LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

UCF20/21 front brake caliper into UCF10/11?? (The Mother thread)

Old 12-03-11, 11:09 PM
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ocr
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thanks RA40. much appreashiated!... working off my phone and an extreamly slow computer gets frusterating.

when i say slow, i mean it takes 2-3 min for a new page to apear.
Old 12-04-11, 12:59 AM
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Ouch on the page loading.
Keep us posted on the swap. These are great supplements to the FAQ and others benefit from seeing these conversions.
Old 03-23-14, 01:28 PM
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Blkdout94
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Default 96 LS brakes on a 94?

Hey guys new to the forum I have been doing a lot of research but can't seem to find a straight answer. Just picked up some calipers off of a 96 ls400 and I want to put them on my 94. What parts do I need in order to make this work? I already have the calipers (gonna get them powdercoated) and pads. I just need to know what rotors to get and any bolts or new brake lines etc. please help me out all I can find are people doing this upgrade for their sc and gs models thanks!
Old 03-23-14, 01:47 PM
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please search, it's been covered.

You'll need '95-00 front rotors, '95-00 front Lower Ball Joints, and possibly the caliper mounting bolts. SHould not need new brake lines.

If you search you'll see exactly why you need these things, specifically the LBJs. (hint, stock ones make the calipers foul the TREs).
Old 02-01-16, 03:04 PM
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I did this on my 1990 ls400. let me try and update this thread with CORRECT information while I still remember it all:

1. For fronts, you obviously need 2nd gen calipers, rotors and pads. Besides that, you also need 2nd gen brake lines; original ones from 1st gen are shorter and you'd be pushing them to the limit every time you make a U-turn.

2. You also need 2nd gen lower ball joints, which are direct bolt-on. No problems there, but new ones will give you the space needed to fit the new calipers.

3. You also need new wheels. 1990-1994 wheels cannot be used with 2nd gen brake calipers. Obviously, 1990 wheels are only 15 in, so they are too small, but even larger 1993-1994 wheels are too small on the inside, and don't have enough clearance for the 2nd gen ls400 calipers. So, you need 1995+ LS400 wheels. Added bonus: they look really good on 1st gen LS.

4. The calipers are a direct bolt-on, and even the bolts don't need to be changed. Funny enough, I seem to remember that somewhere I found out the 2nd gen caliper bolts to be different length, so I ordered them from Lexus, and when they arrived, I found out they were exactly the same as my 1st gen bolts. So no need for new ones.

5. The biggest pain in the rear: if your LS is 1990-1992, your hub is not the correct diameter for new, 2nd gen rotors. I had to find that out the hard way. There may be one post about that on lextreme forum... If you take a careful look at the 1993+ hub, you will see that it has a lip on it, and that lip is where the brake rotor fits. The exact numbers are:

- 1990-1992 LS400 brake rotor inner diameter: 60mm
- 1993+ LS400 brake rotor inner diameter 62.1mm

Therefore, you either need to replace the entire hub or at least add a hub ring of correct inner and outer diameter to be able to fit the new rotor. I used a piece of metal that was 1mm thick and bent it around. It is VERY hard to fit, and I am not in love with that solution, but it works and has no vibrations.

6. Finally, as was said before, you do need to either cut or replace the dust shield that is behind the rotor. Only the bottom part is in the way, the top part is OK. It is thin so it is easy to cut. I used those electric shears from harbor freight tools to cut it, it took a few seconds.

7. Since front brakes do most of the work, most people do not bother with upgrading rear brakes. I did upgrade mine, and now the stopping power is amazing (compared to what it was before). I had at least two or three situations when someone cut me off so badly that with old brakes, I would hit them, but with new ones I managed to stop (and almost got rear-ended). I frequently drive in really bad traffic, surrounded by bad drivers in fast cars, so good brakes are a must, and I am really happy i did the upgrade. It took some work but was well worth it!

8. In case you are wondering about which rotors and pads to use: I used Brembo rotors (not available any more), and Wagner "thermoquiet" pads. Good braking and all, but thermoquiets are never quiet when you first brake on a cold morning, meaning, your neighbors will hate you every time you are leaving the parking lot and braking to check for traffic... After about 10k miles, that went away. But, out of curiosity I switched to Akebono ceramics and Centric Rotors. No noise whatsoever, and good braking performance.

9. If you are bleeding your brakes, after all this work, the correct procedure is this:
- Lift all four corners of the car (need four stands)
- Have an assistant ready to push the break pedal
- Start with the left rear wheel (the one behind the driver)! This is most important.
- 1/4in (or was that 3/16? don't remember any more) plastic tube will fit perfectly over the bleed nipple (forget about the recommendation on lexls.com - it is wrong - 3/8 in is too big!). Run that tube to a small bottle to catch the fluid.
- Open the bleed screw a little, have your assistant press the brake pedal, and while they are keeping it down, you close the bleed screw. If you don't, as they release the pedal, it will suck in the air through your bleed screw. Once you close the bleed screw, have the assistant release the brake pedal and then press it again. You open the bleed screw again, close it, have the assistant release the pedal... and repeat it all a few times, until you are sure there is no air in the brake fluid.
- Move onto the rear right wheel, top up your brake fluid, and repeat the bleeding procedure.
- Then top up the brake fluid again, and do the front right (passenger side) wheel.
- Finally, top up the brake fluid again and bleed the front left wheel.

Drive carefully around the block to make sure everything is a-ok. First 100 miles or so, you should not brake hard, and should not keep the brakes engaged after long braking when your pads are hot. Actually, this is a good thing to remember for always, because hot pads pressed firmly against rotors over an extended period of time (like a minute or two at the red light or in bad traffic) will cause changes in the metal and the rotor will pulsate on braking.

