Dimman's technical stuff.

[Dimman]

Well seeing that news is probably going to be scarce, and to keep some things going, I've decided to start this new fascinating thread.

The plan was that this was going to give some insight to some of the maybe less-technically-savy members here on what may go on in the development of after-market components for the FT/R-86/S. The savy would be sure to assist me and correct any blatant mistakes.

However shortly after I started some preliminary stuff, my shop got slammed with OT so I may not be able to update this in a timely fashion. But I will have more car $$$ when it's done. Nice.

Keep in mind this is NOT a DIY guide and I take NO responsibility for what anyone decides to do with this information.

But anyways here is what I've got.

I decided to go with control arms. I figured a lot of the fundamentals (coil-overs, shock-tower braces, exhausts, etc...) will come out rather quickly. But more hard-core things, not so much. Plus I want to put some on my own car.

So first step it to define what I'm making. In this case adjustable aluminum lateral control links for the rear Chapman-style strut suspension of a BD chassis Subaru Legacy (my daily driver).

They need to be at least as strong as OEM, have provisions to be adjusted length-wise, provisions to mount the anti-roll bar, and maintain a higher degree of precision than the stock ones. In the case of this suspension, increasing the length of the links should allow for an increase in static rear camber.

Now research. I picked up a used rear hub with lower links attached to take my measurements

The assembly that I got:



Pretty basic. This is the old-style rear suspension that was used in all (I believe) Imprezas and Legacy models up until the revision in the new Impreza switching to a new multi link design. Possibly the new one will be shared with the FT/T-86/S. The bottom is similar in concept this one but instead of using the strut as a locating member for the top it uses a compact upper control arm.

Missing from the pictured assembly is the semi-trailing link (often called a toe-control link) which I neglected to pick up (doh!) but it is not as straight-forward for me to make.

The stock links are mild steel tubing or bars (haven't cut them open or weighed them yet to find out) connecting two steel sleeves/housings (I don't really know what to call them) containing rubber bushings with different sized steel shafts.





I believe the size differences are due to the anti-roll bar mount. The link that the bar mounts to is the one with the larger shaft through the bushing. I believe this is due to the increased amount of force that will be applied to this link when the anti-roll bar transfers load to it.

One of the links has a welded-on stamped steel bracket for connecting the anti-roll bar to the suspension.





And that's about as far as I got today.

Let me know what you guys think.

Want me to continue or am I just wasting time?

Thanks,
D

[70NYD]

do continue this is interesting
the links i beleive at that thickness will be tubing and the housings at either end are just plain bearings.
aluminium ay.. you are doing this the proper way man, i would be lazy and just cut a section out of the centre, shorten it, thread the inside of the tubes and stick a bolt to suit :p (the bolt would sit in the piece of tubing that is cutout from the centre and shortend ofcourse :p) adding a few kg but finishing in 3 hours haha

[Midship Runabout]

[ichitaka05]

yup, it's same layout as Impreza.

STI made several ver for it. cheapest one start around $250 and went up to $600 for it. Keep writing it up, it keeps me entertained.

[Dimman]

Next step. More research .

First it must be strong and safe. Now with having decided on aluminum, what do I need to know about it? Well it has a high strength to weight ratio. This is good. So I just replicate the part and aluminum? Not on my life!

Aluminum is typically weaker than steel. But it is MUCH less dense (lighter). So what has to be done is make the components physically larger to account for the strength difference, then see if the density difference in fact makes the parts lighter.

How much bigger? That depends on the aluminum. I will be using either 6061-T6 or 7075-T6 aluminum. Both are often referred to as 'aerospace grade', although 6061-T6 is rather common in all areas of manufacturing.

First a baseline on mild steel's properties, before the final material choice is made. 1018 mild steel has a tensile strength of ...something. It's not in my metallurgy book so I'll step up to 1025 (still mild but a bit stronger than 1018). Its tensile strength is listed as 60000psi to 103000psi from full soft to full hard. Its working strength is rated as 70000psi (basically how you get it in rod form). It also weighs approximately 490lbs per cubic foot.

Now the aluminum I can choose from has the following properties:

6061-T6 tensile strength is 45000psi
7075-T6 tensile strength is 83000psi

Both weigh approx. 170lbs/cu ft.

