How hard is it to replace a rear differential?

[Smurf510]

I just determined that a new knocking sound is coming from my rear end in my 71 510. 

 

How hard is it to replace if I decide to start wrenching myself?

 

If I have a shop do it, what is a ball park price I should expect?

 

Thanks! 

 

Mike

[iceman510]

Assuming sedan, not wagon.  Not the hardest Job.  Keep track of the shims mounting it in the rear crossmember.  Do you have a manual?

 

I have a few spare stock diffs if you need one. 

 

 

[datzenmike]

Four nuts bolts and lock washers on the driveshaft to pinion flange.

 

Four nuts bolts and lock washers on each of the two side driveshafts.

 

Two large vertical bolts, nuts washers with rubber bushings holding the 'mustache' bar to the car.

 

Two nuts, washers holding the 'mustache' bar to the back differential cover.

 

The differential should be clear to move to the rear to clear the pinion flange from the cross member, down and... out.

 

 

I've only pulled an R-200 but got to be the same, just a hell of a lot lighter.

 

[banzai510(hainz)]

put soem jack stands under neath and putin gear and see if obvious.

[datzenmike]

We're assuming you know what you're doing. (no offense intended) There are at least 3 U joints, 2 slip shafts, loose lug nuts, rocks in the wheel disc and loose shock absorbers.

[Smurf510]

@datzenmikeNo offense taken, lol. It's been a while since I have wrenched on a car and I'm a little rusty.  @banzai510(hainz) That is exactly what was done. My guy, used a stethoscope to pin point that the "knock" was coming from the diff.  

[Stoffregen Motorsports]

The 14mm hex nuts on the stub axles can be really tight, and will round easily if you use a crappy wrench. I have a special Craftsman wrench that I ground down on a belt sander to be able to get it completely on the nut to loosen it. If you try to use an open end wrench on those nuts, you will definitely round them off.

[DHale_510]

It's usually a loose half shaft u-joint first. The diffs seldom knock, but they are all old parts now. You can usually just wiggle a loose half shaft joint to check. It ought not wiggle.

Dennis

 

[paradime]

I always used a torque adapter wrench like the one below. It give a formula to apply correct torque. As for a price to have a shop do it, that depends on their hourly rate. Assuming you supply the diff and new bushings, on a stand I would expect it to be about a 3 hour job tops. While there with everything out in the open, you may want to replace the axle u-joins as well. Not a supper pricy part but it's good practice to replace as much as you can while you have the opportunity. 

 

 

[paradime]

8 minutes ago, DHale_510 said:

It's usually a loose half shaft u-joint first. The diffs seldom knock, but they are all old parts now. You can usually just wiggle a loose half shaft joint to check. It ought not wiggle.

Dennis

 

 

8 510s... Are you Dennis (of UFO) Hale? 

[Stoffregen Motorsports]

21 hours ago, paradime said:

 

8 510s... Are you Dennis (of UFO) Hale? 

The one and only!

[SupDoc]

On 3/30/2023 at 11:48 AM, Smurf510 said:

I just determined that a new knocking sound is coming from my rear end in my 71 510. 

 

How hard is it to replace if I decide to start wrenching myself?

 

If I have a shop do it, what is a ball park price I should expect?

 

Thanks! 

 

Mike

 

I'm a newbie when it comes to wrenching on cars, but this was one of the first repairs I had to make on my 510. It's really not that hard, if you pay attention how the diff comes out of the car. Just have to perform the same steps in reverse, to put it back in. If you're going to do it, might as well upgrade to one of the newer Subaru R180 limited-slip versions.

[yenpit]

On 4/1/2023 at 8:33 PM, SupDoc said:

 

I'm a newbie when it comes to wrenching on cars, but this was one of the first repairs I had to make on my 510. It's really not that hard, if you pay attention how the diff comes out of the car. Just have to perform the same steps in reverse, to put it back in. If you're going to do it, might as well upgrade to one of the newer Subaru R180 limited-slip versions.

 

FYI the early & late R180's bolt right in........same axles etc.  If early R180, you want to use the early R180 stub axles!  If you go with a later SNAP RING (stub axle) R180 out of a later Subbie, then you must purchase the custom stub axles (FutoFab, John Williams etc.............there are a few making them).  The early R180's had a long bolt thru the center of the stub axle, threaded into a collar inside the carrier (internal).  The later R180's had a wire "snap ring" holding the stub axle in.  This difference is why you need custom stub axles, if using a later R180!  I think it is safe to say that the change point on the Subbie diffs was around 1990/1991.  The Nissan diffs did not change in a single year period...........the 4x4 720 front diff (yup, you CAN use them!) had snap ring stub axles some time in the early 1980's, as did the 280ZX.  I THINK all of the early RWD Maxima's also had snap rings.  Hope that helps!

[yenpit]

On 3/30/2023 at 12:48 PM, Smurf510 said:

I just determined that a new knocking sound is coming from my rear end in my 71 510. 

 

How hard is it to replace if I decide to start wrenching myself?

 

If I have a shop do it, what is a ball park price I should expect?

 

Thanks! 

 

Mike

 

So ANY 68-73 510 R160 will bolt right in, but there were two ratio's.............auto vs manual.  Those two ratio's were 3.7 vs 3.9..............I think 3.7 was auto, 3.9 was manual......??  You can also look for a 1980's Subaru R160, which is also a bolt right in.  The most common was 4.11, then I think a 3.7 & 3.9.  All were also available in LSD, but those are getting hard to find.  All of the Subbie diffs from that era had a foil sticker on the rear plate, labeling the ratio, which is nice...................the Datsun R160's were NOT labeled & must be identified mechanically.  I do not believe ANY of the casting #'s help identify..............

[Stoffregen Motorsports]

I used to tear them down and install the nut inside the side gear, so you could use the bolt in stub axle. Is this not the case anymore?

[yenpit]

38 minutes ago, Stoffregen Motorsports said:

I used to tear them down and install the nut inside the side gear, so you could use the bolt in stub axle. Is this not the case anymore?

 

Yes, we have installed the threaded collar in OPEN snap ring carriers..............can you install the collar in a snap ring LSD carrier??  We typically install Quaife LSD units in open diffs & the Quaife LSD unit comes with the threaded collar (??) by application, so we have not had to modify/add collars to a Quaife!