Frederik_b

Hello,

Afew years ago I started to think about building a large scale car and bought a small 7x10metal lathe. I bought some parts online and on ebay and now have most of the important mechanical components. After looking at your projects here for a while I thought I could introduce myself and my project. This is a slow progress project as I have plenty of other things to do, let me know what you think.

I own an impreza WRX so naturally when I saw this body on ebay for about 50$ I was very happy! At that time my only hope was that I could remove the paint and do it to look more like a real subie !
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After removing all paint :
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2 coats of blue metallic paint, and subaru logo and windows still tape masked, and quick wheels test fitment. Also added some black detailing around the windows
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Here with the yellow SWRT logo (actuallymasked andpainted, not a sticker), and next to a 7up can and small 1/18 scale (Rallyart die cast) car for size reference :
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I bought MCR rally tires:
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and a pocket bike 37 cc engine (not my engine but it is identical)
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Test fitting used FG wheels(from ebay) with paitend body:
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I bought 2 different kind of balljoints and used FG shockson ebay. I wanted to have something more tangible than my autocad and solidworks drawings to I started to test the suspension principle with a wooden model. It also helps to see where the engine would be etc






Engine placement :


Here you can see the power transmission layout



I want to make it 4WD so I bought timing belt and pulleys, I machined the inside of an aluminium pulleyto mount itright beside the diff gear.There will then be a belt going under the engine and to the front (a la FG baja 4x4) to send power to the front.





Here are some snapshots of my autocad drawings. In the second pic you can see how I planned to install the timing belt that will transfer power to the front wheels

I also use solidworks to test other 3d mechanism like the mechanical disk brakes:

Here are the MCD joints I will be using in the front, bought on ebay from a guy in UK.

As the front and rear will be linked by a timing belt, there will be no center diff (locked front/rear). I'll try to find another diff to put it in the front. Otherwise I might lock the front as well using only a simple pulley with joints on both sides.

Right now I changed my mind again on the suspension and made a new wooden chassis with macpherson suspension, but I don't have pics yet. Here is a snapshot of my cad drawing for the macpherson:



The macpherson strut will not contain the shock. I will mount the shock separately on the lower arm as most cars.

In the rear I will also use the kind of macpherson strut except it has 2 lower arms that prevent strut rotation, and 1 trailing arm (like the actual impreza suspension)

DarkFire989

Holy Cow. Keep up the good work![X(]

Nutech GmbH

Very nice.

visionary

wow that amazing, i love the details !

Frederik_b

Thanks for the nice comments !

I snapped a few pics of my wooden macpherson suspension test.





I didnt bother adding bracing to what holds the upper ball joint as this is a geometry and fitment test only, for the actual frame I will have to think of a simple way to firmly hold the top of the strut with no flex and no breakage..

Frederik_b

Some drawings also to test the geometry of the front and rear suspension

sam123

My Feedback: (1)

Wow!

What means will you be using to machine the parts for the final product?

Keep up the good work!

Frederik_b

Thanks!

I will use my metal lathe for some parts, and I design it to be able to do most of it with simple tools which will not require extremely precise drilling or machining.

For instance, the diff holders will not be directly machined to holdthe bearings; I will machine a roundbearing holder, anddrill mountingholes to mount it to the diff holder. Those mounting holes will allow some adjustment so I dont have to build 2 exactly identical diff holders, plus I don't have to machine bearing holes in a complex part (hard to put that kind of part on a lathe!)

I also thought of a way to make the A arms with simple tools (no pics yet). The A arm would basically be made of 3 parts. I'll put some drawings to show what I mean.

For the more complicated or larger parts, a friend of mine recently acquired a milling machine (sieg X3 Ibelieve)and he is currently modifying it to CNC. (he is building a large scale RCtank). I will ask him to machine some parts, and I am going to machine his wheels and some other parts for his tank.

Frederik

sam123

My Feedback: (1)

Well, it sounds like you have it all sorted out then!

I look forward to seeing how it turns out.

da mad maori

nice work man
i never thought of using wood for testing... cheap, easy to cut and shape and fairly strong........
well done

IloveMYxt2

Wow man you have some skills!

Nice work and I cant wait to see the outcome. Keep us updated, with pics of course!

sheograth

Nice drawings. Great paint job as well.

rckiwi

Wow that is so cool with all the cad drawings etc would love to get a copy of those programmes one day!

troppo

I love the way you work, CAD id great but it needs to be prototyped and thats what your doing. Nice and easy with timber.
Great stuff and i reckon i`ll be following your build, please keep up the pictures.

Lars from Norway

I wood like to see more of your projectThis looks really promising,nice twist to testbuild it with woodparts.Very nice body too!

mcspanners

Great work, can't wait to see it finished, il be following your progress for sure.

C.lyra

Hey Frederik
Awesome build, i wish i had the skills to draw my projekt on a computer like you can. And way to go with the wood prototypes, that is so simpel.......
And great paintjob....
And just make sure that those timings belt is protectet......I think you should build the shocks into the macpherson suspension, and save some weight.
Keep those pics comimg

Frederik_b

Thank you for the comments! I would like to have welding skills and equipment too A welded tube frame would be so cool! but It is probably hard to weld with thin metal.. At some point in my project I had considered this but for some reasons I changed my mind (happen all the time)

mmm yes I will have to think of some type of guard for the timing belt, it will have to be somewhat sealed from fuel dust (and probably mud lol)

Anybody knows how is made the tensioner on the fg baja 4x4 buggy with the belt?(I hope I am not confusing thisbuggy with another)I remember it is inside a housing under the engine but I don't remember a tensioner or any pulley that would make the belt angle under the engine. Maybe it is simply slipping against the belt housing which have a slope shape...

