What diff is best for a 1JZ?

[lifesnotfair]

I know a couple of people in here with 1JZ's and they all use the 7M-GTE diffs... which are, if I remember correctly, about 3.7 or 3.9:1, depending on the year, right? ... I know 4.30's only came in N/A's, and the ones with Sports Package had it LSD.. but I've heard it's a spinfest when you go turbo with that.

Anyways, I have a 4.30 non-LSD I think, so I'd need a diff. But I dont wanna get a 3.7:1 or 3.9:1 if the JZA70's came with that 4.10 Torsen one. Are those hard to get? Are they expensive?

Just curious.

 

[msdg137]

I have a 3.7:1 in the garage wating to replace the open 4.30. We have alot of highway up here and Id reather keep my RPMs down. If the 3.7 is too tall I also will switch to a 4.10 torsen. Lets hear some opinions on the combo's

 

[lifesnotfair]

The 3.7 is probably the best for highways, logic tells us.

However, in my personal case, I don't drive in highways very much. Maybe going to the beach, but that's 30 minutes away on the highway.

Besides, it's not like I want to keep my RPM down while doing 200km/h ... I don't even like speeding on highways. I like more speeding in the city, in gears 1-2-3 ...

 

[zoonwen]

4.10 is the best in my opinion becuase its in between =) and your speedo wont be off with a 4.10 unless you swap out the speed gear.

 

[Ckanderson]

yea i have a 3.73 its great on the highway but would like to go 3.91.... we will see how the car feels with my new setup

 

[lifesnotfair]

zoonwen: nice car! Damn, looks like mine actually. I just need the lip and sideskirts.

 

[devil358]

it seems like a lot of people down the Torsen LSD, but considering most of them came with clips, they may have been abused previously. I understand that they are not the ideal rear to drag race on, but a lot of us are not drag racers....yeah, I'll take mine to the track every now and then, especially after certain mods, but personally, I think I fall more into the category of the canyon carver, backroad burner type and I think the torsen with the 4.10 is a great option for this...

 

[tissimo]

3.73 is way long.. going 120 in 3rd is fun, but sux at the same time..

i say a 4.30 with a high revving 1jz would be fun (7500-8000).. 3.9 would be a good.. still lots of top end, but a little more accel..

i've been tempted to swap my friend for his 4.30 lsd... well see.. maybe one day..

 

[jbsupra89t]

I love my 410, but would like to try a 391 or 373... 120 in 3rd, hmmm.... with a single and cams, I'd love the longer time in the gear and up top as well. Tissimo you have any track times with that setup and the 67? Thanks!

-J

 

[lifesnotfair]

What would cost me more, the 4.30 LSD or the 4.10 Torsen?

 

[tissimo]

not really.. i went there one week at 9 psi.. went a 105 mph.. 14.0 or something (bog really bad).. still havn't got a chance to get on the dyno and tune it though.. one day.. haha

I guess 4.3s lsds are kinda rare? (maybe not) so not sure.. the 4.10 doesn't like a lot of shock load (drag launching) so dunno..

 

[shatter2]

I can testify that the 4.30 from the N/A is geared too short for 1st and 2nd gear, even on my mostly stock 1JZ. 1st gear is gone before I've even lifted off the clutch pedal fully and 2nd gear is similar. 3rd gear and beyond is perfect. But for those of you who like to drag race or street race, I'd go with a 4.10. You waste too much time shifting in 1st and 2nd gears with the 4.30.

Just my $0.02 :biglaugh:

 

[tissimo]

4.30 shifting at 7500 = 40mph in 1st..
2nd at 7500= 66.. short but not horrible..

 

[Troyota]

actually by the looks of it...if the 1JZ had a 7500-8000 RPM redline from the factory. I bet that 4.3 would probably be pretty close to the factory final drive. They like to hit just over 60 in 2nd...helps 0-60 times. I'm going w/ the 4.1 Torsen. One, I have it. Two, my factory N/A diff isn't LSD. Three, I don't do a whole lot of hard launches.

 

[IJ.]

Hard launches aren't the only thing that kills a Torsen

While I've been tuning/developing my car I haven't done a single hard launch, along the way it had many rolling full throttle pulls and I suspect the combination of soft rear springs and lower power around the 300+ mark has totalled the Pinion Bearings.

This was on a freshly rebuilt Torsen!

Once over 450 rwhp/harder rear springs traction just isn't there so it's gentler on the diff.

I've just about trashed my 4.3 LSD in the few weeks it's been in but it's got 260.000 km/160.000 miles on it so I'm not surprised it's raised the white flag!

 

[Troyota]

Wow...that sucks. Definitely something to keep in mind then.

 

[shatter2]

4.30 shifting at 7500 = 40mph in 1st..
2nd at 7500= 66.. short but not horrible..

You are right. I did the calculations and confirmed that. Then that means my gearset must be different. Cuz I can't go past about 28-30 mph in first without redlining it...

 

[mobes]

YAY shatter2, another Supra in the region! I have relatives and friends in Utah. I looked for Supra parts while I was there last summer. Slim pickn's. I found one picked over '89 N/A. It seems everyone there is a bit more partial to domestics.

Back on topic, I think my 3.73's are a bit steep for the 1JZ so I'm swapping in 4.10's. FYI, if all you need are the gears, the ones from a 1995 or older V6 4runner fit and are 4.10's stock

 

[inline6]

I have 4.30 LSD on my 1JZ and I think the gearing is pretty good. Second gear pulls like a SOB. I would have to agree that 1st is a bit short and if I'm rolling at all I just start in 2nd for daily driving. You can take 2nd to 60 no prob. and 3rd to about 95 maybe higher? It is a lil high for highway cruising but not that bad. I would imagine for no traction in 2nd you would need a lot of power and/or too skinny of tires.