The Weight, My Enemy.

[lahondal 17]

Hi all.

 

Im finishing my turbo project and as i cant stop thinking new projects I´m beginning another.

 

I bought a month ago a complete honda k20a2 engine from a type-r ep3, with gearbox, loom and ecu for throw it in a 205 chassis.

 

I want to take this build as my own challenge, taking the weight as a horrendous enemy and i have a lot of questions to solve and i know here is a good place to do it.

 

I want to cut the chassis all from engine mounts to front of the car and build a light spaceframe to support fiberglass wings, bonnet and bumper, this must save a few kg.

 

Plan is use 13" wheels to take single seater slicks and make it wider the right way.

 

The rear beam i have readed that weights a lot, near 60kg, and my plan is make a macpherson rear setup using rear hub carriers and modified struts from a hyundai coupe mk2, using the minimum arms and material to make a lighter rear setup like this:

 

 

Im planning to make a much simpler tubular frame to attach the arms and make my own arms to save some weight.

 

In the front i have a big doubt, as Im thinking on 2 options, make custom tubular wishbones to make it wider and use 306 hub carriers to take off a little of the extra camber they will get and raise the mounting points on the subframe, and lowering the steering rod ends for getting the correct roll center, or take the hassle of adapting vauxhall astra J wishbones and hub carriers, that are made in aluminium and can save some weight (plus the beafier CV joints).

 

I dont know if a aluminium wishbone+hub carrier weight (unsprung weight really) worth the hassle of fitting it or a well designed tubular wishbones+standard hub carrier is a better and easier solution.

 

Sorry if i have writing mistakes as im Spanish and im learning english all the time.

 

What do you think?

 

Thanks, Larry.

 

 

[DBG 16]

Will you be able to get big enough brakes under 13" wheels?

[allanallen 528 2 Cars]

Simplest option would be to make tubular wishbones, I'd look at moving to a 307 (or similar) hub for ease, standard hubs are a pain to work with because of the bbj mount angle, you also gain the advantage of using the two bolt damper mounting for adjusting the camber.

Lowering the steering arm will not alter the roll centre.

 

Using Motorsport 13" wheels and the right calipers will allow 285mm + rotors with serious stopping power.

[lahondal 17]

I only want to lower the steering rod to mate with the new wishbone angle and avoid bumpsteer.

 

Car will be a hillclimb car so massive brakes will not be a serious problem. Just good calipers, the max allowed rotor diameter below 13"s and good pads.

 

The only downside of the 307 hub carrier is the lower balljoint attachment. I will have to design a easy solution to this. CNC machining maybe?

[welshpug 1,622]

there's already a setup on the market using 307 hubs so you could buy those.

[allanallen 528 2 Cars]

The bottom ball joint is very easy, just a screw in boss that will accept a bolt for a rose joint. If you're stuck I can make you some up, in fact I may even have some as from memory they're the same thread as the late 406 hubs.

[welshpug 1,622]

I think they might be the same thread as early 405 but a larger pin.

[lahondal 17]

there's already a setup on the market using 307 hubs so you could buy those.

Im taking this as a challenge and a learning curve, so i want to make the maximum things on my own. If i buy it, althought can be the best solution, i will not learn anything.

 

And for the balljoint adapter, i didnt think a solution like that. Thanks!

[Richie-Van-GTi 70 2 Cars]

If you are going to the effort of new spaceframe front end and tubular independant suspension on the back then why not use some honda hubs so driveshafts are easier. That then allows a huge list of options on brakes and wheels.