For the shocksI would like to be able to make them on the lathe, but I don't know how to make the shock rod big enough while still having enough room inside for oil movement. I am also wondering if I would have to use a rod from an actual damper (like hood and trunk dampers) so that I would have a plated corrosion proof metal and easier to seal oil.

Frederik

C.lyra

On my scooby, i made a tube in alloy with thread outside and made a hole Ø14 mm. I fund a damper from HPI´s Trophy 3,5 buggy to fit inside. This is upside down, so the damperhousing is now the movning part. And the spring is outside, (coilover) This is how the WRC shock suspension is made.
Check this out: http://www.youtube.com/watch?v=BQcAG...C66B7&index=27

Frederik_b

Thanks for the details, and for the wrc link!

Edit: I will look at your thread again because with your explanation now I understand that your setup is not inverted strut, the shock body is at the bottom like on a normal strut design, at first I thought you were to put the shock body on top.

I am a little worried that with the side forces going on the strut, (when cornering, and also because of the angle between the strut and the actual compression axis) it may have a hard time moving smoothly because the outer tube would try to dig in the outside of the shockbody. While trying to sleep yesterday I was thinking of an inverted strut design and was thinking that if I could put some seals on the inside of the outer tube and keep all this oiled it could maybe move smootly enough ? (in your case it would be between the inside of your machined tube, and the outside of the HPI shock body)

But on your side, you already built this strut so you have valuable experience! Does it seems to operate smoothly if you try to compress it whileat the same timeyou try to bend the wholestrut sideways?(to simulate the lateral forces)

I still have to learn how to make threads on my lathe, and have the proper tool to make inside threads.

There is a very nice WRC thread on nasioc.com (north american subaru impreza owner club) with lots of pictures of WRC subarus with mechanical details. Lots of drool there! In case you would like to see too:
http://forums.nasioc.com/forums/show....php?t=1769332

Thanks again for your help! I really love those projects!!

Frederik_b

I am still not sure I understand how you did it on yours, on the pic you posted it looks like the shock body is on top,not moving because it is attached to the chassis:



I searched for trophy 3.5 shocks pictures and the larger part of the shock is on top so I was thinking that the moving part was actually the shock rod and piston, and not the shock body ?



Thanks!

C.lyra

Okay, i did not know the shock is mounted like that.... On some 1:1 cars the damper is like an insert in the mcpherson struts, the damper inside the strut, and the shockrod is moving up and down.
On the WRC cars and on mine, the shockrod is inside the strut, bolted in the bottom. And the damper, with the oil inside is moving up and down. And i tryed to force the damper to see about the flexing, and it looks ok for now....
I see you point with the oil seal between the damper and the tube.....

Fabe

Great job, super CAD illustrations. This looks like it will be loads of fun to drive.

Is your engine a 37 or 47 cc? I have a similar one (47 cc) on a custom built project as well. Any thoughts on the pipe you'll be using

ByronRC

My Feedback: (2)

How did you take the paint off the body?

Frederik_b

C.lyra:

YesI see what you mean, I think mostof the production cars use a setup with the shock body and oil etc is all in the bottom part with the strut and wheel hub, while the shock rod and piston is attached at the top to the chassis.It is like this on my impreza wrx (2003).

I think the impreza STi from 2004 up are all inverted strut, which mean the heavier part (oil, shock body) is all on the top, attached to the chassis. The shock rod and piston (lighter part of the strut) is attached to the wheel hub. If I am not mistaken the advantage of inverted strut is mostly for lower unsprung weight (better handling).

I am not sure for WRC cars but I think it is also inverted strut design, and your description also go in this direction. I will try to see if I can do the same kind of principle but my fg shocks are the cheaper design, I am not sure I will be able to do something nice by modding them. With the lathe I should be able to actually machine a shock but I think I don't have the knowledge yet for this kind of details (how to integrate oil seals in the assembly etc)

Fabe:

Thanks! I am pretty sure it is a 37cc engine, it is what the description said when I ordered it. I am not really settled on a pipe layout yet. I have a muffler (not a pipe, really more like a muffler box, not performance oriented at all) from a weed eater that is straight bolt on, but I will most likely not use it as the exhaust will be under the engine and there is no room for it. I will most likely build a pipe from tubing, with 2 machined ends and a piece of pipe in between, like what is used on most 1/8 scale pipes (with .21 nitro engines) but larger.
I will go simple first and go with more elaborate after it is working. It will not be really a tuned pipe, only an approximation. I dont know yet what size it should be. I would play with the lenght of the tube to find a sweet spot (I think cvec made a pipe like this that you could add lengt of tube to tune for different engine sizes, .21, .28 etc)

ByronRC:

I softened the paint with hot water first. I asked the seller before buying to be sure it was water based paint(I think the paint used was parma water based). Ithentried different stuffs I already had at the house. First I tried hertel plus :



It worked ok but I had to rub pretty hard, and it is slightly corrosive so I had to use gloves, so I triedthen tried alcohol used for fondue. I applied if with a rag, keeping the pain wet for a while and then it would peel off, rubbing with the rag. I could not wait long because the alcohol would evaporate and the paint would become hard again after a minute. I did most of it with the alcohol.Took a few hours to do the whole body...


By the way, I thought I could include a couple pics of the reason why I like subarus my actual subie ! It's the blue one!