differntial mounting differences?

[JRas]

I have an S14, I bought an S13 differential as a spare to swap in my new differential.

I have everything nearly done but now I'm a bit confused on mounting points.

I've been told the s13 mounts solidly into the s13 chassis.

when using an S13 differential into an S14, I have to use the S14 top cover...

my question is the other two mounting points


will I have to use bushings to install the s13 differential into my s14?

hope you guys understand the question, if not let me know

[JRas]

after looking at it, I can clearly see the mounting point back their on a S14 differential is a bit larger.

my guess if I would have to use S14 bushings for the other two mounting points, and for these two I'd have to use S13 bolts and just mount it solidly.. correct me if wrong, Please

[projectRDM]

You're right. There are no bushings in the front points on an S13. Bolts/washers only.

[JRas]

Originally Posted by projectRDM

You're right. There are no bushings in the front points on an S13. Bolts/washers only.

so I just need s13 bolts to mount to my S14?

[projectRDM]

Yes. Or any bolt that fits correctly, plus a washer.

[SoSideways]

So you posted in a forum and asked me the same thing on IM?

I guess I ain't as trust worthy as Russ...

[projectRDM]

Originally Posted by SoSideways

So you posted in a forum and asked me the same thing on IM?

I guess I ain't as trust worthy as Russ...

He killed you in the face with a bag of murder.

I can't imagine if I used IM, I'd never be able to breathe.

[SoSideways]

Originally Posted by projectRDM

He killed you in the face with a bag of murder.

I can't imagine if I used IM, I'd never be able to breathe.

hahaha, yeah, that's why I took my screen name down, cause I had people IMing me about wheel fitment this and that, and when I gave them my advice, they didn't take it anyway.

Wasted my time and energy.

Oh well.

[az_240]

I have the same thing on my S14.... using the S13 diff housing eliminates the bushings... its an upgrade in my opinion.
Just be sure to use good quality bolts. Ace sells some in their auto section.

[roboticnissan]

all you hvae to do is switch the faces of the diff housing and i should bolt right in

[SoSideways]

Originally Posted by az_240

I have the same thing on my S14.... using the S13 diff housing eliminates the bushings... its an upgrade in my opinion.
Just be sure to use good quality bolts. Ace sells some in their auto section.

Those might fit through the S13 diff housing, but they did not fit through the S14 bushings.

Just letting people know now that fact now so nobody gets stranded.

If you're using S14 bolts on the S13 diff, all you have to do is to put a washer or two (depending on their thickness) to take up the extra length of the S14 bolts. Done and done.

And I told JRas this too.

Originally Posted by roboticnissan

all you hvae to do is switch the faces of the diff housing and i should bolt right in

The S13 "ears" up there are thinner, thus requiring shorter bolts.

The S14 "ears", with the bushings in place, are thicker, thus requiring longer bolts.

ACE Hardware, Lowe's and Home Depot bolts will not work. They're all too fat. The Nissan OEM bolts are skinnier, so if you are planning to go from S13 to S14 housing, you might want to get those bolts ahead of time so you're not stuck with the ass end of the car on jackstands for a week.

[JRas]

Originally Posted by SoSideways

So you posted in a forum and asked me the same thing on IM?

I guess I ain't as trust worthy as Russ...

I was just confirming it, to be undeniably correct

Originally Posted by SoSideways

The S13 "ears" up there are thinner, thus requiring shorter bolts.

The S14 "ears", with the bushings in place, are thicker, thus requiring longer bolts.

ACE Hardware, Lowe's and Home Depot bolts will not work. They're all too fat. The Nissan OEM bolts are skinnier, so if you are planning to go from S13 to S14 housing, you might want to get those bolts ahead of time so you're not stuck with the ass end of the car on jackstands for a week.

I just ordered some at the dealership should be in on Friday, I did pay retail

[GSXRJJordan]

Wow, do you guys realize that if you're off (especially with a 1pc driveshaft) this could result in some nasty driveline wear?

I took my Tomei 2way LSD (in pumpkin) with me when I swapped chassis to my S14, and took some measurements - assuming that with both diffs sitting on the ground, the input shafts (from driveshaft) are coplanar (they appeared to be):



.. S14 diff, height from ground to mounting location on the subframe:



... S13 diff, same:



The difference is approximately 1/4", +- about ~1/20" due to "tilt" of the calipers.

