Vrank

iTrader: (4)

What's wrong with the 3.90s from a stock 400? Way cheaper easier to find than tt auto diff, especially if you're set on trd lsd. Gear difference is marginal. I'm getting 21mpg average on the freeway in a 1j single sc400 with a 300 auto 4.27 diff. 3.90s and same setup netted me about 24mpg.

grumpi300

iTrader: (1)

nice. I don't know. that's why I was the one posting the question. lol. I've just read that 3.76 is a great diff ratio with the r154. so if that diff and tranny set up work, i'm not trying to go changing stuff that might not work or work worse or something. its my daily driver so I don't want to risk it being down for any longer than necessary. especially since my dads truck just blew the clutch. my car has the engine out cause of a blown head gasket, (which has already been changed out i'm just painting the engine bay now that the engine is out.) and I don't have another car to use to get to work and school.

czar07

I was using my stock 4.08 soarer ratio with my r154 on a 2jzgte. sat at 2500rpm @ 60mph. Mileage was around 21-22mpg

Vrank

iTrader: (4)

I'd do the 3.90s. They're cheap and plentiful, 3.76 sounds nice if you make enough power to do 180mph and wanna do it not at redline. I can bury the speedo with 3.90s. And get decent fuel mileage. If you can find a cheap auto tt diff with torsen though, that wouldn't be bad. That's one of the few things that really sucks about this chassis, price of a decent lsd and expensive chassis components

Ali SC3

iTrader: (10)

Vrank is def on point there is not a huge difference between the tt auto and the 3.9.
not a bad way to go if you cannot find the whole tt pumpkin.

99SC42

iTrader: (44)

I had a 3.92 from the SC400, it was great setup and its close to the 3.77 from the TT Auto.

Just get a TRD Auto LSD and drop it in!!

I wouldn't worry about swapping the crossmember, just make sure you diff bushings and subframes bushings are on point and you are good to go, I wouldn't worry about swapping it for a TT one.

grumpi300

iTrader: (1)

wait, so at first everybody said 3.76, (best suited for r154). now everybody's saying 3.90 from sc400 auto is the way to go. it seems like 3.76 is a little worse off the line, just slightly, but better for gas milage. exactly opposite for the 3.90. slightly better off the line but worse gas milage. I believe this is due to the fact that the engine and trans spin slightly less, quarter of a turn, in the 3.76 than the 3.90. if that's the deal then why not go bigger, for people who want more torque, or smaller for people who want better fuel efficiency? I read on one of the forums I posted earlier that 3.122 would act funny with a r154. is it because we would need more power, or because the r154 is just not happy with 3.122?

99SC42

iTrader: (44)

I have never ran 3.76, in my opinion anything lower than 4.00 will work great imo.

My favorite is r154 with 3.26 from the SC430, ive ran that for years. I built my cars for Top END so 3.26 is still what I love.

You have to know what you are building the car for and then decide what gear ratio to go with....

CatManD3W

iTrader: (18)

What are your guys opinions on a proper diff with W58....I was thinking the 3.76 would be good with it....the stock gearing is way to short now since I have gone GTE single turbo....I am not really concerned with the gas mileage aspect...just want to be able to stay into boost longer

Keep in mind I will be upgrading to r154 or V160 in late 2015 or early 2016

Ali SC3

iTrader: (10)

you need to tell us what you prefer, quicker acceleration at the cost of mileage and cruising rpm's, or the other way around. my 5spd cam factory with a 4.08 and I think its too short. acceleration is nice and crisp but I hate how high my rpm's are on the highway. I would not hesitate to go to a 3.9 which would make it a little better or a 3.76 would be the sweet spot (for me), which is why alot end up recommending the 3.76 with the lsd all together. I mean the 4.08 worked with the stock power levels, but with a turbo its funny how quick the gears fly past.

If you are going to piece it together though with a trd lsd, then what they are saying is the 3.9 is way way way way easier to find and will be pretty close still, and better than the stock 4.08 for 5 speeds. if you think thats bad enough the supra 5 speeds got a 4.27 ratio which is absurd how short the gears get, but it makes it feel sportier and quicker in n/a for, add a turbo and try not to hit the rev limiter if you can it will seem like you are constantly shifting that thing. so everything is a trade-off and your desires and power levels will (should) factor in the decision

Exactly someones perfect combo isn't going to always be your perfect combo. 3.26 would be great for a 6 speed, or if you want alot of top end on the 5 speed. you will want to be running more power than stock witha 5 speed and this ratio though to make up for the longer gears.
^^^ for example 'O runs at least 3x stock power levels, even on low boost.

the 3.76 is a good match for the 5 speed with a turbo and is recommended by most. if you can get the whole tt auto pumpkin that is the way to go, or just get the sc400 3.9 and drop a lsd unit into it is also close. IT will also work with the r154, but if you are going v160 then you will want the 3.26 there is no question about that. so it will make a difference if you go v160 but r154 is similar to the w58 (not the same but similar).

CatManD3W

iTrader: (18)

Thanks Ali,

Do you think the 3.13 or 3.26 6psd diff would be to much for W58 or r154

Ali SC3

iTrader: (10)

For me personally it would be too long cause I like more of a balance and I am rarely doing those speeds, but if you like top end you might like it.
I will let 99SC42 answer you more on that one but he did say this a few posts ago.

grumpi300

iTrader: (1)

so i decided to go 3.9 for the meantime as there are many of them around considering they were in all 92-97 sc400's. I called the Nevada pic a part and they are only 85$ with a 25$ core. i'll be keeping mine so I can drive it until I put the trd diff in the 3.9 so i'm not worried about the core.
what about welding the diff. I know that its horrible to drive around in welded diff if you make turns or park, cause the rear end would just hop around. but how bad is it exactly? does it destroy the tires or rear end if you drive it every day like that?
i ask because I might buy 2 3.9 diffs. one to weld together so I don't go through high rpm's and get a bit better fuel milage since I drive 50 miles a day minimum. or just decide against the welding and leave the stock diff in if welding it is so bad, at least until I can afford the trd diff.

Ali SC3

iTrader: (10)

welding diff is bad for street use (also dangerous), it does destroy tires as they are always dragged while turning (talk about loud in a parking garage), and the rear end is destroyed.. well because you welded it together. I wouldn't bother with welding unless its only a track use car, as in no plates etc.. just use as an open diff until you get the trd lsd. I am aware there is a crowd that thinks its a good idea on the street and well that is their decision at the end of the day but I wouldn't risk it breaking on the street and potentially causing a slide. I am still on the open diff if your tires aren't slipping you are still applying power to both wheels you just can't drift or have the power to both wheels when there is slipping. Upgrade tires and suspension first as those factor into the grip alot, and then once you are breaking traction on 275+ rear tires from a roll then you can safely say you need the lsd. On the other hand, if you need to drag, drift, or do burnouts its basically a requirement and you would want to do it right away.

grumpi300

iTrader: (1)

ok. thanks ali. I didn't know it was a safety concerns. only reason I ask is cause I looked into the trd diff and its 1100$ + on mvp motorsports. that's just for the diff not including the kit for the washers and bearings and other stuff, another 213$. then theres having a shop rebuild it for me since I don't know how to rebuild a diff. I can do engines all day long, just not a diff. haha. so i'll just buy a 3.9 and drive around with that till I can afford a 3.77 and a trd diff with install.