Wow! 7075-T6 is stronger and significantly lighter than the steel! What's the catch? Money of course. This stuff has aircraft-landing gear as one of its principle uses. However the cost is not as much as I thought it would be.

From a local, small quantity supplier a 6 foot length of 1" diameter 6061-T6 is about $36 CDN. The 7075-T6 same size is about $106 CDN. Both have a listed shipping weight of only 6 lbs (a pound per foot). Think of how much these arms will weigh! Almost nothing.

So I'm going with the 7075-T6. They will be ridiculously light and much stronger than the stock versions.

Edit: I will be making them out of 1" diameter 7075-T6 for purposes to be revealed next major post. Stock diameter is approximately 3/4" or 19mm diameter. This is why I said much stronger.

However if I were going to use 6061-T6, how would I go about it? By comparing the strength of the stock links' material (70 kpsi) to its cross sectional area then increasing the cross-sectional area of the aluminum version until they are approximately the same using the aluminum's lower tensile strength. Conveniently this is pretty much bang on 1" diameter. But for an added amount of safety I would go 1.125" diameter with the 6061-T6.

Next steps, design, more research and wait for payday.

[ichitaka05]

Here you go, this might help

http://boxer4racing.com/suspension.htm

that shows you both STI ver and Whiteline Lateral links (also STI trailing link).

[Dimman]

Originally Posted by ichitaka05

Here you go, this might help

http://boxer4racing.com/suspension.htm

that shows you both STI ver and Whiteline Lateral links (also STI trailing link).

I don't know about the Whiteline ones. I've never seen any in person but the quality doesn't seem up to par (ugly welding, looks like MIG, and probably just mild steel). I'm sure they are strong, being steel but they don't do it for me from an aesthetics point. But I probably will be getting their adjustable anti-roll bars for my car (heard they're good and my options are limited). I also feel that Whiteline stuff is over-priced.

I will be doing something similar to Perrin, for reasons I will discuss on my next long post (regards to welding). But as the BD Legacies cannot use STI anti-roll bars (as far as I know), I will have to change the way the anti-roll bar is mounted, to keep a standard-style 'C' type link (which I may be making out of aluminum as well).

[ichitaka05]

Originally Posted by Dimman

I don't know about the Whiteline ones. I've never seen any in person but the quality doesn't seem up to par (ugly welding, looks like MIG, and probably just mild steel). I'm sure they are strong, being steel but they don't do it for me from an aesthetics point. But I probably will be getting their adjustable anti-roll bars for my car (heard they're good and my options are limited). I also feel that Whiteline stuff is over-priced.

I will be doing something similar to Perrin, for reasons I will discuss on my next long post (regards to welding). But as the BD Legacies cannot use STI anti-roll bars (as far as I know), I will have to change the way the anti-roll bar is mounted, to keep a standard-style 'C' type link (which I may be making out of aluminum as well).

Anti-Roll Bar? Anti-Roll Bar? Anti-Roll Bar? Oh Sway Bar! Sorry, took me long time to figure out what you were talking bout.

Really? I always hear good thing bout Whiteline Sway Bar. Most ppl here get Whiteline or STI's Sway bar installed into their leggy or Imp (older gen). As for me, I wanted to install RalliTEK's Sway bar (RalliTEK Anti-Sway Bar Kit for Impreza).

You said your Leggy was BD... so iirc that's 2nd gen Leggy Sedan right? Yeah, very few parts can be swap from Impreza on that gen.

Man, if you live close to me, I would of ask you to make some custom Aluminum parts for me... but c'est la vie.

Anyways nice write up so far!

[Dark]

Originally Posted by ichitaka05

Anti-Roll Bar? Anti-Roll Bar? Anti-Roll Bar? Oh Sway Bar! Sorry, took me long time to figure out what you were talking bout.

Really? I always hear good thing bout Whiteline Sway Bar. Most ppl here get Whiteline or STI's Sway bar installed into their leggy or Imp (older gen). As for me, I wanted to install RalliTEK's Sway bar (RalliTEK Anti-Sway Bar Kit for Impreza).

You said your Leggy was BD... so iirc that's 2nd gen Leggy Sedan right? Yeah, very few parts can be swap from Impreza on that gen.

Man, if you live close to me, I would of ask you to make some custom Aluminum parts for me... but c'est la vie.

Anyways nice write up so far!

