EITELS123

I have searched and cant come up with a yes or no exact answer. I was thinking about getting the complete SC400 3.92 pumpkin and putting in in my 00 GS400. I know the gears can swap. But is the whole pumpkin direct bolt in, meaning does the input flange bolt up?
I know the most sought after is the 3.76 supra lsd but those are rare. My plan was to install a an LSD in the 3.92 gear set and call it a day!

badblackgs

iTrader: (1)

be prepared for you rpms on the highway to be well into the 3500 range.

iToaster

The SC400 one looks the same. You could just get one from a GS300, it's the same ratio and generally cheaper and more abundant, plus you would know for sure everything would bolt up.

EITELS123

Isn't the GS300 flange different to the driveshaft? and Its not really going to be a freeway cruiser.

RamAirRckt

Go to car-part.com and look up the interchange.

I'd like to know mpg change and 0-60 and 1/4 mile change for 3.27 to 3.92.

Rock-a-Lex

iTrader: (4)

Well, your 0-50 will be quicker but your 0-60 will most likely be slower or the same. This is because the car will now shift again at around 55mph. It shifts again at around 58mph with the 3.73 gears and does this shift at a bit over 60mph with stock gears.

Overall, 1/4 mile will probably be 2-3 tenths quicker but gas consumption will most likely go up by close to 3mpg. Your 80mph highway cruise will run around 3300-3400rpms. For reference, the 3.73 gears shows a hair over 3000rpms at 80mph.

Also, note that this oem 3.92 gearing is an open diff. Steeper gears without an LSD will most likely yield traction issues. The 3.73 setup is essentially an LSD unit from the mid-90's TT Supra.

The 3.73 gears are most desirable as they provide good all around benefits over the stock 3.26 open diff. However, they're not easy to come by and they're expensive. The 3.92's are cool too but they come with more cons.

Good luck.

RamAirRckt

Conversely I'd like to takeva GS300 and toss in the 3.27's out of a GS400 and see what sort of mpg could be had....

colinodon

Off topic but at what hp level does the rear oem gs400 diff fail?

RamAirRckt

I'd say not the hp but the torque. GM put the 7.5" diff in cars that had 255 ft-lbs or torque and 3300 lbs, but when they got over 300, they went to the 8.5" diff.

I've even seen the 4500 lb Fleetwood with the anemic 4.1L v8 still get a 7.5" diff, but when the engine got larger and more torque, even the slow 307 at 255 in a 4500 lb car, the 8.5" came into play.

Our cars make 310 ft-lb torque but at 4000 rpm, and we have a 8" gear, I have heard of no one breaking one yet.

I'd say just a guess, with the 3700 lb curb weight and the LS gets same diff up to 2006, we can take 400 ft-lbs of torque with our light cars.

Note in drag racing with slicks is a very different story

colinodon

I'm running radials in a low 13 second gs400 w/ nitro... Had my car on the lift and notice a little oil stain coming from the driveshaft-differential junction when I got added on some resonators