So I currently have two be nine bolts and am pretty impressed with how stout they are for the small ring gear Yes I under stand their failing points. The first of which the small ring gear which we can't fix that is what it is. The second being the limited selection of parts and upgrades. Parts aren't to hard to find once you look but and better diff is very hard to find. So I have looked and looked found one diff I'm fairly sure will work but it also suggests that IRS m78 diffs might also work. Can anyone confirm this for sure? Would be a huge source for diffs.

 

Someone already did a Torsen upgrade in a 9bolt I believe. They used a diff purchased from Australia because they still use the 9bolt commonly out there.

It was a recent thread.

 

And sure enough. Just searching the transmission sub-forum for "9-bolt" turns up this thread as the 2nd result.

Search button is good button.

https://www.thirdgen.org/forums/tran...installed.html

 

That doesn't discuss using a m78 IRS diff...

 

What it does discuss is a proven Torsen swap.

Considering how difficult it is to get a 9 bolt rebuilt properly this its a very good thread.

If you want more information buy a m78 and attempt to install it yourself.

 

I have a m78 installed what I want to know is has anyone tried a IRS m78 diff in a solid axle m78. No need to be so hostile. We're all on the same team here.

 

you didn't say you already had a m78 diff installed. You asked if it would fit. I gave you a link to a Torsen diff that we know works.

If you think that's a hostile response then your stay here on TGO will be unpleasant.

 

I don't think you understand. The m78 is just another name for the nine bolt

 

Never even heard the term on these forums, and I've been here for a long time.

But so it is.

In any case, same idea applies. You want a torsen differential, there is only 1 other person so far who's swapped a torsen into a 9bolt. And I linked to his thread already. You wanna try yours, then you need to do your own search and possibly install it to find out.

 

That's the whole reason I'm asking. I have looked into it and a lot would suggest it would work but nothing conclusive and I'm currently mid motor build so funds are tight. M78 is the name borg Warner gave the rear end.

 

If funds are tight, I really suggest following in the steps of the link above.

Or find a 4th gen rear from a 98-02 6spd car. This will give you a 10-bolt axle with a 3.42:1 ratio and a factory torsen diff.

 

If you are talking about the IRS from the GTO and G8 then the answer is no, it won't work. They are similar, but not interchangeable.

 

The other thread tell you and what's needed to make it fit, where to buy it from.

If that thread isn't enough to make you unpucker your **** and loosen the pursestrings, you probably should put a downpayment on a minivan instead of making passive aggressive bluff calling threads about your planned mods.

No hostility intended. However, all the answers are in a very recent thread.

 

I looked into this a lot, since I'm the person who swapped a Torsen into my 9-bolt.

I also looked at the IRS M78 diffs and read about them, but eventually I came to the conclusion that it won't fit. I don't remember exactly what the difference is, but they're not the same.

I found a couple of _possible_ alternative diffs to the one I got from SupaFSeriesSpares, one from Quaife for a Morgan which uses M78 but that was too expensive to just buy and cross my fingers that I could get it to fit. Then i found a couple of diffs on ebay for M78 diffs, but no person telling me "it will fit". Since the guy at SupaF told me "it will fit", I took a chance on it and got it to work.

If you want to be the first guy to try something that no one else has tried, you have to be prepared for the possibility that it won't work.

 

That was exactly the answer I was looking for thank you! Made my day man.

 

GTO diff is not an M78. It is an "M80", not an M78. They are very, very similar, but different. Both are "spicer" axles. Spicer was bought by Borg Warner.

They are VERY similar, but different. Although the gears for an M80 will fit the M78. If I recall, I believe the ring gear location on the M80 carrier is in a slightly different spot than it is in the M78 - so the gear teeth dont mesh properly, if at all. I found this on the GTO message boards where they were hoping to use our more common, cheaper 9-bolt gears in their axles, and they had found out that the pinion gear and ring gear are not in the right place relative to each other for it to work, even though most of the other parts interchange.

I've been trying to annoy the 9bolt.com guy into carrying these torsen diffs... he responded quickly saying he could probably get them, and that he would get back to me about it... but I havent heard anything in a few weeks. I suppose he's working on it/considering it... if nothing else he's aware that at least I want one. I'd suggest some of you guys go bother him about it and see if you cna motivate him into carrying them. I cant get supaF Spares to respond to me.

Notice his caveat is the same point mentioned by our own experimenter above... and to be honest shaving the head of the pinion gear is small beans for something like this... we are talking about a carrier that will bring our 9 bolts into the modern era in terms of function.

 

Glenn from 9bolt.com says he has these for $650AUD right now.... Right now that's right about $500 USD.