i built a car

[Klondike1020]

@alex.s - good progress!
@corksil - I wonder about you. lol

[alex.s]

Originally Posted by corksil

good luck with that left-side.

At this point in the project you should inspect the steering rack bushings and dust cover bellows.

Blow the dead leaves off the windshield wiper cover cowling.

Check the spot-welds around the shock towers, inspect the chassis for fatigue points, mainly the LCA or RLCA.. for all you folks at home, that's the lower control arm. Otherwise known as the rear lower control arm.


EDIT -- apparently OP isn't trying to build racecar, so the only thing he should consistently focus on is engine health.

the old chassis is going to the scrap yard

[alex.s]

so i'm making slow but steady progress on the frame design. suspension design has to finish first before the chassis can really be designed for real. but it will be somewhere between a 4 tube chassis and a space frame. lots of people claim to have designed a "true spaceframe" but when you look at it, it's pretty obvious they don't have full triangulation and many support points are not completely dimensionally supported. most people lie (or simply don't know) about what their frame actually is, and most people don't question it. "space frame" sounds F1, so it sells. "attempted space-frame" doesn't sound good. but anyway it looks like i'll be going with 18ga mild steel in 1" square for the 4 main tubes and the suspension boxes along with the bottom rails, and 1" round for interconnecting supports. a few spots will also have .25" bar supports and a handful of 8ga gussets. because of regulations and rules in places like SCCA, the roll cage structure will be 1.3"x12ga dom mild steel round tube. front suspension will be dual uneven a-arm with antidive and inboard linked suspension with a flex tie bar. not done with rear suspension stuff yet. still learning a lot, really. i've been having a hard time going back and forth between rubber-mounted and hard-mounted engines. the thing is going to be a track toy, so i've been thinking hard-mount. but i don't like what it does to the trans. i am mean to transmissions... so maybe i should rubber mount it and just add some extra frame to the rear.

[alex.s]

[mr2peak]

http://www.midlana.com

Been watching this for a few years

[Alex]

Originally Posted by alex.s

I'm pretty sure something's missing.

[alex.s]

Originally Posted by mr2peak

http://www.midlana.com

Been watching this for a few years

definitely one of my inspirations. my uncle has been building a traditional lotus 7 replica for a few years now (front engine rear drive, standard 7 chassis but with rx7 donor parts and the entire rx7 rear sub frame welded in place) and it got me very interested in hand made cars. my interest is less about racing nostalgia though and more about just having fun while learning, so i decided to go "locost midi" style, like the midlana or mev's version and just take a fwd engine and stick it in the back of a tube chassis.

[mr2peak]

Nice. I've always wanted to build a lotus 7 with a liter bike motor. Check this out

https://www.youtube.com/watch?v=RHgjFPhhzY8&feature=kp

[alex.s]

i built a table today

[Singh2jz]

Berry good job. Me like ur progress.

[alex.s]

practice makes perfect

[alex.s]

[alex.s]

this is amazingly helpful for designing suspension:

http://vsusp.com/

[alex.s]

[mr2peak]

Ha nice lighting

[alex.s]

dramatic lighting adds to any scene

[alex.s]

so i built my first wheel hub. and made my first a-arms. nylon bushed connections at the frame and two heim joints at the hub. they are uneven arms so it pulls the camber in as the tire goes up the stroke to maintain traction under compression. the top arm is kicked back for anti-dive. i managed to get the steering axis pretty close to correct also. it has camber adjustability in the top and bottom connections and the bottom connection is at an angle so you can actually change the steering axis inclination if you so desire. the entire mini frame and single arm setup weighs less than 20 lbs i'd guess. i had thought i should buy miata front hubs or something for the car but i think now i'm confident enough to build the front hubs myself. my phone battery was dead so no pictures

[corksil]

Very nice progress.

I did some more tuning on my JRSC b20v water/meth injection CRX yesterday. Slowly leaning out the fuel mixture and dialing in more aggressive spark advance. This thing is beastly. I had to call it quits when a light rain moved in... I was datalogging 4th gear pulls to redline and the car kept breaking the front wheels loose on the tarmac when VTEC kicked in. It's scary when you're suddenly spinning both tires at 90+ mph and you still have 3k rpm until redline.. Atleast the quaife locks up hard and pulls in a straight line.

I recommend a quaife if you're looking for a LSD, which you should be. The quaife's are superior to the m-factory units based on my research and testing experience.

And some very very wide low profile sticky tires. My setup is limited in the traction department as I cannot stuff anything bigger/wider under the fenders without having to raise the car another inch and re-adjust camber etc. 205/65/16 are a little narrow for my taste but I've got an 1/8th inch of clearance to the frame in the front, and an 1/8th inch of clearance between tire and trailing arm in the rear.

Your project looks like fun. Too bad you can't make that thing street legal..

[JohnnyBravo]

I used to love the LSD... Ahh the good ol Honda days

[corksil]

If you do enough of it, you never come down. That has been the consumation of my firsthand research and testing.

But in terms of limited slip differentials, get the quaife. Hand's down.

[alex.s]

using ****** stock fwd diff for now. maybe ill go to a vw trans with an adapter

my brother is trying to do meth injection on his mini fake-s

[alex.s]

my brother posing:

[alex.s]

i decided to call the big car "Kludge"

noun
1.
an ill-assorted collection of parts assembled to fulfill a particular purpose.

