Bluebug's custom made Subaru Impreza WRC

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Bluebug

Member
Messages
11
Location
Canada
Hi all!

In about 2003-2004 I started collecting parts to build a 1/5 scale Subaru STI WRC, based on a Teknokit WRC body I got for cheap on ebay (50$). It was painted poorly and looking quite sad so I started by peeling it all off and doing a proper paint job for a WRC Subaru. I wanted to build a big mini-me of my 1:1 2003 WRX I had back then, in World Rally Blue, and the proper WRC neon yellow scheme. This first batch of pictures is from quite some time ago, I'll start with that and then once it's out I guess I have to commit to it now, get get back at it! :)

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I spent quite a lot of time in Autocad and SolidWorks back then to design a car around the parts I had, and then had kids and let the project on a back burner for a long time. Now as I said in my introduction post, last weekend I came across a relatively cheap Losi DBXL on marketplace, shortly considered jumping into it, but then after a bit of research and thinking, I got the interest back into continuing my 5th scale Subaru again instead.

Some of the parts I have so far:

- FG Marder all metal diff
- FG Marder plastic case diff
- FG Marder shocks
- Wheels squares and axles
- Front MCD CVD axles
- MCD Raly wheels and tires
- Used FG on-road wheels and tires (too much offset for my body though, with my current diff and axles it would stick out of fenders)
- Rear FG dogbones (not sure from what, maybe Marder again)
- FG brake discs (just the discs)
- FG steering assembly with servo saver
- One 5th scale servo, not sure how good or bad of a brand and type it is?
- Random small gas tank from a gas trimmer
- Pocket bike motor, not sure the size. I think it was advertised as a 47cc but the fact the cylinder is smaller than the fins makes me doubt maybe it is more around 40cc? what do you think based on the pictures?
- Secondary sprocket and a chain (being made for a pocket bike, the motor has a sprocked on the clutch)


Here is a mockup from when I was thinking of a double A arm suspension type with cantilever setup (wooden prototype FTW lol!)







But what I really wanted was to have a macpherson front suspension and rear multi link strut like the actual car, so I did another cardboard and wood mock up to test out the geometry. The idea is to either make it all from scratch on the lathe, or repurpose some gas shocks from a car's rear hatch.

Front and rear suspension test in Autocad, in 2D:





Rear suspension in SolidWorks to test a bit further :



Side view:



Rear view:



And a view with the diff installed. As I said, still unsure how I would go about doing these struts...




(continued below, with the next 20 pics!)
 
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Reference picture of rear suspension on a WRX:













My design of a disc brake caliper, while trying to keep materials simple (aluminum angle bars and a machine aluminum block for the knuclke holding the bearings.





Then I started doing the basic chassis and find a way to attach the diff on the chassis plate. In retrospect, I'm thinking this way of attaching the diff side plates will not be strong enough for all the vibration I suppose the motor can do.

Diff bearings holders:





Installed on the diff:





And here are some more pictures of the motor (close up of the carb) in case you can identify that as good or garbage :D







Thanks for looking!

Fred
Very impressive! I'm definitely going to keep an eye on your progress!

Thanks Rep732! I appreciate it. For now it's a lot of virtual stuff and a bunch of parts, but I do like to think stuff through before proceeding lol I have to say I do enjoy testing out stuff in solidworks too, so fun time is not lost time. But now I have to jump in and get things done!
 
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looking forward to this fred (y)(y),
i followed your mk2 escort build and i know this subaru build is gonna be even more involved with problem solving along the way etc,
 
On the strut system. What about using the piston and shock shafts from the shocks and bore the "L" blocks to accept them? You could than shorten the shafts as needed and use heims with a set screw to attach them on a flat on the shaft. This is how we attached the heims on our shocks in the early days when we made them. Of course you will still need a bushing to seal up the body where you installed them and support the shafts in the body once installed because of the bigger pistons than the shafts. Just a thought.
 
looking forward to this fred (y)(y),
i followed your mk2 escort build and i know this subaru build is gonna be even more involved with problem solving along the way etc,

Yes it's a lot problem solving! For some reason in those builds I tend to choose the most complicated stuff I think I can pull off, but there's a fine line between too much and nice result, and also sometimes it's nice to do something just good enough. So I'll see if I mix a bit of both here :D

On the strut system. What about using the piston and shock shafts from the shocks and bore the "L" blocks to accept them? You could than shorten the shafts as needed and use heims with a set screw to attach them on a flat on the shaft. This is how we attached the heims on our shocks in the early days when we made them. Of course you will still need a bushing to seal up the body where you installed them and support the shafts in the body once installed because of the bigger pistons than the shafts. Just a thought.

