climberd

Hi Guys,

This is not a typical thread about putting the BIGGEST possible calipers on a 1990-1992 LS400.
This is about 90-92 LS400 STOCK SIZE ROTOR upgraded caliper options.

I have a stock 1990 LS400, so front calipers with 1 x 64mm piston bore, over 274.9mm x 25mm x height of 47.55mm rotors that weigh just 14lbs
That's a piston area of = Pi*r^2 = 3215mm^2
Crap braking, but low unsprung weight so better ride quality.
I have stoptech front pads, and I still would like more clamping power up front, if cheap and it lets me keep the stock light weight 275mm rotors and aftermarket equivalents. I have a very fast car with F40 calipers and floating 2-piece rotors that costs a stupid fortune to maintain, and this Lexus is NOT going to get any similar sort of treatment, due to reason of sanity.

I see that if you have a 1990-1992 LS400, you can most likely bolt on the following:

1993-1994 front calipers, 2 x 45mm bores, over 295.9mm x 32mm rotors weighing 20.8lbs.
That's a pistons area of = Pi*r^2 = 3179mm^2. About the same
Minimum 16" wheels, so will not fit OEM 15" wheels. Adds almost 8 pounds of unsprung, rotational mass. A downgrade in handling, comfort and performance, which the car is already terrible at. It appears the upgrade here is all in the bigger rotor.

Alternatives:
1992-1998 SC300 calipers, which appear to have the same spindle bolt-up arrangement.
2 x 45mm bore, BUT fit over a 274.8mm x 28mm x height 50.9mm, so 3.5mm more offset.
The greater offset could be compensated for on a LS400 by a shim or something, though I doubt it's needed. Probably is the same 2-pot caliper with a different bracket for the different rotor diameter.
Pads are pretty universal:
LEXUS ES300 (1992 - 1996)
LEXUS LS400 (1990 - 1992)
LEXUS SC300 (1992 - 1998)
TOYOTA AVALON (1995 - 1997)
TOYOTA CAMRY (1992 - 2001)
TOYOTA CELICA (1994 - 1999)
TOYOTA SIENNA (1998 - 2003)

Alternatively, the 1993-1994 appears to be on its own pad standard, with no cross-compatibility. Pad size is about the same, thickness is the same (17mm). Still, this limited model range has a nice selection of pads.

Other alternative, there is a Beck Arnley 2-piston front caliper retrofit for 1990-92 LS400 on rock auto, also 2x 45mm, which I'm guessing holds the 1990-1992 LS400 et al pads.

In short, I don't see a good way to ugrade these, other than to get 16" or 17"+ wheels and much bigger rotors, which is a lot to spend both (money and other compromises) on a car that is meant (for me) for long, comfortable drives.

Questions for the experts on here:
Do you know of a bolt-up OEM-spec caliper upgrade for the 1990-1992 LS400 that fits stock 295.9mm rotors?
Master cylinder upgrade or something else?
Thank you in advance

91LS4OO

I say you start with steel braided brake lines and brake fluid flush,. then enjoy the upgrade.

PureDrifter

iTrader: (10)

MC upgrade for such a minimal difference isn't neccessary at all.

I would just go with a UCF2x bbk....

climberd

My long overdue replies, sorry.

I had already done the SS brake line upgrade and brake fluid flush. Honestly could not tell a difference. But also OEM lines are braided, covered with rubber so they are more resistant to the elements. I don't know how resilient the OEM lines were under pressure, but they're gone now.

While that does look to be the best practical way to go, it requires 16" wheels Maybe one day if the stars align such that my new Michelin tires and existing brake setup are all worn out around the same time, and I still like the car and want to invest more into it. Very unlikely
So it's just good OEM-size upgraded parts for now... though to be fair what I have on the car now far exceeds the braking capacity of the OEM suspension, which is still on the car. Will report back later.

timmy0tool

iTrader: (7)

i feel putting better brake pads will have more of a difference than trying to keep the sizing to fit under a 15" wheel.

was there a caliper difference in 93-94 models? there was a difference in the rear brakes for sure.

climberd

Yup they're different. Covered that in my first post. I have put on the most aggressive pads I feel comfortable running. They definitely work. Any further upgrade than what I've done realistically requires bigger wheels. I wish I had thought of that when I was ordering new Michelin tires. There are some early Lexus SUV wheels in 8" wide format that would have been sweet if in 5x114 format. Oh well. She still works alright.

peterls

I went through the same dilemma as you, and finally installed '97 calipers, rotors and SS lines on my '90 LS400. Braking power is tons better. The real problem is that 1st gen rotors are too small for heat that is produced under heavy braking; where I live we have some loooong downhills, often ending with a completely stopped traffic (on a highway) so panic braking is almost a daily occurence. You drive 60mph, and then all at once just around the curve, there is traffic stopped, and you are on a steep downhill, and were already braking lightly no to exceed speed limit. You hit the brakes, stop the car, and there is hardly any space to go, so your pads are heating the rotors in one and the same spot, changing the structure of the metal in the rotor and developing a spot that will feel like rotor is warped. It happened to me. So rotors get ruing in no time, at least where I live. It takes beefier and bigger rotors to absorb all that heat and disperse it. It won't happen with small dinky rotors our cars have. That's why I decided to upgrade to 2nd gen brakes on all four corners.

