RE: Anyone know R160 differential setup?
Ted Hedman
One small mystery solved, sort of. I should have also consulted the ’73 510 Service Manual, which I keep out in the garage. It has different formulas for calculating the carrier side bearing shim heights! The value H is not even used in the ’73 formulas, and the values E and F are removed from the parentheses. The H value is apparently only used to set the pinion gear height. Here’s the formula from the ’73 manual, which also agrees with the ’73 240Z manual for the R180:
Today I measured the R&P gear backlash, and ring gear runout. Specs are from the ’73 manual:
Spec Measured
Backlash .004-.008” .001”
Runout .002” .0025”
(.003” per ’72 manual)
The ring gear runout is out of spec per the ’73 manual, but within spec per the ’72 manual. Maybe not too big of a deal, but that backlash (or lack thereof) is very disturbing. Before I heap more blame on the shop who did the work, I may repeat the backlash measurement after cleaning off the red paint. Whereas the yellow paint that the shop applied was still soft and wiped right off, this red paint, also oil based, dried hard, and that may have affected my measurement. While I have the paint thinner out, I might also wipe off the paint around the A and B on top of the case to see if I can find the values that are supposedly stamped there. The figure in the ’73 manual, like the 240Z manual, clearly suggests there should be some numbers there:
I’m getting to the point of removing the side covers and removing the LSD/Ring gear assembly. The amount of metal swarf on the drain plug, and the rumble coming from the rear end lead me to believe that, besides the chips on the ring gear, one or more bearings are failing. At least I’ll be able to closely inspect the carrier bearings. I may also remove the driveshaft input flange and pinion seal to get a peak at the front pinion bearing. The only way to inspect the rear and center pinion bearings is to press out the pinion gear, a task I’m not equipped to handle. I will say that by rotating the gears by hand the bearings feel silky smooth and tight, but this crap had to come from somewhere inside the case:
I suppose it’s also possible something is broken and grinding metal inside the LSD, so I might also have to open that up and have a look.
Fun stuff!
-Ted
Sent from Mail for Windows 10
From: Ted Hedman
Sent: Friday, April 16, 2021 6:48 PM
To: 'Andy Klink' via Bluebird510
Subject: Anyone know R160 differential setup?
You might want to sit back with a warm coffee or cold one as this post is somewhat lengthy-
Lately I’ve been reading the ’72 510 Factory Service Manual on how to set up an R160 differential because (setting aside the why for the moment) I might be tearing mine down in the near future.
I’m trying to find get the A, B and H values that go into the formula that determine the shim thicknesses for the carrier bearing side retainers. This is a stock 510 diff with Subaru 4.44 R&P and Nissan Comp LSD installed.
Here’s the relevant page from the manual and a closeup of the paragraph with the formulas and definitions of the vairiables:
I have found the C and D values stamped into the LSD case.
The E and F values come from measuring the bearing thicknesses, and I have found the G values stamped into the side retainer covers. That leaves the A, B and H values.
The manual says the A and B values are marked on the gear carrier, but doesn’t say where. The ’73 240 Z manual gave me a clue as to where to look but I can’t find any stamped numbers. I’m wondering if the paint could be obscuring the numbers?
As for the H value, the manual says it is marked on the side of the ring (drive) gear. This next pic shows the numbers stamped into the Subaru ring gear after an “S” (for Subaru?) and “40:9” which denotes the gear ratio. I might need to look at a Subaru manual to decode them:
The 240Z manual says the H value is written on the end (Head) of the pinion gear. I don’t see any numbers on the end of the pinion gear, but it’s kind of hard to see in there. Looks like there’s a line scribed on the end of one tooth, though:
Then I went and looked at my old Nissan Comp 4.38 ring and pinion gears. Nothing legible on the end of the pinion gear, but there’s numbers stamped into the shaft (6-12-17), and similar numbers stamped into the side of the ring gear (6 12 18), and a “+12” hand written in white ink on the side:
I’m thinking that the 6-12 might be the set number since it is stamped on both gears, and maybe the “18” on the ring gear might denote an H value of 8 since it follows the 1 (in different font) as described in the 510 manual? Or maybe H is the hand written “+12”? Anyone know what the stamped and written numbers mean? It would make sense to me that Motorsports would stamp the critical numbers as an aid to racers in identifying parts and critical numbers used in setup where hand written ink numbers can wear off.