That was also my thinking, and it is mostly what I have done on the 10th scale Escort on the front, but with a strut design in RC and wheels that wide, there will either be a quite large strut angle, or strut misaligned between the top and bottom heim joints. It can result in quite big lateral forces on the struts, so I don't think the FG shocks are ok for that... Especially when you add cornering forces, or landing slightly sideways with the strut completely extended. The strut shaft is the only think preventing the front suspension from collapsing laterally (with the help of the lower arm of course).

Back then I planned to make the struts from scratch, maybe from a car hatch strut (to have proper hardened surface shaft and smooth), and I looked at what I think is Baja shocks for the seal (bottom) area with the brass and orings:

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And I came up with this design below (not actual tried it, just designed in autocad). The idea was to take a bolt that matches the inside diameter of an aluminum tube, and then machine it to remove the hex head, shorten the thread, drill a hold through it for the strut shaft, and cavities to place the brass bushings and orings. Then I would also have to machine the strut shaft to screw the retaining bolt at the top, have the right diameter to fit my heim joints, but also have to figure out how to have a lip that will prevent the strut from just sliding and bottoming out of the heim joint.

Quite complicated.. I do have a small 10x22 manual lathe, but this still seems like very precise work, and even requires kind of C-clip slots to retain the bushings in there... So we'll see how that pan out once I find some old gas struts and measure the shaft diameter and sealing area shape and size.


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This is what hobbies are about.
You're lucky to have that software to work with.

Yes for sure! I use AutoCAD for electrical drawings at work, but SolidWorks is just for fun I got if from a friend and figured out how it works.

Thanks for looking!

Fred
 
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Wow! Really looking forward to watching this. I’m envious of you guys with machining skills, wish I had taken it in school when I was young.
don't let lack of experience put you off bizzer,
i only did minor machining stuff at school,
i just bought a lathe and hobby mill when i could afford to and learnt from my mistakes as i went along (y),

edit, although i did used to work in a foundry that had a big machine shop, so i did pick some stuff up there as well :LOL:
 
Actually Spents it’s been in the back of my mind. I’ve looked at some hobby units on the interweb. One of my best friends is a millwright at work and would tutor me as needed, Real estate is at a premium in my garage currently, too much stuff! Definitely a 1st world problem though. 😀
 
don't let lack of experience put you off bizzer,
i only did minor machining stuff at school,
i just bought a lathe and hobby mill when i could afford to and learnt from my mistakes as i went along (y),

edit, although i did used to work in a foundry that had a big machine shop, so i did pick some stuff up there as well :LOL:

I've been looking for a small lathe myself but can't find what I want.
Dremel used to sell one back in the day but it no longer seems to be available?
 
Wow! Really looking forward to watching this. I’m envious of you guys with machining skills, wish I had taken it in school when I was young.
Thanks Bizzer!! Never too late to learn new stuff I think!
don't let lack of experience put you off bizzer,
i only did minor machining stuff at school,
i just bought a lathe and hobby mill when i could afford to and learnt from my mistakes as i went along (y),

edit, although i did used to work in a foundry that had a big machine shop, so i did pick some stuff up there as well :LOL:

I've been looking for a small lathe myself but can't find what I want.
Dremel used to sell one back in the day but it no longer seems to be available?

I agree you don't need to learn everything in school.. Machining is completely out of my scholarship scope hahaha I am no expert though, but I think the basics of mostly anything can be learned by anyone provided you have enough interest to keep at it, and now with youtube etc it is a great time to self learn. I recently got a welder too, did my first practice welds ever. They were not all that bad for a first time :D Maybe I'll incorporate some of that newly acquired possibility in the Subaru!

