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Well hi,
I havent been very active on this forum but I have received a huge amount of information from it. So I decided to document some of the things I have done to my 1998 Lexus SC300.
This build started in summer of 2019 so a lot of the jobs done on this car are already getting hard to recall. But ill try to eventually list all the mods and add some pictures for clarity. The day of purchase
Since Im in Europe, these cars are quite rare and not many are for sale. In fact, when I went to buy this car, it was the first time seeing one up-close. The car had a lot of problems. The seats were torn, the engine had a misfire, the gas flap didnt open - just to name a few. But it was cheap and I wanted one.
Now, what are my plans for the car? Driving the car I saw that it is very comfortable, smooth shifting, so great for cruising but I can get that from my daily. So the plan was to fix all the small faults, do a manual swap and further down the line maybe go Na-T or do an engine swap. The car came with aftermarket lights, front and back. These will be replaced with orginals.
Following is a list of the major mods done to the car so far. I will describe them in more detail in further posts.
- Replaced the aftermarket lights with originals.
- New front seats
- BC Racing coilovers
- Manual swap
- 2-way diff with poly bushings
- 1JZ-GTE VVTI swap from a JZX110 with stock ECU
- Walbro fuel pump
- Supra front lower control arms
Although the suspension was soft and pretty nice for cruising it didnt go together with the idea of manual swapping it and doing some spirited driving with it.
Also the back end was very twitchy and didnt give a lot of confidence in cornering. To remedy this I went with BC racing coilovers and bought new bushings for the front LCAs. However it turned out that on one side the new bushings were very loose. And also the 98+ LCA bushings have voids in the rubber I felt it would be better to use the supra LCAs with full rubber bushings.
Supra LCAs
BC Racing coilover vs old
After the new coilovers and LCAs were installed I got a wheel alignment and boy, the difference in handling is unbelievable. The car is much more stable and cornering now is pure joy. Really happy with the coils. Only on very rough roads the back end becomes a little jumpy. Since the coils have a 30-position damping adjustment I softened the setting a little.
The original seats are quite heavy, in bad shape and since im about 6 feet and 3 or 4 inches tall my head was very close to the ceiling. So my drving position had to be very laid back.
Luckily by browsing this forum I found excellent replacements by Braum that also match the interior pretty well.
These seats also gave me more headroom. Plus they are very comfortable and provide some well needed side support.
Great project, and very cool to see you with one of these out in Europe! How do you like the Braums after having sat in them a while now? I'm very attracted to them because of how well they match the interior, still being reclineable, etc. I'm scared to go too hardcore with seats and regret it since I don't track my car enough to justify fixed back race seats.
Well, for me they are more comfortable than the originals. The side-support really makes a difference when cornering. Ive taken a few longer trips and dont feel fatigued afterwards. A couple of friends have driven the car and the first thing they complemented was the comfortable seat. And like you said they are reclineable and have rails for front to back movement. Of course seat brackets are required to mount them.
That being said, what is comfortable for me may not be for you. And ive not had them for so long to see how well they hold up over time. But so far im very happy with them.
Awesome - I appreciate the input! I keep hoping to run into a local guy with them installed so that I can sit in them. However, I'm liking the feedback I get. They look great in there with the tan.
Well, for me they are more comfortable than the originals. The side-support really makes a difference when cornering. Ive taken a few longer trips and dont feel fatigued afterwards. A couple of friends have driven the car and the first thing they complemented was the comfortable seat. And like you said they are reclineable and have rails for front to back movement. Of course seat brackets are required to mount them.
That being said, what is comfortable for me may not be for you. And ive not had them for so long to see how well they hold up over time. But so far im very happy with them.
Awesome project!! You're going to love that 1JZ-GTE VVT-i engine. Take a look into uprating rebuilds to the stock CT15B turbo or the Tomei Arms turbo kit for that engine.
