584 replies to this topic

[Asymmetry]

Niceeeeee, Looks like you're not the only one that think 86 platform has locked up potential.

 

 

Nice photos. Would have loved to come out and give it a look.

Weird how a lot of the big hitters choose the 86 platform.

Same

[JDWhiteWRX]

It's a light weight RWD without being a convertible and has exceptionally good low drag body design from factory. It also has a very large engine bay meaning you could put almost any motor in it.

[Asymmetry]

Agreed its a great platform, except Subaru said they cant fit in a turbo but the community managed to with in V8s lol If they just made a turbo STI model they would of killed it.

[JDWhiteWRX]

Got a little done on the car today, I took some leave from work to do some painting on the exterior of our house but it won't stop raining so I'm working on the car instead

 

Today's job was to box the other chassis rail. I got it done reasonably quick since I had already done the other side and knew how to do it.

 

Here is how it looked before I started.

 

 

Here it is after I cut it back and made the patch panel. It was not as easy as the other side to cut because I had to hold my grinder upside-down so the flat edge was against the base plate. This meant it wanted to grab and was shooting sparks towards my face.

 

 

This photo shows how I got the inner edge so neat. Basically just left a small flap of metal that I could tap with a hammer to fold over the patch panel.

 

 

 

Here it is all done with a bit of a clean up and some weld through primer.

 

 

Final photo showing both main chassis rails completely boxed and ready to be joined to the rear suspension cradle.

 

 

If it rains again tomorrow I might get some more done on it

[Asymmetry]

Nice work there, clean!

[Barbbachello]

amazing as usual

[JDWhiteWRX]

So I have hit a bit of a milestone today and completed the majority of the fabrication on the rear end.

 

I started off by cutting and notching some tube to join the lower part to the boxed off chassis rails.

 

 

I love the way it looks from the wheel arch

 

 

With both sides done it was time to get started on the final two rear stays.

 

 

I didn't really take any more progress photos after that as I wanted to get all the welding done, clean it all up and give it a coat of cold gal. So here are some photos of the finished product.

 

 

 

 

 

I'm not sure what to work on next, if I make a start on the front end I really need to buy a motor and trans first and I don't really have the funds for that right now. What I might do is start working on the rear control arms so I can get the rear on sitting on some wheels.

 

I have some thinking to do.....

[Sven Smergberd]

I have Hardrace adjustable LCAs if you want them.

[El_Freddo]

Ooh two awesome pieces of kit - Joel’s artwork and Niko’s gear above.

Cheers

Bennie

[JDWhiteWRX]

I have Hardrace adjustable LCAs if you want them.

Thanks mate, I've just paid for my trip to Japan next year so don't really have any cash at the moment. How much did you want for them anyway?

[Sven Smergberd]

$350, or I could install them and give you my stock ones .

But would have thought you'd knock some up yourself.

[JDWhiteWRX]

$350, or I could install them and give you my stock ones .

But would have thought you'd knock some up yourself.

My initial plan was to build all the arms myself, just got to figure out where to buy that joint that is in the top control arm where it joins the knuckle. All the rest can be done with simple rod ends.

[JDWhiteWRX]

I have started on the control arms, just measured everything and thinking about what I need. Basically I want each arm to be adjustable and I want to remove all rubber bushings so all the joints are either rod ends or spherical bearings. I will modify some of the factory arms and possibly build some from scratch. I may buy some toe arms straight off the shelf.

 

 

In other news I was doing a bit of work on my WRX this weekend as I want to resume racing it next year after taking this year off. After my last race I took all the brake system apart, deleted the booster and ABS. Installed a dual master cylinder and balance bar with hydraulic handbrake.

I also removed the airbags and air conditioning which left a big mess of wires where my center console used to be, the car now weighs around 1210kg.

 

So today I made a small panel to house my engine oil temp gauge, water temp gauge, intercooler waterspray switch and adjustment dial for the balance bar which changes the brake bias. I also added a phone mount.

 

 

 

 

[JDWhiteWRX]

I took my WRX out today for a little skidpan racing. The new hydraulic handbrake is simply awesome!
 

 
Not much happening with the BRZ right now, I'm ready to order everything I need to build the rear control arms but I want to order the parts for the front as well to save on shipping. The problem is I am undecided on how I want to do the front, part of me wants to convert it to double wishbone so I'm looking into that and doing some reading.

[JDWhiteWRX]

Decided to jump in the deep end and convert the McPherson strut front suspension to a double wishbone. It's something I have been thinking about since I bought the shell but the whole idea seemed very daunting and information specific to a conversion was not really available. The only way was to focus my research on designing a double wishbone suspension from scratch and then adapt it to my car.
 
First step was finding some suitable uprights from a car with double wishbone as standard. I also wanted a car that uses the 5x114.3 pcd so that narrowed the choices down a fair bit.
 
Obvious candidates are Honda S2k, Mazda MX5 and RX8. The RX8 is very similar in dimension to the BRZ and the parts are easily available since their motors keep failing.
 
So I picked up a pair of RX8 uprights for $200 complete with wheel bearings and tie rods.
 

