Modifying Seat Position In Ls400

[Tony1M]

Well, this afternoon I finally got to sit in a 1994 LS400. It was a very luxurious car and I'd really love to own one.

Rather than continue the thread about replacing the air suspension with a steel suspension, I figured I'd start a new thread about the possibility of modifying an LS400 driver's seat postion rear-ward.

To make a short story shorter, I extended the steering wheel all the way "out" and tilted it almost all of the way "up" and I was then able to get my right knee somewhat under the wheel - enough so that I could have driven the car. But I did not drive the car because I had already decided as soon as I saw it that I would not buy that particular vehicle under any circumstance.

I was in the vehicle for a total of maybe 5 minutes.

Believe it or not, our 92 Accord has more leg room than the LS.

In order for me to buy an older LS, what I really need to be comfortable is another 2, perhaps 3, inches of leg room.

Head room and cabin room were just fine and I very much like the way the cabin looks and is arranged. I've seen many interior and exterior photos of the LS400 model and to me it looks great.

I believe that I could alter either the actual place on the seat mechanism where it bolts to the floor (cut it and weld in appropriate extensions at the front and back), or fabricate a custom adapter to relocate the seat rearward. The adapter would bolt to the floor where the seat normally would, and then the seat would bolt to the adapter, but 2 or 3" back from where it would normally be. (To be as strong as possible, I'd make the adapter out of 1/4" stainless steel.)

To do this modification, however, I need to be able to see exactly how and where the seat bolts to the floor, so does anyone happen to have a photo of how and where the seat attaches to the floor of the car at the front of the seat and at the back of the seat?

(I don't care if a passenger has zero leg room. In that case, I can put the seat forward enough for a passenger not to suffer too much. My wife doesn't put the seat all the way forward even in our Accord, so likely she'll still be fine in the modified forward-most position.)

Thanks for any help on this, folks.

[Tony1M]

This morning I did a little searching for some illustrations or photos of LS400 seats. Here's one of the front:

As far as I can tell, I could quite easily make an adapter whose front end is similarly-downward curved in order to bolt to the car. I'd then flatten the rounded front part of the OEM seat bracket, slide the OEM bracket back two or three inches and then bolt (or weld) the OEM bracket to the adapter. Very simple.

However, the rear part of the OEM bracket, and how it attaches to the car, is more of a mystery to me because I cannot as yet find a good photo of it. Here's the best I've found so far:

From the lower photo, if what I can make out is correct, the "outer" side of the seat bracket is similar to the front. The front part of the metal bracket- where the hole is drilled -is curved a bit downward - probably fitting over a similarly-curved "beam" on the chassis of the car. Again, this would be an easy place to fit the back of a custom adapter. I'd flatten the curved part of the OEM bracket, then slide it back and bolt, or weld, it to the adapter.

The inisde of the seat bracket (pointed out by the red arrows) is where I cannot make out enough detail to imagine a design for an adapter. They're a sort of weird shape for a reason that I also cannot imagine. At that point do the brackets sit relatively flat on the floor? At the same location, how many bolts hold the bracket to the floor?

Thanks.

[Tony1M]

Hold the phone! I just did a search and found Blake's fantastic thread on this subject:

http://us.lexusownersclub.com/forums/index...hl=seat+bracket

The photos of the car with the seats and carpet removed are exactly what I need.

Thanks Blake!

I hope the arrangement is the same on 90 or 91.

I've taken the liberty to copy Blake's photo here and I've added arrows to what I think are the threaded holes that accept the bolts that hold the seat brackets to the car.

Unless there is something poking down from the seat brackets, I now believe it would be quite a simple matter to fabricate an adapter exactly as I described above. The front of the OEM bracket would be flattened and bolted to the adapter. The back end of the adapter could be curved down to meet the floor of the car in the same way that OEM "rib" does. The back end of the OEM bracket would then bolt to the adapter exactly as is does to the chassis.

As I said above, I'd use 1/4" stainless steel plate for the adapter. (This would probably be several times the strength of anything on the car.)

To ensure that the adapter will be exactly the right dimension to fit the car, I'll use the chassis floor as a template, or "form", against which I will bend a prototype that would probably be a piece of heavy-gauge sheet metal. Once the prototype is perfect, I would take it to a place I have used in the past for similar work.

