Couple quick questions.

Will a 2004 gs300 rear end pumpkin direct bolt with my 1999 gs400.

I understand I will be going from 3.26 to 3.92 gears.

Will my speedo and tach be off? Or is this electronic and the computer will adjust?

How easy to swap?

 

Speedometer is read off the ABS wheel speed sensors, so the gauge will read the same. You have to swap the companion flange(the one that goes to the driveshaft) on the 2 differentials. They are both 3 bolt flanges, but the V8 flange is like 1-2mm bigger. Very hard to tell by eye, but it will have to be swapped or else the driveshaft won't bolt up correctly. Once the flange is swapped, everything goes back in the same way it came out. I would also recommend you using loctite on the threads on all of the bolts. The last thing you want is for those to come loose on the highway. If you plan to do this swap, let me know. I will buy your old GS400 diff from you after you do the swap.

 

Keep in mind you will lose 2 - 3mpg by doing this and your car will be mechanically limited to a top speed of around 125mph. You'll probably be around 3300rpms @80mph. But the acceleration will be great! GL!

 

Will the shifting change? The 04 looks the same as mine

 

Add a torque converter while you're at it and control your right foot. Forget about good gas mileage though. ha ha

 

Shift point will change, no more shifting to 3rd @ 62mph. Now, your car will shift to 3rd @ 56mph. So, technically your 0-60 times will be a little slower due to the extra gear change before hitting 60.

 

Scored a 300 diff today at the local junkyard. What is involved in swaping the flanges??

and sure ill hook you up with the old one

 

Wow...That's hard to believe. Around 25 mph less than with the 3.27 gears...That's a lot!

Acceleration in "general"- even though the 0-60 time might be the same or WORSE, b/c of the extra shift- will def be better though, right? How much of a difference in the 1/4 mile, you think?

 

Put it this way. I have the 3.73 Supra LSD and I believe I am mechanically limited to a top speed of 132mph. With these, or the 3.92 you will have a quicker 1/4 mile, perhaps .2 - .3 quicker but you will be a good deal quicker in say, a rolling race on the highway. Because that extra shift is needed (same with my 3.73s) many people buy power adders such as intake, exhaust, headers, A/F controller and sometimes a high stall torque converter to get out of the hole quicker. All, or even some of these will ensure your 0-60s are a good amount quicker even with our extra shift to 60mph

 

The car will feel like its always in 3rd gear..(5speed manual comparison) ready to go..