Buying Subaru R180 diff, should I buy the axles

Engine, Transmission and related drivetrain.
2DoorJim
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Re: Buying Subaru R180 diff, should I buy the axles

Postby 2DoorJim » 29 Jul 2016 22:50

Axle update

Been meaning to post something about my axle conversion. I got carried away and spent a bag of cash, and though there was upside there was also downside. So where to start?

In brief, I decided I wanted a 3.9 ratio diff in R180 size in order to accept SR20 turbo. I advertised looking for a diff but didn't realize datsun never built such a beast, however subaru did but only for two years, and only on the rear of the STI. I sourced a diff and it included the factory subaru clutch style lsd - great! Now I just had to find stub axles and Dave at Futofab had them.

Something lingering in the back of my mind was chassis vibration due to lowering and discrepancies of half shalft U-joint angles. I built my car using 16" wheels mostly because they were what I had on hand, and then for certain reasons my tire choice was a little tall which required added lowering and this accentuated the problems with half shaft angles. I felt now was the time to address this having discovered a facebook post where a guy bought direct fit Subaru stubs machined for CVs along with the entire axle assemblies. The company is called The Driveshaft Shop.

I placed my order and had to wait a couple weeks for production but then they arrived in short order. In an earlier post within this thread we discussed CV joint and axle weights respecting unsprung weight. Well, the driveshaft shop builds equipment designed to maintain their reputation by NOT breaking. As a result these axles are built as though the car will be used for drag racing, not lending to light weight as would be liked for a road course car. So, I now own a really nice pair of super heavy duty axles which I positively will never, ever, break in my lifetime, well perhaps as long as I don't go V8, which I have done before, some 33 years ago - I was as a teenager gimme a break. Bigger is better right! Heh.

After buying the subaru 3.9 diff which is somewhat rare, then the axles, then covering shipping, duty, brokerage, and Canadian dollar exchange, my rear end has become the one single most expensive aspect of my 510 project. Bleeding $1000 bills. Heck, just a few "aviation units" my airplane friends tell me! Lol.

One concern identified by some other posters was axle splines cut slightly small which resulted in driveline backlash. I can say with certainty this is not the case with the Driveshaft Shop equipment. Further, these splines are rolled, not cut. I was surprised to see this but then driveline is their business and it appears they don't mess around.

Not much else to add but these are 108mm CVs used on the rear of 930 turbos. The axle shafts are, well, BIG. The diff stub and the outer adaptor pucks are said to be 4340 (a very tough alloy commonly used for these sorts of applications). Honestly, 100mm CVs (common to non-tubo porsches) would have been perfectly suitable for our light little cars, without drag slicks I suppose. Whatever, I'm not worked up over this and my car is street rod, not a refined track machine. Chassis vibration has gone down though I still need to deal with a driveshaft issue. Look forward to driveshaft 2.0 the CV version. This time however I might take to building something myself as my funds have nearly dried up.


I sandblasted the diff then painted it. The blue paint was my alternate color choice for my car, but in the end red won. I still have the can of blue sample paint which matches some late volvo suv. Oddly, this is almost an identical blue I painted the R180 diff in my last 510 in 1988.

Used a breaker bar to R&R the input flange as the subaru flange does not mate to a 510 driveshaft.

Cleaned off the wheel flanges with a small file to remove any surface imperfections then bolted on the outboard CV adaptors.

The subaru stubs slip directly into the diff and have spring circlip that snaps into place, unlike the typical datsun flanges which are through-bolt. Then simply torque up the CV bolts and it's ready to go.

Notice the drip tray under my diff in the last picture? My last differential puked oil, this diff pukes oil, and this diff even has a steel shim gasket which covers the vent tube so as to avoid direct splash. Am I over filling? I filled to the bottom of the top NPT hole, the one seen with the temp sender. The rear of my car was up on axle stands but front wheels on the floor so there was a bit of angle. opinions?


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okayfine
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Re: Buying Subaru R180 diff, should I buy the axles

Postby okayfine » 30 Jul 2016 06:23

Diffs shouldn't puke oil. FIlling to the bottom of the top hole is correct. Where's the oil coming from, specifically?

But now you need one of Matt's fancy finned diff covers...
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

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bertvorgon
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Re: Buying Subaru R180 diff, should I buy the axles

Postby bertvorgon » 30 Jul 2016 06:39

Morning Jim,

To eliminate any oil "puking", I ran a hose right up to a small tank in my trunk, next to the fuel tank. Anything that makes it up that far just drains back with no problem.

Not sure if this is your issue but any stock vent left on a diff will always leak out oil as the vapour condenses out and just plain makes a mess over time.

as OK asked...where is it coming out? Only place is that vent I can see.
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"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

2DoorJim
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Re: Buying Subaru R180 diff, should I buy the axles

Postby 2DoorJim » 30 Jul 2016 08:18

Oil is coming from the vent tube and I used the Subaru vent as it's a little shorter than the datsun part, the sube diff cover has a horizontal rib on the inside which interfered with the datsun vent. I used gasket sealer on the vent tube though it did press in snug.

