4.30 Differential in a 1jz swapped mk3??

[Bobbyt5408]

Well my question is driveability, im gonna be driving the car alot, mainly highway at about 65 70 mph.... what kinda of cruzing RPM will i see with the 4.30 lsd in my 1jz R154 swap? Im currently pussing between 400 and 450 wheel if that makes much of a difference. Now im not sure what ratio is in the car now and i would check but there is still 4" of snow on the ground and i dont feel like messing with it.... So im hoping someone on here has experience with the 4.30 diff in a similar setup or any setup for that matter..

Thanks in advance!

 

[IBoughtASupra]

I have a 91 with a 3.73 and I do 60 a little over 2 grand in fifth gear.

 

[CyFi6]

I have a W58 with a 4.3 and its not a highway cruiser... Made a 2 hour trip last weekend and the speed limit was 75-80 and i was sitting at around 3600-3700 RPM for about an hour and a half strait

 

[gurley0916]

http://www.supramania.com/forums/showthread.php?32898-MK3-Gear-Ratio-RPM-Tables

 

[Dimman]

Could you just do this: (4.30/3.73) X current cruise rpm = new cruise rpm ? (or sub in 3.90 for 3.73 if that's your current rear end)

 

[sweaver]

buddy has 4.30s and is at 3000rpm at 55mph in a stock NA.

auto trans

 

[hvyman]

W58 has a different 5th gear ratio. So the 4.30 is different with it.

 

[Dimman]

W58 has a different 5th gear ratio. So the 4.30 is different with it.

It's really close though, so that's a good guesstimate. It may be within 100-200 rpms, not counting different tire sizes...

 

[hvyman]

.030

r154 .753
w58 .783

Add that .03 with .2 difference from the diff and you have 2 completely different shifting cars.

T56 can be had with either a .5 or .65 in 6th gear which is why you can cruise at or below 2k at 80 in 6th gear.

 

[Dimman]

I missed that sweaver's buddy's car was auto.

What I was getting at is that an R154 with 4.30:1 and a W58 with 4.30:1 will be within 100-200 rpm of each other in 5th.

 

[mensrea]

On my old 4.30 with R154 70 was just over 3k something like 3100-3200. Shitty gas milage... Go 3.73 if you got big single.

 

[supra1008]

In my red car, I had 1jz r154 and a 4.3 open. I would drive to DC and back to Philly and would do 80-90 the whole way. rpm would be around 3200-3400. since it is .5L smaller then I would still get decent mpg. If you want good hwy mpg then get the 3.7. If you want good track times, stay with the 4.3 if its an lsd. If you want in between go with the 3.8/3.9.

 

[Bobbyt5408]

WOW! this was great, that chart was awesome! Great information! I think i might go with the 4.30 if the price is right until i find the 3.73 cause its not a 100% Drag car and its not a 100% street car its gonna be used in both worlds, but mostly on the road so i guess the 4.30 doesnt make much sense but this open diff SUCKS! and i dont think i can take it any longer! If anyone knows of some one with a LSD in the 3.73 range please PM me im currently in the market!!!

 

[te72]

Could you just do this: (4.30/3.73) X current cruise rpm = new cruise rpm ? (or sub in 3.90 for 3.73 if that's your current rear end)

Never thought about the math that way, but at 75mph, my car (3.73, stock-ish height tires) cruises at about 2850. According to your proposed math, you'd be turning around 3285 rpm with the 4.30 diff. Seems about right... Then again, my Mk2 (w58, 4.30, stock height tires) cruises at about 3700 at ~75mph. Definitely a different trans, a buddy of mine compared the R154 to a 4-speed with an overdrive gear, while the W58 seemed like a 5 speed without overdrive to him.

 

[mensrea]

In my red car, I had 1jz r154 and a 4.3 open. I would drive to DC and back to Philly and would do 80-90 the whole way. rpm would be around 3200-3400. since it is .5L smaller then I would still get decent mpg. If you want good hwy mpg then get the 3.7. If you want good track times, stay with the 4.3 if its an lsd. If you want in between go with the 3.8/3.9.

I could barely get 5psi with 4.30 in first gear.
To each his own I guess..

 

[Dylan JZ]

3.73 is little high for my taste, at least for around town.. if you do a lot of highway miles, it may be just right though.

3.91 is a great compromise IMO.. that combo turns ~3k at 75mph.

 

[makaveli913]

I have 4.3 in my car and one things for sure its FUN! Highway over here speed limit is 75. Im at about 3200 rpm to 3400 rpm. kinda high but i like it. I removed ps and ac and i get positive boost at 1700 rpms so it burns through the gears quick.

 

[2543arvin]

I have the 4.30 LSD and it sucks! Gas mileage sucks and trying to hook at the track or anywhere else for that fact, is useless! Im currently looking for the 3.73 LSD to swap and get rid of my 4.30. If you are making any kind of power, you will probably want to ditch the 4.30. It was put in the NA for a reason...it has no power.

 

[Bobbyt5408]

Thats all very helpful information!!! And i should also add im on 18" veil side rims with 255's.... so maybe that would help... if i was under 3k at cruzing speed i could deal with it... @ 2543arvin what kind of tires are you running at the track and what suspension? could that be why your not hooking well cause i hear from others that they do much better with the 4.30 at the track?

 

[2543arvin]

Im running street tires with Megan coilovers, so not Im not set up for the track but I can tell you that you will run through ALL 5 gears in the 1/4 mile, and that sucks!