Hello HS250h owners. I joined here hoping to become a HS250h owner myself. (I am a driver of two different Prii presently.) I know that the HS250h is sadly no longer in production. What I am looking for is rather unusual though, so let me explain.

I plan to use the HS250h I eventually purchase as the basis of a conversion. I plan to combine the chassis and mechanical parts of the HS with the body and interior of an old convertible I have owned for many years to create a hybrid convertible. (I hope I'm OK to be a member then!) They both have the same wheelbase, same tread width, and the same outside diameter of the tires.

I am a machine design engineer with 30+ years in the industry, and work in the heavy vehicle market segment (transit bus manufacturer.) Designing modifications and reverse engineering is what I do daily 40 hrs/wk. This project has me really fired up, and I am trying to learn as much as I can while I search for the HS I need.

In actuality, the HS I finally buy can have a collapsed roof and/or hail damage with no problem. For my project, I won't be needing the seats, doors, bumpers, hood, trunk lid, windows, light assemblies, air bags or interior trim. I will need all of the electrical parts and controls, Mechanical parts, HVAC components, batteries, chassis structure with firewall and suspension.

I hope I am welcomed here, since I have a lot to learn about the HS that I hope to find. It was my thought that this would be the best place to meet the most knowledgeable people on all things HS.

Bill the Engineer
Ohio

 

Wow !! You're fired up? I can't wait.

Make sure you start a new thread to keep us updated when you find one to buy.

I need to send you a PM but I don't think you have enough posts for me to do so.

So........ are you planning on removing the hybrid drive from the HS and plugging it into the other car? Or making the HS a convert by "chopping the top"?

The reason I say is, with so many components for the hybrid system built into the chassis, you better be good at reverse engineering. It won't be like plugging a Chevy 350 into a Jeep CJ-7, if you know what I mean!

If you can, send me a PM and I'll write you back as soon as I see it.

 

I will definitely keep everyone posted on my progress!

The old convertible is in need of new floors due to rot. It also has over 167K miles on it, so the mechanicals are shot throughout. Even the gas tank leaks. The last time I tried to start it, I "let the smoke out" of the electrical system. You're not supposed to let the smoke out. :-)

I am not planning to go in either of the directions you mentioned above. The HS contributes its full floor front to back, firewall, power train mechanicals and electricals and dash instruments (but not the dash itself.) The firewall of the HS sits about a foot closer to the front wheels, so the car will end up with a combination of old and new firewall panels with added bridge fillers where I can hide various sub-systems.

The convertible contributes it's full body minus the original floor pans. It keeps the transmission tunnel and seat supports as extra stiffening for the HS chassis. The convertible's engine bay will fully engulf the one from the HS, so I just need to fashion adapter panels between the two. (I have done a lot of preliminary measuring already.) It will have a new but original full vintage interior, and the external appearance will be as close to dead stock as possible. Wheel bolt pattern adapters will actually being the tread width back out to stock for the convertible.

I'm just hoping it doesn't take too long to find the HS with a tree decorated roof. The convertible will be ready for it by mid-summer!

Bill the Engineer

 

Looking into the project further, it would be easier if I actually use parts of two HS250h to adjust the wheelbase to an exact match. I guess that opens things up to one damaged from the front, and one damaged from the back.





I will start a new thread whenever I have anything more to report!

Bill the Engineer

 

Hi Bill - quite an impressive project! Given the HS is a unibody, how do you ensure chassis stiffness when you swap in a different body? Especially one without a roof. Is your old convertible also of unibody design, or body-on-frame?

 

The lower body below the sills of the HS(s) will remain intact. The convertible is actually a strange mixture of frame rails around the engine bay bolted to a unitized body from the cowl back. This was the design of this family of cars from their introduction in 1967. The majority of the sill framing of the convertible will be welded to the tops of the HS sills in a nested configuration, so the resulting sandwiched body will be as strong if not stronger. By doing this, I will also be maintaining the original body height of the car, which originally had more ground clearance than the HS250h.

