Rear Differential gear - Go lower than 3.73

[SupraClaou]

I am planning on getting a V160 6speed getrag trans.
But first I will lower my rear gear.Stock my car has the 3.73 LSD.

I heard that we can get a 3.540 rear ring & pinion that fit into the
8 inch rear pampkin,from Jawsgear.But still I want something closer
to 3.1 / 3.2 that the V160 has from factory.
The only 3.2 rear gear I found out that the mk3 had,was the original
turbo A model.Talked with IJ about that end it is almost impossible to get it.
Some pictures of the 3.2 rear end:

Also heard that we can put 3.071 ring & pinion from a Toyota 4 Runner!
The gear code is G662 and it came in the 2 WD 4 speed trucks from 1984-1990 or so...

Is that true?
Has anybody done this before?
Has anyone gone lower than 3.73?
I know some guys with 3.54 rear gearing from 'Jawsgear'...
Last...mk3 rear diff are 8 inch right? Can we swap the mk4 diff...and
is it the same size?

I made a search on this issue and haven't find much!

 

[Evilempire1.3JZ-GTE]

Have you considered custom half shafts & mounting the better MKIV 9"
It can handle more power and is factory the right gear ratio. You know the drive shaft will be a custom as it is.

 

[SupraClaou]

I know I will go with a custom driveshaft.But thought
about custom half-shafts that won't be easy to make.
Guess what? After some research I found out some very
interested things.
Mk4s have 2 size diff. An 8'inch and 8.5'inch.Never came
with a 9'inch :sarcasm:


Here is my research....handed to you :biglaugh:

And more info on the mk3 Trans and diff
=====================================================

Gearbox model R154
----------------------------
Reverse 3.18
First 3.251
Second 1.955
Third 1.310
Fourth 1.000
Fifth 0.753
Lubricant Capacity - Gearbox 3 Litres
Oil specifications SAE 80W-90 GL4 or 5 Gear Oil

Final Drive Ratio 3.727
Differential Code G305
Drive Pinion - Number of teeth 11
Ring Gear - Number of teeth 41
Ring Gear size 200mm
Driveshaft Diameter 29.60mm

Lubricant Capacity - Differential 1.3 Litres
Oil specifications API GL5 Hypoid Non-LSD Gear oil


Infos on the mk4 trans and diff:
=====================================================
6 Speed Manual Transmission Specifications (JZA80)
Gearbox Model V160 (5/93-8/97) / Gearbox Model V161 (9/97-7/02)

First 3.827 / 3.724
Second 2.360 / 2.246
Third 1.685 / 1.541
Fourth 1.312 / 1.205
Fifth 1.000 / 1.000
Sixth 0.793 / 0.818
Reverse 3.280 / 3.192

Lubricant Capacity - Gearbox 1.8 Litres -
Oil specifications Toyota V160 Gear oil or Castrol Transmax Z

Final Drive Ratio 3.266* - -
Differential Code B03B (5/93 - 5/96) A03B (5/96 - 7/02) A03B (5/96 - 7/02)
Drive Pinion - Number of teeth 15 - 15
Ring Gear - Number of teeth 47 - 47
Ring Gear size 220mm 200mm 200mm
Driveshaft Diameter 29.15mm - -
Lubricant Capacity - Differential 1.35 Litres - -
Oil specifications Standard Non-LSD API GL5 Gear Lube

*3.133 Ratio on Export 6 Speed Supra.

Now...about mk4's differentials
There are 2 differential sizes in the JZA80, the most common is the A series which runs a 200mm crown wheel which was found in the 2JZ-GE manual and automatic as well as the 2JZ-GTE automatic and in the manual 2JZ-GTE from 5/96 up until 7/02 when the JZA80 was no longer produced. The following ratios are available for the A series diff - 3.266, 3.769 & 4.083.

Then there is the B series which runs a 220mm crown wheel. It was found in the 6speed 2JZ-GTE from 5/93 up until the 5/96 where it was discontinued and replaced with the smaller A series. There was only ever 2 ratios offered on the B series diff - Export JZA80's received the 3.133 whilst the JDM ran a slightly shorter 3.266 ratio.

Both of the A & B series run a Type 1 Torsen differential up until the 5/96 when the Type 2 Torsen was introduced.

B Series dimensions
------------------------------
Differential Case OD 133mm
Element Gear Length 61.90mm
Spur Gear OD 36mm
Worm wheel OD 33mm
Side Shaft OD 37.80mm
Side Shaft spline count 35

A Series dimensions
-------------------------------
Differential Case OD 123mm
Element Gear Length 57.1mm
Spur Gear OD 33.3
Worm wheel OD 30.5mm
Side Shaft OD 33.70mm
Side Shaft spline count 30

So...If we can find an A series mk4 diff ring & pinion,which
it has the same dimensionson the crown wheel as the mk3
(200mm) 8"diff. :icon_biggAnd the driveshaft diameter are
almost the same: mk4s is 29.15mm & mk3s is 29.60mm....
That's something to begin with :biglaugh:

 

[IJ.]