Maybe none of this matters in the end since the shim thicknesses will likely get adjusted away from the calculated thicknesses as part of obtaining the proper gear contact pattern, something that was obviously not done properly with my gear set. Here’s the drive and coast patterns I’m seeing:
I found multiple chipped teeth in the “toe” or inner edges on the coast side of the ring gear which would explain the metal chips I found on the drain plug magnet. This after 2000 miles since the rebuild.
Sent from Mail for Windows 10
Ted Hedman
Ted Hedman
Update-
I cleaned off the red paint from the ring and pinion and remeasured the backlash, this time in 4 positions equally spaced by 10 teeth (40 teeth on the ring gear). I measured each position 3 times and calculated averages. Here’s the results, in inches:
tooth # | Run 1 | Run 2 | Run 3 | Avg |
0 | 0.002 | 0.002 | 0.0025 | 0.0022 |
10 | 0.0035 | 0.004 | 0.003 | 0.0035 |
20 | 0.004 | 0.005 | 0.0045 | 0.0045 |
30 | 0.0025 | 0.0035 | 0.003 | 0.0030 |
Avg | 0.0030 | 0.0036 | 0.0033 | 0.0033 |
Clearly the residual paint on the gear teeth was taking up some of the backlash and causing my initial measurement of .001” (as reported in previous message) to be in error. Regardless, the backlash is still out spec on the low side (.004”-.008”). Interestingly, the lowest and highest measured back lash values were at teeth 0 and 20 which are 180 deg across from each other, while the measurements at teeth 10 and 30 are closer to the overall average. This, and the fact that the measured ring gear runout was borderline high relative to the spec, suggests that the ring gear seating surface on the LSD case may not have been completely clean when assembled, or worse, the gear could be warped.
I think I also found my answer to the H, A and B parameters used to calculate the pinion height spacer thickness and the left and right side retainer shim thicknesses. If the H is not marked on the head of the pinion gear, or if the A and B values are not marked on the top of the gear carrier (case), the values are taken to be zero (0). I found this explicitly stated in the 720 P/U Service Manual for the 4x4 R180 front diff on pages PD18, step 5, and PD19 step 2:
Having completed my initial inspection, I think it’s time to remove the side retainers and remove the LSD/ring gear/carrier bearing assembly and have a good look at the carrier bearings, pinion gear, ring gear mating surfaces, and possibly open up the LSD. I can also get a better (though not great) look at the rear pinion bearing, and possibly get a look at the pilot roller bearing by pulling the input flange and seal.
Kelvin Dietz
The one thing in a Datsun 510 that I haven't had apart and
rebuilt is the diff.
All these words and numbers make it look positively scary.
Kelvin
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Ted Hedman
That was me, too, (well, diffs AND gearboxes) until this debacle. Still is, actually, as all I've done so far is remove the diff cover and make some observations and measurements. I have, however, been studying up with the FSMs, Derek's excellent 2-part DQ how-to R160 overhaul article, and of course, YouTube vids. There's one showing an old pro in OR tearing down and reassembling a Subie R180 in about 20 mins. Helps to have all the right tools. I'd love to get my hands on a set of the factory special tools.
Gary Savage
Jordan B
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Ted Hedman
Here’s that YouTube vid of the guy in OR rebuilding a Subie R180. He seems a little careless, but he gets it done. Probably good enough for a drag racer.
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Kelvin Dietz
start kit?
I know I've met him at Canby. I think he's actually from here in Oregon.
Just bought a kit - well, traded for it, really - and I have question.
It's an interesting thing to wire.