As I say this diff has a steel shim gasket and the top right? corner is completely covered over, it looked specifically to cover the vent to avoid splash.

I guess I'll drain some fluid and see if it improves any, otherwise I'll make an extended breather tube similar to what you did Keith.

2DoorJim
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Re: Buying Subaru R180 diff, should I buy the axles

Postby 2DoorJim » 30 Jul 2016 08:27

Finned diff cover... not in the cards. Those things are works of art but I'm just not into billet stuff.

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okayfine
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Re: Buying Subaru R180 diff, should I buy the axles

Postby okayfine » 30 Jul 2016 12:38

So, puking to me means there's measurable amounts of oil coming out, like 2-3" puddles under the car after a drive. My 510 diffs (old Subaru CLSD or factory Datsun) sometimes had a dribble where the plastic vent didn't seal completely into the diff cover boss, which mostly just accumulated dirt on the diff case. If you're getting puking amounts of oil out with a tight vent tube (and vent tube in place in the first place) then it would seem you're seeing some pressurization or dramatic oil flinging that's overcoming the vent tube and the diffuser tab of the gasket.
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

2DoorJim
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Re: Buying Subaru R180 diff, should I buy the axles

Postby 2DoorJim » 30 Jul 2016 14:28

Probably puking while I'm driving Julian, then when I pull in I can see clear diff fluid all over the cover.

Project is failure! Total failure! Up for sale, first offer.....





Lol. I'll drain a little fluid and maybe put some hose onto the vent tube and run it a couple inches into the trunk.

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bertvorgon
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Re: Buying Subaru R180 diff, should I buy the axles

Postby bertvorgon » 30 Jul 2016 15:16

I offer 2,500.00 and I will drive there tonight........
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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okayfine
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Re: Buying Subaru R180 diff, should I buy the axles

Postby okayfine » 30 Jul 2016 15:16

$1, Bob!
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

Three B's Racing
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Re: Buying Subaru R180 diff, should I buy the axles

Postby Three B's Racing » 01 Aug 2016 06:54

I'm running an R180 (3.54) with zero leaking issues zero. What I did before installing was I took the diff vent and added sealer to the stem then installed it with the angled cut on the bottom of the stem pointed towards the diff cover, some of the stems don't have this cut some do. I know that if you run heavy gear lube it get's flung around a lot more so question is what weight gear lube are you running? If I were you I would pull the cover and npt tap the vent hole then add a hose nipple and run it up high like bertvorgon.
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Mattndew76
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Re: Buying Subaru R180 diff, should I buy the axles

Postby Mattndew76 » 01 Aug 2016 12:03

Please don't give up Jim.

I think a remote catch like Three B, and Bert will solve your issue.
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2DoorJim
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Re: Buying Subaru R180 diff, should I buy the axles

Postby 2DoorJim » 01 Aug 2016 12:23

Nahhh not giving up yet Matt, heh.

I did seal the tube in place with gasket compound. Using 80-90 GL-5 Penzoil.

I'm just thinking now that I stuck the Datsun vent into the Subaru cover. The vent is still on the car but is was the type with the open end like 3Bs describes. In this picture is the actual Subaru part on the left which I didn't use because one of the tangs was broken off, hence used the old datsun vent. I'll stick the Subaru part back in since it worked for the last how many years for the previous owner of the diff, will report back later today after going for spin.


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2DoorJim
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Re: Buying Subaru R180 diff, should I buy the axles

Postby 2DoorJim » 01 Aug 2016 21:08

Hour+ drive tonight and no sign of diff fluid coming out! I guess the Subaru diff wasn't happy with a datsun vent.

Car is no longer for sale.

Three B's Racing
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Re: Buying Subaru R180 diff, should I buy the axles

Postby Three B's Racing » 02 Aug 2016 04:38

Well, that's the best news I've heard today. Sometimes its the little things.

Lou
"Lastnight the wife said oh boy when your dead you can't take nothing with you but your soul oh "Think"
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Re: Buying Subaru R180 diff, should I buy the axles

Postby SteadFast » 05 Oct 2016 10:42

I'm going to piggy back off of this thread, as I am in a somewhat similar predicament. I am building a 510 with a F20C swap and Honda 6 speed transmission (likely going to be 220-240hp at the wheels) I currently have a 3.9LSD R180, and am wondering what option would yield the best results. I'm open to spending the money if needed but also am on a budget:

Option 1: The Driveshaft Shop ($1200). Appears to be an easy install, has the most robust axles. The diff will fail long before the axles

Option 2: WCR Axel kit ($900). Appears to be happy mix of price/result.

Option 3: Subaru side axel ($400). Cost effective, still uses the 510 halfshafts. I'm worried about vibration at higher speeds.

I'm leaning towards option 2 as it appears to be a happy medium, and should be able to handle higher HP if I decide in the future to add forced induction... Thoughts?
F20C 510 in progress...


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