four bolt talon limited slip differential.

[fourforty]

so i know someone had just asked about transmission swaps or something similar. i was wondering for my car which is a fairly stock vr4 but i would like a 4 bolt LS diff instead of a 3 bolt open diff. the only hard part is finding out the spline count. i can not seem to find info on that. all i am hoping to do is just get a new diff that is a lot stronger than the current one without getting a new t case or transmission. can anyone explain?

 

[MellowVR4]

What spline count are you speaking of? the axles? Im confused. /ubbthreads/images/graemlins/dunno.gif

 

[fourforty]

Well axels, driveshaft, t case, and anything else that might be involved. I'm not sure what will cause the axels to bind but I want to prevent that from happening.

 

[MellowVR4]

If your looking for a 4bolt diff, all you need to make sure its not from an auto car. Everything else shouldnt matter.

 

[mitsuturbo]

I believe you can use a 4bolt out of an Auto, but only if you plan on doing the swap where you keep 4ws, as you'd be migrating your original ring gear to the new carrier anyhow.

 

[CutlassJim]

Quoting fourforty:
so i know someone had just asked about transmission swaps or something similar. i was wondering for my car which is a fairly stock vr4 but i would like a 4 bolt LS diff instead of a 3 bolt open diff. the only hard part is finding out the spline count. i can not seem to find info on that. all i am hoping to do is just get a new diff that is a lot stronger than the current one without getting a new t case or transmission. can anyone explain?



Every VR4 I have ever owned has come with a 3 bolt LSD rear. Is this an option I luck out on or does every one come with an LSD diff? If it's LSD why change to a 4 bolt? Have you ever broken one? I've beaten the crap out of a 3 bolt LSD rear running 1.7 60ft's and never broke an axle. It's certainly not at the top of my mod list and wouldn't be until I was making some big power and or running a sticky tire. It's in my book as one of those mods that everyone on the internet thinks you need when you really don't. I'm not saying the 4 bolt version isn't stronger but it's not a necessity for everyone.

Plus I like breaking sh*t.

 

[raptorWagon]

No USDM VR4 came with a LSD, It would have been a 90 DSM 3 Bolt LSD. I swapped one in when I had broke a rear axle on mine, couldn't pass up a free 3 bolt LSD.

 

[tektic]

auto dsm rears are different drive ratio and will not work with manual transmissions.

 

[r4pt0x]

Is there really any difference at the differential itself from a rear axle with 3-bolt driveshafts compared to the one with 4 bolts?
I've found 2 LSDs in our warehouse from which one has to come off a rear axle with 3-bolt driveshafts (because we ever had only one with 4...) - both viscous LSD units are absolutely identical!
The open diff is weaker for 2 reasons: 1. the smaller diameter of the housing (=more torsional stress as the leverage effect is bigger), 2. the housing is not closed but only consists of 2 "arms" where the side gears are. So the diff gets huge notch effects on the bases of these arms whereas the closed LSD housing is one closed cylinder which mainly gets torsional stress (which cylinders can take a lot...)

As I only disassembled the one open differential from my car i'm not sure if its true for all rear diff ratios with open diffs, but on mine the crown wheel has a smaller diameter and bolt pattern diameter than the ones on the LSD units. In order to get an LSD with the original ratio and rear steering I had one LSD housing turned down to the inner diameter of the smaller crown wheel - which only takes 0.5mm from the walls. With a high grade surface finish this won't really weaken the housing. At the back of the LSD housing new holes for allen screws were machined to fit the smaller bolt pattern diameter.
The crown wheels can't be machined as they are through-hardened. So this is the only solution for keeping a long rear ratio and rear steering with LSD.

I don't have any experiences yet with this modified LSD as the car is still being restored, but i'm pretty sure there are much weaker parts within the drivetrain...

 

[tektic]

I know people who have shattered multiple rear 3 bolt axles. same people didn't have this problem after swapping to 4. use what ever lsd you have as thats the better rear. if your aiming over 500hp right off the bat than consider looking for a 4 bolt.

 

[mitsuturbo]

I had a 90 DSM with a 3 bolt LSD. I went through two differentials and 9 or 10 axles before i traded that car for a GVR4. Then i broke 3 or 4 more axles in the GVR4.

Then i got a 4 bolt.


I haven't broken an axle since.

 

[mitsuturbo]

Quoting tektic:
auto dsm rears are different drive ratio and will not work with manual transmissions.



If you're only inserting the carrier and axles into your existing housing, keeping your stock ring and pinion, and migrating the 4ws drive gear to the 4 bolt carrier so you can keep 4ws, you can use an auto 4 bolt. Only the ring and pinion differs. Otherwise the internals are the same.

 

[r4pt0x]

Quoting mitsuturbo:
I had a 90 DSM with a 3 bolt LSD. I went through two differentials and 9 or 10 axles before i traded that car for a GVR4. Then i broke 3 or 4 more axles in the GVR4.

Then i got a 4 bolt.


I haven't broken an axle since.



What exactly broke? The driveshafts? joints? the gearing? Tha flange at the wheel side of the axles?
I'm just curious as I compared the 3-bolt N/A rear axle and the VR4 axle and the driveshafts and except for the diameter of the shaft and the type of joint on the inside they are mainly identical. Nothing where i would directly identify a major wakness on the 3-bolt variants of the parts.

BTW: I'll use the whole 4-bolt rear end except for the differential gears.

 

[mitsuturbo]

The axles snap like toothpicks on a hard launch. They usually bust right at the splines, where the axle stub in the diff necks down just a slight bit. Sometimes it's a clean break, and sometimes it shatters the splined area and wreaks havoc in the diff. (this is why i had to replace a diff once, and only had a 3 bolt lsd on hand to replace it with, thus.. more busted axles later on)

4 bolt axles are much larger on the splined area. IIRC they're the same diameter as the front axles.