D14

I agree with Def on all points.

Your gearing is identical to a JZA70 with the exception of final drive, the Supra's have a 4.10, you've got a 4.083. Minute difference. It's not gearing that's limiting you, it's power, revs and tire size. 95% of the "car people" I hang out with are MKIII and MKIV Supra owners, I know from first hand experience that you're not going to get very far with Supras, Vettes or whatever else on a stock twin 1JZ. Put the 17" wheels on (that will net about a 1.25" gain in tire height, slightly lengthening your ratios) and start saving for a single upgrade and supporting mods, your final drive is fine.

And don't switch to a 3.1 final drive, your car will fall flat on it's face, you don't have that kind of torque, it's a 1JZ, not an LS2. If you do decide to switch, don't go lower than 3.692.

Def

Exactly my point.

If you want gears that are a little longer, a J30 LSD would probably be a good compromise at a 3.9x. That plus bigger tires(which will make a big difference) will go a long way towards making your car feel like it's holding gears for longer.

g6civcx

This is your rear wheel curves as your car currently sits.



Top speeds in gear:

1 - 35mph
2 - 58mph
3 - 87mph
4 - 114mph
5 - 150mph

This is what I notice. From 60 you would use 3rd gear, but 3rd gear runs out pretty quickly at 87mph. 4th gear runs out at 114mph. The car probably feels out of breath in 3rd too quickly.

g6civcx

This is what it looks like if you went with 3.133, which is the numerically lowest OEM gear you put into an R200.



This is what I notice.

Top speeds

1 - 46mph
2 - 76mph
3 - 113mph
4 - 148mph
5 - 197mph

If you put this graph next to the graph on the stock diff, you'll start noticing a couple of interesting thing.

1st and 2nd gear may be way too long to be usable on the street. 3rd gear will give you a good stretch all the way up into the 110s whereas before you were running out at about 85.
4th will get you to almost 150 and I have a feeling 5th will be pretty much useless.

In my opinion, I'm not sure if this gearset is right for you unless you plan on throwing a bunch more boost at your engine to bring up your engine torque.

3.133 is actually a little too low even for my V8, but it gives me room to throw more torque at the engine and won't have to run out of gear.

Let me dig around and see if I can recommend something for you.

Def

This sounds like a good case to use a 275/40-17 and a slightly longer diff then.

A 3.91 J30 diff is about 4.4% longer, and a 275/40-17 is 4.0% larger than your current tire.

So that would give you 8.5% longer gears total with those two changes.

Giving you speeds of:

1 - 38 mph
2 - 63
3 - 94
4 - 124
5 - 163

Doesn't sound like bad gearing to me. Hell, sounds better than the long gears you get with a 4.08 on an SR box. You'd also have some tire to put down some speed. Don't go with a 255/45-17, the sidewall would look absolutely ridiculous. Even Mustang guys don't use that much sidewall on a 17" wheel.

g6civcx

These are possible candidates for ring and pinion into an R200 diff available from Nissan dealers:

3.357 from 05-07 Pathfinder 4WD, and 08 Pathfinder 4WD, but be careful because the 08 4WD also comes with R230 diff

3.357 from 350Z autos

3.538 from 350Z manuals


Other than these, you can find an S15 diff, or look towards Infiniti. You can also find some ring and pinions on ebay from old stock for 280Z and 300ZX.

D14

Or he could keep the 4.083, raise the limiter to 8,000 RPM (On your 255/45/17):

1st - 46 mph
2nd - 77
3rd - 115
4th - 151
5th - 201

3.91 might still be a little tall.

EDIT - Forgot to reset the calculator [/quote]

But now that I think about it, unless he's running some monster single that takes forever to spool he's not making much power at 7 or 8,000 RPM anyhow. He'd probably be better off with the 3.91 than trying to hit 8,000 RPM in 3rd with a 4.083. Me = FAIL.

Yeah, give the 3.91 a shot. Should give you what you're looking for and keep you in your power band.

g6civcx

I tend to agree. Make one change at a time. Pick your rubber first then look at how the car responds.

I wouldn't go much lower than a 3.5-3.6 at most for your current setup.

crameur

Ok !! I will Switch The Tires First To see How the car will Respond ... I Think i will install a new set Of Cams Too , Maybe Usdm 2jz Cams Modded To Fit 1jz ... This Will Help My powerband Too !!! 14 Psi Of boost And I will see After If it's Good Or Not ! I would Like To Thanks EveryBody Who Take Time To Help Me , It's very Appreciated !!!

D14

My not-so-expert opinion:

Keep your final drive stock for right now, get rid of the 15s, put the 17s with 255/45/17s on and when you upgrade to a single turbo, look at doing the J30 diff with the 3.91.

crameur

I want To Keep The Stocks TwinsThings i Will Do This Winter

- Put The 17 Inch On the Car
- Upgrading Injectors For jdm 2jz 440cc
- Upgrading Cams For Usdm 2jz Cams
- Map-Ecu Fuel Management
- 80 Or 100 Shots Of Nitrous
- 14 - 16 Psi Of Boost

it Should Be Good , I'll See How the Car Will respond and Get a New Diff If I got the same Problem ...

czarboo

Hi there,

Sorry about the weird thread revival, but this seemed like a good place to post my questions.

Do any of you have any experience regarding the torque capacity of the standard 6-bolt axles? Specifically, are any of you running over 500ft/lb through them? How much are you guys running through them, before they become broken bits?

Also, are there different versions of these, that may have different capacities for acceptable torque loads?

Thanks!