Fitting LS400 brakes to a SC400-Detailed how to do.
I upgraded the brakes on my 92 SC400 today using 96 LS400 front calipers and rotors. Before I started I researched many threads on this subject and it went pretty much as planned. The only hitch was I had to bleed the brakes a second time as the vacuum bleeder I used the first time didn’t work perfectly. The pedal felt a little soft. The second time was done the traditional way, and I found a bubble in the passenger side caliper. That fixed it.
I thought I would detail the details, as these were pretty lacking in many of the threads I read on the subject. Such as brake lines, what you have to do to the SC400 dust shields, what to torque the bolts to and a few tricks I picked up from sorting thru 60 pages of threads on the subject.
The procedure I used was as follows:
1: Remove the wheels.
2: Clamp off the brake lines using Visegrips and a small piece of wood. This minimizes the leakage of fluid in your work area.
3: Remove the brake line from the old caliper (14 mm socket).
4: Remove the old caliper by undoing the two bolts (17 mm socket) holding the caliper to the hub assembly. It is not necessary to take the caliper apart. It just lifts up and off the old rotor. An air impact wrench is convenient for this because of the cramped space behind the rotor. Otherwise you will likely need a breaker bar to get them loose.
5: Remove the rotor. Use 2-8mm bolts in the tapped holes in the rotor to pop it off the hub. Pounding with a plastic mallet didn’t do it for me. The bolts did. Easily.
6: Cut the rolled lip off the dust shield and the small rounded end at the bottom. The attached picture shows the cutoff pieces. Try fitting the rotor and cut a little more if necessary to eliminate rubbing. I used a 4 ½” grinder with a cut-off wheel (recessed hub one, not a straight wheel). Clean up the sharp edges. This took little time as the wheel cuts rather quickly. Wear safety glasses or goggles or a face shield! Sparks WILL fly into your face despite your best efforts.
7: Install the LS400 rotor using a couple of lug nuts and a washer or two to pull it on straight. It is a friction fit and you will have a hard time getting it on without the lug nuts.
8: Bolt the caliper on using the existing mounts and LS400 bolts. Torque to 87 ft-lb. The LS400 bolts are 1.25” long and the SC400 bolts are 1.365” long, so if you use the SC bolts you will need a couple of washers or you will have to grind a little under 1/8” off the end. You will likely have to file a little off the corner of the caliper near the lower mounting hole. I have attached a picture of the required area posted by someone on an earlier thread on this forum. Sorry I don’t remember who to credit for it, but thanks to them as it shows things clearly. If you have trouble getting the bolts in, file a little more. I did on one side, not on the other.
9: Attach the brake lines (I used the stock SC400 lines). The safety hole does not line up with the LS400 caliper so I just rotated the line a bit. Torque the brake line banjo bolts to 29 ft-lb. Remove the clamp from the brake line.
10: Bleed the lines. I used a vacuum bleeder and did it again with the old fashioned way (2 people required) when I was not satisfied with the initial results.
11: Mount the wheels and away you go.
The whole thing took about 4 hours at a U-Fix-It shop. $20/hour for the lift and any tools I lacked. Will go this route in the future.
A couple of observations.
Wheel clearance is critical. I have 2006 GS350 (18”) wheels on my car. I measured 2 ½” of clearance from the old rotor face to the inside of the wheel at a radius of 5 ½” (widest point of the LS400 caliper). Didn’t think it was going to fit, but found pictures of those wheels with the LS brakes and went for it.
It fits, despite the posted requirements of 2 ¾” clearance required. The reason is that the LS rotor is pushed back 3/8” relative to the SC rotor, so my measured 2 ½” clearance on the old SC rotor is actually 2 7/8” clearance on the LS rotor. Take this offset into account when trying to determine if your wheels will clear. Mine have about ¼” of clearance when mounted, a comfortable amount in my mind. Also understand that it not the offset which determines caliper clearance but spoke shape and design.
Also understand (lots of confusion about this in old threads) that the 4 piston LS caliper actually works just fine with the SC master cylinder. The pistons are the same size and the 4-pistons only move half as far as in the 2-piston floating calipers, so the actual fluid displacement is the same.
Finally, does it work? Probably has better fade resistance compared to the SC setup but the stopping distance will be determined by the tire traction and the ABS system. What will improve is the brake feel and reliability, as the caliper has no moving mechanical parts to hang up, stick and flex. Feels more linear and less spongy (I think the old calipers flexed under braking). They certainly look cooler and will look even better after painting.
I used local junk yard parts. Paid $194 with tax for the complete calipers (very clean looking) and good OEM rotors. No shipping as they were just 25 miles from my home. Just cleaned things up (CLR and water to remove rust followed by brake cleaner). Probably on hour with wire brushes and burrs to get the rust off. I disassembled one caliper and found it to be perfect inside. Reassembled with the original seals. Didn’t bother messing with the second, just used it as bought. I just hand sanded (100 grit alum-oxide) the rotor surfaces by hand to remove any imbedded rust and did not bother with surfacing, as they were quite good looking and full thickness. Used the included pads as they were almost new.
Future plans include SS brake lines and painting the calipers. After reading of people who painted first and then scratched up their perfect calipers due to inadequate wheel clearance, I decided to get them installed and working and then worry about appearance.
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It's a shame this post got no responses. It's one of the best DIYs for LS400 brakes I've seen. Especially the part about measuring how much rotor-wheel clearance is really needed. Detailed yet concise.
The doubly crazy thing is it only had ~600 views in 8 months before I bumped it. Threads usually get that many views in a couple weeks... Somehow, it slipped under the radar and never gained any traction.
you guys are right its an excellent write-up that covers alot of details that get repeatedly asked so as part of my effort to pay more attention to the brake and suspension forum and get it in order I am going to stick this one.
I removed the dust shield completely though and used 2 ls400 bolts I bought from Lexus. didn't want to do the washer method on the brakes but I would have if I didn't plan ahead and get the LS bolts.