UPSP or UPS shipping doesn't cost too much I joke, I Joke.

I don't really know much about these stuff, but I'm really interested in talking about Sway Bar and Suspension.

[Dimman]

Originally Posted by ichitaka05

Anti-Roll Bar? Anti-Roll Bar? Anti-Roll Bar? Oh Sway Bar! Sorry, took me long time to figure out what you were talking bout.

Really? I always hear good thing bout Whiteline Sway Bar. Most ppl here get Whiteline or STI's Sway bar installed into their leggy or Imp (older gen). As for me, I wanted to install RalliTEK's Sway bar (RalliTEK Anti-Sway Bar Kit for Impreza).

You said your Leggy was BD... so iirc that's 2nd gen Leggy Sedan right? Yeah, very few parts can be swap from Impreza on that gen.

Man, if you live close to me, I would of ask you to make some custom Aluminum parts for me... but c'est la vie.

Anyways nice write up so far!

Sway bar? Anti-roll bar! Anti-roll bar! Anti-roll bar! Grrrr... this is a HUGE PET PEEVE of mine. Not your fault as companies like Whiteline also incorrectly refer to their products as swaybars.

When talking about rotational motion and car suspension stuff there is NO 'sway'. Rotational motion is divided into Yaw (car spinning out), Pitch (nose dropping under braking), and Roll. Ask a pilot.

When talking about suspension geometry engineers talk about locating roll centers. Not sway centers.

Ok, rant's done.

As for Whiteline not being good, I didn't exactly say that. In fact I said I heard good things about their anti-roll bars. However the fabrication quality on their lateral links isn't anything to get excited about. They look like they're done in a hurry.

My next big post will be tomorrow, when I'll have some more show and tell stuff... (ie pics)

[ichitaka05]

Originally Posted by Dimman

Sway bar? Anti-roll bar! Anti-roll bar! Anti-roll bar! Grrrr... this is a HUGE PET PEEVE of mine. Not your fault as companies like Whiteline also incorrectly refer to their products as swaybars.

When talking about rotational motion and car suspension stuff there is NO 'sway'. Rotational motion is divided into Yaw (car spinning out), Pitch (nose dropping under braking), and Roll. Ask a pilot.

When talking about suspension geometry engineers talk about locating roll centers. Not sway centers.

Ok, rant's done.

As for Whiteline not being good, I didn't exactly say that. In fact I said I heard good things about their anti-roll bars. However the fabrication quality on their lateral links isn't anything to get excited about. They look like they're done in a hurry.

My next big post will be tomorrow, when I'll have some more show and tell stuff... (ie pics)

IC, I must mis-read it. My bad

Cool! Can't wait to read.

[70NYD]

Originally Posted by Dimman

Sway bar? Anti-roll bar! Anti-roll bar! Anti-roll bar! Grrrr... this is a HUGE PET PEEVE of mine. Not your fault as companies like Whiteline also incorrectly refer to their products as swaybars.

When talking about rotational motion and car suspension stuff there is NO 'sway'. Rotational motion is divided into Yaw (car spinning out), Pitch (nose dropping under braking), and Roll. Ask a pilot.

When talking about suspension geometry engineers talk about locating roll centers. Not sway centers.

Ok, rant's done.

As for Whiteline not being good, I didn't exactly say that. In fact I said I heard good things about their anti-roll bars. However the fabrication quality on their lateral links isn't anything to get excited about. They look like they're done in a hurry.

My next big post will be tomorrow, when I'll have some more show and tell stuff... (ie pics)

that we do :p never heard of a sway centre

whiteline doesnt make BAD products perse, they are good for the money, but overall they arent the best option out there. with fabricated parts, you allways get exactly what you pay for, even when paying for a majorly overpriced part, that part has been (usually) engineered and manifactured with close tolerances and will definately perform exactly how it is designed.

[Dimman]

Today I want to play a couple of kids' games with you guys. One is 'Show and Tell'. The other is 'Make believe' or 'Let's Pretend'.

First a look at the shop where I work.






Oooh... Two Haas CNC milling machines, two Haas CNC lathes. And an Okuma CNC lathe (best of the bunch). Now you guys are probably thinking 'Damn, it's going to be a piece of cake to make anything he wants!'

I wish, people. Let's wander over to my department...





