It's not so much how much power, but how the power is being applied on launch.

6 spd - go with 220mm, Auto - go with 200mm. Both diffs have had 1200+HP put thru them, but auto is much easier with a footbrake launch than a clutch sidestep.

Oh yeah, there is also the gearing thing; 3.13 or 3.26 (220mm) is perfect for a 6 spd, and 3.76 (200mm) is perfect for an auto.

Al

 

On ebay they have a bunch of diffs for sale. I need to get the auto one..but they have them by size like 8" or 8.7" which will fit the auto?

 

The only ratios suitable for an auto installed in JDM or US spec Supras came in the 200mm diff, which is roughly 8in (200mm/25.4mm/in = 7.87in) and the 220mm diff is roughly 8.7in (220mm/25.4mm/in = 8.66 in)
It's worth noting that I've seen other references to the 200mm diff specifying it as a 205mm, but I haven't bothered actually measuring any of the 200mm diffs I own. The 205mm value brings it to just over 8in (205mm/25.4mm/in = 8.07in)

The 200mm/8in diffs came with a large variety of ratios. If you are using the toyota automatic, the TT auto rear diff is the best with a 3.769:1 and a factory fitted LSD. Other options include the 3.916:1 92-97 SC400 diff, 4.082:1 SC300 5-spd diff, and the 4.272:1 NA Supra & SC300 automatic diff.

Note that the SC300 and NA Supra differentials will require swapping out the 3-hole companion flange that bolts to the driveshaft 'donut' in order to be used with a TT auto drive shaft. The SC400 and TT auto Supra use the larger companion flange, and that will be a direct swap so long as you're using a TT auto drive shaft. If you're using a 6-spd drive shaft, you may need to have the DS shortened slightly depending on your application.

Other info here: http://www.supraforums.com/forum/showthread.php?608545-JZA80-Differential-Info!

 

thanks for the respond guys . The car will have a viper T56 6 speed. Will the 200mm with a TRD lsd hold 1000hp reliable ? Or should i just cash out and buy a 220mm diff ?

 

The car will have a viper T56 6 speed.

Many have tried this - none of them have been satisfied.
The 220mm diff isn't even available in ratios that would be T56 friendly as its ratio spread is entirely different than the V160/V161's.
What Toyota made is all we got, this isn't a diff where you can just call up Richmond and order whatever..

 

Both rear ends have held the HP. What you are still not getting is the gearing ... you do not understand the final drive ratio so you might end up with a very poor driving car.

 

Yes I understand the t56 have 5 and 6 as overdrive. that is why I would like to run the 200mm rear end so I can
Run 4.26 gear. Just concern if the 200mm will be able to hold the power

 

The Facelift JDM 6 speed cars had the smaller casing diff with 3.26 gearing.

People utilising that setup had no issues with power until they hit the track with hard launching.

 

Most of the differential-grenading problems can be solved by using all of the billet differential mounts to help eliminate wheelhop, as well as avoiding drag radials entirely and using a full wrinklewall slick instead.

I've seen ~450hp BPU 6-spd cars grenade that 220mm diff because of wheelhop on drag radials.

 

GS430 straight drop in?

 

yup....ask quickgs he installed it

And early SC430 , same 3.26 and straight drop in !

 

yup....ask quickgs he installed it