The closest washers I could come up with were .23" stacked together:


... and I used stock bolts, but I don't remember which car they came from.

[az_240]

^I remember putting my s14 and s13 diffs side by side and they appeared to be the same distance from the ground so I just tossed it in there.

I have not noticed anything unusual but I think I'll take another look

[JRas]

I now have to decide:

keep my differential setup in the S13 pumpkin.. which I had professionally setup


or remove them and put into my S14 differential case, a lot of work.. headache, I think about the only problem I'll have is removing the pinion and maybe the sideseals.

[GSXRJJordan]

As we discussed via PM, just follow the washer measurements (about 1/4") and you'll be fine.

[SoSideways]

If there is danger from going from S14 to S13 diff on an S14, don't you think it would be dangerous to go from S13 diff to S14/J30/Z32 diff on an S13?

Seeing as instead of the pumpkin tilting up by the nose of the diff (where the driveshaft bolts up) like it would be on the S14 w/ an S13 diff without any washers, the S14 type diff on an S13 would cause the diff to tilt down, no?

And how many people have broken anything due to just having S14/J30/Z32 diffs on their S13s?

I'm just curious.


Also, if you wanted to find out the height difference between the 2 diffs, shouldn't you have taken a measurement of the distance between the studs on the rear cover vs the front ears instead?

Taking a measurement of how tall the ear is from the ground isn't going to proof anything, because your diff isn't going to be mounted on the ground in relation to the chassis. It is mounted on the rear subframe via the studs on the rear cover, then 2 bolts holding the ears up front.

Again, I just don't see how your measurements really mean anything if you just measured the height difference of the ears from the ground...

[az_240]

^I was thinking the same thing... but edited my post in fear of sounding like a jackass.

[GSXRJJordan]

I'll update this thread with the reasons for what I did, for those that can't see from the pictures (or actually working on your car with the parts mentioned) that the "bottom" of the diffs looks identical, and when on the ground side by side, the driveshaft inputs are co-planar - this means just the ears are different.

The S14 ears with bushings in them would be "higher", making the input to the diff "point down" - I don't see how it would work in an S13. If you took the bushings out and used "sleeves" to make the S13 bolts fit tightly, that might work for the S14 diff in an S13 subframe.

... or just put an S14 subframe in, they're supposed to be mildly better anyway.

Drivetrain wear is something you want to be very careful about, because it robs power, makes noise, and will eventually fuck up stuff that's very expensive.

[Dousan_PG]

i ran s13 diff in my s14
at least a year of solid tack events AND daily driving
and the diff and all other goods are still a-ok (moved it all to my current car)

so i dont think its a big deal if its s13 diff in a s14

[GSXRJJordan]

Originally Posted by Dousan_PG

i ran s13 diff in my s14
at least a year of solid tack events AND daily driving
and the diff and all other goods are still a-ok (moved it all to my current car)

so i dont think its a big deal if its s13 diff in a s14

That's cool, I'm glad you didn't have any problems. I assume that's when you were using a OEM 2pc driveshaft in the 14?

It's all hypothetical, anyway, but I wanted to measure it out to do it 'right' anyway. Like I said, drivetrain wear manifests itself as a giant pain in the ass down the road.

[Dousan_PG]

yeah i do
i dont run that single business
oem is fine. and then i was making like 250rwhp max

[MrChow]

Originally Posted by GSXRJJordan

That's cool, I'm glad you didn't have any problems. I assume that's when you were using a OEM 2pc driveshaft in the 14?

It's all hypothetical, anyway, but I wanted to measure it out to do it 'right' anyway. Like I said, drivetrain wear manifests itself as a giant pain in the ass down the road.

Yes keep us posted.

I also run S13 diff in a S14. I used a lot of washers to fill the bolt and it's holding up just fine.

[SoSideways]

Originally Posted by GSXRJJordan

I'll update this thread with the reasons for what I did, for those that can't see from the pictures (or actually working on your car with the parts mentioned) that the "bottom" of the diffs looks identical, and when on the ground side by side, the driveshaft inputs are co-planar - this means just the ears are different.