I got my lathe in the early 2000s, it is a King Canada, 10x22 (I corrected the previous post where I said 7x12). Back then I was also looking at the smaller ones, 7x12, but those are really small and not very torquey so I stepped up a bit. I also looked at combinations lathe-milling but came to the conclusion that maybe they are not very good at either so I got a standard lathe. A buddy has a Sieg milling that he converted to CNC though, so maybe for a part here and there I could use his help. Funny he has no machining background either, he's a programmer lol
 
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I've been looking for a small lathe myself but can't find what I want.
Dremel used to sell one back in the day but it no longer seems to be available?
i have a hobbymat md65 that i bought back around 1990, they're not made by hobbymat anymore but i recall seeing a copy being made now,
300mm between centres and has served me well over the years, in hindsight i'd have bought a slightly larger one though,
my mini mill is a french made no name i got about a year after the lathe,
supposed to be bolted to the back of a lathe and use the lathes cross slides ,
but i converted it to a stand alone mill and added a small cross slide with t slots for clamping etc (y)
 
Thanks for that spents.
I just want one for cutting small tubing and maybe making the odd pulley or bolt etc.
I have limited experience with metal lathes but I can use a wood lathe OK.
 
Looking at the picture showing the up rights. The heims you have are long looking. Shorten them up and this will give you more room. Plus looking at it more. The upper heim area. Use two heims up there. Meaning thread them together and have the pivot holes 90 degrees from each other. This will give you more travel up and down. Plus camber adjustment if they not bottomed to each other. On the bushing end of the shock. Our early ones we made we counter bored a step in the body and used a snap ring to hold it in. Later model ones we made new bodies with thread in bushings. 10x20 lathe is fine if you have the collet setup for it and runs true. You can thread the shalves and body in it. Our early shocks we had snap ring grooves in it to adjust the spring. Later ones we threaded the body of it. Just more thoughts to throw out there for you. Good luck on this
Looking at pics again. You could do same double ended heims on the bottom to give you more travel in the suspension or just turn the lower heims 90 degrees.
 
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Thanks for that spents.
I just want one for cutting small tubing and maybe making the odd pulley or bolt etc.
I have limited experience with metal lathes but I can use a wood lathe OK.
you're welcome phil (y),
something else to consider is tooling as well, it costs a fair bit,
i have a mix of fairly decent stuff and some cheap stuff as well,
cheaper stuffs ideal for when you need to grind a tool for a specific job,
the last cheap set i bought was a 36 piece set (on special offer) and worked out at just over £1 a tool,
dirt cheap but they're half decent (y),

sorry for hijacking your thread to talk about lathes etc fred, sorry mate :)
 
Looking at the picture showing the up rights. The heims you have are long looking. Shorten them up and this will give you more room. Plus looking at it more. The upper heim area. Use two heims up there. Meaning thread them together and have the pivot holes 90 degrees from each other. This will give you more travel up and down. Plus camber adjustment if they not bottomed to each other. On the bushing end of the shock. Our early ones we made we counter bored a step in the body and used a snap ring to hold it in. Later model ones we made new bodies with thread in bushings. 10x20 lathe is fine if you have the collet setup for it and runs true. You can thread the shalves and body in it. Our early shocks we had snap ring grooves in it to adjust the spring. Later ones we threaded the body of it. Just more thoughts to throw out there for you. Good luck on this
Looking at pics again. You could do same double ended heims on the bottom to give you more travel in the suspension or just turn the lower heims 90 degrees.

Thanks Todd for the advice, I am still trying to process everything you said hahaha I think I understand the 90 degrees rotation of heims so they are not limited in angle, but the one at the bottom of the strut I think still needs to be on horizontal pane since it has to do the steering which is a large angle. If you have any pictures to help represent the ideas you are explaining I feel like I would understand better. What do you mean by using two heims in the upper area?

I don't have a collet setup for the lathe, I actually had to lookup what it is. I have a 3 jaw self centering and a 4 jaw. As I understand it the collet will center much better than a regular 3 jaw chuck?

you're welcome phil (y),
something else to consider is tooling as well, it costs a fair bit,
i have a mix of fairly decent stuff and some cheap stuff as well,
cheaper stuffs ideal for when you need to grind a tool for a specific job,
the last cheap set i bought was a 36 piece set (on special offer) and worked out at just over £1 a tool,
dirt cheap but they're half decent (y),

sorry for hijacking your thread to talk about lathes etc fred, sorry mate :)

No problem buddy! :) It's all interesting chat and actually has to do with the build since I bought the lathe exactly for that build initially :) Would have been cheaper to just buy a 5th scale car but that was not the point! I like to create stuff.

Thanks guys!
 
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