 
It would have been nice to buy the entire RX8 front suspension including the subframe as it all comes as one piece and I could have potentially just made a jig of it and grafted it to the front of my car. Unfortunately I could not find one for a reasonable price but the guy I bought the uprights off was kind enough to let me measure all the factory control arms.
 
Next step was to make a jig to position an upright in the correct position in space that it would sit if it were mounted to a 18x11" wheel with a 295/35/18 tyre on it.
 

 
With the upright in the jig I was then able to accurately measure the ball joint and steering arm locations, these are your "fixed" points that you can not alter. The arm lengths, angles and points at which they attach to the chassis are all the points you have freedom the play with.
 

 
I spent the majority of Saturday night and most of today measuring everything and plugging the numbers into some software I got off the Locost forums. I have tried to stay as close to as possible the Mazda RX8 geometry as it is considered to be very good. The software takes a bit to get used to but basically it just plots everything in X,Y,Z coordinates and allows you to see what the camber and roll center is doing in bump and roll or both.
 
I then lowered the shell back to its planned "lowest" ride height and positioned the jig inside the front wheel well such that the face of the wheel bearing is in the same position as it would be on a stock BRZ.
 

 
Now I was able to take my arm lengths and angles and see where the inner pivot points would land on the chassis. The RX8 has longer arms than the BRZ since the engine bay is not as wide so the stock RX8 arm lengths would require major surgery to fit to the BRZ.
 
I then went back to the computer with my shorter or more appropriate arm lengths as measured to see what effect shorter arms would have on the geometry. The results were good, I am seeing a 1.4 degree gain in camber with 2 degrees of roll. With 1" of bump I am gaining 0.5 degree of neg camber and combining both I am seeing 1 degree positive camber. Roll center migration is very minimal at less than 1 degree under 2 degrees of roll. The results are actually very similar to the stock RX8 arm lengths once you change the angles around to suit the shorter arms.
 
I have not yet factored in the steering other than doing my "fixed point" measurements with 7 degrees of positive caster in the upright. Ideal positioning the steering rack is not too difficult to work out however there is the chance of something being in the way of the ideal position and then I have to get creative.

[El_Freddo]

Well that stepped up a notch!

All the best with it. Builds like this where you have to research, think and get creative is what I like the best. I hope you’re enjoying the build as you go too.

Cheers

Bennie

[JDWhiteWRX]

I spent the afternoon measuring all the pivot points in the rear suspension so I could enter them into my software and see how it compares to what I have designed for the front.

 

 

The car is super low in this photo but you wouldn't know it from the angles on the control arms. This is at my lowest possible setting but I found the roll center and camber gains where much better with the car raised about 20mm from this position. Actually the camber gain numbers almost mirrored my front design but the roll center was slightly lower.

[JDWhiteWRX]

So I did all my measurements of the rear suspension to see what the camber is doing in roll, bump or both which is basically what happens in a corner.

 

With the car sitting at my lowest ride height it was giving a fair amount of camber gain in bump which is probably not ideal. What I found though was that at this low ride height which is like super low (90mm to the pinch welds under the sills) is that my drive shaft angles for the diff would be a little extreme and maybe at risk of fouling on the frame.

 

Luckily I built the diff mounts with the ability to raise the diff 25mm if needed. So with the diff raised and the ride height lifted about 20mm everything was looking perfect again.

 

This is an old photo to show how removing one spacer allows me to raise the diff.

 

 

at the rear mounts it simply moves up one hole.

 

 

So here it is with the slightly lifted rear ride height and the mock up drive shaft showing zero degrees at the position it would be in with the diff lifted.

 

 

With the new ride height I re-measured the inner pivot positions and put them in my software. The camber gain is now much better.

 

Moving to the front of the car now.

 

I have been going round in circles with my suspension design for many weeks but I am now at a point where I think I am happy enough to start with the fabrication side of things. I will build enough adjustability into it anyway so I can fine tune it later. Similar to how I did the rear end.

 

Today I measured where my tyres would be sitting and begun removing metal that would foul on the tyres. Under the rules I must retain the strut towers but I am free to remove material for tyre clearance.

 

In this photo you can see black dotted marks where the tyres would hit on the left of this line. 

Note everything in front of the strut towers will come off at a later date and be replaced with tube but I need to keep it for now so I can mount the standard panels and make fiberglass molds.

 

 

After lots of cutting and drilling of spot welds.

 

 

Side view.

 

 

With that gone it will be much easier to work on as I make the new control arm mounts. The plan is to run tube from the roll cage up to the strut towers and back down to the main chassis rails to triangulate everything.

 

This will also help with venting the wheel wells for better aero. I will be doing a bit more trimming around that area to create some smooth transitions for air to escape.

[Barbbachello]

This is amazing

[El_Freddo]

This is amazing

Too right! Many would’ve given up or got a stock vehicle to make the best combo for intended purpose from the available off the shelf parts.

Keep on going, I don’t recall you wanting to torch the whole thing so you must be doing something really right!!

Cheers

Bennie