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Old 12-05-2018, 04:50 PM   #26
lockheed
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Quote:
Originally Posted by NSFW View Post
I salute you for taking on the challenge.

If it was me - and keep in mind I've never done this - I'd want to attach that jig to the chassis somehow, and probably attach the knuckle's steering link to the jig, and then re-measure everything about ten times just to be sure. Then put the pivot points on the chassis (and re-measure another ten times). Then the knuckle + pivots basically becomes a jig for the wishbones. Though I guess it might get crowded in there.
do this , im familiar with the auto robot jig repair system. you must keep accurate datum points and maybe create a measuring system.
I love your thread keep it up
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Old 12-05-2018, 05:47 PM   #27
Sharona
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Looks fast and expensive
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Old 12-09-2018, 05:48 AM   #28
JDwhiteWRX
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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.
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Old 12-16-2018, 06:59 AM   #29
JDwhiteWRX
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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.
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Old 12-18-2018, 07:50 AM   #30
Hardrvin
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Awesome project.

Look into the Griggs setups for Mustangs on SLA setups / conversions for strut cars. Some other companies make kits as well.

There was a NASA national winning FC RX7 with a super home brew double wishbone setup. There was some info out there on it.
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Old 12-18-2018, 11:43 AM   #31
JDMJNKY
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Sub'd this is awesome! Blessed to have such skill!
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Old 12-18-2018, 08:39 PM   #32
EastEndRaceshop
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What an incredible build! Can't wait to see more updates!
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Old 12-19-2018, 12:12 PM   #33
gills
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Keep up the great work!

Curious as to what your threshold was for too much camber gain in the rear and what is typically considered an ideal range/rate. I know this is highly setup dependent, but considering the similarity of production cars that most of us normal people race and the shrinking performance gap of 200TW "street tires" to race rubber, it'll be helpful.

The car I race (S14 240) is notorious for what many people say is excessive camber gain in compression in the rear.
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Old 12-20-2018, 04:21 AM   #34
JDwhiteWRX
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Quote:
Originally Posted by gills View Post
Keep up the great work!

Curious as to what your threshold was for too much camber gain in the rear and what is typically considered an ideal range/rate. I know this is highly setup dependent, but considering the similarity of production cars that most of us normal people race and the shrinking performance gap of 200TW "street tires" to race rubber, it'll be helpful.

The car I race (S14 240) is notorious for what many people say is excessive camber gain in compression in the rear.
Thanks,

I don't know the answer to what is considered ideal but I did some looking at published figures I found online for some sports cars considered to have good suspension. For example the miata has 0.91 degrees of camber gain for 1" of bump at the front suspension but I did not find anything about the rear suspension. Further reading suggested they should have more camber gain in the rear to aid traction on power down corner exit but I learnt this after writing my comments above in the previous post.

From my estimates the BRZ rear suspension has about 1.2 degrees of camber gain for 1" bump.
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Old 01-05-2019, 09:27 PM   #35
JDwhiteWRX
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Happy new year to you all.

Not a lot has been happening with the car with Christmas and all that but yesterday I did manage a full day of work on the front suspension.

After lots of back and forth on the design I finally came up with a method to attach the inner control arms to the chassis. Similar to the rear I wanted to be able to adjust the geometry as much as possible.

I started out with cutting up some 75mm x 50mm x 3mm rectangular box steel.



Then I cut out one face of the box. There are 8 in total which is enough to do upper and lower control arm mounts on both sides of the car.



Then I had to cut out 16 squares from 3mm sheet to box in the open faces.



I then tig welded them all and it took a really long time! I calculated after I had finished that I had welded 2.8m in length. Anyway it was really good practice and by the time I welded a couple my settings were dialed in perfectly and my welds were very consistent.



I also beveled both faces before welding for maximum penetration.



So this is the finished product before it gets welded into the chassis. The rod end is just an old one I had from my wrx to show how it works. I will be using one size smaller than this when I do my bulk order for all the control arms.



They will be mounted in the chassis with the bolt running vertical so the rod end is sitting horizontal. This will allow me to use spacers to position the rod end on the bolt at different heights to adjust the pivot height which changes control arm angles for camber gain and roll center.

Using the rod ends also allows me to adjust the length of the arms for static camber and caster adjustment.
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Old 01-09-2019, 02:14 PM   #36
WhiteZombie
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This is intense! Good luck with your build and have some fun ripping when it's done!
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Old 01-13-2019, 08:42 PM   #37
binny
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Coming along nicely Joel
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