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Tamaren None
3/18/20 8:09 p.m.

Been a reader here for a while, thought a few of you might be interested- It's more of a build thread so please keep in mind that it's far from finished, but here's what I've been working on now that everyone is stuck inside.

I've spent a good amount of time in Boxster 986's, owned 3 of them, and really enjoy the platform. So I went out searching for the worst condition Boxster in the country to use as a donor. (If anyone needs some spares I have a ton by the way...) I eventually found one close to me that was perfect- a 2002 S with 200k miles, a lot of questionable things, a spray painted rear bumper, and the evap line was plugged with a 5.5mm hex driver. something that I didn't mind tearing up. It also somehow has machined Victor racing wheels, and Fabspeed headers... My purchase price was about the cost of the wheels if I had to figure correctly. It ran and drove great, and made it 100 miles back in traffic.

I'm a bored college student with a history major and never claimed to be an engineer- I usually throw things at the wall and if it doesn't break it's good to go. However, a few structural components get tested in Solidworks for structural rigidity and motion, with a 10% error on the weakest component- for the frame I'm using 4130 with ER70-2 filler, so therefore 10% error on the properties of the weld since it's the weakest. I also overbuild things because I don't want to die, at the sacrifice of weight.

I'm calculated out at 500 kg curb weight. I'm planning on using megasquirt for the fueling, and individual throttle bodies on a custom intake. Boxster brakes will be more than enough, and petals use factory brake and clutch master.

I have a 2 car garage in the suburb of Phoenix so I'm not exactly flush with room, so it's a tight fit, but my shop does okay. Plasma table has made it a lot easier on smaller components, and pushrod suspention- so far it's working out well. The goal for styling is 60's F1 cars, Think Lotus 49. 

Below are some pictures- I'm open to criticisim, and I know at this point it looks like I have no idea what I'm doing but I do sorta have a plan and once it's a rolling chassis it'll come together a bit more. Feel free to ask any questions or make recommendations. Let me know your thoughts!


To start, Here's the donor... (Again if y'all need parts let me know...)

Engine and rear subframe pulled.

Front suspension Design (It changed but this is the only picture I had.)

Clean your radiators, people.

My tubing bender setup. Luckily I built my bumper with a front hitch...

The rear subframe missing some pieces

An A arm

All the parts that go into a front A arm, not counting suspension. If anyone works at McMaster Carr I'm open to sponsorship opportunities. Please.

Front shock sleeve mount. I wanted to use the factory hubs and needed something to hold in the shock mount because I'm going pushrod.

Rear Shock Sleeve mount.

Drivers rear. You can really see how bad the axle angle is on the factory 6 speed boxsters.


Rear with tires

Petals (designed to use factory clutch/brake master)


I was already out of room.

trumant New Reader
3/18/20 8:26 p.m.

Also don't mind that 6 wheel jeep and 928 in the background of the last picture....

Sounds like quite the project and one I'm curious to see evolve.

Hasbro SuperDork
3/18/20 8:28 p.m.

Hey Tamaren, you mentioned ITBs on another site. Could you expound on that?

californiamilleghia Dork
3/18/20 9:07 p.m.

What are you doing for the body design ?

Tamaren New Reader
3/18/20 9:45 p.m.

In reply to trumant :

Thanks! Yeah also fun projects honesty. 

Tamaren New Reader
3/18/20 9:50 p.m.

In reply to Hasbro :

Sure, I'm planning on using throttle bodies from a Motorcycle like a GSXR or Ducati 996/999, although I don't think I need both injectors. It really depends on what happens with fuel management and what someone who knows more than my basic knowledge of fuel management. It will take some work, as soon as I get mounts for Radiators and fuel tank I can work on getting things running and tuning. 

Tamaren New Reader
3/18/20 9:52 p.m.

In reply to californiamilleghia :

Will probably lay fiberglass, I'd love to be traditional and build an aluminum body but I don't have an English wheel and also 0 Experience in body work. 

OjaiM5 Reader
3/18/20 10:08 p.m.

I have a feeling this is going to be a really cool build.

I would love to draw it if you can get me some napkin sketches. 

Tamaren New Reader
3/18/20 10:12 p.m.

In reply to OjaiM5 :

Totally game, I have most things drawn structurally in solidworks, are you talking body panels and overall design or CAD Drawing?

OjaiM5 Reader
3/18/20 10:31 p.m.

Thinking more of like a creative design sketch. That is cool you know SolidWorks, great program. 

AnthonyGS Dork
3/19/20 12:07 a.m.