Speaking of which...........I made a custom seat for our 84 Yamaha Venture Royale motorcycle that had been both raised and moved rearward about 4". Here's the process I went through to make a custom adapter out of 1/4" ss that raised the passenger foot pegs: (The three bolts at the bottom of the adapter are where the peg could normally be bolted)

The seat adapter will take a little longer and cost a bit more, but it will be far more rewarding than foot pegs for my wife. I won't bother making an adapter for the passenger side.

[blake918]

Tony, I hope you'll keep us posted on the progress of your project! The arrows in the picture of my gutted car do point to the the holes that the seat bolts to (The first group of pictures you posted are pictures of GS and ES seats, btw.). ;) I believe that the first gen seat has a similar bolt pattern for the seat. That's a very nice looking adaptor that you made for your bike--it looks like factory! B)

I drove a relative's '06 GX470 extensively last weekend, and I found it to be another typical Lexus--it drives and looks fantastic, but it was too small especially in the hip and leg room. It had the smoothest drive-by-wire of any car I've ever driven.

[SW03ES]

This morning I did a little searching for some illustrations or photos of LS400 seats. Here's one of the front:

Here's the best I've found so far:

Don't know whether it matters or not, but as blake said those are not LS seats. The black seat is off a 98-05 GS and the tan seat is of a 92-96 ES.

Yes, we can tell by the stiching pattern. Yes, we're dorks

[Tony1M]

Blake and Steve, thanks for that information on the photos I posted of the seats.

Blake, have you ever tried removing your shoes to give you more legroom. When I do that in our Honda, I can then slide my foot right under the brake pedal and I can stretch my right leg just about as flat as you show yours in one of your photos. For any trip over an hour, I always remove my shoes. Pathetic what we long-legged folks have to go through, eh?

Here's a tenative, very rough, not-to-scale drawing of what I had in mind:

If the head of the bolt securing the front of the OEM braket interferes with the slide of the seat, no biggie, the adapter can be "dipped" at that point to more closely match the original downward curve of the OEM bracket and this allowing the seat slider to slide over it.

To tighten the bolt that secures the rear of the adapter to the chassis, a hole large enough for that purpose can be drilled through the portion of the adapter that extends beyond and above the bolt. (To make the hole in the adapter as small as possible, I'd probably change the rear chassis bolt to an Allen-head design.) Again, no biggie.

1/4" stainless steel is so strong that I believe the rear end of the adapter (where the OEM bracket bolts to it) does not have to be welded to the chassis floor. I think 3" more travel rearward is going to be just fine for me, so the force required to bend 1/4" ss plate, 3" long, would be astronimical - several tons, at least. The "brake" that the place uses to bend the plate exerts a force of 150 tons. (Before my body exerts enough force on the seat belt, or seat, to bend that adapter, my body will be doing one of those Terminator II, "metal man" maneuvers - the one where the bars of the security door go THROUGH Mr. Metal. Ufortunately, I won't be recovering from it quite as well as Mr. Metal.)

For added strength, if necessary, I could "box in" the end of the adapter from the downward-sloping portion of the adapter at the rear (where it is bolted to the car) to the very end of the adpater - where the bracket bolts into it (where it is "hanging there").

I could either use two separate adapters for each side of the seat bracket, or, after fitting them to the car, weld them together with one or two cross pieces. In the latter case, the then-one-piece adapter will probably weigh ten or 15 lbs.

The sheet metal prototype will allow me to "iron out the kinks" with something easy to bend before commiting to the SS final product. I figure the thing will cost a total of about $250 and a fair amount of labor for me to fit, but it will be well worth the trouble.

Should work.

All I need to do now is convince my wife that it's time to get a "new" car!

[blake918]

Blake, have you ever tried removing your shoes to give you more legroom. When I do that in our Honda, I can then slide my foot right under the brake pedal and I can stretch my right leg just about as flat as you show yours in one of your photos. For any trip over an hour, I always remove my shoes. Pathetic what we long-legged folks have to go through, eh?

Oh yeah, I do it all that all the time! The LS has a great little (well, I guess it's somewhat large if I can shove my big foot up there huh?!?! lol) space for your foot between the gas and brake. I think your adaptor will work quite well!! ;) Please keep us updated if you do end up buying the LS and move the seat!