The S14 ears with bushings in them would be "higher", making the input to the diff "point down" - I don't see how it would work in an S13. If you took the bushings out and used "sleeves" to make the S13 bolts fit tightly, that might work for the S14 diff in an S13 subframe.

... or just put an S14 subframe in, they're supposed to be mildly better anyway.

Drivetrain wear is something you want to be very careful about, because it robs power, makes noise, and will eventually fuck up stuff that's very expensive.

What I said was that, did you ever consider the rest of the stuff that comes into play when you're talking about "it's out of plane"?

Do you know for a fact that the motor/tranny mounts the exact same way on the S13 chassis versus the S14 chassis?

And that the rear cover studs on the diff physically places the diff higher/lower in relations to the mounting ears up front on the diff?

I may be wrong here, but it just seems like you're making a big deal out of something small, and in the process you're calling every one a jackass for "not doing it right", and now you're starting to get snooty on us.

Dousan just said he beat the shit out of his car for over a year on his S14, then he put all his shit back into his current S13, which has been beat on for about another year now, same components, no failure due to "out of alignment diff".

I'd say, bolt everything up, S13 diff in S14, then do all your measurements, if you want to be 100% accurate, and "do it right". Then take that diff out and put an S14 diff on there, and remeasure everything.

That's the only way to do it right, because everything else is just going to turn into speculation, unless you have measurements for how the engine/tranny mounts to the car, and how the subframe mounts to the car, etc.

[Def]

^ This.

It's a lot more complex than just looking at one dimension of the diff mounting.

[GSXRJJordan]

What's your point of reference for "taking it all out, then swapping, then measuring", if you're using the same subframe?

Who's the jackass here, anyway? I answered a direct question with the research (pics included for trolls that want to delve into shit and argue about it), my assumptions, my hypothesis, and my conclusion. You asked questions about why I did what I did, and I answered them.

Def, with respect to the fellow engineer in you, the input plane (and it's position up/down) is all that matters - the diff housings are the same, and the covers place them in the correct spot in the subframe - as long as you get the input shaft to the diff lined up, the job is done.

Whatever, I'm through.

[Def]

The S14 rear subframe has an entirely different stamping for the front different mounting than the S13 rear subframe(S13 has a stamping that has the traction rod mounting included, S14 does not, and the curvature is different up top and bottom).

The back of the diff being positioned relative to the front diff mounting points also depends on the subframe differences as well.

Like I said, the situation is more complicated than one measurement of the diffs when you're talking about swapping cases between two differently designed rear subframes. They might position everything the same, but most the stampings are different between the two so it's hard to really make that call without lots of detailed measurements.

Just playing devil's advocate here. Universal joints in driveshafts don't like to operate at zero angle, so a small angle change probably isn't the end of the world as emperical results show.

[g6civcx]

I am running 400+ ft-lbs through a 1piece propeller shaft to a Pathfinder diff, which is similar dimensionally to an S14 diff on my S13. The only mod I had to do was use longer bolts on the mounting ears. The S13 rear cover fits perfectly with no mod.

I report no problems in terms of wear/tear, vibration, noise, etc.

[az_240]

I don't see how GSXR was doing anything wrong or acting "snooty" Just pointing something out so we don't all start breaking stuff.

I think the above post should end this thread but if you guys really want to know I can take a measurement of the s13 diff on the s14 if someone wants to take a measurement of the s14 diff on an s14. Just PM me and we can work on finding points to measure.

[SoSideways]

Originally Posted by az_240

I don't see how GSXR was doing anything wrong or acting "snooty" Just pointing something out so we don't all start breaking stuff.

Well, this is the line that I had a problem with:

Originally Posted by GSXRJJordan

It's all hypothetical, anyway, but I wanted to measure it out to do it 'right' anyway. Like I said, drivetrain wear manifests itself as a giant pain in the ass down the road.

Maybe it's just me, but to me it sounds like he is saying that by measuring everything out, that he's "doing it right", and anybody else that didn't measure stuff out is "doing it wrong", aka everyone else in this thread.

If not, that's cool.

All I was saying, was that, if you want to "do it right", you'd have more than just the mounting ears to measure, and Def agreed.