I like it!  I need interior bits for my 00 S if yours are in better shape than mine.  If the top is in good shape, I'd love a better top too.  Mine has a mediocre rear window replacement.  The top is good, but whoever did the rear window replacement, should've redone about 25% of their work.

Tamaren New Reader
3/19/20 12:37 a.m.

In reply to OjaiM5 :

Sure, once I get an established wheelbase I'll let you know and send you some pictures! 

Tamaren New Reader
3/19/20 12:41 a.m.

In reply to AnthonyGS :

Shoot me a PM, the interior suprisingly is in pretty good shape. Would be more than willing to sell you some parts, and the top is in alright shape however still has the regular window. More than happy to shoot some pictures your way as well 

Rodan Dork
3/19/20 2:21 a.m.

Watching with great interest... yes

Love the Thruxton!  I'd be happy to meet up for a ride if you want to bring it north (Prescott) when the weather gets better... wink

914Driver MegaDork
3/19/20 6:43 a.m.

Hold on, I've been doinking with cars for decades and never seen this bit of ingenuity!  The only reason I don't have a tubing bender is it takes up so much room after thunder studding it to a special spot of concrete floor.

Cool project Tamaren.

Box4VIR New Reader
3/19/20 8:05 a.m.

Yes! Can't wait to see this one.  Do you have a sketch of your plan?   Single seater?

Rodan Dork
3/19/20 8:29 a.m.
914Driver said:

Hold on, I've been doinking with cars for decades and never seen this bit of ingenuity!  The only reason I don't have a tubing bender is it takes up so much room after thunder studding it to a special spot of concrete floor.

I don't want to totally jack Tamaren's thread, but there's no reason a bender has to be anchored to the floor...  the hitch mount works great, and if you bend in the vertical plane, you can put it on a rolling stand.

More info here:  GRM Tubing bender thread

Adrian_Thompson MegaDork
3/19/20 8:53 a.m.

Pity you are so far away.  I need the engine undertray and some various bits from underneath, but I fear shipping from Az to Mi (48025 ZIP) would be prohibitive.  Ditto the rear bumper as mine has a dent.

Nice build, often wondered why I hadn't seen more like this already.

Any sketches of what you want the finished product to look like?

spandak HalfDork
3/19/20 9:05 a.m.

I love all of this. And I want that Triumph. Following with interest 

newrider3 New Reader
3/19/20 9:36 a.m.

Neat project. 


Tamaren said:

Front suspension Design (It changed but this is the only picture I had.)

An A arm



Can you show us your most current front suspension design? I don't want to sound rude, but what you've shown in the model is not going to work, stop now before you expend more time and materials. Equal length parallel arms will have no camber gain (no camber change at all through travel), weird behavior of the roll center during bump, droop, and roll, and generally bad handling. 

You're going to want to do some reading on unequal length dual wishbone front suspension (short/long arm or SLA), I'm sure members here can suggest their favorite race car suspension design books. A useful tool for playing with geometry and understanding the impact of changes on handling behavior is VSusp: vsusp.com


I would also shy away from using a heim on the outer end of the lower control arm; loading the shank of a heim joint in bending like this is generally bad practice and will fail if not oversized and overbuilt. I saw lots of these fail in FSAE and SAE Baja cars, but people online seem to get away with this design pretty often.

dps214 Reader
3/19/20 10:20 a.m.

In reply to newrider3 :

Pretty sure "rod end in bending" was the free spot on the "FSAE Design Judging fail" bingo card.

As a former member of a FSAE team that did some some weird stuff, parallel arms can be made to work decently, but they definitely need to be different lengths and be paired with fairly stiff springs/bars. On the other hand, we did that because some other design choices forced our hand on that one and we worked under the philosophy of "any suspension is good if you don't let it move". Given the opportunity to have them non-parallel, there's really no reason not to. The rear suspension looks decent considering the packaging constraints there, again assuming there's a fair amount of roll stiffness involved, and probably a diff or there might be some inside wheel wheelspin troubles.

That aside, I like the concept and the fab work looks awesome.

Lof8 - Andy
Lof8 - Andy SuperDork
3/19/20 10:23 a.m.

This is looking pretty rad. 

java230 UberDork
3/19/20 10:35 a.m.

Following along!!

Tamaren New Reader
3/19/20 1:52 p.m.

In reply to Rodan :

Always down! Always need an excuse to get out of the city especially close to summer... Thanks!

Tamaren New Reader
3/19/20 1:54 p.m.

In reply to 914Driver :

Credit goes to my dad, I had a pneumatic unit all built and then he said to just mount it to a hitch. Sometimes the simple answer works.  

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