Kelvin
Ted Hedman
Continued my R160 disassembly/inspection this afternoon. Got the LSD/Gear assy out of the R160 case, but had to remove one ring gear bolt first. Found some metal debris that looked like pulled threads in the stub axle bolt button area. I’m wondering if any of that junk got inside the LS assy? I will be opening it up to have a looksee.
Here’s the whole mess on my bench:
The carrier bearings and races still look like new.
A pic of the aforementioned debris and where I found it. You can see a curved metallic sliver sitting in the bottom of the splines in the first pic. After finding this sliver I pushed the magnet through the button thread holes and came out with what you see in the second pic.
I couldn’t see anything wrong with the pinion gear. No chipped teeth. The pinion shaft rotates smooth as silk. Looks like there may have been a number ‘9’, ‘0’ or ‘6’ painted on the head of the gear with white paint. That would be the “H” value, and my gut says it was a ‘9’, but who knows?
There was a lot of swarfy looking stuff (probably mostly Loc-tite) and more curved slivers and metallic filings on the LS case ring gear flange after I pulled the bolts. WTF? Hey, wait a minute. Looking at the photo just now I noticed that it looks like the ring gear flange through holes may have been drilled out. A ha! 💡
Just went out to the garage to look at it again. Yes! The new ring gear bolts are M11 fine thread, while the old bolts (returned to me, thankfully, along with the old R&P) were M10, and of coarser thread. Makes sense! The new Subie 4.44 ring gear takes M11 bolts per Derek’s DQ article, while the Nissan ring gear and LS Assy obviously used M10 bolts. The shop must’ve drilled the LS case to fit the Subie M11 bolts. FWIW, the M11 bolts are 2 mm shorter and 17mm ATF while the Nissan ones are 14mm ATF. No wonder why I couldn’t get the gear/diff assy out of the case! Bolt comparison:
And then they failed to properly deburr at least one of the drilled out holes on the ring gear side! 💡💡 There’s a nice lip on this hole, and at least one other hole could use a cleanup:
Well, it seems I’m finally getting at a possible root cause! It might be kind of hard to get a good gear pattern with proper backlash when the ring gear’s not sitting flat on the diff flange, ya think? I bet most of the metal debris I found inside was from the mess created by drilling and grinding the diff flange.
I guess the good news is that I can see a path to recovery that shouldn’t be too painful. Pretty sure the bearings are all still good, and the R&P gears still look pretty good as long as I can get a proper pattern, which should be a lot easier to achieve with a properly seated ring gear. I still plan to open up the LS Assy and take a look. I do have most of the parts to rebuild it, and if I’m lucky, I can reuse the parts for which I don’t have replacements. The fun never stops…
Jordan B
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Ted Hedman
Jordan, thanks for the words of encouragement. You echo my hopes for the best case scenario, but when does that ever happen? ☺
It's kind of weird that the right side had all of the shims (3) and none on the left. I would've thought the opposite, given that the ring gear was not fully seated. I'd sorely like to have any shims the shop may have removed as it would be a minor miracle if I can get it right just juggling those three. I also gave the shop a new set of the special "long" 10mm ring gear bolts, which they kept. Gonna have to order some fresh 11mm ones from Subaru, and maybe grind the gear carrier a bit so I can get the diff back in with all the ring gear bolts installed and torqued.
I found a couple of the factory special tools on eBay for setting the pinion height (dummy pinion shaft and height gauge), but the $1500 ask is awfully steep. Sigh. I suppose I can always make an offer. Hopefully I won't need to mess with shimming the pinion gear. 🙏
I had also considered just sticking the LS assy in the open 3.90 R160 that is currently in Zeke, but to do that I'd need to shim the 10mm ring gear bolt thru holes now that they've been drilled out to 11mm. First things first, I guess.
Wish me luck!
-Ted
paolo
Buona fortuna signore Ted!