Good luck!
Old 02-02-16, 11:25 AM
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good job on the write up. from what i read, the 2nd gen rotors have a larger center bore than 1st gen 90-92 hubs? can the 2nd gen rotors be screwed into the hub using the two rotor screws? did those holes line up?
Old 02-02-16, 01:02 PM
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Originally Posted by timmy0tool
good job on the write up. from what i read, the 2nd gen rotors have a larger center bore than 1st gen 90-92 hubs? can the 2nd gen rotors be screwed into the hub using the two rotor screws? did those holes line up?
Yes, yes and yes. Everything lines up, two little screws are the same, everything is the same... it's just the center bore that is bigger by 2 millimeters. Obviously, don't plan on those two little screws holding the rotor for anything more than just to help you change the brakes. They are not supposed to carry any weight.

I bought a pack of those worm gear hose clamps of various sizes from Harbor Freight and cut one of the largest ones lengthwise so that it is only about 4 mm wide and wrapped it around the hub, so it only supports the rotor, but does not interfere with the wheel. Works like a charm and way cheaper than replacing the entire hub.
Old 02-02-16, 05:41 PM
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If you're due for wheel bearings upgrading to a '93+ hub would also work
Old 02-03-16, 12:58 PM
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I've only had a 98 LS so I have no comparison to make but I've always wondered why guys love these big calipers so much? Is the added braking power or whatever worth the hassle of dealing with wheel fitment issues? To me, they should be a tad smaller. That way we could fit a lot more aftermarket wheels.
Old 02-03-16, 01:25 PM
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go drive a 1st gen down a mountain road at even a normal speed.
you'll realize why they're so terrible in comparison. Aesthetics are important but not at teh expense of everyday safety and performance.
Old 02-06-16, 06:13 PM
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Originally Posted by PureDrifter
go drive a 1st gen down a mountain road at even a normal speed.
you'll realize why they're so terrible in comparison. Aesthetics are important but not at teh expense of everyday safety and performance.
Yeah, and there are literally HUNDREDS of other models of cars, Lexus or otherwise, that do just fine with smaller brake setups. Just don't know why the designers made ours so huge. What was the reason? Did they all come from Hakone or something?
Old 02-08-16, 02:57 AM
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Originally Posted by Hiroshi12
I've only had a 98 LS so I have no comparison to make but I've always wondered why guys love these big calipers so much? Is the added braking power or whatever worth the hassle of dealing with wheel fitment issues? To me, they should be a tad smaller. That way we could fit a lot more aftermarket wheels.
Originally Posted by Hiroshi12
Yeah, and there are literally HUNDREDS of other models of cars, Lexus or otherwise, that do just fine with smaller brake setups. Just don't know why the designers made ours so huge. What was the reason? Did they all come from Hakone or something?
You're creatingn a problem that doesn't exist for manufacturers, engineers aren't concerned with fitting aftermarket wheels. They made the best brakes for the job, and simply spec'd the wheels they designed for the car to fit the brakes. And other vehicles of similar weight do have larger brake setups, S-class mercedes being a comparable example. Similar american cars (non P-71 Crown Victoria sedans for example) have abysmal braking performance. (the P71 is somewhat better with larger "cop-spec" brakes but still not great.)

What bothers you isn't an issue to 99.9999% of buyers of LS400s or comparable vehicles. That it is an inconvenience for you does not make it a defect.

Ignoring the fact that you can easily buy wheels that fit the calipers easily, as high disk type wheels have been made for literally decades, and most major manufacturers sell wheels designed to fit over big brakes. Work, Rays, Enkei, American Racing,TSW, Rota, literally all the major manufacturers.
Old 02-08-16, 09:26 AM
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"What bothers you isn't an issue to 99.9999% of buyers of LS400s or comparable vehicles." That statement is pure speculation on your part. If that's true, then why are there literally hundreds of posts on CL dealing with wheel fitment issues/questions? Did I write them all? No.

Last edited by Hiroshi12; 02-08-16 at 09:33 AM.
Old 02-09-16, 02:37 AM
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Technically it's postulation as i'm approximating the number of unique posters on these issues divided by the roughly 500,000+ LS400s made for global consumption between 1989-2000. Then the percentage of those posters willing to decrease braking performance to fit wheels (one would assume, a relatively smaller number based on the actual miniscule number of '95+ owners who have downgraded to '89-94 brakes).

Even if thousands rim up their cars and run into issues, they're a tiny fraction of the total number of owners. And the figures ignore "similar" vehicles.


End of day, you can easily and cheaply downgrade your car to '89-94 brakes to fit wheels. You won't be the first nor last guy to do it. Would I do it? Hell no. Would I approve? Does it matter?
Would your insurance approve if you ever rear end anyone? Bet your ***.
Old 03-31-18, 08:16 PM
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Hey guys, I know this is an old thread about upgrading your front brake calipers to a big caliper. I had changed mine and you really don't need to change anything on the knuckle part, just the rotors and calipers will fit, the brake pad shims were already attached to the pads. Only modification you really need to do is, cut/bend the back part of the heat/dust shield by the steering knuckle I believe. Also, you will need an RCA(30mm) spacer to have clearance, if not, the bottom part of the caliper will hit it. Here are some pictures I have taken in case anyone would like to know. The downside of the big calipers is clearance for the wheels to not it. For example, I have S55 AMG +45 offset, I am using a 1" spacer conversion to fit a 5x114.3 hub to a 5x112 wheels.


Last edited by ucf31CRB63; 03-31-18 at 08:19 PM.

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