Just picked up this sweet 1995 SC400 with 144k miles. Really clean car, zero accidents, stack of maintenance records. Has a little scuff on the rear bumper otherwise it's pretty dang clean.

It's had some love put into it. I noticed the whole ignition system was recently replaced, had a timing belt done 6 months ago, good tires, good brakes, etc. I think it may have a valvebody or some transmission mods because it shifts hard as hell.

It is build date 6/94 and has square fuel rails, I think that means it's got the big rods?

Some issues: amp was fried. Gas cap cover broke off, gas filler drain hose had been pulled off the nipple, so water came in through the gas filler drain and dumped directly on the amp. Filled the inner fender area with 6 inches of water. Got a replacement coming off eBay. Driver's seat has something wrong with it, won't lean back fully and not all adjustments work and heated seat doesn't work. Probably will just go with a totally different make and model seat as Supra seats are impossible to find. I'd rather have something sporty than Lay-Z-Boy spec.

Coolant tank is leaking, ordered a replacement.

Short term goals are to install an LSD and 6-speed, convert to COPs, DIY something cool with the exhaust and some 17" wheels. It really pains me to drive it with the auto but for now it's a cheap daily.

Long term maybe supercharger and definitely suspension. Swap the brown interior for grey or black.

First thing I did was install my A.P.E. Flex Fuel kit I had from a previous vehicle. Then I filled the tank with E85.

Diagnosed the amp, ordered a replacement.

Glued the gas door back together.

Filled it with E85 and took it drifting in the snow and I don't even have license plates yet

 

Polished my headlights, used a Rain-X kit which only had a spong applicator thing. Wasn't a great kit but results are pretty good and it was fast and easy. Also aimed them because they were all over the place. The car has insanely bright bulbs for the brights which is nice but they had been aimed completely wrong also.




Scored some parts at the U-Pull. Got some LS400 front calipers and an RX300 steering wheel, the air bag was blown so I'm looking for a matching one now. The local U-Pulls inventory has been really lame recently.

I started pulling some '00 LS400 headers but it was a pain in the ***. Going back later when the weather is better.




I also scored some '03 Boxster seats! $70 for the pair. I think they would fit in the SC, the mounting measurements are similar to S2000 seats but I'm going to put them in my Miata instead and find something different for the SC.



Lastly I scored an Aristo A01B Torsen LSD locally. Supposedly has 80k miles. I pulled the cover off to confirm it was Torsen before I bought it because it was too good of a deal I think this diff has 4.08:1 ratio, is that right?

 

Mine are Corbeau Supra hand adjustable race seats. Very light weight, thats what you want, have lasted long time.
Basically bolt right in
It's an old car. You don't want to abuse it too much
Good Luck

 

Corbeau...sounds expensive. I was looking at some BMW seats at the U-Pull that would fit. Also saw a Saab 9-5 and the seats look like they would fit well and are also really low to the floor. I need to do something about the driver's seat. The lumbar adjustment doesn't do anything and it won't lean back very far. It's very uncomfortable. Going to pull it out and maybe I can fix it.

You'd probably get a kick out of this @Barbary , this car came with a CB radio installed, you can see it on the passenger side of the console. I'm not sure where the antenna plugs in, haven't investigated it yet.

The A01B diff I picked up is 3.7:1, just counted the rotations. Was hoping I could just throw it in but I should swap the R&P first.

 

Yep, if the 200mm Torsen diff originally came from a 2JZ-GTE Aristo then it would have come with a 3.769:1 ring and pinion ratio as you found out. Same final drive gears that 93-98 Supra Turbo A/T's came with. This will be slightly longer than your SC400's stock 3.92:1 final drive ratio. But the ring and pinion gears are rarer and in more demand than 3.92's.

You'll need to swap to an SC/Soarer companion flange (make sure to dial torque it correctly following the TSRM so as to not upset the ring and pinion mesh alignment inside) but other than that it will bolt right in.

I would recommend restoring that diff's exterior with some new paint (POR-15 + UV protecting final coat after a de-rust prep works well with lots of tape masking-- wear a filtration mask around that stuff!) before you get into it.

 

Thanks, I think I'll just put the Torsen carrier into my SC diff housing and use the 3.92s. That will be better with the auto and I want to put a CD009 in it and it would be good with the 3.9 I think.

