to chase out the ring gear threaded holes. Red Loctite had been (effectively) utilized to lock the bolts in place, so the old stuff needed to be cleaned out before assembly. The bolts were just wire wheeled, no issues. Cleaning the holes - use a tap. Now when tapping anything hardened, you take it easy. So when the tap goes "crrreeeeeek" - you stop! And you very carefully try to back out. Thankfully, the drama ended well, but I still had the issue of copious amounts of Loctite in the holes.
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The solution;
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Zip cutting a slot in this old bolt (M10x1.25) worked well. But running it continually into the bottom of the hole did have an effect, so 2/3rds of the way through I made a second one, but the results were good. Thank god for power tools!
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Next up was addressing the missing countersink screw - found one that looked really short, but in place there was plenty of thread available - win!
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Next up was taking a closer look at these clutches - since they were new it was a good time to take some measurements for comparison later, or if they would ever need to be replaced. Height, thickness.
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Byron510
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Re: CLSD Identification

Post by Byron510 »

Time to start assembly, here are the parts after 3 hours of hand scrubbing scotch-bright work,
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While cleaning, I snapped this shot of the case clearencing nessesdary to fit the LSD unit in the late 720 diff case. Not sure if this needs to be done with all gear sets, because it's really close. As you can see hardly any material removal is necessary for the 4.37 gear set.
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I planned to take some time on this, and spent the afternoon playing. Here the clutch pack is assembled as per factory, A (internal splaine) and B (external key) clutches are set A-B-A-B-A-B on each side. I dipped each plate in gear oil before assembly.
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I tested breakaway and got a higher reading than prior to disassembly 155 lbs break away - way too high.
So I tried assembling with some CRC friction modifier (GM Sure Trac fluid).
This lowered the breakaway to 115 ft-lbs, still way too high.

So I tried a trick used on some other CLSD diffs, but changing the order of the clutches.

Disassembled and reassembled with the clutches set for ABAABB.
This had no effect, still the same break away.

So I reassembled leaving 1x A clutch out - the inside spline one.
the result was nearly what I needed - about 52 lbs break-away. Thats close 45-55 would be noce.

But what happens when you use a diff with 1 clutch place different on one side from the other? It seamed to have the same break-away in both directions - within 1 lb, so that's even. At 1.71mm thickness, if I were to split that into 2x 0.85mm clutches. Or the complete pack is 20.52mm, if I could get each clutch at 1.56mm, we'd be good and even between them all. But that would be tough as that's not a standard thickness - using 16 gauge would put me 0.6mm too thin overall.
This maybe a project fro another day, I'd need to do some homework on the material to use, then a hardness range it would need to be in. Could be a good project on it's own.

Anyways, the diff is assembled for now. But at 155 lbs break away - that's a stiff diff!
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Byron
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IMG_3993 (Medium).JPG
IMG_3993 (Medium).JPG (256.48 KiB) Viewed 1208 times
IMG_3992 (Medium).JPG
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iceman510
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Re: CLSD Identification

Post by iceman510 »

Fun project!

How do you measure the breakaway torque? Basically lock one side from turning by holding the stub shaft, then apply torque to the other side until you get movement? I see the one photo of the ratchet adapter on the stub shaft. Any other pictures of the setup to do this?

Thanks.
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Re: CLSD Identification

Post by 2DoorJim »

Byron I believe I have an identical diff to yours, casting looks the same. I presumed mine was a datsun competition unit but the fellow who sold it to me said it was from an early 70s skyline. Mine has four spiders like yours which I thought was the competition unit where the production 180s were two spiders (I was told), but this goes back six years and four car brands and I've put most of this out of my mind. My diff is used, but supposedly had the clutch pack replaced by the second prior owner to me (who I distantly know) then it was shelved as a spare for his race car. It's breakaway was right around 45 lbft when I measured it.

Best.
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