[alex.s]

for the little car, i made the right side control arms. i started using round tube now on the little one since i decided that i will go with 4130 18ga round tube. still need to make the right side upright, and the control arm mounting points. need to figure out front brakes for the little one. also need to mount the shocks. i will be making my own steering system for the little car... just a rotating lever and pushrods like a go-cart. the rear end is a single swing arm like a motorcycle but with two wheels instead of one which means there will be very low roll with a lot of roll pressure on the outside rear wheel, which means it will more easily break the rear loose so it will be a fun little kart for only having 5 hp. tomorrow we are getting the first batch of 4130 tube... it will be used to make the engine box and control mounts for the rear. the big car will go in 3 distinct pieces... the rear end+gas box structure, the front end, then the passenger cockpit. the rear end will use the old civic cross member and rear engine mount as the base which also locates the LCA, then i'll build tube up and around to get to the side and front engine mounts. and the RUCA mounts. the rear suspension is basically just the front suspension from the civic moved to the rear with small modifications. front control arms will be 1" round tube in 14 or 16 gauge i think. dual uneven wishbones with a 3* steering axis inclination. the suspension setup i'm going for in the front is -2* static castor at sag. 3" travel and 0* castor at 4* of roll. the front will get a loose sway bar. braking and bumps won't be the best but it should corner like it's on rails. trying to setup to get a 2" roll center height throughout the travel... coming close on the simulations. we'll see how things go.

[alex.s]

second set of wishbones turned out better than the first. still pretty ****** though. i suspect the 3rd and 4th sets will almost be usable

[alex.s]

[alex.s]

i should have taken a photo when i finished today... the engine box outer perimeter tubes are all cut and coped and tacked together. next up is the front suspension box. then i will build the small box surrounding the gas tank between the engine and driver seat. after that i will do the large radius bent outer tubes (i think i will go with 2.5") and attach them to the front and rear end boxes. after that, i'll be doing lots of little tubes for triangulation. most 1 inch. some plate work for supports between tubes on specific areas.

[alex.s]

you can see some of the tubes coped and tacked here... the tops are just laying there. there will be more interfacing with plate between the tubes and the crossmember. though i'm wondering how much i need. maybe a good welder like @Motofool would know

[Motofool]

Originally Posted by alex.s

you can see some of the tubes coped and tacked here... the tops are just laying there. there will be more interfacing with plate between the tubes and the crossmember. though i'm wondering how much i need. maybe a good welder like @Motofool would know

Sorry, Alex, I have not been following your progress.

I don't understand: how much of what you are not sure about ???

[nickjpass]

you'll finish this before i finish my sexr

[alex.s]

[alex.s]

finally found a large radius bender to do the nice curved outer tubes. went to HF and they said they had 4. looked around, i couldn't find them. they assured me they were there so i asked them to get one for me... they couldn't find them after combined 45 minutes of looking. so today i called another HF. similar story, computer says they got it, they can't find it. so finally the third harbor freight managed to actually locate one, so they have it on hold for me so i can go pick it up once i get off work. $180. not cheap, but a whole lot cheaper than the other brands for this type of bender.

[alex.s]

http://ntnu.diva-portal.org/smash/ge...FULLTEXT01.pdf

The mechanical trail should not be to large compared to the pneumatic trail,
as the pneumatic trail approaches zero as the tire approaches its slip angle. This directly
decreases the self centering torque, which gives a signal to the driver that the tire is near
“breakaway” (initiation of under steer). This “breakaway signal” might be reduced in effect
by to large mechanical trail compared to the pneumatic trail.

[corksil]

The mechanical trail should not be to large compared to the pneumatic trail,
as the pneumatic trail approaches zero as the tire approaches its slip angle. This directly
decreases the self centering torque, which gives a signal to the driver that the tire is near
“breakaway” (initiation of under steer). This “breakaway signal” might be reduced in effect
by to large mechanical trail compared to the pneumatic trail.

For the folks at home, we are now studying the effect of rake on steering wheel control and suspension geometry.

To summarize the above quoted statements, "If the damper runs itself out of the sweet spot between the spring and typical terrain adjustments, re-design the car. If a car does not have the proper suspension damper travel; given the terrain, it will beat itself into pieces before the driver has a chance to wonder why his steering wheel feels heavy.

What in the actual...?

Hey did anyone notice that the intake manifold of the engine looks like a fist?

Hey look again.. he even put a level on it.

[alex.s]

so i think i'm going to go with about an inch of negative scrub and a kpi of around 14 degrees. but i think i will go with a "long arm" hub. 14" LCA and the top of the front box around 27" (matching the steering rack) to give a track width with the spindles and tires of about 59" front and rear, same as the civic.

[alex.s]

[corksil]

rear engine, rwd, that thing is going to be fun. I think it's going to take a few tries to get the suspension geometry right, but you'll learn a hell of a lot along the way.

Any automotive off the shelf dampers are going to be a bit stiff for your needs, as your chassis is so light.

Power to weight ratio = speed, only variable is traction. If you can't get the power to the ground, you won't move. But I'm sure you know that thus far.

[alex.s]

[corksil]

Hey look at some pictures. Your head is not supposed to be above the roll-zone of the chassis in the unfortunate event of a weld cracking and causing the car to go into a spin.



That's the same reason they were banned from the track. ^^ it didn't look safe.

[alex.s]

you are looking at the bottom tube. the top tube will be higher, and then on top of that will be a roll cage