LOL told ya it wasn't a 9"

 

[SupraClaou]

LOL told ya it wasn't a 9"

Yes... you're de man :thumbup:
My car (about 400 bhp) with 3.73 & R154 still feels lazy on
pulling 3rd 4th not to mention 5th gear...but I like top speeds:biglaugh:
If I swap the 3.54 in,it will be more lazy?
What do you think IJ?
What rear gear do you run?...How does it feel yours in mid range
pulling?
I know you have more power (bhp) though ....:sarcasm:

 

[mdr40z]

maybe this is the ticket for me too, as some know I swapped in the TH350 a couple years ago and all is well but the highway is a pain at 90 mph or so I'm almost redlined

 

[IJ.]

Yes... you're de man :thumbup:
My car (about 400 bhp) with 3.73 & R154 still feels lazy on
pulling 3rd 4th not to mention 5th gear...but I like top speeds:biglaugh:
If I swap the 3.54 in,it will be more lazy?
What do you think IJ?
What rear gear do you run?...How does it feel yours in mid range
pulling?
I know you have more power (bhp) though ....:sarcasm:

Not much more at all and I'm Auto now.
(423rwhp this weekend just gone)

I run a set of 3.5:1 in the 9".

If yours feels lazy with 3.7's it's only got to be worse with anything lower but this all changes when the Getrag goes in.

 

[figgie]

lazy with a 3.7 on 3rd & 4th but you want to go to a higher ratio?

That would make

2nd, 3rd, 4th feel lazy. So instead of two "lazy" gear now you have three??

 

[Quin]

But he's also swapping in a V160 which changes everything.

 

[suprabad]

Why the 6 speed? Wouldn't you want to go with maybe a 4.30 since you'll have an extra gear. Possibly change trans gear ratios to take advantage of it?

IJ: Did you do a build-up thread on your Ford (I assume) 9" rear? I think I looked a couple of times and didn't find it. Link?

 

[figgie]

But he's also swapping in a V160 which changes everything.

no.

Only way it MIGHT is to have the MKIV rear end in there. Anything else is a tree stump puller and on the stock 3.73 will make 1st gear a very good rock climbing gear and that is it as 2nd through 5th

Gear R154 v160
1st 3.251 3.827
2nd 1.955 2.360
3rd 1.310 1.685
4th 1.000 1.312
5th .753 1.00
6th ---- .793

pay attention to the monstrosity that is first and a super tall 2nd. Tree stump pulling anyone? Notice that 6th is SMALLER than the R154 5th

 

[IJ.]

SB: Not really I posted a few pics in my pics thread.

Yes it's a Strange Nodular case with Motion gears on a Detroit Preloaded Truetrac Torsen style centre.

 

[SupraClaou]

lazy with a 3.7 on 3rd & 4th but you want to go to a higher ratio?

That would make

2nd, 3rd, 4th feel lazy. So instead of two "lazy" gear now you have three??

Yes...But I want to swap a V160 soon.
Ofcaurse the R154 with a lower rear gear than 3.73 will be more lazy :biglaugh:
I just want to fix the rear gearing (for the getrag) issue first :sarcasm:

 

[Evilempire1.3JZ-GTE]

Whoa learn something new every day can the drive gear ad ring gear be machined or direct swap into our housing? if both come in a 200mm form ?

 

[Jostar]

Whoa learn something new every day can the drive gear ad ring gear be machined or direct swap into our housing? if both come in a 200mm form ?

I"m very interested in this.....

 

[MrOizo]

I"m very interested in this.....

thought i would ask on the progress on this information....

i am looking at changing my ratio in the diff. i have the V160 with the 3.9:1 from the original auto and its not all that bad.

Anyone know if the crown and pinion are interchangable acoss the JZA80 and JZA70's?

Cheers.

 

[Doward]

Considering how much a V160 costs, I'd rather put a T56 with a stock 4.30 differential in there.

Better all around Sure, the tunnel requires a little massaging, but for what you get back, that's not a bad ROI at all

Just my .02. Hell, a 4.30 with the new 5th gear for the R154 I'm bringing out may work out better in the long run, as well.

 

[IJ.]

thought i would ask on the progress on this information....

i am looking at changing my ratio in the diff. i have the V160 with the 3.9:1 from the original auto and its not all that bad.

Anyone know if the crown and pinion are interchangable acoss the JZA80 and JZA70's?

Cheers.

No they're not.

 

[Nick M]

pay attention to the monstrosity that is first and a super tall 2nd. Tree stump pulling anyone? Notice that 6th is SMALLER than the R154 5th

The JZ series needs the short gearing. :icon_razz

I think a T56 is a better choice if you are going to fabricate. There is far more aftermarket and support for it. Many different ratio's also. The Mustan Cobra, F-Body, and Viper all used the same trans, with slight differences in gearing. Well, big if you count 6th.

Don't get too carried away with tall gearing for top end. If your car doesn't have the grunt, you won't pull that tall gear anyway. Case in point, and old 5.0 Mustang. It was tall enough to go 205 mph before fuel cut. Think it can go that fast? Not even with 500 horsepower it won't. For example, Cartech put together a turbo Mustang with serious balls. They couldn't get it over 177. Not that 177 is a piece of cake or slow. The gearing is just too tall.