The seats you have chosen are excellent! What brand, model and color code are they? I really like the way they look in the SC. I have to agree with you about side bolstering having a huge advantage over the factory SC seats. This was a major complaint of mine when I would take my car through windy and technical mountain roads. I was sliding all over them because there was nothing to hold me in place.
I had previously come from a 5th gen Honda Prelude which had modest but good bucket seats with adequate side bolstering. Swapping a set of Supra MKIV seats into the SC both lowered my seating position (preferable in my personal opinion) and cured the side bolstering issue which made the car easier to control in the turns. I have taken several very long trips the SC with the MKIV buckets and I've been very comfortable as long as I got out and stretched every couple of hours which is for me the same with any vehicle.
Those seats you have area even more aggressive yet they match the interior nicely. I'm intrigued since you report they are comfortable too.
During last winter I decided that the auto box has gotta go. But what do replace it with? R154 prices are pretty high and I dont really see many for sale. Then I stumbled across Lettut´s build thread. He used a 5-speed gearbox from a BMW 530d. Since there are a lot of those gearboxes available it was an easy choice. However I went with the 6-speed version GS6-53DZ.
A firm called PMC motorsport makes an adapter plate specifially for this conversion, it comes with the original BMW clutch and a very light flywheel.
The flexplate from the automatic is retained to use the starter. The flywheel is quite unusual looking.
The biggest problem with this conversion are the gear ratios of the diesel box. Basically the 1st gear is useless (1st gear ratio is 5.08). Considering also that the rear diff has a 4.27 ratio. Down the line this problem shall be sorta remedied by installing a diff with a more suitable ratio.
The carpet had to be removed to get better access to the transmission tunnel. And of course more rust was found on the floor pans. Looks like the previous owner had hit a rock or something because there was a hole in the floor pan.
The hole is under the drill, so you cant see it Rust converter applied Black paint A little sound deadening.
For some reason there were 6 RCA cables running from the front to the back. Plus a bunch of wires for god knows what. So the unnecessary wires were all removed.
I ordered a clutch master cylinder, clutch and brake pedal from Xcessive manufacturing. Clutch master. Its a tight fit.
With everything set up the gearbox was ready to be mounted to the engine. There wasnt much room in the tunnel but it fits. The gearbox is as close to the tunnel as possible to keep the angle to the rear diff suitable.
With the gearbox installed and the clutch bled I was excited to try the new manual transmission. But the clutch wasnt working. So off comes the box. Everything looks good. Then my buddy realized (he does the fabrication work and has been a tremendous help) that there simply isnt enough travel in the master cylinder. The pedal was adjusted to its max position and with the carpet removed behind the pedal the clutch was disengaging. The clutch slave cylinders output shaft was then lengthened. The clutch still disengages quite low but it is driveable and it doesnt take too long to get used to while driving.
Good early catch dealing with that floor pan rust before it became a larger issue! Looks like you got lucky overall.
Interesting use of the BMW 6-speed GS6-53DZ manual transmission. Not relevant to your swap but it sounds very similar to the model code on the 6-speed M/T gearbox found in some Euro BMW 520D model that just so happened to bolt up to the MKV Supra's version of the B58 3.0L engine. I've read that these related gearboxes are very strong but have slightly long internal gearing. Maybe it's not the case with the one you used and it's nothing that a final drive ratio change can't address. I'm not sure if we have as much access to that same 530D 6-speed in the U.S.
Very interesting about the 520D. As far as my final drive ratio I ended up going with 3.76 rear diff with a Kaaz 2-way already installed. The first gear is somewhat usable now, but the 1J has so much more low down torque that I usually set off in second gear. Plus the 3.76 rear diff has brought my rpm to roughly the same ballpark as it was with the automatic at highway speeds.
And your previous comment about the uprating of the 1JZ CT15b turbo is also something I considered (and still consider).
12-04-20, 02:42 AM
Black 98 SC300 1JZ VVTI manual