I adjusted the throttle and transmission cables. You had to really bury your foot in the floor to get it to kick down at all. I also found that it wasn't opening the throttle fully. I adjusted them and now it shifts a lot smoother. I thought it had a valve body but someone just messed with the trans cable to make it shift really hard.

I have given up on trying to get the factory Nakamichi sound system working. I got another amp off ebay but it was blown too and only one speaker worked. I opened it up and there are clearly spots on the board where things overheated, it looks like it could probably be repaired but I don't have the patience to deal with that. Going to stick with my bluetooth speaker for now and maybe do a new head unit and amp this spring.

Went back to the U-pull and got those headers. I think these are the best UZ factory headers.

 

Mine are Corbeau Supra hand adjustable race seats. Very light weight, thats what you want, have lasted long time.
Basically bolt right in
It's an old car. You don't want to abuse it too much
GPurple Bullet at former Home by Coast, on Flickr


The story behind the Corbeau's was I considered my car a sport coupe and didn't like the stock (brick) seats and wanted to lighten the car anyway. Went to a local speed shop in San Fransisco to see if I could like something there real quick, saw the Corbeau's among others and instant. I had to have them especially they were Supra seats that just bolt right in. Really comfortable on my long trip.

So sometime you just pull the trigger
I've always considered the car and the Corbeau's a match made in heaven

 

Those are definitely sweet. I'm trying to keep the budget low on this car, though. I also want heated seats and leather.

I got it up on my lift to check it over. Have oil leaking on the rear driver's side of the engine. Otherwise everything is dry.

Car came with an aftermarket under tray but otherwise looks completely stock underneath.

I also weighed it to see what I was starting with and it's about 3550lbs with 1/4 tank of fuel.

 

I happened upon those black Boxster seats a few weeks ago and I really liked them a lot. I test fit them in the SC400 and they fit pretty good which lead me to try and find a set of Porsche seats that would match the Lexus interior. I found a set of tan seats from a 2008 Cayman and went and looked at them. In the dark under sodium bulbs I thought the seats were pretty close to the beige/tan of the Lexus, but once I got them home I realized they're much more orange than beige. I think they still look ok and don't clash too bad. Long term I can either swap in some beige Porsche seats or get some replacement covers or whatever.

I ground the rear mounting brackets off the SC seats and used them to anchor the Cayman seats. I welded the inboard bracket to the rail and for the outboard side I welded a piece of steel to the SC bracket and a matching angle on the Cayman rail with a bolt. That way I can bolt down the bracket, then place the seat over the top. I reused one front bolt hole and installed a rivnut for the other hole. The seatbelt receptacle swaps straight over.

The Porsche seats are heated which was simply a matter of hooking up the power for the heating elements to the Lexus output. I did add a relay so I could pull power from the larger gauge 30A door fuse for the seat heaters, but still use the smaller gauge wire to switch it on and off. That part is easy and works great. The seats heat up really quick.

Wiring in the Cayman power adjustment to the Lexus is easy for the passenger seat but more complicated for the driver's seat. The Cayman passenger seat doesn't have memory control, so you simply power up the seat and the controls will move the motors and adjust the seat.

But the Cayman driver's seat does have a memory ECU in it. I either have to swap the seat ECU to the non-memory version and rewire everything, or I can use an Arduino to spoof the CAN messages and operate the seat. Apparently the Porsche community has tried this and the seat won't operate without the CAN messages and the Arduino thing has been done more than a few times.

For now I just used a 12v battery and some test leads on the motor directly to adjust the seat for mounting, and then set the final position.

Long story short: other than the color mismatch, the seats fit really well in the SC400. There is a lot of room on either side which does look a little awkward, but you won't lose your phone. The seats are super comfy and sporty. It also lowers the seating position a good 1-2 inches, no more bumping your head on the sunroof. They are lighter than the SC seats and I plan to remove the airbags to lighten them up some more.

The PO of the Porsche left a little baggie of something that fell out of the seat when I was working on it

 

"I also want heated seats and leather.
Thats another qwerky deal on my 400. Never had heated seats, are no heat control buttons on the consul


I got it up on my lift to check it over.
Wow! You guys with your own lifts, must be nice"

 

The Porsche Cayman seats look like a good fit in there!