But there are gotchas:

- Yes, you need 16" wheels, from '95 and up LS400. 93-94 16" wheels won't work, I tried them (and have two to sell if anyone needs them! They are in a really nice condition). If you keep checking your local craigslist, you will find from time to time people selling all four wheels with tires on them for not much money. I found mine for $400, with really nice wheels, but only a few weeks later someone else was selling identical ones for $300! The cheapest I saw was around $200 for all four, but with worn out tires and wheels were not in the best shape.

Also, junk yards have them... and the trick there is to get only spares as they are most likely as good as new... or buy all four with tires, which usually should sell for about $50-100 ea.

- The 2nd gen calipers are not too heavy, I believe they are aluminum so your unsprung weight does not make much difference. In that regard, I find that tires make incredible difference on our cars; talked to a really good Toyota tech who is also an owner of a shop and owns the exact same LS as I do, and he confirmed that if you go with anything other than Michelins, you are gambling. He hated Goodyears for instance and had to change them soon after he installed them, they felt that bad... and my used 16" wheels came with Falken ziex 912 (or 512?) and I absolutely hate them. They are as bad as having toy baloons wrapped around rims... their side walls are so soft that the whole car buckles every time I make a turn. It just feels absolutely horrendous. I also found this to be true on some other Falken tire sizes as there are reviews out there for Falkens where people say "buy at your own peril" and so on. Besides, the tire is so bad, that it is actually directional AND assymetrical, meaning - they should have "left" and "Right on them, but they don't. Basically, it was designed by a moron and produced by a dumb company and then sold to unsuspected public. Never checked this when I was buying so I am stuck with tires that I hate and cannot wait for thanksgiving deals to get new Michelins.

- The biggest discovery for me was that center hub is smaller on 1990-1992 LS400 than on later models. This is not obvious at all, as published hub sizes are the same for all LSs: 60.1mm; but what is not obvious is that there is a little step where rotors fit, and diameter there is 62mm, NOT 60.1mm. This makes upgrading our rotors a bit of a pain. You have to make or order a ring with ID=60.1mm and OD 62mm (and they should be at least 5.5mm deep, rounding it up to 6mm will probably work; keep in mind that rotor only rests on the last 2mm of that ring, so that's another "gotcha"... its a really weird design; if you check out pictures of hubs for 2nd gen, you'll see what I mean), otherwise your rotors will be loose there, just enough for them to make noises and vibrate and so on... not the end of the world, but it could sound like one and enough to ruin your day and make you go "How come no one ever encountered this before me?"

And when bleeding your brakes, I find that lexls tutorial is not that great, especially when it comes to the size of the tubing used: the diameter of the bleed valve is 1/4in, so ID of a tube needs to be 1/4in, not bigger than that (I believe he suggests 3/8").

I still haven't put on rings on my center hubs as I just have no time to deal with it right now, but will do it asap. 1st gen LS is heavier than second gen, so in my view, upgrading brakes to 2nd gen is a must. Having smaller brakes on a heavier car makes no sense and whatever extra cost this inccurs will be saved over time as you won't have to change your pads and rotors as frequently. Not to mention that it only takes ONE incident where panic braking was needed to make you thank yourself for installing them.

climberd

Peter that is great info, thank you!
Lots of little annoyances there... One quick idea I had when thinking about your spacer rings was to just order a sheet or strip of shim steel, 0.45mm thick, and wrap it around each centering hub. That's probably way too thin to make on a lathe as a ring collar. Wondering if there is a 90' compatible bolt-on hub with 62mm center... Doubt it...

Separately:
I've seen simple DIY brake ducting work wonders on other cars, could be great for our cars. The 1990 LS wheels are designed to create more airflow through the wheel spokes... Weird design, but does raise an interesting 'why' given the size of the rotors.

Very cool post, thank you!

peterls

You're welcome.
And, btw, I was thinking of changing the hubs to gen2, but it appears that the work involved is the same as changing the wheel bearing, and that's a lot more than I am willing to do right now.

You're right about just bending a piece of sheet metal around the hub, I haven't had the time to do it yet, but plan on doing it. My wife is looking at me in disbelief because every now and then I would reach for my caliper (sitting right no my computer desk), to measure stuff such as - thickness of the metal ruler (i believe it is steel, and if memory serves, it was 0.5mm, so not bad), then an aluminum edge for some shelf (0.9mm thickness), a coca-cola can (0.1mm), and so on... Next I want to measure is thickness of one of those 90deg steel squares, I have one sitting somewhere, just can't find it, but I am certain it is thicker than a regular ruler, so maybe that's the one that will be cut up.