Ive got too much money in my 9 bolt. It came with PBR brakes. But it now has LCARBs, Panhard relocation brackets, and some 3.70 gears, and I paid to have the cones/case machined last year to bring the posi back into spec. Found out I had some bent axles, so I replaced the axles last year as well. Granted, that's still less than $1k in it, but it's still too much.

I also have a 10 bolt Zexel Torsen carrier. No gears, no axles, nothing else. Just the Torsen unit. So I'd have to build my own 10 bolt axle. Move my brakes over to it (not many have the PBR's on them), move my Torsen to it, probably source some 28 spline axles, and buy some 3.73-3.90ish gears for it. I'd love to have 4.11s. Then I'd need to have LCARBs and another panhard relocation bracket installed on it to set it up like my 9 bolt. This all costs a good bit of money by the time I'm done with it.

My car is going to be a track day/autocross car by the time Im finished. RIght now I just autocross when Im not too busy with school, but school wont last forever. So here's my question, just wanted to know what you guys would do.

I can spend $500-$800 building a 10-bolt and view everything that breaks on it as cheap and expendable.

OR

I can spend $500-$600 importing a torsen type carrier for my 9 bolt. If I tear up my 3.70's, replacing them will cost a pretty penny... Motive sells gears for $200, but many are nearly $400.

I will not be doing any drag racing. But Im worried that if I eventually get to the 400-500hp range, that even some road race slicks or some R Comps like my NT01's will be enough to tear that differential apart since I have a T56.

How far would YOU guys trust a 9 bolt on sticky tires in a road race environment?

I'd REALLY like to stay 9 bolt or 10 bolt for the lighter weight (unsprung mass and so on)... and honestly I feel like the 9 bolt is just an all around much better option IF the horrible cone posi can be eliminated. It's just the costs of it blowing up are so much higher.

Any of you guys live in Australia and know what those 80s skylines and Holdens with the M78 axles are generally able to handle in terms of road race usage? I think the 04-06 GTO's use the same size ring gears, even though the gears dont interchange with ours, they're very close... anyone know how prone those are to failure with this kind of use? Worst case scenario we're talking 500hp with Hoosier R6's on it.

 

All I can do is give my best guess. You may have already discovered that the Borg Warner differential may slip in a hard turn and allow the inside wheel to spin, which will cost a lot of time. The new Torsen style differential would probably help a lot with that. Your axles are retained with pressed on tapered roller bearings which will work well with this type of use and probably have less caliper kick back than a c clip axle. As far as breaking anything, that's hard to say.

 

If I was setting up my car for R7's and RR I would use the torsen in the 9 bolt. Auto cross with A7's would probably be an auburn pro series.

The torsen would get unloaded in autocross and have traction issues with the super sticky tires.

Auto cross and track days take a pretty different setup "if" you want to be competitive. Remember "Jack of all trades, master of none" My experience comes from auto crossing and tracking a Miata.

 

You narrowed it down to 2 options. That's easy.

The 9-bolt is a stronger 4-pinion, slightly larger ring, bolt-in axles, diff.

Source the gear bias diff. Research whether there are combination gear bias / clutch pack versions for the 9-bolt (like a T-2R Torsen for a 10-bolt and whether they're worth using before you finalize your purchase.

If you gears break, source the 3.91 gears Nissan used in overseas applications. Or wait to run across a 10-bolt with PBRs and build it with your Torsen as a spare.

 

The 4 pinions in the 9 bolt are only in the factory carrier, though. This aftermarket torsen setup probably doesnt have anything like that in it. So that advantage is negated.

There's also basically no other option that I can find in terms of a T2.R for a 9bolt. If there is it's probably so cost prohibitive that a 9" is cheaper. But with that said, I'd imagine there's still a performance advantage with the 9 bolt for this application.

I didnt consider the idea that a torsen would be less than ideal for autocross, but it's probably a better option than the cone posi it normally has. I think the goal would be to have this be more of a track day car I take to autocrosses than an autocross car. I just autocross now because it's easier for the wallet.