1. Why all the time & $$ into this old diff?
2. Why not do another Quaife?
3. What model Quaife did you use on your SR20 car?
Paolo ———
David Bliese
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Ted Hedman
Thanks, Paolo! In response to your Q’s:
- Because I already had it. I liked the 4.38 gears with the ZX 5spd. The LS assy was still good, and over the years I’ve collected nearly all of the parts to rebuild it when the time comes. I’ve got plenty of time, and I’m not out that much $ on this thing, at least not yet… 😉
- Quaife prices have more than doubled since I bought mine 20 yrs ago, and I’d have to find another R180 with the right gears. Cheaper to rebuild the R160, and Zeke doesn’t need an R180.
- R180 with 115mm ID ring gear.
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Ted Hedman
Yesterday I opened the LSD case and found a few surprises. In summary:
- Someone has been in there before, likely the shop that did the shoddy work.
- No unusual deposits of metallic debris found inside
- Scored spring plates, spring disks and worn/scored outer clutch plates on both sides of the diff will need replacing
- Inner clutch disks and plates, side and pinion gears, pinion shaft and pressure rings all look good on both sides of the diff
- Scoring between outer face of the spring plate and the case on each side of the diff suggest metallic contamination entered the case from the openings in the case ends on each side.
As to (1), someone before me had obviously attempted to remove the phillips head screws that hold the case together. Mind you, this was a new LSD unit from Comp installed into my diff with new R&P in the early ‘90s, and had never been removed or serviced until this latest work was performed. Even then, they should have had no reason to open the case, but more on that in a minute. When I removed the screws they came out surprisingly easily using my ratcheting screw driver by hand without having to apply much force at all, so it definitely wasn’t me who messed up the screw slots. The screws do not require much torque since they are captured under the ring gear. Here’s what they look like. You can see damage on some of the slots from previous removal:
I clamped the case halves with c-clamps before removing the screws so I could gradually release the spring plate/disk pressure inside without drama or damage to the screw threads. Here’s a pic of the case as I was releasing the clamps, and unclamped after screw removal. You can see how much the spring plates and disks (basically Belleville washers) must compress for the case halves to mate properly:
Opening up the case, here’s my first view into the case and the cover, respectively. The topmost component in the case is a spring plate. For further reference, plates have outward tabs and rotate with the case, while disks have inward tabs and rotate with the axles. One of the first things I noticed were a pair of dings inside the cover, the most obvious one shows in the photo at 2 o’clock at the outer edge of the recess in the cover. The other one is at about 4 o’clock. The dings match the tabs on the spring plate.
A better pic showing the dings. I put a green sharpie mark on the flange by each ding:
Here’s the whole mess disassembled on my bench, the components removed from the case cover side of the diff, arranged in two rows in order from upper right as if reading backwards from right to left, towards the diff center, and finally the side gears on either side of the pinion gears on the pinion shaft:
Here’s a view into the now empty case. Closer inspection of the case cover mating plane reveals that the bonehead tech had closed the case with the outermost spring plate misregistered, pinching the tabs under the cover and creating tab shaped indents at the top of two of the four tab channels (closest to 12 and 3 o’clock in the pic), as well as the two dings in the case cover previously noted:
Based on the evidence, I’m pretty sure the misregistered and pinched spring plate was not discovered until after the ring gear was re-installed and bolts fully torqued, as that’s the only way enough pressure could be applied to leave such deep marks. This also begs the question as to why the LSD case was opened in the first place? Might the tech (I really hesitate to use that moniker to describe the jackass) have realized that chips from his drilling operation found their way through the windows in the ends of the case, and decided to open the case and attempt to cleanup his mess? Hmmm. Stay tuned…
Ted Hedman
>Might the tech (I really hesitate to use that moniker to describe the jacka$$) have realized that chips from his drilling operation found their way through the windows in the ends of the case, >and decided to open the case and attempt to cleanup his mess?
I’m going with that theory. Except he didn’t completely clean up his mess, and some of that crap made it inside the LSD case, working its way from the case ends inward, and ending up between the ends of the case and the spring plates, and between the spring plates and the spring clutches, and between the spring clutches and the outermost friction plates. All of those friction surfaces show scoring, some quite bad.
