awdandrwd

iTrader: (1)

^^ It's refreshing to see a proper opinion on brake sizing for a street car on a car forum, it is extremely rare for some reason. The rule of sizing the brakes is if you can lock them up, you have enough braking power. Only reason to have larger rotors is for greater heat dissipation, but you really shouldn't be experiencing brake fade due to too much heat in any street situation.

Also look up "unsprung weight".

Stan

jtamulis

iTrader: (1)

Thanks. Since I have 4x GS300s and 2x LS400s and I have had over 2 dozen MKII/MKIII Supras in my life, and done brake upgrades and downgrades on tons and tons of cars, I have a very unique perspective.

The best stopping vehicle I have put together is a MKIV supra TT with MKIV N/A brakes on it (he did that so it would fit the smaller drag wheels). I should have gotten before and after runs, but I expected it to be -MUCH- worse, when in fact it was just about the same. The ABS kicked in, just barely on both heavy brake stop attempts.

HOWEVER, on my 95 GS300, brake fade was a concern I considered as I want to be able to road race the car, a point where thermal energy management actually matters, unlike the street car.

And the LS400 calipers weigh less than the GS300 calipers by a lot, but the rotors weigh slightly more. So technically I have less un-sprung weight, but slightly more rotational mass. It's a tradeoff I'm willing to live with as I have plenty enough power to make the car go forward in a hurry.

And I'm doing it because it looks cool on the Aristo. I'm also changing out the ABS/Trac pump and ECU so that it knows I have the bigger brakes on it, and making sure the speed sensors send the same signals. My "abs system" will know about the different sized brakes, something almost NO-ONE does. And if you do that, in a true panic situation where the ABS is engaged, the car will actually stop WORSE with the bigger brakes, this is a proven fact, simply because the ABS pump/computer doesn't give the correct amount of braking pressure for the pre-programmed Factory calibration.

Basically if you put HUGE brakes on a car, the ABS system will "over correct" because it won't understand why the brakes are working erratically better. So the few milliseconds that the car needs to figure out in a panic may make a difference, and since I have all the components of both cars on two separate, running vehicles, swapping from one, and back to the other is as simple as unbolting/bolting.

NOTE: The for the original poster: the 1996 LS400 I have with just GS300 front brakes and no other change stops quite well, and does engage ABS, and stop the car in snow (we had some last night, and I tested).

mr. tetsuo

iTrader: (3)

Interesting, you'd be the first person Ive heard running that set up. Hrmm... I'll keep that as an option and see what my local yard has. Thanks for the input.

jtamulis

iTrader: (1)

When I got my 96 I was going to use it as a parts car, and took the bigger brakes off, and sold them. Then though, huh, this engine is actually pretty good, so I put it back together, and put the GS300 brakes I had laying around.

Car drives just fine, and brakes fine, doesn't pull funny, etc. Of course, your mileage may vary, don't hold me responsible, and all that 8-).

AYEmike

i have 15mm on and yes its causing every ****ty problem that wouldnt BE a problem if there wasnt a bbk.

PureDrifter

iTrader: (10)

really now? i've been running high disk wheels and H&R 15mm spacers on the front of my car for some time now w/o any issues.... What problems are you having exactly?

Since the main OP's question on if 2pot brakes will fit has been answered I'm going to refrain from turning this into a commentary on the merits of such a conversion or braking systems in general, and request that everyone else do the same.