The factory heated seat pre-wired circuit is rated at 15A. You should still be able to pick up the combination seat heater switches as a used assembly that plugs right in to the body harness plug under the shifter area. A/T models with TRAC usually got this... unless your SC400 came without TRAC in which case it's another version of those switches... but I think only TRAC equipped SC400's got the seat heater option.

If that's the case you can always carefully remove the TRAC switch from one of those combined switch assemblies and de-pin the appropriate terminal ends to leave you with just the A/T seat heater switches. I am sure a simple panel blank could be made to go in place of an absent TRAC switch.

To note for reference, M/T SC300's got another version of the seat heater switches and all of those have a totally different pre-wired connector under the center console shifter area.

I've attached a PDF of the circuit diagram for the SC400 seat heater circuit from the TSRM. The connector pinouts are for the console seat heater switches themselves. The small and slim version of the connector pictured in the diagram is for M/T SC300's and the larger one is for A/T models.

Thank you for posting that very helpful visual pinout guide for the SC300/400 body side seat connectors! I think I found the full numbered pinout for the body side seat connector at one point when I was planning to install seat heater pads in my car. If I can find it I'll post it.

But really don't need it at this point. If you can, look very closely on the body of the original SC400 *seat side* connector for a small five-digit embossed number somewhere on its casing. 99% of all Toyota connectors have this.

With that half part number and using the Toyota Wiring Repair TSRM we can get you the exact OEM repair terminal pin part number(s) to order to populate the absent seat heater connection and if still available you may still be able to order a whole new connector without cannibalizing the original one from your factory seat.

 

Thanks, yeah if I didn't make it clear I used the wiring pigtails from the original seats and connected them to the Cayman seats so it just plugs into the stock Lexus cabin wiring harness. I used that same wiring diagram to figure out the pins (attached)

 

Excellent!! Yeah that's the best way to do it. Stock SC seats can always be reinstalled if you ever need to.

The seat heater pads should work out perfectly too! I need to get a set installed into my MKIV seats this year. I just need to pick out a suitable aftermarket set that will work at around 10 amps or so. Did you install aftermarket heating pads into your Cayman seats or did they come with a set pre-installed from the factory?

 

The Cayman seats have heating from factory.

Today I tried installing an aftermarket amp. I found a 5-channel Sonpex amp (https://amzn.to/40nf1k1) which I wired into the factory wiring. I took the plugs off the original SC400 amp that was fried.

I put it in and it worked but I still only got sound from the driver's door speakers. Everything else was quiet. I am guessing the head unit is bad. I am just assuming the speakers are ok. I was hoping I could get the stereo working quick and easy but it looks like I'll have to dive into it.

Luckily with the new amp I can test all the speakers by moving the inputs around and at least figure out if the head unit is putting out all channels or not.

 

Really nice and clean work rewiring the factory amp connectors for the new aftermarket amplifier!

Does your SC400 have the factory optional Nakamichi stereo system or the standard (no markings on the head unit) Pioneer system? I could be wrong but if you have the non-Nakamichi factory system you may be running into an issue with your new amp because it is not driving the factory sub-amplifier under the rear package tray that all non-Nakamichi SC's have.

In Pioneer equipped SC's that sub-amplifier is activated and controlled by the main factory amplifier which drives the two right and left package tray speakers as well as the center mini subwoofer under the rear package tray.

The rear speakers and rear center subwoofer probably need new wire routing. The rear center subwoofer in Pioneer equipped SC's pretty much requires that factory sub-amp in order to drive it. In Nakamichi equipped SC's the factory subwoofer is a little larger and can be driven by a standard type aftermarket amplifier.

Someone please correct me if I'm incorrect about any of this but I think that's what may be going on in your case J1000.

The factory head units, their cassette deck section aside, tend to be very long lasting. Their LCD and old capacitors are usually all that ever go wrong with them.

(They are known to be very electrically noisy however and when you introduce other more modern electronics alongside them they can pick up interference never accounted for by the electrical engineers of the late 80's. This is why an in-line ground loop isolator is always needed if doing the aux-in stereo jack mod for instance.)