I guess it is finally time to reveal what the convertible is that I will be converting. I wanted to hold back on this until I made my case, since the potential of getting lots of negative feedback from other owners of similar cars. The photo is at the bottom of the message.

Moderator, if you want to break this group of messages off into a new thread, please do. There should be a copy-paste function in the moderator's tools. (I am a moderator on a diecast toy forum elsewhere on the web.)

Bill the Engineer

 

Thinking about it, it sounds doable in theory.

But what about the traction battery? Other than moving it to the trunk, with the transmission tunnel and the 2 + 2 seating, I can't envision a place for it, especially if you plan on keeping the interior stock.

 

Good question! While the final fit-up obviously isn't finalized, the entirety of the Firebird floorpan will be removed. Visible in the photo is the structural plate that the rear backrest of the original interior rests against. The lower portion of this will likely need to be trimmed higher so that the traction battery components can fit. The good news is that I could always make the car a two seater! Otherwise, I may just use the HS rear seat recovered in a matching material. Figuring this area out will be part of the fun!



In model railroading, we used to call this "Kitbashing." (I have done many such projects in model railroading for decades... and written many articles in magazines about them!)

Bill the Engineer

 

That may work, but that plate is probably one of the main structural components of the convert. If you cut an access hole for the battery, I'd add some stiffeners around the cutout.

And looking at those doors......... the HS has a body electronics module. I'm wondering how the extensive electrics of a 4 door can be adapted to a 2 door. A lot relies on door position.

I guess you'd have to wire both front and rear door switches to the front door alone. Other than that, I don't think the HS will go into drive with the front door not in the closed position.

I guess the electric part of the project is way down the list, huh?

Oh, BTW, I used to play around with Z scale until it ruined my bank account........... and made me go blind, painting all that stuff under a magnifying glass !!

 

Moderator, many thanks for splitting this thread off!

Here is an attempt to show how the HS and Firebird align. This is only approximate, since I am using .jpg files rather than scale drawings. The actual difference in wheelbase is 1.5".



Looking at the relative positions of the driver's seat between the two cars, it looks like I'll be sitting half way between the front and back seat of the HS. :-)

Wiring is not a problem. I've designed machines with more complex wiring than the HS! The door switches are as easy as crimping the two ends of the rear door wires together. I plan to use the original ignition key switch wired into the circuit of the start button. The shift selector will end up down on the console where the original shifter was, along with a number of switches that have no other place to go on the Firebird's dash. It should be fun! :-)

I have done a simple scale AutoCAD drawing to show the relative positions of the firewall, steering column, radiator support, and hood opening when the center of the front wheels and centerline of the cars are aligned. The Firebird swallows the HS whole.



Bill the Engineer

 

Anybody know of a lonely rear half of a HS looking for a new home for a reasonable price, preferably near the mid-west USA? :-)

Bill the Engineer

 

http://erepairables.com/salvage-cars.../lexus/hs+250h

Good luck !!

 

Been watching that site and others for a while. I keep getting out bid... for now.

Bill the Engineer

 

While I'm still searching for the right donor car(s), I've been doing some planning too. The exit of the battery cooling duct on the HS is hidden inside the right end of the rear bumper.

That posed a problem since I want the car to look as close to "Dead Stock as it can externally. The chromed rear bumper on the convertible is quite small. Then I realized that many "67 Firebirds had dual exhaust. Now I know what will be coming out of the second tailpipe.

Bill the Engineer

 

Project update:

Central Ohio does not seem to have been a hotbed of HS250h activity. The local Lexus dealers have not had a used HS for me to test drive in over two months of searching. In addition, the numerous local salvage yards around Columbus don't even have one. All of the recent salvage auctions have been states away, making transport of the car quite costly.

I have also recently learned that the HS mg2 electric drive motor pumps out 107kW vs 70kW in a Prius, so falling back to a Prius is very undesirable. The search for an HS continues!

I just wonder why Toyota didn't think of putting the HS power train in a Prius and calling it a sport model?

Bill the Engineer