Here’s a pic of the LSD case, and you can see one of the four rectangular windows in the cylindrical wall of the case, each of which sits just above the ring gear flange that was drilled. You can also see that there are four circular holes and two rectangular windows in the end of the case under the carrier bearing. There are also two similar rectangular windows in the case cover which forms the opposite of the case. All of these apertures represent possible paths for foreign material to enter the case.
Here’s a view looking into the long end of the case at the surface that interfaces with the spring plate. You can see scored paths emanating from the hole at ~3:30, one running CCW towards the hole at ~12:30, and another running CW from the same hole towards the squarish aperture at ~5:00. The second pic shows mirror image score marks (harder to see) on the outer surface of the spring plate, running CCW from the tab at ~12:00 in the pic . There were similar mirror image score marks on the opposite end between that spring plate and the case cover, as well as between the spring plates and the spring disks, and between the spring disks and friction plates at both ends. The inner friction plates and disks look normal.
I believe this is the other side of the spring disk in the previous pic, and the next pic shows the facing spring plate. Ugly.
I won’t bore you with pics of all of the scored plates and disks, but you get the idea. To me it looks like damage caused by metal chips rather than normal frictional wear and tear, but I’m no expert. I also can’t rule out chips from failing carrier bearings because the shop did not return the old bearings. As mentioned previously, the new bearings still look new.
So far, none of this a show stopper since I have spare spring plates and spring disks, and I know where to get friction plates. However, today I was looking a little closer at the pinion gears and found one that should probably be thrown away. You can see that the finish in the convex face is deteriorating and could have been a possible source for some of the swarf that was found inside. I have no spare pinion gears and they are NLA.
Here’s another pinion gear (there are four) with what looks like normal wear, except for the nick in the face at 3:00. It looks like it could have been caused by contact with the edge of a gear tooth during careless assembly. This gear could probably be reused if I burnish off any high spots from the nick.
Now, the part # for the pinion gears (38425-18000) was asterisked in the Motorsports catalog, which meant it was a stock part. Turns out it was used in the 1200 and ’74 B210 H145A open diff, albeit in a two-pinion configuration. So, if anyone knows someone with a stash of NOS 1200/B210 parts or anyone who might have any H145A pinion gears, please shoot me an email! Otherwise this epic saga may (mercifully?) be coming to a screeching halt.
Ted Hedman
> Otherwise this epic saga may (mercifully?) be coming to a screeching halt.
Or not. I just ordered 4 new Subie R160 LSD pinion gears from Japan, along with a set of friction plates. But before that, I had considered possibly leaving out my two bad pinion gears and putting it back together as a 2-pinion LSD. Normally that thought wouldn’t have even crossed my mind, but in looking at the exploded view of the Subie LSD again, it only shows 2 pinion gears on a 4 pinion shaft. Seems like it could work? Just not as strong as a 4-pinion setup. See items 9 and 10 in the diagram:
Anyone know if the Subie R160 LSDs are really only 2-pinion?
Also, a guy on eBay is selling VAL-Racing torque biasing (Torsen helical gear style) LSD units for Subie R160 diffs. $330 BIN with $100 shipping from Russia. I know, Russia, and the price seems too good to be true, but he’s got 100% positive feedback and has sold 10, with one more available. At that price, even with shipping, gotta admit it’s tempting. Found this vid on a Subie forum.
Found a link to their website. It’s in Russian, so use your favorite translator. Looks like you need snap ring axles. Sigh…
“ATTENTION : THE DIFFERENTIAL COMES WITH INSTALLED STOP RINGS IN SEMI-AXIS GEARS (FOR FIXING INTERNAL SHREDS).”
I could really use me some internal shred fixing. 😊
Ted Hedman
Answering my own question, of course the Subie LSD is also a 4-pinion, as shown in the photo on page 5 in Derek's DQ 10.3 rebuild article.
Brock Johnson
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If a car is being pulled from the front, doesn't that mean it's being towed?
I can explain it to you, but I can't understand it for you.