350z or Q45 final gear in a j30 diff? Want longer gear...

[spent27]

I am trying to maker my second gear a bit longer for autocross because I am running out of gear currently. By dropping down to the 350z 3.54 final gears from the j30 3.9 and going with slightly taller tires, I could gain about 10mph. I am not sure, however, that these final gears are simply interchangeable. I am hoping to keep my 4 lug wheels, that is why I am not simply swapping in a q45 diff...

Thanks

[silva.240]

great write up on this site,
KA24DEvelopment.com :: VLSD Swap Information (http://www.ka24development.com/vlsd.html)

[spent27]

I'm specifically asking about swapping the internal gears... that is a great site though !!

[drift freaq]

A lot of info on all of this stuff is in the archive and faq section. Seriously I do not think you want to go to the 3.54 gears anyways as it would make your second gear an absolute dog. Perhaps you should look around for a 3.70 gear. They were very common in S15 diffs.. Again though you have to look at a couple of things here besides just making 2nd gear longer. Do you have the HP to support a taller gear? Are you running a turbo? All of this stuff counts.
In fact MrMeph was selling a 3.70 ring and pinion a month or so ago and I am not sure he sold it. Also I think MrMcgarret has one as well.

[Weedm]

even if it was possible to swap Z33 gears, you wouldnt want it. theyre so frikken long its ridiculous. most of us Z33 guys who upgrade our gears swap to 4.08 or 3.9 gears, and sometimes 3.7.

DONT DO IT!

[spent27]

Sorry, I guess it would have helped to say that this is a VQ swap car.

I have the J30 3.916 gears in the rear now and I'm hitting the rev limiter (bumped from 6600 to 7k) way to early. One of the competitive drivers in my region mentioned 75 in 2nd is what most shoot for. With the 3.54, I'd still would be under 70 in 2nd gear. If anything, more horsepower will come down the road. Trust me, I'm not worried about the car being 'sluggish'.

[Weedm]

adding the VQ swap helps :hs:

if youre strictly autocrossing at the same track layout then go for it as it fits your needs.

i think im hitting 75 in 2nd but thats with a HR motor redlining at 7.5k.

just be prepared that 3.5 gears wont allow you to be in the most efficient powerband for the VQ.

[drift freaq]

adding the VQ swap helps :hs:

if youre strictly autocrossing at the same track layout then go for it as it fits your needs.

i think im hitting 75 in 2nd but thats with a HR motor redlining at 7.5k.

just be prepared that 3.5 gears wont allow you to be in the most efficient powerband for the VQ.

well I already said what I said about the gears and given the added factor of the VQ? I would still go by what the man above says.

[spent27]

Well, that being said, you guys still haven't told me if they would work :)

I also have added incentive to stay in 2nd because I just found out I have a troublesome 3rd gear (350z synchro problem....). I can replace tranny for 700$ or gears for < 80$

[camaro379ss]

I think they are not saying whether or not it will work because it seems that there isnt a point.

The powerband wont be at its best. Maybe I missed reading something but is this a track car? What type of racing?

[Corbic]

Well, that being said, you guys still haven't told me if they would work :)

I also have added incentive to stay in 2nd because I just found out I have a troublesome 3rd gear (350z synchro problem....). I can replace tranny for 700$ or gears for < 80$

350Z Gears do not fit in a 240sx pumpkin. End of story.

[spent27]

350Z Gears do not fit in a 240sx pumpkin. End of story.


That is all I was looking for :). And I assume this means the same for the J30 pumpkin that I currently have?

And I appreciate everyone's input on what they think is best for my car, but I am really just looking for options to get my gearing to how I want it... I need a longer 2nd gear, simply put. This is for scca solo and the car is only used for that. Like I said, I am hoping for 70+ mph in 2nd, and currently I am only getting to the mid/high 50s.

[Kouks]

Instead of losing your torque and grunt outta corners, could you gain by modifying the vq35 for another 500rpm and a slightly taller tire would allow you mph and still have a grunty final drive......

[drift freaq]

That is all I was looking for :). And I assume this means the same for the J30 pumpkin that I currently have?
.


If you reread your own post and how it is worded, you clouded your question with proposition of you gearing idea, instead of just asking straight out if a 350z ring and pinion would fit in a J30 pumpkin.

At which point we responded with, we do not think you will get optimal results based off your idea.
Which we expressed, which would lead to a why even bother situation.

Which would lead to your bottom line question not needing to be answered, because there is no reason for it.

Now I understand you feel an express need to go this direction despite suggestions based off your own theories. It does not mean you get the results your after due the fact that like others of said you will be in a different section of your powerband which might not be optimal.

I also did already suggest running the 3.70 gears from a s15 diff ( as well as a few other r200 diffs) as good compromise. It sits directly between the stock 3.54 gears and the 3.91 gears ratio wise thereby giving you a bit more length in your gear while not completely sacrificing the off the line acceleration you have picked up with lower than stock gears.

Oh and yes the 350z pumpkin is a R230 I believe while the our cars and the J30 are R200 pumpkins.

[spent27]

Fair enough. I'll go with the 3.7 q35 diff for now, that way I can use J30 6 bolt axles and keep my 4 lug wheels. We'll see how that plays out for now. Thanks for the input. I provided information on what I was doing in my OP because I knew people would wonder why is the world I wanted longer gears :)

I'm still alittle confused about which q45s I can use the j30 axles for though... and which ones I have to switch to 5 lug with z32 tt/q45 axles.

[MrMcgarrett]

You can use the 97-01 Q45 3.7 diff with J30 axles.
Only thing you have to do is redrill the input flange on the diff to the S13/S14 driveshaft pattern.
The 90-96 Q45 diffs need the Z32TT/Q45 axles and hubs.
Or you can swap the 90-96 Q45 3.54 ring and pinion into the the J30 housing.

[spent27]

You can use the 97-01 Q45 3.7 diff with J30 axles.
Only thing you have to do is redrill the input flange on the diff to the S13/S14 driveshaft pattern.
The 90-96 Q45 diffs need the Z32TT/Q45 axles and hubs.
Or you can swap the 90-96 Q45 3.54 ring and pinion into the the J30 housing.

Ok, that covers about everything :)...

Actually, one more question and then I'll call it a day... can I do the 3.7 in my J30 diff?

[MrMcgarrett]

Yes you can:bigok:

[drifter92]

Yes you can:bigok:



Thread revival!

Are you 100% sure this works and is proven?