CN-what? All manual here. Hell only one of the lathes has a digital readout. Secondly I'm limited to working only a bit before I officially start, through my breaks, and a bit after I clock out. And NO CNC time.

If I had just one of those CNC mills, I would have my own business making parts for Toyota and Subaru cars. But I don't.

Anyways back to the lateral link development.

Previously I covered basically just the bar linking the two bushings and shafts. Going to be 1" dia. solid 7075-T6 aluminum round bar. (Actually what I am looking for now is a source for 1.125" OD/.750" ID 7075-T6 extruded tube.)

Now we need the mechanism to attach the links to the body and hub, as well as make any adjustments in length. The chassis side attachement points appear to be a 12mm bolt and a 13mm bolt, from measuring the inner diameter of the shafts in the bushings (Ichi is this right? They're different?) The hub side is a single bolt that I haven't taken off yet that goes through both links. Either way I'm going to need something that I can get a 13mm bolt through. What I've decided on is the relatively simple and common racecar technique of using rod-ends (also called Rose or Heim joints) on the ends. These are basically a spherical bearing in a mount that has a threaded end. See pic.



(This one is a non-precision one from my work scrap bin. Not going on the finished product. This is basically just a mock-up for illustration.)

They are available in left and right hand threads so if the rod has one of each on the each end, the length between the centers of the bearings can be adjusted while they are attached to the vehicle. Turning one way with draw them together, opposite way push them apart. Then jam nuts are used to lock them in place. I'm going to be using 5/8 UNF RH and LH rod ends, simply because they are large and strong enough, and I have the taps for them.



This is also one reason why I'm going with 1" diameter bars, so there is enough material to tap into and keep it strong. So that is basically one of the links. 1" diameter aluminum bar with 5/8 NF tapped holes on each end RH and LH. Literally 5 minutes of work (for both of them) once I finalize the length I need.



I will also have to machine some spacers so the inner diameter is the appropiate size for the bolts, and to keep them centered in the mounting brackets (more than 5 minutes, stay tuned for that...)

I will be sourcing motorsports quality rod ends for the finished product, but so far it looks like OT on
the weekends too so I can't get to the bloody store...

[Dimman]

Part 2.

The second link is the tricky one. It needs a place for the anti-roll bar to attach to. How to do it? Well the steel ones are welded, so I could just figure out the thickness of alunminum I need and weld some aluminum ones on? Nope.

First I can't weld. However my buddy at work can.



Some aluminum welds he did.





Pretty nice, eh? So problem solved? Nope.

Firstly 7075-T6 is generally listed as being un-weldable. Doh! Maybe going back to the less expensive 6061-T6 will do it? Well 6061-T6 is considered a very weldable aluminum (what is welded in the pics). But there is a problem. The T6 part of the aluminum code is its heat-treat condition. In this case it is precipitation hardened and artificially aged. This is its strongest condition giving the previously mentioned 45000 psi tensile strength. When 6061 aluminum is welded IT IS NO LONGER CONSIDERED TO BE T6 heat treat. It loses a SIGNIFICANT amount of its strength. I honestly don't know how much, but if it is considered to be 'annealed' state at the weld, its new tensile strength would be only 18000psi! MUCH weaker.

It can be re-heat-treated after welding, but I don't have the facilities to do so, and am not interested in paying for it when there is an alternative.

Machined from billet. This is a pretty common solution and also allows me to continue on the path of using 7075-T6. What I will be doing is figuring out the dimensions I need and just cutting it out on the mill. I will also be boring the piece to accept a spherical bearing. The ends will be drilled and tapped for 5/8 UNF RH, a chrome-moly piece of hex stock will be turned and threaded to match on both sides, a couple of jam nuts and voila. End piece with tabs for anti-roll bars. Here is the final mock-up all assembled (and machined with a black sharpie!)...



And held upside down! Doh! STI ones have the tabs up. WRX and Legacies have them down with a 'C' shaped link wrapping around the bar.

The 'Let's Pretend' game comes in here. Pretend the rod-end is not some used POS, the rod is the right length, the anti-roll bar connector side is the right dimensions and fully machined, the 5/8 UNF redi-rod is actually the aforementioned chrome-moly hex mounting piece, everything's nicely finished, etc... and you get the idea of what's coming.

More to come...








Oops. How'd that get there? Heh. (turbo tattoo for the win!)